Endangered and Threatened Wildlife and Plants; Endangered Species Status With Critical Habitat for Texas Heelsplitter, and Threatened Status With Section 4(d) Rule and Critical Habitat for Louisiana Pigtoe, 16776-16832 [2023-05107]
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Federal Register / Vol. 88, No. 53 / Monday, March 20, 2023 / Proposed Rules
DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS–R2–ES–2022–0026;
FF09E21000 FXES1111090FEDR 234]
RIN 1018–BE46
Endangered and Threatened Wildlife
and Plants; Endangered Species
Status With Critical Habitat for Texas
Heelsplitter, and Threatened Status
With Section 4(d) Rule and Critical
Habitat for Louisiana Pigtoe
Fish and Wildlife Service,
Interior.
ACTION: Proposed rule.
AGENCY:
We, the U.S. Fish and
Wildlife Service (Service), propose to
list the Texas heelsplitter (Potamilus
amphichaenus) as an endangered
species and the Louisiana pigtoe
(Pleurobema riddellii) as a threatened
species under the Endangered Species
Act of 1973, as amended (Act). Both
species are freshwater mussels. This
document serves as our 12-month
finding on a petition to list the Texas
heelsplitter and Louisiana pigtoe. For
the Louisiana pigtoe, we also propose a
rule issued under section 4(d) of the Act
(a ‘‘4(d) rule’’) to provide for the
conservation of the species. In addition,
we propose to designate critical habitat
for the Texas heelsplitter and Louisiana
pigtoe under the Act. In total,
approximately 831.8 river miles (1,338.6
river kilometers) in 31 counties in Texas
fall within the boundaries of the
proposed critical habitat designation for
the Texas heelsplitter, and
approximately 1,028.2 river miles
(1,654.3 river kilometers) in 3 counties
in Arkansas, 6 parishes in Louisiana, 2
counties in Mississippi, 1 county in
Oklahoma, and 21 counties in Texas fall
within the boundaries of the proposed
critical habitat designation for the
Louisiana pigtoe. We announce the
availability of a draft economic analysis
of the proposed designation of critical
habitat for the Texas heelsplitter and
Louisiana pigtoe. Finally, we announce
an informational meeting followed by a
public hearing on this proposed rule. If
we finalize this rule as proposed, it
would extend the Act’s protections to
these species and their critical habitats.
DATES: We will accept comments
received or postmarked on or before
May 19, 2023. Comments submitted
electronically using the Federal
eRulemaking Portal (see ADDRESSES,
below) must be received by 11:59 p.m.
eastern time on the closing date.
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SUMMARY:
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Public informational meeting and
public hearing: We will hold a public
informational session from 5 p.m. to 6
p.m., central time, followed by a public
hearing from 6:30 p.m. to 8 p.m., central
time, on May 2, 2023.
ADDRESSES: You may submit comments
by one of the following methods:
(1) Electronically: Go to the Federal
eRulemaking Portal: https://
www.regulations.gov. In the Search box,
enter FWS–R2–ES–2022–0026, which is
the docket number for this rulemaking.
Then, click on the Search button. On the
resulting page, in the panel on the left
side of the screen, under the Document
Type heading, check the Proposed Rule
box to locate this document. You may
submit a comment by clicking on
‘‘Comment.’’
(2) By hard copy: Submit by U.S. mail
to: Public Comments Processing, Attn:
FWS–R2–ES–2022–0026, U.S. Fish and
Wildlife Service, MS: PRB/3W, 5275
Leesburg Pike, Falls Church, VA 22041–
3803.
We request that you send comments
only by the methods described above.
We will post all comments on https://
www.regulations.gov. This generally
means that we will post any personal
information you provide us (see
Information Requested, below, for more
information).
Availability of supporting materials:
For the proposed critical habitat
designation, the coordinates or plot
points or both from which the maps are
generated are included in the decision
file and are available at https://
www.fws.gov/southwest/es/
arlingtontexas/, at https://
www.regulations.gov under Docket No.
FWS–R2–ES–2022–0026, and at the
Arlington Ecological Services Field
Office (see FOR FURTHER INFORMATION
CONTACT). Additional supporting
information that we developed for this
critical habitat designation will be
available on the Service’s website, at
https://www.regulations.gov, or both.
Public informational meeting and
public hearing: The public
informational meeting and the public
hearing will be held virtually using the
Zoom online video platform and via
teleconference. See Public Hearing,
below, for more information.
FOR FURTHER INFORMATION CONTACT:
Debra Bills, Field Supervisor, U.S. Fish
and Wildlife Service, Arlington
Ecological Services Field Office, 501
West Felix Street, Suite 1105, Fort
Worth, Texas 76115; telephone 817–
277–1100. Individuals in the United
States who are deaf, deafblind, hard of
hearing, or have a speech disability may
dial 711 (TTY, TDD, or TeleBraille) to
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access telecommunications relay
services. Individuals outside the United
States should use the relay services
offered within their country to make
international calls to the point-ofcontact in the United States.
SUPPLEMENTARY INFORMATION:
Executive Summary
Why we need to publish a rule. Under
the Act, a species warrants listing if it
meets the definition of an endangered
species (in danger of extinction
throughout all or a significant portion of
its range) or a threatened species (likely
to become endangered within the
foreseeable future throughout all or a
significant portion of its range). If we
determine that a species warrants
listing, we must list the species
promptly and designate the species’
critical habitat to the maximum extent
prudent and determinable. We have
determined that the Texas heelsplitter
meets the definition of an endangered
species and that the Louisiana pigtoe
meets the definition of a threatened
species; therefore, we are proposing to
list them as such and proposing a
designation of critical habitat for both
species. Both listing a species as an
endangered or threatened species and
designating critical habitat can be
completed only by issuing a rule
through the Administrative Procedure
Act rulemaking process.
What this document does. We
propose to list the Texas heelsplitter as
an endangered species and to list the
Louisiana pigtoe as a threatened species
with a 4(d) rule. We also propose to
designate critical habitat for both
species.
The basis for our action. Under the
Act, we may determine that a species is
an endangered or threatened species
because of any of five factors: (A) The
present or threatened destruction,
modification, or curtailment of its
habitat or range; (B) overutilization for
commercial, recreational, scientific, or
educational purposes; (C) disease or
predation; (D) the inadequacy of
existing regulatory mechanisms; or (E)
other natural or manmade factors
affecting its continued existence. We
have determined that habitat loss
through changes in water quality, the
gradual accumulation of additional
layers of fine sediments, and altered
hydrology (Factor A) are the primary
threats to these species, all of which are
exacerbated by the ongoing and
expected future effects of climate
change (Factor E). Additionally,
predation (Factor C) and collection
(Factor B), as well as other natural or
human-induced events/activities that
result in direct mortality, are also
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affecting those populations already
experiencing low stream flow, and
reservoirs and other instream barriers to
fish movement (Factor E) that limit
dispersal and prevent recolonization
after stochastic events.
Section 4(a)(3) of the Act requires the
Secretary of the Interior (Secretary) to
designate critical habitat concurrent
with listing to the maximum extent
prudent and determinable. Section
3(5)(A) of the Act defines critical habitat
as (i) the specific areas within the
geographical area occupied by the
species, at the time it is listed, on which
are found those physical or biological
features (I) essential to the conservation
of the species and (II) which may
require special management
considerations or protections; and (ii)
specific areas outside the geographical
area occupied by the species at the time
it is listed, upon a determination by the
Secretary that such areas are essential
for the conservation of the species.
Section 4(b)(2) of the Act states that the
Secretary must make the designation on
the basis of the best scientific data
available and after taking into
consideration the economic impact, the
impact on national security, and any
other relevant impacts of specifying any
particular area as critical habitat.
Information Requested
We intend that any final action
resulting from this proposed rule will be
based on the best scientific and
commercial data available and be as
accurate and as effective as possible.
Therefore, we request comments or
information from other governmental
agencies, Native American Tribes, the
scientific community, industry, or any
other interested parties concerning this
proposed rule. We particularly seek
comments concerning:
(1) The species’ biology, range, and
population trends, including:
(a) Biological or ecological
requirements of the species, including
habitat requirements for feeding,
breeding, and sheltering;
(b) Genetics and taxonomy;
(c) Historical and current ranges,
including distribution patterns and the
locations of any additional populations
of these species;
(d) Historical and current population
levels, and current and projected trends;
and
(e) Past and ongoing conservation
measures for the species, their habitats,
or both.
(2) Threats and conservation actions
affecting these species, including:
(a) Factors that may affect the
continued existence of the species,
which may include habitat modification
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or destruction, overutilization, disease,
predation, the inadequacy of existing
regulatory mechanisms, or other natural
or manmade factors.
(b) Biological, commercial trade, or
other relevant data concerning any
threats (or lack thereof) to these species.
(c) Existing regulations or
conservation actions that may be
addressing threats to these species.
(3) Additional information concerning
the historical and current status of these
species.
(4) Information on regulations that are
necessary and advisable to provide for
the conservation of the Louisiana pigtoe
and that we can consider in developing
a 4(d) rule for the species. We
particularly seek information
concerning the extent to which we
should include any of the section 9
prohibitions in the 4(d) rule or whether
we should consider any additional
exceptions from the prohibitions in the
4(d) rule.
(5) Specific information on:
(a) The amount and distribution of
Texas heelsplitter and Louisiana pigtoe
habitat;
(b) Any additional areas occurring
within the range of the Louisiana pigtoe,
i.e., Howard, Little River, and Sevier
Counties, Arkansas; Allen, Beauregard,
Rapides, St. Tammany, Vernon, and
Washington parishes, Louisiana; Marion
and Pearl River Counties, Mississippi;
McCurtain County, Oklahoma; and
Anderson, Angelina, Cherokee, Gregg,
Hardin, Harrison, Houston, Jasper,
Jefferson, Liberty, Montgomery,
Nacogdoches, Orange, Panola, Polk,
Rusk, Smith, Trinity, Tyler, Upshur, and
Wood Counties, Texas, and Texas
heelsplitter, i.e., Anderson, Angelina,
Cherokee, Ellis, Freestone, Gregg,
Grimes, Hardin, Harrison, Henderson,
Houston, Jasper, Jefferson, Kaufman,
Leon, Madison, Navarro, Orange,
Panola, Polk, Rains, Rusk, Sabine,
Shelby, Smith, Trinity, Tyler, Upshur,
Van Zandt, Walker, and Wood Counties,
Texas, that should be included in the
designation because they (i) are
occupied at the time of listing and
contain the physical or biological
features that are essential to the
conservation of the species and that may
require special management
considerations, or (ii) are unoccupied at
the time of listing and are essential for
the conservation of the species; and
(c) Special management
considerations or protection that may be
needed in critical habitat areas we are
proposing, including managing for the
potential effects of climate change; and
(d) To evaluate the potential to
include areas not occupied at the time
of listing, we particularly seek
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comments regarding whether occupied
areas are adequate for the conservation
of the species. Additionally, please
provide specific information regarding
whether or not unoccupied areas would,
with reasonable certainty, contribute to
the conservation of the species and
contain at least one physical or
biological feature essential to the
conservation of the species. We also
seek comments or information regarding
whether areas not occupied at the time
of listing qualify as ‘‘habitat’’ for the
species.
(7) Land use designations and current
or planned activities in the subject areas
and their possible impacts on proposed
critical habitat.
(8) Any probable economic, national
security, or other relevant impacts of
designating any area that may be
included in the final designation, and
the related benefits of including or
excluding specific areas.
(9) Information on the extent to which
the description of probable economic
impacts in the draft economic analysis
is a reasonable estimate of the likely
economic impacts and any additional
information regarding probable
economic impacts that we should
consider.
(10) Whether any specific areas we are
proposing for critical habitat
designation should be considered for
exclusion under section 4(b)(2) of the
Act, and whether the benefits of
potentially excluding any specific area
outweigh the benefits of including that
area under section 4(b)(2) of the Act. If
you think we should exclude any
additional areas, please provide
information supporting a benefit of
exclusion.
(11) Whether we could improve or
modify our approach to designating
critical habitat in any way to provide for
greater public participation and
understanding, or to better
accommodate public concerns and
comments.
Please include sufficient information
with your submission (such as scientific
journal articles or other publications) to
allow us to verify any scientific or
commercial information you include.
Please note that submissions merely
stating support for, or opposition to, the
action under consideration without
providing supporting information,
although noted, do not provide
substantial information necessary to
support a determination. Section
4(b)(1)(A) of the Act directs that
determinations as to whether any
species is an endangered or a threatened
species must be made solely on the
basis of the best scientific and
commercial data available and section
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4(b)(2) of the Act directs that the
Secretary shall designate critical habitat
on the basis of the best scientific
information available.
You may submit your comments and
materials concerning this proposed rule
by one of the methods listed in
ADDRESSES. We request that you send
comments only by the methods
described in ADDRESSES.
If you submit information via https://
www.regulations.gov, your entire
submission—including any personal
identifying information—will be posted
on the website. If your submission is
made via a hardcopy that includes
personal identifying information, you
may request at the top of your document
that we withhold this information from
public review. However, we cannot
guarantee that we will be able to do so.
We will post all hardcopy submissions
on https://www.regulations.gov.
Comments and materials we receive,
as well as supporting documentation we
used in preparing this proposed rule,
will be available for public inspection
on https://www.regulations.gov.
Because we will consider all
comments and information we receive
during the comment period, our final
determinations may differ from this
proposal. Based on the new information
we receive (and any comments on that
new information), we may conclude that
Texas heelsplitter is threatened instead
of endangered or that Louisiana pigtoe
is endangered instead of threatened, or
we may conclude that one or both
species do not warrant listing as either
an endangered species or a threatened
species. For critical habitat, our final
designations may not include all areas
proposed, may include some additional
areas that meet the definition of critical
habitat, or may exclude some areas if we
find the benefits of exclusion outweigh
the benefits of inclusion. In addition, we
may change the parameters of the
prohibitions or the exceptions to those
prohibitions in the 4(d) rule if we
conclude it is appropriate in light of
comments and new information we
receive. For example, we may expand
the prohibitions to include prohibiting
additional activities if we conclude that
those additional activities are not
compatible with conservation of the
species. Conversely, we may establish
additional exceptions to the
prohibitions in the final rule if we
conclude that the activities would
facilitate or are compatible with the
conservation and recovery of the
species.
Public Hearing
We have scheduled a public
informational meeting and public
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hearing on this proposed rule. We will
hold the public informational meeting
and public hearing on the date and at
the times provided above under Public
informational meeting and public
hearing in DATES. We are holding the
public informational meeting and public
hearing via the Zoom online video
platform and via teleconference so that
participants can attend remotely. For
security purposes, registration is
required. You must register in order to
listen and view the meeting and hearing
via Zoom, listen to the meeting and
hearing by telephone, or provide oral
public comments at the public hearing
by Zoom or telephone. For information
on how to register, or if you encounter
problems joining Zoom the day of the
meeting, visit https://www.fws.gov/
office/arlington-ecological-services.
Registrants will receive the Zoom link
and the telephone number for the public
informational meeting and public
hearing. If applicable, interested
members of the public not familiar with
the Zoom platform should view the
Zoom video tutorials (https://
support.zoom.us/hc/en-us/articles/
206618765-Zoom-video-tutorials) prior
to the public informational meeting and
public hearing.
The public hearing will provide
interested parties an opportunity to
present verbal testimony (formal, oral
comments) regarding this proposed rule.
The public informational meeting will
be an opportunity for dialogue with the
Service. The public hearing is a forum
for accepting formal verbal testimony. In
the event there is a large attendance, the
time allotted for oral statements may be
limited. Therefore, anyone wishing to
make an oral statement at the public
hearing for the record is encouraged to
provide a prepared written copy of their
statement to us through the Federal
eRulemaking Portal, or U.S. mail (see
ADDRESSES, above). There are no limits
on the length of written comments
submitted to us. Anyone wishing to
make an oral statement at the public
hearing must register before the hearing
(https://www.fws.gov/office/arlingtonecological-services). The use of a virtual
public hearing is consistent with our
regulations at 50 CFR 424.16(c)(3).
Previous Federal Actions
The Texas heelsplitter was identified
as a category 2 candidate species on
January 6, 1989 (54 FR 554). The
category 2 designation was assigned to
taxa for which information indicated
that proposing to list as endangered or
threatened was possibly warranted, but
for which conclusive data on biological
vulnerability and threats were not
currently available to support proposed
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rules. The species remained so
designated in subsequent candidate
notices of review (CNORs) (56 FR
58804, November 21, 1991; 59 FR
58982, November 15, 1994). In the
February 28, 1996, CNOR (61 FR 7596),
we discontinued the designation of
category 2 species as candidates;
therefore, with the publication of that
CNOR, the Texas heelsplitter was no
longer a candidate species.
On June 25, 2007, we were petitioned
to list both the Texas heelsplitter and
Louisiana pigtoe. We published a
substantial 90-day finding for Texas
heelsplitter on December 15, 2009 (74
FR 66260), and for Louisiana pigtoe on
December 16, 2009 (74 FR 66866).
This document constitutes our 12month warranted petition finding, our
proposed listing rule, and our proposed
critical habitat rule for the Texas
heelsplitter and Louisiana pigtoe.
Supporting Documents
A species status assessment (SSA)
team prepared an SSA report for the
Texas heelsplitter and Louisiana pigtoe.
The SSA team was composed of Service
biologists, in consultation with other
species experts. The SSA report
represents a compilation of the best
scientific and commercial data available
concerning the status of the species,
including the impacts of past, present,
and future factors (both negative and
beneficial) affecting the species. In
accordance with our joint policy on peer
review published in the Federal
Register on July 1, 1994 (59 FR 34270),
and our August 22, 2016, memorandum
updating and clarifying the role of peer
review of listing actions under the Act,
we sought the expert opinions of 11
appropriate specialists regarding the
SSA. We received 6 responses.
I. Proposed Listing Determination
Background
General Mussel Biology
A thorough review of the taxonomy,
life history, and ecology of the Texas
heelsplitter and Louisiana pigtoe is
presented in the SSA report (USFWS
2022, entire), and briefly summarized
here.
Freshwater mussels, including the
Texas heelsplitter and Louisiana pigtoe,
have a complex life history involving
parasitic larvae, called glochidia, which
are wholly dependent on host fish. As
freshwater mussels are generally sessile
(immobile), dispersal is accomplished
primarily through the behavior of host
fish and their tendencies to travel
upstream and against the current in
rivers and streams. Mussels are
broadcast spawners; males release
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sperm into the water column, which is
taken in by the female through the
incurrent aperture (the tubular structure
used to draw water into the body of the
mussel). The developing larvae remain
with the female until they mature and
are ready for release as glochidia, to
attach on the gills, head, or fins of fishes
(Vaughn and Taylor 1999, p. 913;
Barnhart et al. 2008, pp. 371–373).
Glochidia die if they fail to find a host
fish, attach to the wrong species of host
fish, attach to a fish that has developed
immunity from prior infestations, or
attach to the wrong location on a host
fish (Neves 1991, p. 254; Bogan 1993, p.
599). Successful glochidia encyst
(enclose in a cyst-like structure) on the
host’s tissue, draw nutrients from the
fish, and develop into juvenile mussels
(Arey 1932, pp. 214–215). The glochidia
will remain encysted for about a month
through a transformation to the juvenile
stage. Once transformed, the juveniles
will excyst from the fish and drop to the
substrate.
Freshwater mussel species vary in
both onset and duration of spawning,
how long developing larvae are held in
the marsupial gill chambers (gills used
for holding eggs and glochidia), and
which fish species serve as hosts. The
mechanisms employed by mussel
species to increase the likelihood of
interaction between host fish and
glochidia vary by species.
Mussels are generally immobile; their
primary opportunity for dispersal and
movement within the stream comes
when glochidia attach to a mobile host
fish (Smith 1985, p. 105). Upon release
from the host, newly transformed
juveniles drop to the substrate on the
bottom of the stream. Those juveniles
that drop in unsuitable substrates die
because their immobility prevents them
from relocating to more favorable
habitat. Juvenile freshwater mussels
burrow into interstitial substrates and
grow to a larger size that is less
susceptible to predation and
displacement from high-flow events
(Yeager et al. 1994, p. 220). Adult
mussels typically remain within the
same general location where they
dropped off (excysted) from their host
fish as juveniles.
Host specificity can vary across
mussel species, which may have
specialized or generalized relationships
with one or more taxa of fish. Mussels
have evolved a wide variety of
adaptations to facilitate transmission of
glochidia to host fish, including mantle
displays (lures) mimicking fish or
invertebrates; packages of glochidia
(conglutinates) that mimic worms,
insect larvae, larval fish, or fish eggs;
and release of glochidia in mucous webs
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that entangle fish (Strayer et al. 2004, p.
431). Polymorphism (existence of
multiple forms) of mantle lures and
conglutinates frequently exists within
mussel populations (Barnhart et al.
2008, p. 383), representing important
adaptive capacity in terms of genetic
diversity and ecological representation.
Texas Heelsplitter
The Texas heelsplitter was first
described as the species Unio
amphichaenus by Frierson (1898, p.
109) from the Sabine River near
Logansport, Louisiana. The current
recognized scientific name for Texas
heelsplitter is Potamilus amphichaenus
(Williams et al. 2017a, pp. 35, 42). The
Texas heelsplitter is a medium- to largesized freshwater mussel (up to 177
millimeters (mm) (7 inches (in)) shell
length) that has a tan to brown or black
elliptical shell, with lighter coloration
on the beaks, and a relatively straight
hinge line. Texas heelsplitters exhibit
slight sexual dimorphism; females have
a broadly rounded posterior margin and
males are more pointed (Howells 2010b,
p. 2). The base of the anterior margin
exhibits a long, narrow gape, while a
shorter, much wider gape is located
along the posterior margin, presumably
to accommodate the incurrent and
excurrent apertures (Neck and Howells
1995, p. 4).
Although information specific to
Texas heelsplitter reproduction is
unavailable, other species from the tribe
Lampsilini release glochidia in packets,
called conglutinates, and are known to
use mantle lures to attract sight feeding
fishes that attack and rupture the
marsupium, thereby becoming infested
by glochidia (Barnhart et al. 2008, pp.
377, 380). Related species are long-term
brooders (bradytictic), spawning and
becoming gravid in the fall and
releasing glochidia in the spring
(Barnhart et al. 2008, p. 384).
Freshwater drum (Aplodinotus
grunniens) have been confirmed as host
fish for the Texas heelsplitter (Bosman
et al. 2015, p. 15).
A related freshwater mussel species,
bleufer (Potamilus purpuratus), from the
southeastern United States was reported
to reach a maximum age of 9–26 years,
and other related species ranged from 4–
50 years with a higher growth rate
compared to other species (Haag and
Rypel 2011, pp. 229, 234, 239). The
Texas heelsplitter has been reported
mature at approximately 60 mm (2.4 in)
(Ford et al. 2016, p. 31).
Texas heelsplitters occur in streams
and rivers of the Trinity, Neches, and
Sabine drainages in east Texas and in
the Sabine River at the western border
of Louisiana on substrates consisting of
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‘‘firm mud, sand, or finer gravels
bottoms, in still to moderate flows’’ and
sometimes associated with fallen timber
(Howells 2014, p. 69; Howells 2010b, p.
3 and table 2.3). Additionally, Texas
heelsplitters can tolerate manmade
impoundments and have been found in
several East Texas reservoirs (Howells
2010b, p. 3).
Louisiana Pigtoe
The Louisiana pigtoe was originally
described as the species Unio riddellii
(Lea 1862, p. 228) from the Trinity River
near the City of Dallas, Dallas County,
Texas. The current recognized scientific
name for Louisiana pigtoe is
Pleurobema riddellii (Williams et al.
2017a, pp. 35, 42). The Louisiana pigtoe
is a medium-sized freshwater mussel
(shell lengths to greater than 62 mm (2.4
in)) with a brown to black, triangular to
subquadrate shell without external
sculpturing, sometimes with greenish
rays. For a detailed description, see
Howells et al. 1996 (pp. 91–92) and
Howells 2014 (p. 65). Other native
mussel species (e.g., pimpleback
(Cyclonaias pustulosa), Texas pigtoe
(Fusconaia askewi), Trinity pigtoe (F.
chunii), and Wabash pigtoe (F. flava))
can easily be mistaken for Louisiana
pigtoe when identified by shell
morphology alone.
Louisiana pigtoe are bradytictic (i.e.,
long-term brooders; spawning occurs
during the summer, and glochidia are
held by the female over winter and
released the following spring); however,
gravid females have been observed in
July (Marshall 2014, pp. 46–47). A
closely related congener, the rough
pigtoe (Pleurobema plenum), is known
to utilize the tachytictic reproductive
cycle (i.e., short-term brooders;
fertilization occurs in the spring, and
glochidia are expelled during the
summer or early fall) (EPA 2007, p. 37).
The primary host fish for Louisiana
pigtoe has not been confirmed. Bullhead
minnow (Pimephales vigilax), blacktail
shiner (Cyprinella venusta), and red
shiner (Cyprinella lutrensis) have been
suggested as potential fish hosts based
on a fish host distribution modeling
effort (Marshall 2014, pp. 59–60).
A single juvenile Louisiana pigtoe
from the Neches River, Texas, was
reported to grow 15 mm (0.6 in) during
its first year from an initial shell length
of 2 mm (0.08 in) (Ford et al. 2016, p.
30). Sexual maturity is achieved at shell
lengths around 40 mm (1.6 in) (Ford et
al. 2016, pp. 28, 30), and Louisiana
pigtoe could reach maturity in 3 to 4
years. Based on egg production, sexually
mature females were estimated by
external annuli to be between 4 and 12
years of age with shell lengths ranging
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from 29–59 mm (1.1–2.3 in) (Hinkle
2018, p. 19).
Louisiana pigtoes occur in mediumto large-sized streams throughout
portions of east Texas, Louisiana, west
Mississippi, southeast Oklahoma, and
southwest Arkansas (Vidrine 1993, p.
66; Howells et al. 1997, p. 22; Randklev
et al. 2013, p. 269; Randklev 2018,
entire) in flowing waters (0.3–1.4 meters
per second (m/s)) over substrates of
cobble and rock or sand, gravel, cobble,
and woody debris; they are often
associated with riffle, run, and
sometimes larger backwater tributary
habitats (Ford et al. 2016, pp. 42, 52;
Howells 2010a, pp. 3–4; Williams et al.
2017b, p. 21). Specimens are typically
found in shallower waters (0.1–1.2 m
(0.3–3.9 feet (ft) in depth; Howells
2010a, p. 3)); however, recent surveys
found Louisiana pigtoe as deep as 3.33
m (10.9 ft) in the lower Neches River
(Corbett 2020, pp. 2, 4).
Regulatory and Analytical Framework
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Regulatory Framework
Section 4 of the Act (16 U.S.C. 1533)
and the implementing regulations in
title 50 of the Code of Federal
Regulations set forth the procedures for
determining whether a species is an
endangered species or a threatened
species, issuing protective regulations
for threatened species, and designating
critical habitat for endangered and
threatened species. In 2019, jointly with
the National Marine Fisheries Service,
the Service issued a final rule that
revised the regulations in 50 CFR part
424 regarding how we add, remove, and
reclassify endangered and threatened
species and the criteria for designating
listed species’ critical habitat (84 FR
45020; August 27, 2019). On the same
day, the Service also issued final
regulations that, for species listed as
threatened species after September 26,
2019, eliminated the Service’s general
protective regulations automatically
applying to threatened species the
prohibitions that section 9 of the Act
applies to endangered species (84 FR
44753; August 27, 2019).
The Act defines an ‘‘endangered
species’’ as a species that is in danger
of extinction throughout all or a
significant portion of its range, and a
‘‘threatened species’’ as a species that is
likely to become an endangered species
within the foreseeable future throughout
all or a significant portion of its range.
The Act requires that we determine
whether any species is an endangered
species or a threatened species because
of any of the following factors:
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(A) The present or threatened
destruction, modification, or
curtailment of its habitat or range;
(B) Overutilization for commercial,
recreational, scientific, or educational
purposes;
(C) Disease or predation;
(D) The inadequacy of existing
regulatory mechanisms; or
(E) Other natural or manmade factors
affecting its continued existence.
These factors represent broad
categories of natural or human-caused
actions or conditions that could have an
effect on a species’ continued existence.
In evaluating these actions and
conditions, we look for those that may
have a negative effect on individuals of
the species, as well as other actions or
conditions that may ameliorate any
negative effects or may have positive
effects.
We use the term ‘‘threat’’ to refer in
general to actions or conditions that are
known to or are reasonably likely to
negatively affect individuals of a
species. The term ‘‘threat’’ includes
actions or conditions that have a direct
impact on individuals (direct impacts),
as well as those that affect individuals
through alteration of their habitat or
required resources (stressors). The term
‘‘threat’’ may encompass—either
together or separately—the source of the
action or condition or the action or
condition itself.
However, the mere identification of
any threat(s) does not necessarily mean
that the species meets the statutory
definition of an ‘‘endangered species’’ or
a ‘‘threatened species.’’ In determining
whether a species meets either
definition, we must evaluate all
identified threats by considering the
expected response by the species, and
the effects of the threats—in light of
those actions and conditions that will
ameliorate the threats—on an
individual, population, and species
level. We evaluate each threat and its
expected effects on the species, then
analyze the cumulative effect of all of
the threats on the species as a whole.
We also consider the cumulative effect
of the threats in light of those actions
and conditions that will have positive
effects on the species, such as any
existing regulatory mechanisms or
conservation efforts. The Secretary
determines whether the species meets
the definition of an ‘‘endangered
species’’ or a ‘‘threatened species’’ only
after conducting this cumulative
analysis and describing the expected
effect on the species now and in the
foreseeable future.
The Act does not define the term
‘‘foreseeable future,’’ which appears in
the statutory definition of ‘‘threatened
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species.’’ Our implementing regulations
at 50 CFR 424.11(d) set forth a
framework for evaluating the foreseeable
future on a case-by-case basis. The term
‘‘foreseeable future’’ extends only so far
into the future as the Services can
reasonably determine that both the
future threats and the species’ responses
to those threats are likely. In other
words, the foreseeable future is the
period of time in which we can make
reliable predictions. ‘‘Reliable’’ does not
mean ‘‘certain’’; it means sufficient to
provide a reasonable degree of
confidence in the prediction. Thus, a
prediction is reliable if it is reasonable
to depend on it when making decisions.
It is not always possible or necessary
to define foreseeable future as a
particular number of years. Analysis of
the foreseeable future uses the best
scientific and commercial data available
and should consider the timeframes
applicable to the relevant threats and to
the species’ likely responses to those
threats in view of its life-history
characteristics. Data that are typically
relevant to assessing the species’
biological response include speciesspecific factors such as lifespan,
reproductive rates or productivity,
certain behaviors, and other
demographic factors.
Analytical Framework
The SSA report documents the results
of our comprehensive biological review
of the best scientific and commercial
data regarding the status of the species,
including an assessment of the potential
threats to the species. The SSA report
does not represent a decision by the
Service on whether the species should
be proposed for listing as an endangered
or threatened species under the Act. It
does, however, provide the scientific
basis that informs our regulatory
decisions, which involve the further
application of standards within the Act
and its implementing regulations and
policies. The following is a summary of
the key results and conclusions from the
SSA report; the full SSA report can be
found at Docket No. FWS–R2–ES–2022–
0026 on https://www.regulations.gov.
To assess the viability of the Texas
heelsplitter and Louisiana pigtoe, we
used the three conservation biology
principles of resiliency, redundancy,
and representation (Shaffer and Stein
2000, pp. 306–310). Briefly, resiliency
supports the ability of the species to
withstand environmental and
demographic stochasticity (for example,
wet or dry, warm or cold years),
redundancy supports the ability of the
species to withstand catastrophic events
(for example, droughts, large pollution
events), and representation supports the
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ability of the species to adapt over time
to long-term changes in the environment
(for example, climate changes). In
general, the more resilient and
redundant a species is and the more
representation it has, the more likely it
is to sustain populations over time, even
under changing environmental
conditions. Using these principles, we
identified the species’ ecological
requirements for survival and
reproduction at the individual,
population, and species levels, and
described the beneficial and risk factors
influencing the species’ viability.
The SSA process can be categorized
into three sequential stages. During the
first stage, we evaluated each individual
species’ life-history needs. The next
stage involved an assessment of the
historical and current condition of each
species’ demographics and habitat
characteristics, including an
explanation of how the species arrived
at its current condition. The final stage
of the SSA involved making predictions
about each species’ responses to
positive and negative environmental
and anthropogenic influences.
Throughout all of these stages, we used
the best available information to
characterize viability as the ability of a
species to sustain populations in the
wild over time. We use this information
to inform our regulatory decision.
Summary of Biological Status and
Threats
In this discussion, we review the
biological condition of the species and
their resources, and the threats that
influence the species’ current and future
condition, in order to assess the species’
overall viability and the risks to that
viability. We analyze these factors both
individually and cumulatively to
determine the current condition of the
species and project the future condition
of the species under several plausible
future scenarios.
Using various timeframes and the
current and projected future resiliency,
redundancy, and representation, we
describe the species’ levels of viability
over time. For the Texas heelsplitter and
Louisiana pigtoe to maintain viability,
their populations or some portion
thereof must be sufficiently resilient. A
number of factors influence the
resiliency of their populations,
including occupied stream length,
abundance, and recruitment. Elements
of the species’ habitat that determine
whether Texas heelsplitter and
Louisiana pigtoe populations can grow
to maximize habitat occupancy
influence those factors, thereby
increasing the resiliency of populations.
These resiliency factors and habitat
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elements are discussed in detail in the
SSA report and summarized here.
Species Needs
Occupied Stream Length
Most freshwater mussels, including
the Texas heelsplitter and Louisiana
pigtoe, are found in aggregations called
mussel beds that vary in size from about
50 to over 5,000 square meters (m2),
separated by stream reaches in which
mussels are absent or rare (Vaughn
2012, p. 2). Mussel populations in
streams are highly patchy, especially at
a small scale (less than 100 stream
meters) (Strayer 1999, p. 468). We
define a mussel population at a larger
scale than a single mussel bed; it is the
collection or series of mussel beds
within a stream reach between that
infested host fish may travel, allowing
for ebbs and flows in mussel bed
density and abundance over time
throughout the population’s occupied
reach. Therefore, adequately resilient
mussel populations must occupy stream
reaches that are long enough such that
stochastic events that adversely affect
individual mussel beds do not eliminate
the entire population. Repopulation by
glochidia-infested fish from other
mussel beds within the reach, if present
and connected, allow the population to
recover from the temporary loss of
individuals due to occasional disruptive
events.
For our analysis, we consider
populations extending greater than 50
river miles (river mi) (80 kilometers
(km)) to have a high probability of
persistence to stochastic events because
a single event is unlikely to affect the
entire population. Populations
occupying reaches between 20 and 50
river mi (32 and 80 km) have moderate
resiliency to stochastic events, while
populations occupying reaches less than
20 mi (32.19 km) have low resiliency.
Note that we define populations
occupying a stream length at or
approaching zero miles as being
functionally extirpated (populations
with abundance that is currently at such
low levels that we expect them to
become extirpated in the near future) or
extirpated.
Abundance
Populations require a minimum
number of individuals to ensure
stability and persistence. This threshold
is often referred to as the minimum
viable population and is generally
calculated through a population
viability analysis that estimates
extinction risk given a number of input
variables. There are no published
minimum viable population estimates
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for the Texas heelsplitter or Louisiana
pigtoe; therefore, it is unknown how
many individuals are required to sustain
populations of these mussels. However,
population health is dependent on
species abundance as well as water
availability and the ability for mussels
to meet life-history needs within their
habitats, which were evaluated as part
of the SSA.
It is important to recognize that
Louisiana pigtoe observations used to
determine abundance in the SSA report
may include misidentified individuals.
Without genetic confirmation,
identification of Louisiana pigtoe in the
field based on shell morphology is
questionable, with seasoned experts
accurately identifying the species only
76 percent of the time (Inoue 2018, p.
1). Unfortunately, genetic testing was
not available for the majority of reported
Louisiana pigtoe historical observations,
which relied solely on shell
morphological characteristics for
species identification (Randklev 2018,
entire). Since there is no way to know
the margin of error or to otherwise
account for potential misidentifications,
we determined abundance for Louisiana
pigtoe based on reported observations
(as is) and did not adjust or modify the
survey data to compensate for potential
misidentifications. We do not consider
misidentification to be an issue for
Texas heelsplitter observations, since
they are recognizable based on
morphological characteristics observed
in the field and not easily confused with
other species.
Mussel abundance in a given stream
reach is a product of the number of
mussel beds and the density of mussels
within those beds. For populations of
Texas heelsplitter and Louisiana pigtoe
to be healthy (i.e., adequately resilient),
mussel beds of sufficient number and
density must be present to allow
recovery from natural and local
stochastic events, allowing the mussel
bed to persist and the overall local
population to survive within a stream
reach. Mussel abundance is indicated by
the number of individuals found during
a sample event. Mussel surveys are
rarely a complete census of the
population, but density can be
estimated by the number of individuals
found during a survey effort using
various statistical techniques (i.e.,
estimate the total population from a
subset of surveyed individuals).
Population estimates are not available
for all Texas heelsplitter and Louisiana
pigtoe populations, and techniques for
available surveys are not always directly
comparable (i.e., same area size
searched, similar search time, etc.).
When available, we used the number of
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individuals captured relative to the
amount of time surveys were conducted
to estimate population abundance,
hereafter referred to as overall catch per
unit effort (CPUE). Although overall
CPUE was the preferred metric to
estimate population abundance, when
overall CPUE was not available, the
number of individuals detected during
the most recent comprehensive survey
effort was used as a surrogate metric.
Calculation of abundance in this
manner is intended to be an estimate
and is considered the best available
information when population trend data
do not exist and precise population
abundance cannot be determined. Using
CPUE, we are able to estimate if the
species is currently (since year 2000)
common or rare within populations.
Abundance for each population is rated
from ‘‘high’’ to ‘‘low’’ (or functionally
extirpated/extirpated) based on overall
CPUE (or number of individuals found
when survey effort is not reported)
according to live or recent dead found
during surveys since the year 2000, as
follows: ‘‘high’’ is overall CPUE of
greater than or equal to 4.0 (or 100 or
more individuals); ‘‘moderate’’ is overall
CPUE greater than or equal to 2.0 and
less than 4.0 (or between 25 individuals
and 99 individuals); ‘‘low’’ is overall
CPUE greater than or equal to 0.5 and
less than 2.0 (or between 3 and 24
individuals); and ‘‘functionally
extirpated/extirpated’’ is overall CPUE
less than 0.5 (or fewer than 3
individuals).
Reproduction/Recruitment
Sufficiently resilient Texas
heelsplitter and Louisiana pigtoe
populations must also be reproducing
and recruiting young individuals into
the population to replace individuals
lost to old age, disease, or predation.
Population size and abundance are a
reflection of habitat conditions,
environmental stressors, and other past
influences on the population. The
ability of populations to successfully
reproduce and recruit will determine if
a population may be stable, increasing,
or decreasing over time. For example, a
large, dense mussel population that
contains mostly old individuals is not
likely to remain large and dense into the
future if there are few young individuals
to sustain the population over time (i.e.,
death rates exceed birth rates resulting
in negative population growth).
Conversely, a population that is less
dense but has many young and/or
gravid individuals is likely to grow,
becoming more densely populated in
the future (i.e., birth rates, and
subsequent recruitment of reproductive
adults, exceed death rates, resulting in
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positive population growth). Detection
rates of very young juvenile mussels
during routine abundance and
distribution surveys are extremely low
due to sampling bias because sampling
involves tactile searches and mussels
less than 35 mm (1.4 in) can be difficult
to detect (Strayer and Smith 2003, pp.
47–48). For this evaluation, we
concluded there was evidence of
reproduction/recruitment for a
population when surveys detected
small-sized individuals (near the low
end of the detectable range or
approximately 35 mm (1.4 in) in size)
since the year 2000 or gravid females
(eggs and/or glochidia visible) were
observed during the reproductively
active time of year.
Risk Factors for Texas Heelsplitter and
Louisiana Pigtoe
We reviewed the potential risk factors
(i.e., threats, stressors) that could be
affecting the Texas heelsplitter and
Louisiana pigtoe now and in the future.
In this proposed rule, we will discuss
only those factors in detail that could
meaningfully impact the status of the
species. Many of the threats and risk
factors are the same or similar for both
species. Where the effects are expected
to be similar, we present one discussion
that applies to both species. Where the
effects may be unique to one species, we
will address that specifically. The
primary risk factors (i.e., threats)
affecting the status of the Texas
heelsplitter and Louisiana pigtoe all fall
under Factor A of the Act and are: (1)
Water quality changes, (2) altered
hydrology, (3) changes to habitat
structure and substrate, and (4) habitat
fragmentation. These factors are all
exacerbated by the ongoing and
expected effects of climate change
(Factor E). Additionally, predation
(Factor C) and collection (Factor B), as
well as other natural or human induced
events/activities that result in direct
mortality, are also affecting those
populations already experiencing low
stream flow, and reservoirs and
instream barriers to fish movement
(Factor E) limit dispersal and prevent
recolonization after stochastic events.
Changes to Water Quality
Freshwater mussels require water in
sufficient quantity and quality on a
consistent basis to complete their life
cycles and those of their host fishes.
Water quality can be degraded through
contamination or alteration of water
chemistry. Environmental contaminants
include a broad array of natural,
synthetic, and chemical substances
introduced to the environment that can
be hazardous to living organisms.
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Chemical contaminants are ubiquitous
throughout the environment and are a
major contributor to the current
declining status of freshwater mussel
species nationwide (Augspurger et al.
2007, p. 2025). Contaminants enter the
environment through both point (e.g.,
hazardous spills, industrial wastewater,
municipal effluents) and non-point (e.g.,
urban stormwater and agricultural
runoff) sources. These sources
contribute organic compounds, trace
metals, pesticides, plastics, petroleum
hydrocarbons, flame retardants, and a
wide variety of emerging contaminants
(e.g., pharmaceuticals and personal care
products). Ammonia is of particular
concern below wastewater treatment
plant outfalls because freshwater
mussels have been shown to be
particularly sensitive to increases in
ammonia levels (Augspurger et al. 2003,
p. 2569). The extent to which
environmental contaminants adversely
affect aquatic biota can vary depending
on many site-specific variables, but
species diversity and abundance
consistently ranks lower in waters that
are known to be polluted or otherwise
impaired by contaminants. For example,
freshwater mussels are not generally
found for many miles downstream of
municipal wastewater treatment plants
(treatment plants) (Gillis et al. 2017, p.
460; Goudreau et al. 1993, p. 211; Horne
and McIntosh 1979, p. 119).
There are approximately 386
treatment plant discharge permits
issued for the Trinity River Basin from
its headwaters above the Dallas-Fort
Worth metroplex down to the Gulf of
Mexico (Texas Commission on
Environmental Quality (TCEQ) 2018,
entire). The San Jacinto Basin, although
geographically smaller than most other
basins in Texas, has approximately
1,052 treatment plant outfalls, while the
Neches and Sabine rivers have 218 and
191 outfalls, respectively. In addition,
some industrial permits can discharge
millions of gallons per day and have
ammonia limits that exceed levels that
inhibited growth in juvenile fatmucket
(Lampsilis siliquoidea) and rainbow
mussel (Villosa iris) during 28-day
chronic tests (Wang et al. 2007, entire).
Immature mussels (juveniles and
glochidia) are especially sensitive to
water quality degradation and
contaminants (Cope et al. 2008, p. 456;
Wang et al. 2017, pp. 791–792; Wang et
al. 2018, p. 3041).
An additional type of water quality
impairment is the alteration of water
quality parameters such as dissolved
oxygen, temperature, total dissolved
solids (TDS), and salinity levels.
Dissolved oxygen levels may be reduced
from increased nutrients in the water
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from runoff or wastewater effluent, and
juveniles seem to be particularly
sensitive to low dissolved oxygen
(Sparks and Strayer 1998, pp. 132–133).
Increases in water temperature from
water diversions, climate change, or low
flows during droughts can exacerbate
low dissolved oxygen levels as well as
have its own effects on juvenile and
adult mussels.
Total dissolved solids, a measure of
the mineral content of water (i.e.,
inorganic salts, metals, cations, or
anions dissolved in water, including
calcium, magnesium, potassium,
sodium, bicarbonates, chlorides, and
sulfates), is commonly elevated in
watersheds impacted by a variety of
industrial, commercial, urban, and
agricultural activities and has been
associated with acute and chronic
toxicity to aquatic organisms.
Watersheds with increasing trends in
conductivity or TDS are experiencing
declines in water quality that can be
harmful to mussels and other aquatic
organisms. Increasing trends in TDS are
common in watersheds impacted by
anthropogenic activities.
Contaminant spills are also a concern.
Texas leads the nation in crude oil and
natural gas production, and various
chemicals, refined fuels, and wastewater
related to oil and natural gas exploration
are routinely transported along
highways. These facilities and
equipment used for extraction,
transportation, and refinement of
hazardous materials are all potential
sources of hazardous spills, and can
originate from human error, equipment
failure, or catastrophic events like
industrial accidents, fires, or floods.
Although spills are relatively short-term
events and may be localized, water
resources nearby can be severely
impacted and degraded for years after
the incident along with the biological
resources that inhabit the area. A
reduction in surface flow drought,
instream diversions, or groundwater
extraction serve to concentrate
contaminant and salinity levels,
increases water temperatures in streams,
and exacerbates effects to Texas
heelsplitter and Louisiana pigtoe.
Poor water quality affects most Texas
heelsplitter and Louisiana pigtoe
populations currently to some degree,
and future water quality is expected to
decrease due to decreasing stream flow
and increasing temperatures. We foresee
threats to water quality increasing into
the future due to the effects of climate
change as demand and competition for
limited water resources grows (USFWS
2022, pp. 61–62).
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Altered Hydrology
Altered hydrology, through changes to
historical flow regimes, leads to
inundation, or low- or high-flow
conditions that may reduce the quality
of affected habitats to the point where
they are no longer suitable for
freshwater mussels. While Texas
heelsplitter and Louisiana pigtoe have
adapted to survive natural fluctuations
in flows, populations that experience
sustained higher than normal flows,
prolonged flooding, or unnatural
fluctuations in the frequency or
intensity of high/low flows or extended
(or repeated) drying events will not
persist. Virtually every watershed
within the range of these two freshwater
mussels has experienced some level of
alteration, a trend that has continued
into the 21st century, particularly in
areas with rapid population growth.
Inundation of previously free-flowing
rivers and streams by impoundments
has arguably had the single largest
human-related impact on the
distribution of freshwater mussels. The
construction of reservoirs and other
impoundments permanently alters the
hydrology and, hence, the ecology of
rivers, often with deleterious effects to
water quality, water quantity, host fish
movement, and dispersal of mussel
glochidia, nutrient cycling, sediment
deposition, fate and transport of
contaminants, and numerous other
changes to the physical, chemical, and
biological characteristics of affected
areas (upstream and downstream). The
close relationship of flow to mussels
makes them uniquely vulnerable to
hydrology changes.
Both mussel species are adapted to
flowing water (lotic habitats) rather than
standing water (lentic habitats).
Louisiana pigtoe require free-flowing
water to survive. The Texas heelsplitter
has also been observed in lentic habitats
and appears to be tolerant of reservoir
conditions; this species may occur in
higher densities in areas of reservoirs
that are influenced by stream inflows
where conditions more closely resemble
their preferred riverine habitat
(Whisenant 2019, p. 1; Neck and
Howells 1995, p. 15).
Inundation of mussel habitat has
primarily occurred upstream of dams,
including major flood control and water
supply reservoirs, such as Toledo Bend
Reservoir, and smaller structures like
low water vehicle crossings and
diversion dams typically found along
tributaries on privately owned land.
These structures alter the hydrology of
rivers by slowing, impeding, or
diverting normal flow patterns, and
increasing deposition in some areas and
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eliminating the interstitial spaces that
juvenile Texas heelsplitters and
Louisiana pigtoes inhabit.
Large reservoirs that release water
from the hypolimnion, the deeper water
is cold and often devoid of oxygen and
necessary nutrients, can adversely affect
mussel survival, as cold water can stunt
mussel growth and delay or hinder
spawning (Vaughn and Taylor 1999, p.
917). Cold water releases from reservoirs
like Broken Bow Lake in southeast
Oklahoma can affect water temperatures
for miles downstream. These cold
releases create an extinction gradient,
where freshwater mussels are absent or
presence is low near the dam, and
abundance does not rebound until some
distance downstream where ambient
conditions raise the water temperature
to within the tolerance limits of mussels
(Davidson et al. 2014, p. 29; Vaugh and
Taylor 1999, pp. 915, 916).
The construction of dams for flood
control and drinking water supply, and
the subsequent management of water
releases from those reservoirs (e.g.,
timing, intensity, and duration), often
resulting in higher base flows and peak
flows of reduced intensity but longer
duration, has significant impacts on the
natural function and hydrology of rivers
and streams. The additional shear stress
caused by these sustained high base
flows can incise channels, erode river
banks, scour mussel beds, and remove
substrate preferred by mussels. Over
time, the physical force of these higher
base flows can dislodge mussels from
the sediment and permanently alter the
geomorphology of rivers.
During flood events, along with water,
rivers transport sediment, mostly as
solids, suspended in the water column.
The increase in flooding severity results
in greater sediment transport, with
important effects to substrate stability
and benthic habitats for freshwater
mussels, as well as other organisms that
are dependent on stable benthic
habitats. Further, water released by
dams is usually clear due to reduced
sediment load and results in incision
(downcutting of the bed) and coarsening
of the bed material until a new
equilibrium is reached (Kondolf 1997, p.
535). The extent to which downcutting
and erosion occurs as a result of dam
releases varies, but in some cases leads
to bank collapse, burial of mussel beds,
and mortality. Conversely, depending
on how dam releases are conducted,
reduced flood peaks can lead to
accumulations of fine sediment in the
river bed (i.e., loss of flushing flows;
Kondolf 1997, pp. 535, 548).
Operation of reservoirs for flood
control, water supply, and recreation
results in altered hydrologic regimes,
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including an attenuation of both highand low-flow events. The changes to
flood flows alters sediment dynamics, as
sediments are trapped above and
scoured below major impoundments,
and negatively affect freshwater mussels
and their habitats (Gascho Landis and
Stoeckel 2016, p. 234; Ford 2013, p. 3).
Evidence that the Texas heelsplitter is
able to tolerate reservoir conditions
leads us to believe the overall impacts
of reservoirs may be more pronounced
for the Louisiana pigtoe (Howells 2010b,
p. 3).
Very low flows and low water levels
are also detrimental to Texas
heelsplitter and Louisiana pigtoe
populations. Droughts that occurred in
the recent past led to extremely low
flows in several east Texas rivers. Some
rivers, or portions thereof, are resilient
to drought because they are spring-fed
(Calcasieu, Neches rivers), contain large
volumes of water (Trinity River), have
large reservoirs in the upper reaches
that release water for downstream users
(all, excluding Calcasieu River), or have
significant return flows (Pearl, Sabine,
Trinity rivers); however, drought in
combination with increasing trends in
groundwater extraction may lead to
lower river flows of longer duration
than previously recorded. Reservoir
releases can be managed to some extent,
but in many cases dam operators must
stop releases during droughts to
conserve water and protect water
supplies, or to maximize flood releases
during major floods to protect public
safety and property, both can negatively
affect mussels downstream.
Streamflow and overall discharge for
rivers inhabited by the Texas
heelsplitter and Louisiana pigtoe are
expected to decline due to climate
change and projected increases in
temperatures and evaporation rates,
resulting in more frequent and intense
droughts (Lafontaine et al. 2019, entire)
(Factor E). Return flows, consisting
primarily of treated municipal
wastewater, are projected to continue to
increase in areas with population
growth and may serve to ameliorate
some of the effects of climate change
downstream of metropolitan areas,
albeit with notable impacts to water
quality; however, these benefits may
become less significant as
municipalities increase wastewater
reuse as a conservation measure. The
Trinity River, for example, has been a
significantly modified, highly
controlled, and highly regulated system
since the 1960s, with low flows steadily
increasing as the population has grown,
resulting in base flows that are
significantly higher compared to
historical flows (Clark and Mangham
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2019, p. 9). The increase in base flows
can be attributed to substantial return
flows from Dallas/Fort Worth
metropolitan area wastewater treatment
plants and are projected to continue to
increase in the future. Surface and
alluvial aquifer groundwater
withdrawals will likely increase in the
future due to the effects of more intense
droughts, with reductions in stream
flows putting an additional strain on
aquatic resources. However, with the
exception of stream segments where
municipal effluent return flows
supplement base flows, most streams
experience lower base flows and
reduced high-flow events after major
reservoirs are constructed (U.S.
Geological Survey (USGS) 2008, pp.
964, 966).
Many streams within the range of
these two freshwater mussel species
receive significant groundwater inputs
from multiple springs associated with
aquifers. As spring flows decline due to
drought, climate change, or groundwater
pumping, habitat for freshwater mussels
in affected streams is reduced and could
eventually cease to exist. While the
Texas heelsplitter and Louisiana pigtoe
may survive short periods of low flow,
as low flows persist, mussels can be
subjected to oxygen deprivation,
increased water temperature, stranding,
increased predation, and, ultimately,
desiccation which leads to reduced
survivorship, reproduction, and
recruitment to the population. Highflow events can lead to increased risk of
mortality through physical removal,
transport, or burial of mussels as
unstable substrates are transported
downstream by flood waters
(entrainment) and dislodged mussels are
later redeposited in locations that may
not be suitable habitat.
The distribution of mussel
communities and their habitats is
affected by large floods returning at least
once during the typical life span of an
individual mussel (generally from 3–30
years), as mediated by the presence of
flow refuges, where shear stress is
relatively low, sediments are relatively
stable, and mussels must either tolerate
high-frequency disturbances or be
eliminated and can colonize only areas
that are infrequently disturbed between
events (Strayer 1999, pp. 468–469).
Shear stress and relative shear stress are
limiting to mussel abundance and
species richness (Randklev et al. 2017,
p. 7), and riffle habitats may be more
resilient to high-flow events than bank
habitats.
The Texas heelsplitter and Louisiana
pigtoe undoubtedly evolved in the
presence of extreme hydrological
conditions, including severe droughts
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leading to dewatering, and heavy rains
leading to damaging scour events and
movement of mussels and substrate,
although the frequency, duration, and
intensity of these events may be
different from what is observed today.
These same patterns led to the
development of flood control and
storage reservoirs throughout Texas in
the 20th century. The increasing
variability, frequency, and severity of
extreme weather events is a contributing
factor to the contraction of populations
for both species.
Another source of alteration to
hydrology is from sand and gravel
mining directly from rivers or from
adjacent alluvial deposits (Kondolf
1997, p. 541). Instream mining directly
impacts river habitats by removal of
substrates used by mussels, and can
indirectly affect river habitats through
channel incision, bed coarsening, and
lateral channel instability (Kondolf
1997, p. 541). Excavation of pits in or
near to the channel can create a
knickpoint, which can contribute to
erosion (and mobilization of substrate)
associated with head cutting (Kondolf
1997, p. 541). Pits associated with offchannel mining of the floodplain can
become involved during floods, such
that the pits become hydrologically
connected, and thus can affect sediment
dynamics in the stream or river
(Kondolf 1997, p. 545). Sand and gravel
mines occurred historically and
continue to operate in some basins
throughout the ranges of the Texas
heelsplitter and Louisiana pigtoe.
Specifically, a change to the number
of days with zero flow was limiting for
the Louisiana pigtoe, and the number of
high pulses was limiting for the Texas
heelsplitter. In summary, results to date
indicate natural flow regimes have been
altered in east Texas rivers, as was
expected, which has led to modification
of instream habitats and contributed to
declines in freshwater mussels (Khan
and Randklev 2019, entire). These
findings agree with the estimate of many
experts, who based on their research
believe: (1) Portions of the Trinity River
have been significantly modified and
may no longer support mussels
(particularly in the upper basin where
stream hydrology and geomorphology
have been permanently altered), and (2)
the Neches River is the least altered and
has some of the best remaining mussel
habitat, along with the most abundant
and diverse mussel populations, in east
Texas.
Changes to Habitat Structure/Substrate
Texas heelsplitters and Louisiana
pigtoes inhabit microhabitat along river
stream beds that have abundant
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interstitial spaces or small openings in
an otherwise closed matrix of stable
substrates created by gravel, cobble,
boulders, bedrock crevices, tree roots,
and other vegetation, with some amount
of fine sediment (i.e., clay and silt)
necessary to provide appropriate
shelter. Excessive amounts of fine
sediments can reduce available
microhabitat by filling in these
interstitial spaces, effectively
smothering mussels in place. Interstitial
spaces provide essential habitat for
juvenile mussels, offering protection
from predation and vital nutrients.
While adult mussels can be physically
buried by excessive sediment, the main
impacts of excess sedimentation on
freshwater mussels are often sublethal
and include interference with feeding
mediated by valve closure (Box and
Mossa 1999, p. 101).
Under a natural flow regime,
sediments are naturally washed away
from one microhabitat to another, the
amount of sediment in the substrate is
relatively stable, and different reaches
within a river or stream may be
aggrading or degrading sediment at any
given time (Poff et al. 1997, pp. 770–
772). Current (and past) human
activities often result in enhanced
sedimentation in river systems,
including legacy sediment from past
land disturbances and reservoir
construction. These activities continue
in many basins occupied by the Texas
heelsplitter and Louisiana pigtoe, and
influence river processes and sediment
dynamics (Wohl 2015, pp. 31, 39), with
legacy effects that can result in
degradation of mussel habitat.
Sediments deposited by large-scale
flooding or other disturbance may
persist for several years until adequate
cleansing flows can redistribute that
sediment downstream. Conversely,
when water velocity decreases from
reduced streamflow or inundation,
water loses its ability to carry sediment
in suspension and sediment falls to the
substrate, eventually smothering
mussels not adapted to soft substrates
(Watters 2000, p. 263).
Sediment accumulation can be
exacerbated when there is a
simultaneous increase in the sources of
fine sediments in a watershed,
including streambank erosion from
development, agricultural activities,
livestock and wildlife grazing, inchannel disturbances, roads, and
crossings, among others (Poff et al.
1997, p. 773). In areas with ongoing
development, runoff can transport
substantial amounts of sediment from
ground disturbance related to
construction activities with inadequate
or absent sedimentation controls. While
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these construction impacts can be
transient (lasting only during the
construction phase), the long-term
effects of development on water
quantity and quality are long lasting and
can result in hydrological alterations as
increased impervious cover increases
run off and resulting shear stress causes
streambank instability and additional
sedimentation.
Habitat Fragmentation
Historically, the Texas heelsplitter
and Louisiana pigtoe were likely
distributed in areas with suitable habitat
throughout the river basins described
above under Background. Today, the
remaining Texas heelsplitter and
Louisiana pigtoe populations are
isolated from one another by major
reservoirs, habitat alterations, and dewatering events, prolonged drought,
among other reasons, such that natural
recolonization of areas previously
extirpated is extremely unlikely, if not
impossible, due to barriers to host fish
movement. With the exception of the
Louisiana pigtoe populations in the Red
River Basin in Arkansas and Oklahoma,
there is currently no opportunity for
substantial interaction among extant
Texas heelsplitter and Louisiana pigtoe
populations, resulting in genetic
isolation.
The impacts of reservoirs are
significant, causing permanent changes
to fish movement, water quality, and
hydrology, with cascading effects to
river ecology and aquatic species that
utilize areas downstream. Small
populations are more affected by limited
host fish immigration potential because
they are susceptible to genetic drift
(random loss of genetic diversity) and
inbreeding depression. At the species
level, populations that are eliminated
due to stochastic events cannot be
recolonized naturally, leading to
reduced overall redundancy and
representation.
The confirmed or assumed primary
host fish species for both the Texas
heelsplitter and Louisiana pigtoe are
known to be common and widespread
throughout the range of both mussel
species and are therefore not believed to
be a limiting factor to dispersal at this
time (Nico and Sturtevant 2022, entire;
Nico et al. 2022, entire; Nico and Fuller
2022, entire; Fuller et al. 2022, entire).
Each of the identified fish hosts are
known to tolerate lake environments
and may utilize impoundments as
corridors to facilitate migration between
hydrologically connected tributaries,
thus aiding mussel dispersal. If fish host
species are indeed abundant, existing
dams, the construction of new major
dams and reservoirs, and other barriers
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to fish movement are the primary
mechanism through which remaining
populations are isolated. Furthermore,
reservoir impacts to river ecosystems
can be difficult and costly to manage or
minimize.
Most reservoirs function primarily to
provide water supply and/or flood
control, and meeting those objectives
typically involves holding on to as
much water as possible (i.e., not
releasing); this may limit the ability of
reservoir managers to modify releases
for the purpose of meeting wildlife
conservation or recovery goals.
Although dams have been managed to
allow fish passage for spawning, to our
knowledge, fish passage has not been
facilitated specifically to allow
movement of host fish for the benefit of
freshwater mussels, nor would this be
cost-effective considering host fish for
the Texas heelsplitter and Louisiana
pigtoe are believed to be abundant.
Nevertheless, reservoirs represent a
permanent barrier to freshwater mussel
dispersal. The overall impact of
reservoirs is believed to be greater for
the Louisiana pigtoe than for the Texas
heelsplitter, which is able to persist in
reservoir conditions although questions
remain about their reproductive success
in lake environments.
Direct Mortality
Direct mortality includes any activity
or event, whether human-induced or
natural, that results in the death of
mussels within a localized area due to
removal, crushing, burying,
consumption, desiccation, or poisoning.
Potential activities or events causing
direct mortality include, but are not
limited to, development projects (such
as bridge replacement, stream
channelization, and impoundment
construction), undeveloped low-water
crossings with vehicular traffic that
intersect mussel beds, bank collapse,
accidental release of hazardous
materials, predation, vandalism, and
collection (whether for scientific
purposes or recreation) (USFWS 2022,
pp. 57–58). The frequency, intensity,
and magnitude of these impacts likely
vary in time and by location and are
difficult to quantify with any certainty
other than to acknowledge that they
exist and negatively affect mussel
survival to some degree.
Predation on freshwater mussels is a
natural ecological interaction. Raccoons,
feral hogs, muskrats, snapping turtles,
and fish are known to prey upon
mussels (East et al. 2013, p. 692; Walters
and Ford 2013, p. 480; Kaller et al. 2007,
p. 174; Neves and Odom 1989, p. 939).
Under natural conditions, the level of
predation occurring is not likely to pose
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a significant risk to any given
population; however, during periods of
low flow, terrestrial predators have
increased access to portions of the river
that are otherwise too deep under
normal flow conditions, resulting in
unnaturally high levels of predation that
can decimate mussel populations.
Predation during drought has been
observed for the Texas heelsplitter on
the Sabine River (Walters and Ford
2013, p. 479). Drought, low-flow
conditions, and reductions in minimum
summer base flows are predicted to
occur more often and for longer periods
due to the effects of future climate
change; therefore, the tributaries and
upper portions of focal areas for the
Texas heelsplitter and Louisiana pigtoe
are expected to experience increased
predation pressure into the future
(Lafontaine et al. 2019, entire).
Additionally, certain mussel beds
within some populations, due to ease of
access, are vulnerable to over-collection
and vandalism. These areas have well
known and well documented mussel
beds that are often sampled multiple
times annually by various researchers
for various scientific projects.
Populations subjected to repeated
sampling or monitoring may experience
increased stress or higher rates of
mortality. Mortality may also occur in
areas where local fishing enthusiasts
have been observed using freshwater
mussels as bait. The risk of direct
mortality from recreation or overcollection for scientific purposes are
compounded by the additional stressors
discussed in this section, which can
influence mussel survival in a
cumulative manner. Because collection
of Louisiana pigote is localized and
could affect populations, we carried this
risk factor forward as a population-level
threat. Service biologists recently hosted
a meeting with State biologists,
consultants, and academia who are
involved in mussel research to discuss
ongoing monitoring and scientific
collections and to reduce the likelihood
of over-harvesting mussels from any
given population (USFWS 2018, p. 1),
and we anticipate this collaboration
among researchers will continue into
the future with ongoing coordination
and annual meetings.
Invasive Species
Invasive species, such as Asian clam
(Corbicula fluminea), zebra mussel
(Dreissena polymorpha), feral hog (Sus
scrofa), floating water hyacinth
(Eichhornia crassipes), giant salvinia
(Salvinia molesta), and hydrilla
(Hydrilla verticillata), occur throughout
the ranges of the Texas heelsplitter and
Louisiana pigtoe and can negatively
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impact mussel survival. These impacts
include predation (feral hog), habitat
destruction or modification (feral hog,
floating water hyacinth, giant salvinia,
hydrilla), changes to water quality (feral
hog, zebra mussel), increased resource
competition (Asian clam, zebra mussel),
or physical impairment (zebra mussel,
hydrilla) (Kaller and Kelso 2006, pp.
172–174; Howells 2010a, p. 13; Howells
2010b, pp. 14–15).
Although zebra mussel infestations
occur in several Texas reservoirs,
including Lewisville Lake and Lake
Livingston, populations have not yet
become established in nearby river
habitats occupied by the Texas
heelsplitter and Louisiana pigtoe (Ford
et al. 2016, p. 47; Texas Parks and
Wildlife Department (TPWD) 2019,
entire; USGS 2019e, entire).
Feral hogs occur throughout the range
of both mussel species and are known
to engage in a variety of activities that
cause bank and streambed damage,
contribute to erosion and increased
sedimentation, and their presence
appears to cause native mussel diversity
and abundance to decrease through
organic enrichment of the water and
unfavorable changes to microbial
community composition (Kaller et al.
2007, p. 174; Howells 2010b, p. 10).
Invasive macrophyte infestations of
floating water hyacinth, hydrilla, and
giant salvinia negatively impact native
mussels and their host fish throughout
the southern half of the ranges of the
Texas heelsplitter and Louisiana pigtoe
by creating hypoxic conditions through
respiration and during decay (Karatayev
and Burlakova 2007, p. 298; USGS
2019b, entire; USGS 2019c, entire;
USGS 2019d, entire). Dense mats of
hydrilla can also impede native mussel
movement during periods of fluctuating
surface water levels, leaving them
stranded as water levels recede.
Climate Change
Climate change in the form of the
change in timing and amount of
precipitation and air temperature
increase is occurring, and continued
greenhouse gas emissions at or above
current rates will cause further warming
(Intergovernmental Panel on Climate
Change (IPCC) 2021, pp. 1–13–1–15).
Warming in Texas is expected to be
greatest in the summer (Maloney et al.
2014, p. 2236, figure 3), with the
number of extremely hot days (high
temperatures exceeding 35 °C (95 °F))
projected to double by around 2050
(Kinniburgh et al. 2015, p. 83). Changes
in stream temperatures are expected to
reflect changes in air temperature, at a
rate of an approximately 0.6–0.8 °C (33
°F) increase in stream water temperature
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for every 1 °C (33 °F) increase in air
temperature (Morrill et al. 2005, pp. 1–
2, 15), with implications for
temperature-dependent water quality
parameters such as dissolved oxygen
and ammonia toxicity. Given that
freshwater mussels in Texas exist at or
near the ecophysiological edge of
climate and habitat gradients of
freshwater mussel biogeography in
North America, they may be particularly
vulnerable to future climate changes in
combination with current and future
stressors (Burlakova et al. 2011a, pp.
156, 161, 163; Burlakova et al. 2011b,
pp. 395, 403).
While projected changes to rainfall in
Texas may seem relatively small (U.S.
Global Change Research Program
(USGCRP) 2017, p. 217), higher
temperatures caused by anthropogenic
activity will lead to increased soil water
deficits because of higher rates of
evapotranspiration. In turn, higher
evapotranspiration rates will likely
result in increasing drought severity in
future climate scenarios, and the
warming atmosphere is projected to
continue across the United States
(USGCRP 2017, p. 231). Even if
precipitation and groundwater recharge
remain at current levels, increased
groundwater pumping and resulting
aquifer shortages due to increased
temperatures are nearly certain
(Loaiciga et al. 2000, p. 193; Mace and
Wade 2008, pp. 662, 664–665; Taylor et
al. 2013, p. 3).
Effects of climate change, such as
changes to seasonal rainfall patterns, air
temperature increases, and increases in
drought frequency and intensity, have
been shown to be occurring throughout
the ranges of the Texas heelsplitter and
Louisiana pigtoe (Andreadis and
Lettenmaier 2006, p. 3; USGCRP 2017,
p. 188); these effects are expected to
exacerbate several of the stressors
discussed above, such as water
temperature and flow loss (Wuebbles et
al. 2013, p. 16). A recent review of
future climate projections for Texas
concludes that both droughts and floods
could become more common in east
Texas, with droughts like 2011 (the
driest on record) becoming
commonplace by the year 2100 (Mullens
and McPherson 2017, pp. 3, 6). This
trend of more frequent droughts is
driven by increases in hot temperatures
(e.g., daily maximum) and the number
of days projected to be at or above 37.8
°C (100 °F), which is set to ‘‘increase in
both consecutive events and the total
number of days’’ (Mullens and
McPherson 2017, pp. 14–15). Similarly,
floods and extreme runoff are projected
to become more common and severe in
the 21st century as the frequency,
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magnitude, and intensity of heavy
precipitation events increase (Mullens
and McPherson 2017, p. 20; USGCRP
2017, p. 224).
In the analysis of the future condition
for the Texas heelsplitter and Louisiana
pigtoe, climate change is considered
further under various plausible future
scenarios, serving to exacerbate already
deteriorating conditions through an
increase of fine sediments, changes to
water quality, loss of flowing water, and
predation, among others.
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Summary of Risk Factors for Texas
Heelsplitter and Louisiana Pigtoe
Our analysis of the past, current, and
future influences on the needs of the
Texas heelsplitter and Louisiana pigtoe
for long-term viability revealed that
there are four that pose the greatest
impact on current condition and future
viability: degradation of water quality,
altered hydrology, substrate changes,
and habitat fragmentation, all of which
are exacerbated by climate change.
Conservation Efforts and Regulatory
Mechanisms
The level of interest among
stakeholders, regulatory agencies, and
partners to better understand the status,
threats, and conservation of freshwater
mussels in Texas has increased
significantly since 2017, when the
Service initiated reviews of several
Texas mussel species for possible listing
under the Act. This led to improved
communication among interested
parties and multiple partnerships
seeking to conduct research and
improve our understanding of the health
and distribution of mussel populations
across Texas, as well as increased efforts
to protect and conserve known
populations. Although there are
currently no formal conservation
agreements in place designed to
specifically provide benefits to the
Texas heelsplitter or Louisiana pigtoe,
we are in discussions with multiple
stakeholders who are interested in
strengthening partnerships to conserve
rare species, including several river
authorities that are in the process of
developing candidate conservation
agreements with assurances (CCAAs).
The CCAAs, if finalized, would
implement voluntary conservation
actions in river basins that would result
in a net conservation benefit for the
species. Additionally, several
stakeholders have voluntarily funded
research to ensure that we have the best
available information upon which to
base a listing decision, and we
commend them for their efforts to
improve the science of freshwater
mussels in Texas. Interested
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stakeholders and potential future
conservation partners include the
Trinity River Authority, Lower Neches
Valley Authority, North Texas
Municipal Water District, Sabine River
Authority, the Cities of Dallas and Fort
Worth, Tarrant Regional Water District,
Texas Department of Transportation,
Texas Parks and Wildlife Department,
U.S. Army Corps of Engineers, Texas
Comptroller of Public Accounts, Texas
A&M University, Texas State University,
and others.
With regard to silvicultural operations
that occur on forested areas across the
range of the species, we recognize that
private timber companies routinely
implement State-approved best
management practices (BMPs; as
reviewed by Cristan et al. 2018, entire).
Adherence to these BMPs, such as citing
river crossings away from sensitive
areas and leaving intact habitat as
buffers for areas adjacent to streams,
broadly protects water quality by
reducing timber harvest-related impacts,
particularly erosion and sedimentation
(as reviewed by Cristan et al. 2018;
Warrington et al. 2017, entire; and
Schilling et al. 2021, entire). However,
it is important to recognize that while
BMPs reduce timber harvest impacts,
they do not eliminate impacts; therefore,
sensitive species and their habitats may
still be impacted even when BMP
guidelines are followed.
Some voluntary habitat restoration
projects have been completed on private
lands within the river basins currently
known to be occupied by one or both
species. These restoration projects
include upland and riparian habitat
enhancements coordinated by our State,
Federal, and nongovernmental partners,
as well as our Partners for Fish and
Wildlife Program. There are also
regulatory mechanisms in place to
protect water quality and quantity, such
as protections afforded by the Clean
Water Act (33 U.S.C. 1251 et seq.), that
are implemented by the States with
oversight by the EPA. While these
regulations are in place and provide
some level of protection, population
declines continue to be documented in
some species of freshwater mussels,
indicating that existing regulations may
not be sufficient to prevent extinction.
Species Condition
Here we discuss the current and
future condition of each known
population, taking into account the risks
to those populations that are currently
occurring, as well as management
actions that are currently occurring to
address those risks. We consider climate
change to be currently occurring,
resulting in changes to the timing and
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amount of rainfall affecting streamflow,
which can alter stream characteristics
such as an increase in stream
temperatures, erosion, and the
accumulation of fine sediments. The
current condition of each species and
population is based upon the
cumulative effects of these factors. In
the SSA report, for each species and
population, we developed and assigned
condition categories for three
population factors (occupied stream
length, abundance, reproduction/
recruitment; see Species Needs, above)
and three habitat factors (habitat
structure/substrate, hydrological regime,
and water quality; see Risk Factors for
Texas Heelsplitter and Louisiana Pigtoe,
above) that are important for the
viability of each species. The
summation of all six condition scores
assigned to each factor were then used
to determine the overall condition of
each population: high (healthy),
moderate (moderately healthy), low
(unhealthy), or functionally extirpated/
extirpated. All six factors were weighted
equally in importance except
abundance, which was viewed as the
most relevant and direct measure of
current biological condition; therefore,
overall condition was capped by the
abundance score such that no
population’s overall condition could
exceed the abundance score. These
overall conditions translate to our
presumed probability of persistence of
each population, with healthy
populations having the highest
probability of persistence over 20 years
(greater than 90 percent), moderately
healthy populations having a
probability of persistence that falls
between 60 and 90 percent, unhealthy
populations having the lowest
probability of persistence (between 10
and 60 percent). Functionally extirpated
populations (less than 10 percent) are
not expected to persist over 20 years or
are already extirpated.
Texas Heelsplitter
There are five remaining Texas
heelsplitter populations, occurring in
three adjacent river basins (Neches,
Sabine, and Trinity River basins) in east
Texas and on the Sabine River to the
western border of Louisiana.
Historically, populations likely occurred
throughout the entirety of each basin
where connectivity was not an issue and
conditions were suitable. Based on our
analysis, three populations are
considered to have a low current
condition, and two populations are
considered functionally extirpated/
extirpated (see Table 1, below).
Neches River Basin: There are two
Texas heelsplitter populations in the
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Neches River Basin, one in the Neches
River/B.A. Steinhagen Reservoir and the
other in the Lower Neches River; these
populations are fragmented and isolated
from each other by the dam that forms
B.A. Steinhagen Reservoir. The Neches
River/B.A. Steinhagen Reservoir
population occurs in habitat on a fairly
long reach (240.9 river mi (387.6 km)) of
the Neches River that extends from just
below Lake Palestine to B.A. Steinhagen
Reservoir and includes the portion of
mainstem Angelina River between B.A.
Steinhagen and Sam Rayburn reservoirs.
This population is characterized by low
abundance and a lack of evidence of
reproductive success, resulting in low
recruitment of new individuals. Further,
water quality in tributaries and
segments of the occupied habitat is
affected by a variety of point and nonpoint source pollution, and infrequent
but substantial drawdowns of the B.A.
Steinhagen Reservoir have resulted in
direct mortality of Texas heelsplitters.
The Lower Neches River population
extends 74.2 river mi (119.4 km)
downstream from Lake B.A. Steinhagen
Reservoir’s Town Bluff Dam to
approximately 4.5 river mi (7.2 km)
downstream of the Village Creek
confluence. This population is also
characterized by low abundance and
lack of evidence of reproductive
success, with subsequent low
recruitment of new individuals. Further,
hydrology and water quality in this
reach are affected by water releases from
the B.A. Steinhagen Reservoir. The
Neches River/B.A. Steinhagen Reservoir
population and the Lower Neches River
population have a low overall current
condition, resulting in low resiliency for
both populations.
Sabine River Basin: This Texas
heelsplitter population occurs in a fairly
long reach (245.8 river mi (395.5 km)) of
the Sabine River Basin, that includes the
Toledo Bend Reservoir, Sabine River
upstream to Lake Tawakoni’s Iron
Bridge Dam, a portion of Lake Fork
Creek upstream from its confluence
with the Sabine River, and a portion of
Patroon Bayou upstream from its
confluence with Toledo Bend Reservoir.
While the overall water quality, habitat
structure/substrate, and occupied
habitat reach length are in high
condition, construction of Lake
Tawakoni and Toledo Bend Reservoir
have altered the natural hydrologic
conditions through dam releases
causing substrate scouring and
elimination of habitat downstream. Due
to lack of evidence of reproduction and
recruitment, as well as extremely low
abundance (CPUE = 0.14) based on 99
surveys since 2000, this population of
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Texas heelsplitter is considered
functionally extirpated/extirpated.
Trinity River Basin: There are two
populations of the Texas heelsplitter in
the Trinity River Basin, one within
Grapevine Lake and another within the
Trinity River/Lake Livingston, that are
hydrologically isolated from one
another by the dam that forms
Grapevine Lake. The habitat structure/
substrate rating for the Grapevine Lake
population is in high condition, with
stormwater runoff and the discharge of
municipal wastewater and associated
pollutants limiting water quality to
moderate condition. Reservoir-related
changes to natural flow regimes likewise
limited the hydrology rating to moderate
condition. However, with only two
individuals found during population
surveys, abundance is extremely low,
this combined with the lack of juveniles
and gravid females, the Grapevine Lake
population is considered to be
functionally extirpated. The Trinity
River population is characterized by
high current condition for the relatively
large habitat reach length currently
occupied, while habitat structure/
substrate is affected by unnaturally
elevated base flows and is in moderate
current condition. Large daily volumes
of municipal wastewater discharge and
associated pollutants are impacting
water quality and hydrology, which are
in low current condition. This
population is also characterized by low
abundance and lack of evidence of
reproductive success, with subsequent
low recruitment of new individuals. The
Trinity River/Lake Livingston
population has a low overall current
condition and low resiliency.
reducing the impact that any one event
might have in terms of overall loss to
the species. Redundancy is
characterized by having multiple
healthy, resilient populations
distributed across the range of the
species. It can be measured by
population number, resiliency, spatial
extent, and degree of connectivity. Our
analysis explored the influence of the
number, distribution, and connectivity
of populations on the species’ ability to
withstand catastrophic events.
Within the identified representation
areas (Neches, Sabine, and Trinity River
basins), only the Neches and Trinity
River basins currently have at least one
known population (the Sabine River/
Toledo Bend population in the Sabine
River Basin and Grapevine Lake in the
Trinity River Basin are considered
functionally extirpated). The Neches
River Basin currently has two
populations (Neches River and Lower
Neches River populations); however,
these populations are hydrologically
isolated, and therefore provide only
minimal redundancy.
Representation describes the ability of
a species to adapt to changing
environmental conditions over time. It
is characterized by the breadth of
genetic and environmental diversity
within and among populations. Our
analysis explores the relationship
between the species life history and the
influence of genetic and ecological
diversity and the species ability to adapt
to changing environmental conditions
over time.
We consider the Texas heelsplitter to
have representation in the form of
genetic, geographic, and ecological
diversity in the three currently occupied
river basins. Because there are no
TABLE 1—ESTIMATED CURRENT OVER- freshwater connections between the
ALL
CONDITION
OF
TEXAS three basins, we treated each river basin
HEELSPLITTER POPULATIONS
as separate areas of representation.
[USFWS 2022, pp. 40–44]
River
basin
Population
Sabine .....
Sabine River/Toledo
Bend.
Neches River/B.A.
Steinhagen.
Lower Neches River
Grapevine Lake ......
Trinity River/Lake
Livingston.
Neches ....
Trinity ......
Overall
current
condition
FE/E.1 2
Low.2
Low.2
FE/E.1 2
Low.2
1 FE/E
= Functionally extirpated/extirpated.
representation areas where overall condition was capped by abundance.
2 Indicates
Redundancy describes the ability of a
species to withstand and recover from
catastrophic events. High redundancy is
achieved through multiple populations
that serve to spread risk, thereby
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Louisiana Pigtoe
Overall, there are 13 remaining
populations of Louisiana pigtoe in
multiple river drainages throughout
portions of east Texas (Big CypressSulphur, Neches-Angelina, Sabine, and
San Jacinto river basins), Louisiana
(Calcasieu, Sabine, and Pearl river
systems), west Mississippi (Pearl River),
southeast Oklahoma (Little River), and
southwest Arkansas (Cossatot, Saline,
Rolling Fork, and Little rivers). Because
reported populations from the Ouachita
River system in Arkansas were
determined to be phylogenetically
distinct (a separate species) from
Louisiana pigtoe, they were not
considered in the SSA. In 2019, an
additional population was discovered
within the Lower Neches Valley River
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Authority canal system in Beaumont,
Texas (Bio-West 2021, p. 1). Because
this population occupies artificially
maintained habitat that may not persist
without active operational management
by the Lower Neches Valley River
Authority, it was not considered for
analysis in the SSA.
Historically, the Louisiana pigtoe
likely occurred throughout each basin
wherever conditions were suitable and
connectivity was not an issue, with
populations connected by fish
migration; however, due primarily to
impoundments, the populations are
currently isolated from one another, and
repopulation of functionally extirpated/
extirpated locations is unlikely to occur
without human assistance. Two
populations are currently considered to
be in high condition, four populations
are in moderate condition, five
populations are in low condition, and
two populations are considered
functionally extirpated/extirpated (see
Table 2, below).
Big Cypress-Sulphur Basin: Although
Louisiana pigtoes have not been
genetically confirmed and observations
may be misidentified as Wabash pigtoe
(Fusconaia flava), past surveys
indicated Louisiana pigtoe presence
(Randklev 2018, entire) in this basin.
Therefore, we included this population
in this assessment. The Louisiana pigtoe
population in Big Cypress Bayou
includes approximately 32.0 river mi
(51.5 km) of Big Cypress Bayou and
Little Cypress Bayou upstream of their
confluence. This population is
characterized by moderate condition for
occupied habitat stream length,
abundance, habitat structure/substrate,
hydrology, and water quality; the
habitat factors are influenced by a
variety of anthropogenic activities that
vary by watershed, including
stormwater runoff and discharges from
multiple wastewater treatments plants.
However, there has been a lack of
reported juveniles or gravid females, so
this population is in low condition for
reproduction and recruitment.
Calcasieu River Basin: Louisiana
pigtoe has a single population in the
Calcasieu-Mermentau Basin that occurs
along an approximately 134-river-mi
(216-km) section of hydrologically
connected portions of the mainstem
Calcasieu River, and the Whisky Chitto
and Tenmile creeks located in Allen,
Rapides, and Vernon parishes,
Louisiana. This population is
characterized as being in high condition
for occupied habitat reach length and
habitat structure/substrate, while
hydrology and water quality are in
moderate condition due to fluctuations
in flow rates and municipal wastewater
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effluent discharges, among other sources
of pollution. However, abundance,
reproduction, and recruitment are in
low condition, which corresponds to
low resiliency.
Neches River Basin: The Neches River
Basin in Texas has three populations of
Louisiana pigtoe, one each in the
Angelina (above Sam Rayburn
Reservoir), Neches (above B.A.
Steinhagen Reservoir), and Lower
Neches rivers (below B.A. Steinhagen
Reservoir). These three populations
combined extend over 400 river mi (644
km) in a basin that many experts believe
contains some of the best remaining
habitat and most diverse populations of
freshwater mussels in Texas. The
Neches River and Lower Neches River
populations are hydrologically isolated
from each other by the Town Bluff Dam
that forms B.A. Steinhagen Reservoir,
and the Angelina River population is
isolated from the Neches River
population by Sam Rayburn Dam and
Reservoir. The Neches River
population’s current condition is
characterized as high condition for the
occupied habitat reach length (203 river
mi (326.7 km)), abundance, habitat
structure/substrate, and hydrology, and
moderate condition for reproduction/
recruitment and water quality. The
Lower Neches River population is
characterized by high current condition
for occupied habitat reach length (160.4
river mi (258.1 km)) and habitat
structure/substrate, and a moderate
current condition for hydrology, water
quality, and reproduction/recruitment
due to the impacts of fluctuating stream
flows, pollution loading from point and
non-point sources, and few reports of
gravid females or juvenile mussels. In
addition, few individuals have been
observed, resulting in a low current
condition for population abundance.
The Angelina River population is in
high condition for occupied habitat
reach length (53.2 river mi (85.6 km)),
habitat structure/substrate, and
hydrology; however, water quality
impacts such as elevated bacteria, fecal
coliform, and ammonia resulted in a
moderate current condition for water
quality. Like the Lower Neches River
population, due to the few numbers of
individuals observed and a lack of
juvenile or gravid female presence,
abundance and reproduction/
recruitment are in low condition for the
Angelina River population. The Neches
River population has a high overall
current condition, and the Lower
Neches River and Angelina River
populations have a low overall current
condition (primarily due to being
capped by low abundance).
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Pearl River Basin: The Pearl River
Basin in Louisiana and Mississippi has
a single population of the Louisiana
pigtoe within the main stem that
extends approximately 280 river mi (450
km) below Ross Barnett Dam near
Jackson to Picayune, Mississippi
(upstream of Interstate 59). A new
impoundment proposed by the RankinHinds Pearl River Flood and Drainage
Control District, located 9 mi (14.5 km)
downstream of Ross Barnett Reservoir,
intended for flood control, is still under
review. For the Pearl River population,
we determined that occupied habitat
reach length is in high condition, and
habitat structure/substrate, hydrology,
and water quality are in moderate
condition due to erratic flows and
pollutants from urban areas and
industry wastewater discharge. Because
few individuals have been reported and
there is a lack of juvenile or gravid
female presence, abundance and
reproduction/recruitment are in low
condition. The Pearl River population
has an estimated overall low current
condition and low resiliency.
Red River Basin: The Red River Basin
contains four distinct populations of the
Louisiana pigtoe that extend along 88.3
river mi (142.1 km) within the Little
River drainage in Arkansas and
Oklahoma, including populations in the
Cossatot River, Little River/Rolling Fork,
Lower Little River, and Saline River.
Millwood Lake, located in southwest
Arkansas, hydrologically separates the
Cossatot River, Saline River, and Little
River/Rolling Fork populations from the
Lower Little River population. The
current condition evaluation for the
Cossatot River population determined
that abundance, reproduction/
recruitment, and habitat structure/
substrate are in high condition, and
occupied habitat reach length,
hydrology, and water quality are in
moderate condition due to fluctuations
of stream flows from Gillham Lake, as
well as pollutant discharges from
agriculture and other sources. No
habitat or population factors are
determined to be in low condition. The
Little River/Rolling Fork population’s
current condition evaluation
determined occupied habitat reach
length and reproduction/recruitment are
in high condition. All other population
and habitat factors are in moderate
condition due to lower abundance,
fluctuations in instream flow (which
affect benthic habitat, substrate, and
stream hydrology), and increased levels
of zinc, lead, and salinity (among other
pollutants), leading to moderate water
quality. The Saline River population’s
current condition evaluation found
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occupied habitat reach length,
abundance, hydrology, and water
quality in moderate condition caused by
prolonged high water levels and low
levels of dissolved oxygen. Due to the
lack of evidence of reproductive success
and subsequent recruitment of new
individuals, and altered flow conditions
downstream of Dierks Lake,
reproduction/recruitment and habitat
structure/substrate are in low condition.
The Lower Little River population’s
current condition evaluation
determined that reproduction/
recruitment and all habitat factors are in
low condition primarily because of its
short reach length (8.5 river mi (14.16
km)), altered flow regime, and paucity
of survey data. This population is
located downstream of Millwood Lake
and Dam, a flood control reservoir, and
is subject to altered hydrology that
further impacts habitat structure and
substrates during flood events.
Agricultural runoff associated with the
lower section of this reach impacts
water quality. Due to the extremely low
numbers of individuals observed
(abundance), this population is
considered functionally extirpated/
extirpated. In summary, the Cossatot
River population has a high overall
current condition and high resiliency,
the Little River/Rolling Fork and Saline
River populations have a moderate
overall current condition and moderate
resiliency, and the Lower Little River
population is considered functionally
extirpated/extirpated.
Sabine River: There are two known
populations of the Louisiana pigtoe
within the Sabine River, one located
along 87 river mi (140 km) between
Hawkins and Tatum, Texas, and a
second population within a 9-river-mi
(15-km) segment of Bayou Anacoco in
Louisiana. These populations are
hydrologically separated by Toledo
Bend Dam and Reservoir. The Sabine
River population’s current condition
evaluation determined that occupied
habitat reach length and habitat
structure/substrate are in high
condition. Dam releases from Lake
Tawakoni and Toledo Bend Reservoir,
wastewater releases, and water quality
degradation (including elevated levels
of bacteria) are primary causes for
moderate current conditions for
hydrology and water quality. Due to an
extremely low number of individuals
detected during surveys, and the lack of
juveniles or gravid females observed,
abundance and reproduction/
recruitment are in low condition, and
this population is considered
functionally extirpated/extirpated. The
Bayou Anacoco population’s current
condition evaluation found habitat
structure/substrate is high condition,
and abundance, hydrology, and water
quality are in moderate condition.
However, the occupied habitat reach
length and reproduction/recruitment are
in low condition due to the distribution
of observed individuals and lack of
reported juveniles or gravid females.
The Bayou Anacoco population is in
moderate current overall condition and
has moderate resiliency.
East Fork San Jacinto River: There is
one known population of Louisiana
pigtoe that occurs within a short (1.3river-mi (2-km)) segment of the East
Fork San Jacinto River near Plum Grove,
Texas. The population’s current
condition evaluation determined that
hydrology and water quality are in
moderate condition, whereas sand and
gravel mining are affecting the habitat
structure/substrate, which is in low
condition. Due to a low number of
individuals detected and lack of
juveniles or gravid females observed,
population abundance and
reproduction/recruitment are in low
condition. The East Fork San Jacinto
River population is determined to be in
overall low condition and has low
resiliency.
TABLE 2—ESTIMATED CURRENT OVERALL CONDITION OF KNOWN LOUISIANA PIGTOE POPULATIONS
[USFWS 2022, pp. 34–40]
River basin
Population
Red ....................................................................
Little River/Rolling Fork ....................................
Cossatot River ..................................................
Saline River ......................................................
Lower Little River .............................................
Big Cypress Bayou ...........................................
Calcasieu River ................................................
Pearl River ........................................................
Sabine River .....................................................
Bayou Anacoco ................................................
Angelina River ..................................................
Neches River ....................................................
Lower Neches River .........................................
East Fork San Jacinto River ............................
Big Cypress-Sulphur ..........................................
Calcasieu-Mermentau ........................................
Pearl ..................................................................
Sabine ................................................................
Neches ...............................................................
San Jacinto ........................................................
1 FE/E
Overall current condition
Moderate.
High.
Moderate.
FE/E. 1 2
Moderate.
Low. 2
Low. 2
FE/E. 1 2
Moderate.
Low. 2
High.
Low.2
Low.
= Functionally extirpated/extirpated.
representation areas where overall condition was capped by abundance.
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2 Indicates
Within identified representation
areas, the Big Cypress-Sulphur,
Calcasieu-Mermentau, Pearl, and San
Jacinto River basins each have only one
known current population, and
therefore lack redundancy should
catastrophic events occur that cause
extirpation of one or a few populations.
The Sabine River Basin has two separate
populations (Sabine River and Bayou
Anacoco populations) but lacks
redundancy due to the Sabine River
population being functionally
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extirpated. The Neches and Red River
basins each currently have three known
populations (the Lower Little River
population in the Red River Basin is
considered functionally extirpated),
however each population is
hydrologically isolated within their
respective river basins and are,
therefore, considered to provide only
limited redundancy.
We consider Louisiana pigtoe to have
representation in the form of genetic,
ecological, and geographical diversity
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between each of seven river basins: Big
Cypress-Sulphur, Calcasieu-Mermentau,
Neches, Pearl, Red, Sabine, and San
Jacinto. Because there are no unimpounded, freshwater connections that
allow movement between the seven
basins, each river was considered a
separate area of representation.
Future Conditions
As part of the SSA, we developed
multiple future condition scenarios to
capture the range of uncertainties
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regarding future threats and the
projected responses by the Texas
heelsplitter and Louisiana pigtoe. Our
scenarios included a status quo
scenario, which incorporated the
current risk factors continuing on the
same trajectory that they are on now.
We also evaluated two future scenarios
that incorporated varying levels of
increasing risk factors with elevated
negative effects on Texas heelsplitter
and Louisiana pigtoe populations.
However, because we determined that
the current condition of the Texas
heelsplitter is consistent with an
endangered species (see Texas
Heelsplitter: Determination of Status,
below), we are not presenting the results
of the future scenarios in this proposed
rule. Please refer to the SSA report
(Service 2022) for the full analysis of
future scenarios.
We forecasted the Louisiana pigtoe’s
responses to two plausible future
scenarios of environmental conditions
projected across the next 10, 25, and 50
years. Ten years represents one to two
generations of mussels, assuming an
average reproductive life span of five to
10 years. Twenty-five years similarly
represents at least two to four mussel
generations and 50 years represents at
least five or more generations of
mussels. The scenarios project the
threats into the future and consider the
impacts those threats could have on the
viability of the Louisiana pigtoe. We
apply the concepts of resiliency,
redundancy, and representation to the
future scenarios to describe possible
future conditions of the Louisiana
pigtoe. The scenarios described in the
SSA report represent only two possible
future conditions. Uncertainty is
inherent in any projection of future
condition, so we must consider
plausible scenarios to make our
determinations. When assessing the
16791
by Louisiana pigtoe are altered such that
base flows are diminished, floods are
more severe if not more frequent, and
mussels and their habitats are adversely
affected through degradation of water
quality and quantity. These altered
hydrological conditions are primarily
caused by a combination of increasing
anthropogenic stressors and climate
change. Due to a lack of resolution of
the available data, we were unable to
distinguish any meaningful difference
between a moderate increase in stressors
and a moderate decrease in stressors. As
a result, we limited the future forecasts
to these two scenarios, which we
projected over a 50-year period. We
restricted our evaluation to 50 years
primarily due to limitations projecting
non-modeled, extrapolated future
conditions for water quality, road
density, and habitat fragmentation. Fifty
years encompasses about 5 generations
of the Louisiana pigtoe; additionally,
projected human population growth and
the limitations of existing resources are
expected to increase and interact with
climate effects to exacerbate the effects
of drought which is likely to impact
water quality and quantity (i.e., the
ability to provide the minimum flow
needed by the Louisiana pigtoe). A full
description of the future scenarios and
our methods is available in the SSA
report (USFWS 2022, pp. 63–73).
Under Scenario 1, populations of the
Louisiana pigtoe decline in resiliency,
redundancy, and representation over
time as conditions moderately decline
from current conditions. One
population will remain in moderate
condition, seven in low condition, and
five functionally extirpated in 50 years.
This species will lose two areas of
representation, diminishing the overall
adaptive capacity to future
environmental change in the next 50
years (see Table 3).
future, viability is not a specific state,
but rather a continuous measure of the
likelihood that the species will sustain
populations over time.
We included climate change in our
future scenarios as a factor that would
add to the negative impacts of the
primary threats on the species’ habitat.
Climate change is expected to alter the
natural flow regime through increased
drought and flooding worsening
desiccation, scour, and sedimentation.
Global climate models project changes
in global temperature and other
associated climatic changes based on
potential future scenarios of greenhouse
gas concentrations in the atmosphere
(i.e., Representative Concentration
Pathways, or RCPs). RCP 4.5 assumes
major near-future cuts to carbon dioxide
emissions, and RCP 8.5 assumes that
current emissions practices continue
with no significant change (Terando et
al. 2020, p. 10). Thus, these RCPs
represent conditions in the upper and
lower ends of the range of what can
reasonably be expected for the future
effects of climate change (Terando et al.
2020, p. 17).
Scenario 1 assesses the species’
responses to moderate increases in
stressors influencing Louisiana pigtoe
populations. Scenario 1 is based on RCP
4.5 emission trajectory and associated
model projections, and represents
medium-term increases in emissions
followed by a decline through the rest
of the century. Scenario 2 assesses the
species’ responses to severe increases in
stressors and is based on RCP 8.5
projections. Scenario 2 also includes
anthropogenic actions, such as the
construction of new reservoirs,
wastewater treatment plants, and other
currently proposed projects, and
manifests as a future where the
hydrological conditions of many of the
rivers and streams currently occupied
TABLE 3—FUTURE CONDITION OF LOUISIANA PIGTOE POPULATIONS WITH A MODERATE INCREASE IN STRESSORS
[Scenario 1]
Scenario 1 future condition
Species
River basin
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Louisiana Pigtoe ........
Population
Red Little River/Rolling Fork.
Cossatot River ..........
Saline River ...............
Lower Little River ......
Big Cypress-Sulphur
Calcasieu ..................
Pearl ..........................
Sabine .......................
Neches ......................
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10 years
25 years
Moderate ...................
High ...........................
Moderate ...................
FE/E 1 ........................
Low ............................
High ...........................
Moderate ...................
FE/E 1 ........................
Low. ...........................
Moderate. ..................
Low. ...........................
FE/E.1
Big Cypress Bayou ...
Calcasieu River .........
Pearl River ................
Sabine River .............
Bayou Anacoco .........
Angelina River ...........
Neches River ............
Lower Neches River
Moderate ...................
Low ............................
Low ............................
FE/E 1 ........................
Low ............................
Low ............................
High ...........................
Low ............................
Moderate ...................
Low ............................
Low ............................
FE/E 1 ........................
Moderate ...................
Low ............................
Low ............................
Low ............................
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FE/E.1
Low.
FE/E.1
Low.
FE/E.1
Low.
Low.
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TABLE 3—FUTURE CONDITION OF LOUISIANA PIGTOE POPULATIONS WITH A MODERATE INCREASE IN STRESSORS—
Continued
[Scenario 1]
Scenario 1 future condition
Species
River basin
Population
San Jacinto ...............
1 FE/E
East Fork San Jacinto
River.
10 years
25 years
Low ............................
Low ............................
50 years
FE/E. 1
= Functionally extirpated/extirpated.
Under Scenario 2, populations of the
Louisiana pigtoe further decline in
resiliency, redundancy, and
representation over time as the effects of
climate change impact populations
through extremely low stream flows,
severe increases in sedimentation,
Louisiana pigtoe is projected to lose four
of the seven current representation areas
in 50 years, with eight populations
remaining or becoming extirpated;
therefore, the adaptive capacity of this
species is projected to be severely
reduced in the future (see Table 4).
reductions in water quality, and an
increase in potential for desiccation of
habitat. Eight populations of Louisiana
pigtoe are expected to become either
functionally extirpated or extirpated
within 50 years, with the remaining five
populations in low condition. The
TABLE 4—FUTURE CONDITION OF LOUISIANA PIGTOE POPULATIONS WITH A SEVERE INCREASE IN STRESSORS
[Scenario 2]
Scenario 2 future condition
Species
River basin
Louisiana Pigtoe ........
Population
Red ............................
Big Cypress-Sulphur
Calcasieu-Mermentau
Pearl ..........................
Sabine .......................
Neches ......................
San Jacinto ...............
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Little River/Rolling
Fork.
Cossatot River ..........
Saline River ...............
Lower Little River ......
Big Cypress Bayou ...
Calcasieu River .........
Pearl River ................
Sabine River .............
Bayou Anacoco .........
Angelina River ...........
Neches River ............
Lower Neches River
East Fork San Jacinto
River.
10 years
25 years
50 years
Moderate ...................
High ...........................
Moderate ...................
FE/E 1 ........................
Low ............................
High ...........................
Low ............................
FE/E 1 ........................
Low.
Low.
Low.
FE/E.1
Moderate ...................
Low ............................
Low ............................
FE/E 1 ........................
Low ............................
Low ............................
High ...........................
Low ............................
Low ............................
Moderate ...................
Low ............................
Low ............................
FE/E 1 ........................
Moderate ...................
Low ............................
Low ............................
Low ............................
FE/E 1 ........................
Low.
FE/E.1
FE/E.1
FE/E.1
FE/E.1
FE/E.1
Low
FE/E.1
FE/E.1
= Functionally extirpated/extirpated.
We note that, by using the SSA
framework to guide our analysis of the
scientific information documented in
the SSA report, we have not only
analyzed individual effects on the
species, but we have also analyzed their
potential cumulative effects. We
incorporate the cumulative effects into
our SSA analysis when we characterize
the current and future condition of the
species. To assess the current and future
condition of the species, we undertake
an iterative analysis that encompasses
and incorporates the threats
individually and then accumulates and
evaluates the effects of all the factors
that may be influencing the species,
including threats and conservation
efforts. Water quality degradation,
altered hydrology, changes to habitat
structure/substrate, habitat
fragmentation, invasive species, climate
change, and collecting are all factors
that influence or could influence the
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viability of these two freshwater mussel
species. These factors also have the
potential to act cumulatively to impact
Texas heelsplitter and Louisiana pigtoe
viability and their cumulative impacts
were considered in our characterization
of the species’ current and future
condition in the SSA. Because the SSA
framework considers not just the
presence of the factors, but to what
degree they collectively influence risk to
the entire species, our assessment
integrates the cumulative effects of the
factors and replaces a standalone
cumulative effects analysis.
Determination of Status
Section 4 of the Act (16 U.S.C. 1533)
and its implementing regulations (50
CFR part 424) set forth the procedures
for determining whether a species meets
the definition of an endangered species
or a threatened species. The Act defines
an ‘‘endangered species’’ as a species in
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danger of extinction throughout all or a
significant portion of its range, and a
‘‘threatened species’’ as a species likely
to become an endangered species within
the foreseeable future throughout all or
a significant portion of its range. The
Act requires that we determine whether
a species meets the definition of an
endangered species or a threatened
species because of any of the following
factors: (A) The present or threatened
destruction, modification, or
curtailment of its habitat or range; (B)
overutilization for commercial,
recreational, scientific, or educational
purposes; (C) disease or predation; (D)
the inadequacy of existing regulatory
mechanisms; or (E) other natural or
manmade factors affecting its continued
existence.
Status Throughout All of Its Range
After evaluating threats to the Texas
heelsplitter and Louisiana pigtoe and
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assessing the cumulative effect of the
threats under the Act’s section 4(a)(1)
factors, we found that both species of
freshwater mussels have declined
significantly in overall distribution and
abundance. At present, most of the
known populations exist in very low
abundances and show limited evidence
of recruitment. Furthermore, existing
available habitats are reduced in quality
and quantity, relative to historical
conditions. Our analysis revealed six
primary threats that caused these
declines and pose a meaningful risk to
the viability of the species. These
threats are primarily related to habitat
changes (Factor A): impairment of water
quality, altered hydrology, the
accumulation of fine sediments, and
habitat fragmentation, all of which are
exacerbated by the effects of climate
change (Factor E). Predation (Factor C)
and collection (Factor B), as well as
other natural or human-induced events/
activities that result in direct mortality,
are also affecting those populations
already experiencing low stream flow,
and reservoirs and instream barriers to
fish movement (Factor E) limit dispersal
and prevent recolonization after
stochastic events.
Populations of the Texas heelsplitter
and Louisiana pigtoe are faced with a
myriad of stressors from natural and
anthropogenic sources that pose a risk
to their survival in both large and small
river segments. Climate change has the
noteworthy distinction of being able to
directly or indirectly exacerbate the
most relevant stressors to freshwater
mussels wherever they occur. Climate
projections suggest persistent droughts
over the continental United States that
are longer, cover more area, and are
more intense than what has been
experienced in the 20th century (APA
2019, p. 4; Terando et al. 2018, p. 786;
Wehner et al. 2017, p. 237). Humans are
likely to respond to climate change in
predictable ways to meet their needs,
such as increased groundwater pumping
and surface water diversions, and
increased use of reverse osmosis to treat
sources of water that are of poor quality
(thereby generating increasing volumes
of wastewater). These activities will
increase overall demand for freshwater
resources at a time when those very
resources are strained and less abundant
(reviewed in Banner et al. 2010, entire).
We expect climate change impacts to
occur throughout the range of both the
Texas heelsplitter and the Louisiana
pigtoe.
The threats to the species, acting
alone or in combination with each other
and climate change, could result in the
extirpation of additional mussel
populations, further reducing the
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overall redundancy and representation
of the Texas heelsplitter and Louisiana
pigtoe. Historically, each species,
bolstered by large, interconnected
populations (i.e., with meta-population
dynamics), would have been more
resilient to stochastic events such as
drought, excessive sedimentation, and
scouring floods. As locations became
extirpated by catastrophic events, they
could be recolonized over time by
dispersal from nearby surviving
populations, facilitated by movements
of host fish. This connectivity across
potential habitats made for highly
resilient species overall, as evidenced
by the long and successful evolutionary
history of freshwater mussels as a
taxonomic group, and in North America
in particular. However, under current
conditions, restoration of that
connectivity on a regional scale is not
feasible. Because of these current
conditions, the viability of the Texas
heelsplitter and Louisiana pigtoe now
primarily depends on maintaining the
remaining isolated populations and
potentially restoring new populations
where feasible.
Texas Heelsplitter: Status Throughout
All of Its Range
The Texas heelsplitter has declined
significantly in overall distribution and
abundance over the past 100 or more
years. Most known populations of the
Texas heelsplitter are isolated and
currently exist in very low numbers
(low abundance), have limited evidence
of recruitment, and are believed to
occupy much less habitat than in the
past (range contraction). Of the five
remaining populations of Texas
heelsplitter, three are small in
abundance and have low resiliency, and
two are considered functionally
extirpated/extirpated. While the three
low resiliency populations (Neches
River/B.A. Steinhagen Reservoir, Lower
Neches River, and Trinity River/Lake
Livingston) have habitat in high or
moderate current condition, all three
have very little evidence of
reproduction and are therefore likely to
decline due to a lack of young
individuals joining the population as
the population ages. Low abundance,
combined with the lack of evidence of
reproduction and recruitment, results in
populations with very little population
resiliency. Overall, these low levels of
resiliency, redundancy, and
representation currently result in the
Texas heelsplitter having a high risk of
extinction.
Our analysis of the species’ current
condition, as well as the conservation
efforts discussed above, show that the
Texas heelsplitter is in danger of
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extinction throughout all of its range
due to the severity and immediacy of
threats currently impacting their
populations. The risk of extinction is
high because the remaining fragmented
populations have a high risk of
extirpation, are isolated, and have
limited potential for recolonization. We
find that a threatened species status is
not appropriate for the Texas
heelsplitter because its current range is
already contracted, all populations are
fragmented and isolated from one
another, the threats are occurring across
the entire range of this species, and the
species currently exhibits low
resiliency, redundancy, and
representation. Because these
conditions place the species already in
danger of extinction throughout its
range, a threatened status is not
appropriate.
Texas Heelsplitter: Status Throughout a
Significant Portion of Its Range
Under the Act and our implementing
regulations, a species may warrant
listing if it is in danger of extinction or
likely to become so in the foreseeable
future throughout all or a significant
portion of its range. We have
determined that the Texas heelsplitter is
in danger of extinction throughout all of
its range and accordingly did not
undertake an analysis of any significant
portion of its range. Because the Texas
heelsplitter warrants listing as
endangered throughout all of its range,
our determination does not conflict with
the decision in Center for Biological
Diversity v. Everson, 2020 WL 437289
(D.D.C. Jan. 28, 2020), because that
decision related to significant portion of
the range analyses for species that
warrant listing as threatened, not
endangered, throughout all of their
range.
Texas Heelsplitter: Determination of
Status
Our review of the best available
scientific and commercial information
indicates that the Texas heelsplitter
meets the Act’s definition of an
endangered species. Therefore, we
propose to list the Texas heelsplitter as
an endangered species in accordance
with sections 3(6) and 4(a)(1) of the Act.
Louisiana Pigtoe: Status Throughout All
of Its Range
Many Louisiana pigtoe populations
are relatively abundant, but populations
are isolated from one another; therefore,
the species is unable to recolonize
following stochastic events that may
reduce or eliminate populations.
Additionally, many populations occur
in degraded habitats. Although some
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conservation efforts are underway, they
are not sufficient to prevent the decline
of the species. Thirteen populations of
Louisiana pigtoe remain. Two
populations are in high condition, four
in moderate condition, five are in low
condition, and two are functionally
extirpated/extirpated. The Red River
Basin has four populations, and only
one is in high condition (Cossatot
River), two are in moderate overall
condition, and one (Lower Little River)
is functionally extirpated/extirpated.
The Neches River is the only other
population with a high overall current
condition. Only two populations, Little
River/Rolling Fork and Cossatot River
(both within the Red River Basin), have
strong evidence of reproduction and
recruitment as indicated by presence of
fish hosts, juveniles, and gravid females;
two (Neches and Lower Neches rivers)
have moderate evidence of reproduction
and recruitment; the remaining nine
populations have low evidence of
reproduction and recruitment. Two
populations have high abundance
(Cossatot and Neches rivers) four
populations have moderate abundance
(Little River/Rolling Rock, Saline River,
Big Cypress Bayou, and Bayou
Anacoco), and five populations have
extremely low abundance (Calcasieu,
Pearl, Angelina, Lower Neches, and East
Fork San Jacinto rivers), and population
abundance is too low to support
resiliency of two populations (Lower
Little River (tributary to the Red River)
and Sabine River), which are
functionally extirpated/extirpated
We considered whether the Louisiana
pigtoe is presently in danger of
extinction throughout all of its range
and determined that endangered status
is not appropriate. The current
conditions as assessed in the SSA report
show two of the populations in two of
the representative units are in high
current condition, and four are in
moderate current condition; they are not
currently subject to declining flows or
extreme flow events. While threats are
currently acting on the species and
many of those threats are expected to
continue into the future, we did not find
that the species is currently in danger of
extinction throughout all of its range.
In the future, as extreme flow events
become more frequent as rainfall
patterns change, and increased
urbanization results in reduced
groundwater levels, we expect even
these populations to be at an increased
risk of extirpation. Given the likelihood
of climate change and other
anthropogenic effects in the foreseeable
future, within 50 years we estimate at
least five populations will become (or
remain) functionally extirpated/
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extirpated, seven will be in low
condition, and one population will be in
moderate condition. In the future, we
anticipate that the Louisiana pigtoe will
have reduced viability, with no highly
resilient populations and limited
representation and redundancy.
According to our assessment of
plausible future scenarios in the SSA
report, the species is likely to become an
endangered species in the foreseeable
future of 50 years throughout all of its
range. Fifty years encompasses about 5
generations of the Louisiana pigtoe;
additionally, projected human
population growth and the limitations
of existing resources are expected to
increase and interact with climate
effects to exacerbate the effects of
drought on surface water resources
throughout all of its range. These effects
are likely to impact the ability to
provide the minimum flow needed by
the Louisiana pigtoe. As a result, we
expect increased incidences of low
flows followed by scour events, as well
as persistent decreased water quality, to
be occurring in 50 years.
After evaluating threats to the species
and assessing the cumulative effect of
the threats under the Act’s section
4(a)(1) factors, we find that the
Louisiana pigtoe populations will
continue to decline over the next 50
years so that this species is likely to
become in danger of extinction
throughout all of its range within the
foreseeable future due to increased
frequency of drought and extremely
high-flow events, decreased water
quality, and decreased substrate
suitability.
Thus, after assessing the best available
information, we determine that the
Louisiana pigtoe is not currently in
danger of extinction but is likely to
become in danger of extinction within
the foreseeable future throughout all of
its range.
Louisiana Pigtoe: Status Throughout a
Significant Portion of Its Range
Under the Act and our implementing
regulations, a species may warrant
listing if it is in danger of extinction or
likely to become so in the foreseeable
future throughout all or a significant
portion of its range. The court in Center
for Biological Diversity v. Everson, 2020
WL 437289 (D.D.C. Jan. 28, 2020)
(Everson), vacated the aspect of the
Final Policy on Interpretation of the
Phrase ‘‘Significant Portion of Its
Range’’ in the Endangered Species Act’s
Definitions of ‘‘Endangered Species’’
and ‘‘Threatened Species’’ (Final Policy)
(79 FR 37578; July 1, 2014) that
provided that the Service does not
undertake an analysis of significant
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portions of a species’ range if the
species warrants listing as threatened
throughout all of its range. Therefore,
we proceed to evaluating whether the
species is endangered in a significant
portion of its range—that is, whether
there is any portion of the species’ range
for which both (1) the portion is
significant; and (2) the species is in
danger of extinction in that portion.
Depending on the case, it might be more
efficient for us to address the
‘‘significance’’ question or the ‘‘status’’
question first. We can choose to address
either question first. Regardless of
which question we address first, if we
reach a negative answer with respect to
the first question that we address, we do
not need to evaluate the other question
for that portion of the species’ range.
Following the court’s holding in
Everson, we now consider whether
there are any significant portions of the
species’ range where the species is in
danger of extinction now (i.e.,
endangered). In undertaking this
analysis for the Louisiana pigtoe, we
choose to address the status question
first—we consider information
pertaining to the geographic distribution
of both the species and the threats that
the species faces to identify any
portions of the range where the species
may be endangered.
For the Louisiana pigtoe, we consider
abundance to be the most direct
measure of the health and status of the
species (see Species Condition, above).
Measures like water quality and
hydrology may rank moderate or high,
indicating higher quality habitat—but
that does not necessarily indicate the
presence of Louisiana pigtoe, only
presence of suitable habitat. All six
factors were weighted equally in
importance except abundance, which
was viewed as the most relevant and
direct measure of current biological
condition; therefore, overall condition
was capped by the abundance score
such that no population’s overall
condition could exceed the abundance
score. By capping abundance, we
ensured that the overall current
condition score is based on speciesspecific information. There are five
populations that are considered to be in
low overall current condition (with
between 3–25 individuals found per
population survey) and two that are
considered functionally extirpated/
extirpated (with less than 3 individuals
found per population survey). In
addition to low abundance, there was a
lack of evidence of reproduction in 9 of
the 13 populations; these two
population factors are similar in scope,
scale, and distribution across the range
of the species (See Reproduction/
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Recruitment in Species Needs above).
We then considered whether these
populations that are at higher risk of
extirpation are geographically
concentrated in any portion of the
species’ range at a biologically
meaningful scale.
We examined the range of Louisiana
pigtoe for biologically meaningful
portions that may be at higher risk of
extirpation, as reflected by current
population resiliency. The range of
Louisiana pigtoe is relatively large, and
populations are distributed in varying
conditions across the range. Therefore,
we examined the range based on
accepted mussel faunal provinces (i.e.,
Haag 2010, p. 18), which reflect
phylogenetic relationships as well as
physiogeographical differences in
stream habitat. The faunal provinces
germane to the range of the Louisiana
pigtoe are Interior Highlands (includes
the Little River and tributaries),
Mississippi Embayment (includes Big
Cypress Bayou), Sabine-Trinity
(includes Upper Calcasieu, Sabine,
Angelina, Neches, and East Fork San
Jacinto Rivers, and Bayou Anacoco), and
Pontchartrain-Pearl-Pascagoula
(includes Pearl River). Of these faunal
provinces, the Interior Highlands,
Sabine-Trinity, and Pontchartrain-PearlPascagoula faunal provinces contain
populations in low condition or that are
functionally extirpated and therefore are
at higher risk of extirpation.
The Interior Highlands faunal
province is characterized by upland
streams in the Ozark and Ouachita
mountains. This province has numerous
endemic aquatic species of both fish and
freshwater mussels, due to the isolation
of the river systems within the province
from each other and from other upland
river systems (Haag 2012, pp. 82–83). In
this faunal province, the Lower Little
River is functionally extirpated, with
the remaining populations in moderate
(Little River and Saline River) or high
(Cossatot River) condition. While the
populations in this faunal province are
subject to threats such as erratic flows
capable of causing bed movement or
dislocation of mussels, increased
sedimentation, altered water chemistry
(e.g., low temperatures), and decreased
water quality due to higher pollutant
loads from urban areas and industrial
wastewater discharges, the threats are
primarily occurring in the future. Under
a moderate increase in stressors based
on the lower greenhouse gas emissions
trajectory (RCP 4.5), model projections
expect an increase in global mean
surface temperatures that will alter
precipitation events resulting in drought
and flooding in the next 25–50 years,
this combined with future human
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demand for water resources indicate an
overall decline in populations in the
future. Louisiana pigtoe within the
Interior Highlands faunal province are
not currently in danger of extinction;
therefore, they do not have a different
status from the remainder of the species’
range.
The Sabine-Trinity faunal province is
located in the central Gulf Coast of
Texas, and characterized by lowland
streams and rivers, with lentic and
wetland habitats bordering the main
channels (Haag 2012, pp. 86–87). In this
faunal province, the Upper Calcasieu
River, Angelina River, Lower Neches
River, and the East Fork San Jacinto
River are in low condition, the Sabine
River is functionally extirpated, with
the remaining populations in moderate
(Big Cypress Bayou) or high condition
(Neches River). While the populations
in this faunal province are being
affected by impoundments resulting in
threats such as excessive sedimentation
and water quality degradation, as well
as ongoing agricultural activities,
groundwater withdrawals, and surface
water diversions, these threats are
primarily occurring in the future. Under
a moderate increase in stressors based
on the lower greenhouse gas emissions
trajectory (RCP 4.5), model projections
expect an increase in global mean
surface temperatures that will alter
precipitation events resulting in more
extreme drought and flooding
conditions that reduces water quality,
mobilizes substrates, eroded habitat or
deposits sentiments on Louisiana pigtoe
populations in the next 25–50 years.
The Sabine-Trinity faunal province are
not currently in danger of extinction;
therefore, they do not have a different
status from the remainder of the species’
range.
The Pontchartrain-Pearl-Pascagoula
faunal province lies entirely within the
Coastal Plain and is characterized by
lowland streams filled with sandy and
fine sediments, with lentic and wetland
habitats alongside the main stream
channels (Haag 2012, p. 87.). This
province has numerous endemic aquatic
species of both fish and freshwater
mussels, the majority of which are
shared with the Mobile Basin province
(Haag 2012, pp. 87–89), and includes
the Pearl River population in an overall
low condition. The Pearl River
population in this faunal province is
subject to threats such as erratic flows
from water releases from the Ross
Barrett Dam that are capable of causing
bed movement or dislocation of
mussels, increased sedimentation, and
altered water chemistry (e.g., low
temperatures), the threats are primarily
occurring in the future. Under a
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moderate greenhouse gas emission
trajectory (RCP 4.5), model projections
no changes from current condition are
expected within 10-years. Within 25years, hydrologic conditions would be
negatively affected by the construction
of a flood control reservoir proposed for
the upper portion of the focal area,
resulting in a moderate decline in
substrate condition as sediments
accumulate on mussel beds from a lack
or cleansing flows, and water quality
degradation. Although these threats are
not unique to this area, they may be
acting at a greater intensity here, either
individually or in combination, than
elsewhere in the range, given the low
abundance of Louisiana pigtoe in this
reach. The small size of this population,
coupled with the current condition
information in the SSA report
suggesting the population in this area
has low resiliency, indicates the
populations in the Pontchartrain-PearlPascagoula faunal province may be in
danger of extinction now.
We evaluated the available
information about this portion of the
range of Louisiana pigtoe that occupies
the upper Pearl River in this context,
assessing its biological significance in
terms of the three habitat criteria
(habitat/structure, hydrology, and water
quality; see Species Condition) used to
assign the current condition of
Louisiana Pigtoe populations, and
determined the information did not
indicate it may be significant. Louisiana
pigtoe in this population exhibit similar
habitat and host fish use to Louisiana
pigtoe in the remainder of its range;
thus, there is no unique observable
environmental usage or behavioral
characteristics attributable to just this
area’s population. The Pearl River is not
essential to any specific life-history
function of the Louisiana pigtoe that is
not found elsewhere in the range.
Further, the habitat in the Pearl River
does not contain higher quality or
higher value than the remainder of the
species’ range of the Louisiana pigtoe
(see Table 3). Additionally, this
population does not interact with other
populations of the species. Overall, we
found no substantial information that
would indicate the population in the
Pearl River may be significant. While
this reach provides some contribution to
the species’ overall ability to withstand
catastrophic or stochastic events
(redundancy and resiliency,
respectively), the species has larger
populations in adjacent faunal
provinces. The best scientific and
commercial information available
indicate that this populations’
contribution is very limited in scope
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due to small population size and
isolation from other populations.
Therefore, because we could not answer
both the status and significance
questions in the affirmative, we
conclude that the Pearl River does not
warrant further consideration as a
significant portion of the range of the
Louisiana pigtoe.
Therefore, no portion of the species’
range provides a basis for determining
that the species is in danger of
extinction in a significant portion of its
range, and we determine that the
species is likely to become in danger of
extinction within the foreseeable future
throughout all of its range. This does not
conflict with the courts’ holdings in
Desert Survivors v. Department of the
Interior, 321 F. Supp. 3d 1011, 1070–74
(N.D. Cal. 2018), and Center for
Biological Diversity v. Jewell, 248 F.
Supp. 3d, 946, 959 (D. Ariz. 2017)
because, in reaching this conclusion, we
did not need to consider whether any
portions are significant and, therefore,
did not apply the aspects of the Final
Policy’s definition of ‘‘significant’’ that
those court decisions held were invalid.
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Louisiana Pigtoe: Determination of
Status
Our review of the best available
scientific and commercial information
indicates that the Louisiana pigtoe
meets the Act’s definition of a
threatened species. Therefore, we
propose to list the Louisiana pigtoe as
a threatened species in accordance with
sections 3(20) and 4(a)(1) of the Act.
Available Conservation Measures
Conservation measures provided to
species listed as endangered or
threatened species under the Act
include recognition as a listed species,
planning and implementation of
recovery actions, requirements for
Federal protection, and prohibitions
against certain practices. Recognition
through listing results in public
awareness, and conservation by Federal,
State, Tribal, and local agencies, private
organizations, and individuals. The Act
encourages cooperation with the States
and other countries and calls for
recovery actions to be carried out for
listed species. The protection required
by Federal agencies, including the
Service, and the prohibitions against
certain activities are discussed, in part,
below.
The primary purpose of the Act is the
conservation of endangered and
threatened species and the ecosystems
upon which they depend. The ultimate
goal of such conservation efforts is the
recovery of these listed species, so that
they no longer need the protective
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measures of the Act. Section 4(f) of the
Act calls for the Service to develop and
implement recovery plans for the
conservation of endangered and
threatened species. The goal of this
process is to restore listed species to a
point where they are secure, selfsustaining, and functioning components
of their ecosystems.
The recovery planning process begins
with development of a recovery outline
made available to the public soon after
a final listing determination. The
recovery outline guides the immediate
implementation of urgent recovery
actions while a recovery plan is being
developed. Recovery teams (composed
of species experts, Federal and State
agencies, nongovernmental
organizations, and stakeholders) may be
established to develop and implement
recovery plans. The recovery planning
process involves the identification of
actions that are necessary to halt and
reverse the species’ decline by
addressing the threats to its survival and
recovery. The recovery plan identifies
recovery criteria for review of when a
species may be ready for reclassification
from endangered to threatened
(‘‘downlisting’’) or removal from
protected status (‘‘delisting’’), and
methods for monitoring recovery
progress. Recovery plans also establish
a framework for agencies to coordinate
their recovery efforts and provide
estimates of the cost of implementing
recovery tasks. Revisions of the plan
may be done to address continuing or
new threats to the species, as new
substantive information becomes
available. The recovery outline, draft
recovery plan, final recovery plan, and
any revisions will be available on our
website as they are completed (https://
www.fws.gov/program/endangeredspecies).
Implementation of recovery actions
generally requires the participation of a
broad range of partners, including other
Federal agencies, States, Tribes,
nongovernmental organizations,
businesses, and private landowners.
Examples of recovery actions include
habitat restoration (e.g., restoration of
native vegetation), research, captive
propagation and reintroduction, and
outreach and education. The recovery of
many listed species cannot be
accomplished solely on Federal lands
because their ranges may occur
primarily or solely on non-Federal
lands. To achieve recovery of these
species requires cooperative
conservation efforts on private, State,
and Tribal lands.
If these species are listed, funding for
recovery actions will be available from
a variety of sources, including Federal
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budgets, State programs, and cost-share
grants for non-Federal landowners, the
academic community, and
nongovernmental organizations. In
addition, pursuant to section 6 of the
Act, the States of Arkansas, Oklahoma,
Louisiana, Mississippi, and Texas
would be eligible for Federal funds to
implement management actions that
promote the protection or recovery of
the Texas heelsplitter and Louisiana
pigtoe. Information on our grant
programs that are available to aid
species recovery can be found at:
https://www.fws.gov/service/financialassistance.
Although the Texas heelsplitter and
Louisiana pigtoe are only proposed for
listing under the Act at this time, please
let us know if you are interested in
participating in recovery efforts for
these species. Additionally, we invite
you to submit any new information on
these species whenever it becomes
available and any information you may
have for recovery planning purposes
(see FOR FURTHER INFORMATION CONTACT).
Section 7(a) of the Act requires
Federal agencies to evaluate their
actions with respect to any species that
is proposed or listed as an endangered
or threatened species and with respect
to its critical habitat, if any is
designated. Regulations implementing
this interagency cooperation provision
of the Act are codified at 50 CFR part
402. Section 7(a)(4) of the Act requires
Federal agencies to confer with the
Service on any action that is likely to
jeopardize the continued existence of a
species proposed for listing or result in
destruction or adverse modification of
proposed critical habitat. If a species is
listed subsequently, section 7(a)(2) of
the Act requires Federal agencies to
ensure that activities they authorize,
fund, or carry out are not likely to
jeopardize the continued existence of
the species or destroy or adversely
modify its critical habitat. If a Federal
action may affect a listed species or its
critical habitat, the responsible Federal
agency must enter into consultation
with the Service.
Federal agency actions within the
species’ habitat that may require
conference or consultation or both as
described in the preceding paragraph
include management and any other
landscape-altering activities on Federal
lands administered by the Federal
Emergency Management Agency
(related to disaster recovery projects),
National Park Service, Natural
Resources Conservation Service,
National Wildlife Refuge System, U.S.
Army, U.S. Army Corps of Engineers,
and the U.S. Forest Service.
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The Act and its implementing
regulations set forth a series of general
prohibitions and exceptions that apply
to endangered wildlife. The prohibitions
of section 9(a)(1) of the Act, codified at
50 CFR 17.21, make it illegal for any
person subject to the jurisdiction of the
United States to take (which includes
harass, harm, pursue, hunt, shoot,
wound, kill, trap, capture, or collect; or
to attempt any of these) endangered
wildlife within the United States or on
the high seas. In addition, it is unlawful
to import; export; deliver, receive, carry,
transport, or ship in interstate or foreign
commerce in the course of commercial
activity; or sell or offer for sale in
interstate or foreign commerce any
species listed as an endangered species.
It is also illegal to possess, sell, deliver,
carry, transport, or ship any such
wildlife that has been taken illegally.
Certain exceptions apply to employees
of the Service, the National Marine
Fisheries Service, other Federal land
management agencies, and State
conservation agencies.
We may issue permits to carry out
otherwise prohibited activities
involving endangered wildlife under
certain circumstances. Regulations
governing permits are codified at 50
CFR 17.22. With regard to endangered
wildlife, a permit may be issued for the
following purposes: For scientific
purposes, to enhance the propagation or
survival of the species, and for
incidental take in connection with
otherwise lawful activities. The statute
also contains certain exemptions from
the prohibitions, which are found in
sections 9 and 10 of the Act.
It is our policy, as published in the
Federal Register on July 1, 1994 (59 FR
34272), to identify to the maximum
extent practicable at the time a species
is listed, those activities that would or
would not constitute a violation of
section 9 of the Act. The intent of this
policy is to increase public awareness of
the effect of a proposed listing on
proposed and ongoing activities within
the range of the species proposed for
listing. The Act allows the Secretary to
promulgate protective regulations for
threatened species pursuant to section
4(d) of the Act. The discussion in the
following section, Proposed Rule Issued
Under Section 4(d) of the Act, regarding
protective regulations under section 4(d)
of the Act for the Louisiana pigtoe
complies with our policy.
For the Texas heelsplitter, based on
the best available information, the
following actions are unlikely to result
in a violation of section 9, if these
activities are carried out in accordance
with existing regulations and permit
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requirements; this list is not
comprehensive:
(1) Normal agricultural and
silvicultural practices, including
herbicide and pesticide use, that are
carried out in accordance with any
existing regulations, permit and label
requirements, and best management
practices; and
(2) Normal residential landscaping
activities.
Based on the best available
information, the following activities
may potentially result in a violation of
section 9 of the Act, if they are not
authorized in accordance with
applicable law; this list is not
comprehensive:
(1) Unauthorized handling or
collecting of the species;
(2) Unauthorized destruction or
alteration of Texas heelsplitter habitat
by dredging, channelization,
impoundment, diversion, recreational
vehicle operation within the stream
channel, sand or gravel removal, or
other activities that result in the
destruction or significant degradation of
channel or bank stability, streamflow/
water quantity, substrate composition,
and water quality used by the species
for foraging, cover, and reproduction;
(3) Modification of the channel or
water flow of any stream, including the
withdrawal (decrease) or
supplementation (increase) of surface or
ground waters where the Texas
heelsplitter is known to occur;
(4) Livestock grazing that results in
direct or indirect destruction of riparian
or instream habitat; and
(5) Unauthorized discharge of
chemicals (including pesticides and
fertilizers in violation of label
restrictions), household waste, silt,
sediments, fill material, or other
pollutants (e.g., sewage, oil and
gasoline, heavy metals), into any waters
or their adjoining riparian areas where
the Texas heelsplitter is known to occur.
Questions regarding whether specific
activities would constitute a violation of
section 9 of the Act should be directed
to the Arlington Ecological Services
Field Office (see FOR FURTHER
INFORMATION CONTACT).
II. Proposed Rule Issued Under Section
4(d) of the Act
Background
Section 4(d) of the Act contains two
sentences. The first sentence states that
the Secretary shall issue such
regulations as she deems necessary and
advisable to provide for the
conservation of species listed as
threatened. The U.S. Supreme Court has
noted that statutory language similar to
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the language in section 4(d) of the Act
authorizing the Secretary to take action
that she ‘‘deems necessary and
advisable’’ affords a large degree of
deference to the agency (see Webster v.
Doe, 486 U.S. 592 (1988)). Conservation
is defined in the Act to mean the use of
all methods and procedures which are
necessary to bring any endangered
species or threatened species to the
point at which the measures provided
pursuant to the Act are no longer
necessary. Additionally, the second
sentence of section 4(d) of the Act states
that the Secretary may by regulation
prohibit with respect to any threatened
species any act prohibited under section
9(a)(1), in the case of fish or wildlife, or
section 9(a)(2), in the case of plants.
Thus, the combination of the two
sentences of section 4(d) provides the
Secretary with wide latitude of
discretion to select and promulgate
appropriate regulations tailored to the
specific conservation needs of the
threatened species. The second sentence
grants particularly broad discretion to
the Service when adopting the
prohibitions under section 9.
The courts have recognized the extent
of the Secretary’s discretion under this
standard to develop rules that are
appropriate for the conservation of a
species. For example, courts have
upheld, as a valid exercise of agency
authority, rules developed under section
4(d) that included limited prohibitions
against takings (see Alsea Valley
Alliance v. Lautenbacher, 2007 U.S.
Dist. Lexis 60203 (D. Or. 2007);
Washington Environmental Council v.
National Marine Fisheries Service, 2002
WL 511479 (W.D. Wash. 2002)). Courts
have also upheld 4(d) rules that do not
address all of the threats a species faces
(see State of Louisiana v. Verity, 853
F.2d 322 (5th Cir. 1988)). As noted in
the legislative history when the Act was
initially enacted, ‘‘once an animal is on
the threatened list, the Secretary has an
almost infinite number of options
available to [her] with regard to the
permitted activities for those species.
[She] may, for example, permit taking,
but not importation of such species, or
[she] may choose to forbid both taking
and importation but allow the
transportation of such species’’ (H.R.
Rep. No. 412, 93rd Cong., 1st Sess.
1973).
The provisions of this proposed 4(d)
rule would promote conservation of the
Louisiana pigtoe by encouraging
riparian landscape conservation while
also meeting the conservation needs of
the Louisiana pigtoe. By streamlining
those projects that follow best
management practices and improve
instream habitat (such as streambank
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stabilization, instream channel
restoration, and upland restoration that
improves instream habitat),
conservation is more likely to occur for
Louisiana pigtoe, improving the
condition of populations in those
reaches. The provisions of this proposed
rule are several of many tools that we
would use to promote the conservation
of the Louisiana pigtoe. This proposed
4(d) rule would apply only if and when
we make final the listing of the
Louisiana pigtoe as a threatened species.
As mentioned previously in Available
Conservation Measures, section 7(a)(2)
of the Act requires Federal agencies,
including the Service, to ensure that any
action they fund, authorize, or carry out
is not likely to jeopardize the continued
existence of any endangered species or
threatened species or result in the
destruction or adverse modification of
designated critical habitat of such
species. In addition, section 7(a)(4) of
the Act requires Federal agencies to
confer with the Service on any agency
action that is likely to jeopardize the
continued existence of any species
proposed to be listed under the Act or
result in the destruction or adverse
modification of proposed critical
habitat.
If a Federal action may affect a listed
species or its critical habitat, the
responsible Federal agency (action
agency) must enter into consultation
with us. Examples of Federal actions
that are subject to the section 7
consultation process are actions on
State, Tribal, local, or private lands that
require a Federal permit (such as a
permit from the U.S. Army Corps of
Engineers under section 404 of the
Clean Water Act (33 U.S.C. 1251 et seq.)
or a permit from the Service under
section 10 of the Act) or that involve
some other Federal action (such as
funding from the Federal Highway
Administration, Federal Aviation
Administration, or the Federal
Emergency Management Agency).
Federal actions not affecting listed
species or critical habitat—and actions
on State, Tribal, local, or private lands
that are not federally funded,
authorized, or carried out by a Federal
agency—do not require section 7
consultation.
These requirements are the same for
a threatened species with a speciesspecific 4(d) rule. For example, a
Federal agency’s determination that an
action is ‘‘not likely to adversely affect’’
a threatened species will require the
Service’s written concurrence.
Similarly, a Federal agency’s
determination that an action is ‘‘likely
to adversely affect’’ a threatened species
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will require formal consultation and the
formulation of a biological opinion.
Provisions of the Proposed 4(d) Rule
Exercising the Secretary’s authority
under section 4(d) of the Act, we have
developed a proposed rule that is
designed to address the Louisiana
pigtoe’s specific conservation needs. As
discussed previously in Summary of
Biological Status and Threats, we have
concluded that the Louisiana pigtoe is
likely to become in danger of extinction
within the foreseeable future primarily
due to habitat changes such as the
accumulation of fine sediments, altered
hydrology, and impairment of water
quality; predation and collection; and
barriers to fish movement. Section 4(d)
requires the Secretary to issue such
regulations as she deems necessary and
advisable to provide for the
conservation of each threatened species
and authorizes the Secretary to include
among those protective regulations any
of the prohibitions that section 9(a)(2) of
the Act prescribes for endangered
species. We find that, if finalized, the
protections, prohibitions, and
exceptions in this proposed rule as a
whole satisfy the requirement in section
4(d) of the Act to issue regulations
deemed necessary and advisable to
provide for the conservation of the
Louisiana pigtoe.
The protective regulations we are
proposing for the Louisiana pigtoe
incorporate prohibitions from section
9(a)(1) to address the threats to the
species. Section 9(a)(1) prohibits the
following activities for endangered
wildlife: importing or exporting; take;
possession and other acts with
unlawfully taken specimens; delivering,
receiving, transporting, or shipping in
interstate or foreign commerce in the
course of commercial activity; or selling
or offering for sale in interstate or
foreign commerce. This protective
regulation includes most of these
prohibitions for the Louisiana pigtoe
because the Louisiana pigtoe is at risk
of extinction in the foreseeable future
and putting these prohibitions in place
will help to preserve the species’
remaining populations, slow its rate of
decline, and decrease synergistic,
negative effects from other stressors.
In particular, this proposed 4(d) rule
would provide for the conservation of
the Louisiana pigtoe by prohibiting the
following activities, unless they fall
within specific exceptions or are
otherwise authorized or permitted:
Importing or exporting; take; possession
and other acts with unlawfully taken
specimens; delivering, receiving,
transporting, or shipping in interstate or
foreign commerce in the course of
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commercial activity; or selling or
offering for sale in interstate or foreign
commerce.
Under the Act, ‘‘take’’ means to
harass, harm, pursue, hunt, shoot,
wound, kill, trap, capture, or collect, or
to attempt to engage in any such
conduct. Some of these provisions have
been further defined in regulations at 50
CFR 17.3. Take can result knowingly or
otherwise, by direct and indirect
impacts, intentionally or incidentally.
Regulating incidental and intentional
take would help preserve the species’
remaining populations, slow their rate
of decline, and decrease synergistic,
negative effects from other stressors.
Therefore, we propose to prohibit take
of the Louisiana pigtoe, except for take
resulting from those actions and
activities specifically excepted by the
4(d) rule.
Exceptions to the prohibition on take
would include most of the general
exceptions to the prohibition against
take of endangered wildlife, as set forth
in 50 CFR 17.21 and certain other
specific activities that we propose for
exception, as described below.
The proposed 4(d) rule would also
provide for the conservation of the
species by allowing exceptions that
incentivize conservation actions or that,
while they may have some minimal
level of take of the Louisiana pigtoe, are
not expected to rise to the level that
would have a negative impact (i.e.,
would have only de minimis impacts)
on the species’ conservation. The
proposed exceptions to these
prohibitions include the following
activities that are expected to have
negligible impacts to the Louisiana
pigtoe and its habitat:
(1) Channel restoration projects that
create natural, physically stable
(streambanks and substrate remaining
relatively unchanging over time),
ecologically functioning streams or
stream and wetland systems (containing
an assemblage of fish, mussels, other
invertebrates, and plants) that are
reconnected with their groundwater
aquifers. These projects can be
accomplished using a variety of
methods, but the desired outcome is a
natural channel with low shear stress
(force of water moving against the
channel); bank heights that enable
reconnection to the floodplain; a
reconnection of surface and
groundwater systems, resulting in
perennial flows in the channel; riffles
and pools composed of existing soil,
rock, and wood instead of large
imported materials; low compaction of
soils within adjacent riparian areas; and
inclusion of riparian wetlands and
woodland buffers. This exception to the
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proposed 4(d) rule for incidental take
would promote conservation of
Louisiana pigtoe by creating stable
stream channels that are less likely to
scour during high-flow events, thereby
increasing population resiliency.
(2) Bioengineering methods such as
streambank stabilization using live
native stakes (live, vegetative cuttings
inserted or tamped into the ground in a
manner that allows the stake to take root
and grow), live native fascines (live
branch cuttings, usually willows, bound
together into long, cigar-shaped
bundles), or native brush layering
(cuttings or branches of easily rooted
tree species layered between successive
lifts of soil fill). These methods must not
include the sole use of quarried rock
(rip-rap) or the use of rock baskets or
gabion structures. In addition, to reduce
streambank erosion and sedimentation
into the stream, work using these
bioengineering methods must be
performed at base flow or low water
conditions and when significant rainfall
is not predicted. Further, streambank
stabilization projects must keep all
equipment out of the stream channels
and water. Similar to channel
restoration projects, this exception to
the proposed 4(d) rule for incidental
take would promote conservation of
Louisiana pigtoe by creating stable
stream channels that are less likely to
scour during high-flow events, thereby
increasing population resiliency.
(3) Soil and water conservation
practices and riparian and adjacent
upland habitat management activities
that restore instream habitats for the
species, restore adjacent riparian
habitats that enhance stream habitats for
the species, stabilize degraded and
eroding stream banks to limit
sedimentation and scour of the species’
habitats, and restore or enhance nearby
upland habitats to limit sedimentation
of the species’ habitats. We recommend
that these practices and activities
comply with specifications and
technical guidelines developed by the
U.S. Department of Agriculture’s
Natural Resources Conservation Service
(NRCS), as soil and water conservation
practices and aquatic species habitat
restoration projects associated with
NRCS conservation plans are designed
to improve water quality and enhance
fish and aquatic species habitats. This
exception to the proposed 4(d) rule for
incidental take would promote
conservation of Louisiana pigtoe by
creating stable stream channels and
reducing sediment inputs to the stream,
thereby increasing population
resiliency.
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We include other standard exceptions
to the prohibitions in the proposed 4(d)
rule for the Louisiana pigtoe.
Despite these prohibitions regarding
threatened species, we may under
certain circumstances issue permits to
carry out one or more otherwiseprohibited activities, including those
described above. The regulations that
govern permits for threatened wildlife
state that the Director may issue a
permit authorizing any activity
otherwise prohibited with regard to
threatened species. These include
permits issued for the following
purposes: for scientific purposes, to
enhance propagation or survival, for
economic hardship, for zoological
exhibition, for educational purposes, for
incidental taking, or for special
purposes consistent with the purposes
of the Act (50 CFR 17.32). The statute
also contains certain exemptions from
the prohibitions, which are found in
sections 9 and 10 of the Act.
We recognize the special and unique
relationship with our State natural
resource agency partners in contributing
to conservation of listed species. State
agencies often possess scientific data
and valuable expertise on the status and
distribution of endangered, threatened,
and candidate species of wildlife and
plants. State agencies, because of their
authorities and their close working
relationships with local governments
and landowners, are in a unique
position to assist us in implementing all
aspects of the Act. In this regard, section
6 of the Act provides that we must
cooperate to the maximum extent
practicable with the States in carrying
out programs authorized by the Act.
Therefore, any qualified employee or
agent of a State conservation agency that
is a party to a cooperative agreement
with us in accordance with section 6(c)
of the Act, who is designated by his or
her agency for such purposes, would be
able to conduct activities designed to
conserve Louisiana pigtoe that may
result in otherwise prohibited take
without additional authorization.
Nothing in this proposed 4(d) rule
would change in any way the recovery
planning provisions of section 4(f) of the
Act, the consultation requirements
under section 7 of the Act, or our ability
to enter into partnerships for the
management and protection of the
Louisiana pigtoe. However, interagency
cooperation may be further streamlined
through planned programmatic
consultations for the species between us
and other Federal agencies, where
appropriate. We ask the public,
particularly State agencies and other
interested stakeholders that may be
affected by the proposed 4(d) rule, to
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provide comments and suggestions
regarding additional guidance and
methods that we could provide or use,
respectively, to streamline the
implementation of this proposed 4(d)
rule (see Information Requested, above).
III. Critical Habitat
Background
Critical habitat is defined in section 3
of the Act as:
(1) The specific areas within the
geographical area occupied by the
species, at the time it is listed in
accordance with the Act, on which are
found those physical or biological
features
(a) Essential to the conservation of the
species, and
(b) Which may require special
management considerations or
protection; and
(2) Specific areas outside the
geographical area occupied by the
species at the time it is listed, upon a
determination that such areas are
essential for the conservation of the
species.
Our regulations at 50 CFR 424.02
define the geographical area occupied
by the species as an area that may
generally be delineated around species’
occurrences, as determined by the
Secretary (i.e., range). Such areas may
include those areas used throughout all
or part of the species’ life cycle, even if
not used on a regular basis (e.g.,
migratory corridors, seasonal habitats,
and habitats used periodically, but not
solely by vagrant individuals).
Conservation, as defined under
section 3 of the Act, means to use and
the use of all methods and procedures
that are necessary to bring an
endangered or threatened species to the
point at which the measures provided
pursuant to the Act are no longer
necessary. Such methods and
procedures include, but are not limited
to, all activities associated with
scientific resources management such as
research, census, law enforcement,
habitat acquisition and maintenance,
propagation, live trapping, and
transplantation, and, in the
extraordinary case where population
pressures within a given ecosystem
cannot be otherwise relieved, may
include regulated taking.
Critical habitat receives protection
under section 7 of the Act through the
requirement that Federal agencies
ensure, in consultation with the Service,
that any action they authorize, fund, or
carry out is not likely to result in the
destruction or adverse modification of
critical habitat. The designation of
critical habitat does not affect land
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ownership or establish a refuge,
wilderness, reserve, preserve, or other
conservation area. Such designation also
does not allow the government or public
to access private lands. Such
designation does not require
implementation of restoration, recovery,
or enhancement measures by nonFederal landowners. Where a landowner
requests Federal agency funding or
authorization for an action that may
affect a listed species or critical habitat,
the Federal agency would be required to
consult with the Service under section
7(a)(2) of the Act. However, even if the
Service were to conclude that the
proposed activity would likely result in
destruction or adverse modification of
the critical habitat, the Federal action
agency and the landowner are not
required to abandon the proposed
activity, or to restore or recover the
species; instead, they must implement
‘‘reasonable and prudent alternatives’’
to avoid destruction or adverse
modification of critical habitat.
Under the first prong of the Act’s
definition of critical habitat, areas
within the geographical area occupied
by the species at the time it was listed
are included in a critical habitat
designation if they contain physical or
biological features (1) which are
essential to the conservation of the
species and (2) which may require
special management considerations or
protection. For these areas, critical
habitat designations identify, to the
extent known using the best scientific
and commercial data available, those
physical or biological features that are
essential to the conservation of the
species (such as space, food, cover, and
protected habitat).
Under the second prong of the Act’s
definition of critical habitat, we can
designate critical habitat in areas
outside the geographical area occupied
by the species at the time it is listed,
upon a determination that such areas
are essential for the conservation of the
species.
Section 4 of the Act requires that we
designate critical habitat on the basis of
the best scientific data available.
Further, our Policy on Information
Standards Under the Endangered
Species Act (published in the Federal
Register on July 1, 1994 (59 FR 34271)),
the Information Quality Act (section 515
of the Treasury and General
Government Appropriations Act for
Fiscal Year 2001 (Pub. L. 106–554; H.R.
5658)), and our associated Information
Quality Guidelines provide criteria,
establish procedures, and provide
guidance to ensure that our decisions
are based on the best scientific data
available. They require our biologists, to
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the extent consistent with the Act and
with the use of the best scientific data
available, to use primary and original
sources of information as the basis for
recommendations to designate critical
habitat.
When we are determining which areas
should be designated as critical habitat,
our primary source of information is
generally the information from the SSA
report and information developed
during the listing process for the
species. Additional information sources
may include any generalized
conservation strategy, criteria, or outline
that may have been developed for the
species; the recovery plan for the
species; articles in peer-reviewed
journals; conservation plans developed
by States and counties; scientific status
surveys and studies; biological
assessments; other unpublished
materials; or experts’ opinions or
personal knowledge.
Habitat is dynamic, and species may
move from one area to another over
time. We recognize that critical habitat
designated at a particular point in time
may not include all of the habitat areas
that we may later determine are
necessary for the recovery of the
species. For these reasons, a critical
habitat designation does not signal that
habitat outside the designated area is
unimportant or may not be needed for
recovery of the species. Areas that are
important to the conservation of the
species, both inside and outside the
critical habitat designation, will
continue to be subject to: (1)
Conservation actions implemented
under section 7(a)(1) of the Act; (2)
regulatory protections afforded by the
requirement in section 7(a)(2) of the Act
for Federal agencies to ensure their
actions are not likely to jeopardize the
continued existence of any endangered
or threatened species; and (3) the
prohibitions found in section 9 of the
Act. Federally funded or permitted
projects affecting listed species outside
their designated critical habitat areas
may still result in jeopardy findings in
some cases. These protections and
conservation tools will continue to
contribute to recovery of this species.
Similarly, critical habitat designations
made on the basis of the best available
information at the time of designation
will not control the direction and
substance of future recovery plans,
habitat conservation plans (HCPs), or
other species conservation planning
efforts if new information available at
the time of these planning efforts calls
for a different outcome.
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Prudency Determination
Section 4(a)(3) of the Act, as
amended, and implementing regulations
(50 CFR 424.12) require that, to the
maximum extent prudent and
determinable, the Secretary shall
designate critical habitat at the time the
species is determined to be an
endangered or threatened species. Our
regulations (50 CFR 424.12(a)(1)) state
that the Secretary may, but is not
required to, determine that a
designation would not be prudent in the
following circumstances:
(i) The species is threatened by taking
or other human activity and
identification of critical habitat can be
expected to increase the degree of such
threat to the species;
(ii) The present or threatened
destruction, modification, or
curtailment of a species’ habitat or range
is not a threat to the species, or threats
to the species’ habitat stem solely from
causes that cannot be addressed through
management actions resulting from
consultations under section 7(a)(2) of
the Act;
(iii) Areas within the jurisdiction of
the United States provide no more than
negligible conservation value, if any, for
a species occurring primarily outside
the jurisdiction of the United States;
(iv) No areas meet the definition of
critical habitat; or
(v) The Secretary otherwise
determines that designation of critical
habitat would not be prudent based on
the best scientific data available.
As discussed earlier in this document,
there are well documented beds of
Louisiana pigtoe that are sampled for
scientific projects, and to a lesser degree
collected by fishing enthusiasts for use
as bait. Because these areas are already
well known, and they are not being
collected for private collections, there is
currently no additional imminent threat
of collection or vandalism identified
under Factor B for these species, and
identification and mapping of critical
habitat is not expected to initiate any
such threat. In our SSA and proposed
listing determination for the Texas
heelsplitter and Louisiana pigtoe, we
determined that the present or
threatened destruction, modification, or
curtailment of habitat or range is a
threat to these species and that those
threats in some way can be addressed by
section 7(a)(2) consultation measures.
These species occur wholly in the
jurisdiction of the United States, and we
are able to identify areas that meet the
definition of critical habitat. Therefore,
because none of the circumstances
enumerated in our regulations at 50 CFR
424.12(a)(1) have been met and because
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the Secretary has not identified other
circumstances for which this
designation of critical habitat would be
not prudent, we have determined that
the designation of critical habitat is
prudent for the Texas heelsplitter and
Louisiana pigtoe.
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Critical Habitat Determinability
Having determined that designation is
prudent, under section 4(a)(3) of the Act
we must find whether critical habitat for
the Texas heelsplitter and Louisiana
pigtoe is determinable. Our regulations
at 50 CFR 424.12(a)(2) state that critical
habitat is not determinable when one or
both of the following situations exist:
(i) Data sufficient to perform required
analyses are lacking, or
(ii) The biological needs of the species
are not sufficiently well known to
identify any area that meets the
definition of ‘‘critical habitat.’’ When
critical habitat is not determinable, the
Act allows the Service an additional
year to publish a critical habitat
designation (16 U.S.C. 1533(b)(6)(C)(ii)).
We reviewed the available
information pertaining to the biological
needs of the species and habitat
characteristics where these species are
located. This and other information
represent the best scientific data
available and led us to conclude that the
designation of critical habitat is
determinable for the Texas heelsplitter
and Louisiana pigtoe.
Physical or Biological Features
Essential to the Conservation of the
Species
In accordance with section 3(5)(A)(i)
of the Act and regulations at 50 CFR
424.12(b), in determining which areas
we will designate as critical habitat from
within the geographical area occupied
by the species at the time of listing, we
consider the physical or biological
features that are essential to the
conservation of the species and that may
require special management
considerations or protection. The
regulations at 50 CFR 424.02 define
‘‘physical or biological features essential
to the conservation of the species’’ as
the features that occur in specific areas
and that are essential to support the lifehistory needs of the species, including,
but not limited to, water characteristics,
soil type, geological features, sites, prey,
vegetation, symbiotic species, or other
features. A feature may be a single
habitat characteristic or a more complex
combination of habitat characteristics.
Features may include habitat
characteristics that support ephemeral
or dynamic habitat conditions. Features
may also be expressed in terms relating
to principles of conservation biology,
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such as patch size, distribution
distances, and connectivity.
For example, physical features
essential to the conservation of the
species might include gravel of a
particular size required for spawning,
alkaline soil for seed germination,
protective cover for migration, or
susceptibility to flooding or fire that
maintains necessary early-successional
habitat characteristics. Biological
features might include prey species,
forage grasses, specific kinds or ages of
trees for roosting or nesting, symbiotic
fungi, or a particular level of nonnative
species consistent with conservation
needs of the listed species. The features
may also be combinations of habitat
characteristics and may encompass the
relationship between characteristics or
the necessary amount of a characteristic
essential to support the life history of
the species.
In considering whether features are
essential to the conservation of the
species, we may consider an appropriate
quality, quantity, and spatial and
temporal arrangement of habitat
characteristics in the context of the lifehistory needs, condition, and status of
the species. These characteristics
include, but are not limited to, space for
individual and population growth and
for normal behavior; food, water, air,
light, minerals, or other nutritional or
physiological requirements; cover or
shelter; sites for breeding, reproduction,
or rearing (or development) of offspring;
and habitats that are protected from
disturbance.
We derive the specific physical or
biological features (PBFs) essential for
the conservation of the Texas
heelsplitter and Louisiana pigtoe from
studies of these species’ habitat,
ecology, and life history. The life
histories of these two freshwater mussel
species are very similar—mussels need
suitable water quality, flowing water,
suitable substrate, flow refuges, and
appropriate host fish—and so we will
discuss their common habitat needs and
then describe their species-specific
needs.
Physiological Requirements: Water
Quality Requirements
Freshwater mussels, as a group, are
sensitive to changes in water quality,
including parameters such as dissolved
oxygen, salinity, ammonia, and
environmental pollutants (e.g.,
pesticides and trace metals). Habitats
with appropriate levels of these
parameters that are pollutant-free or
have low levels of pollutants are
considered suitable, while those
habitats with levels outside of the
appropriate ranges or that contain
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elevated pollutants are considered less
suitable. We have used information for
the Texas heelsplitter and Louisiana
pigtoe, where available, and data from
other species when species-specific
information is not available. Juvenile
freshwater mussels are particularly
susceptible to low dissolved oxygen
levels. Juveniles will reduce feeding
behavior when dissolved oxygen is
between 2–4 milligrams per liter (mg/L),
and mortality has been shown to occur
at dissolved oxygen levels below 1.3
mg/L. Increased salinity levels may also
be stressful to freshwater mussels, with
some species showing signs of stress at
salinity levels of 2 ppt or higher (Bonner
et al. 2018; pp. 155–156).
The release of pollutants into streams
from point and nonpoint sources have
immediate impacts on water quality
conditions and may make environments
unsuitable for habitation by mussels.
Early life stages of freshwater mussels
are some of the most sensitive
organisms of all species to ammonia and
copper (Augspurger et al. 2007, p.
2025). Additionally, sublethal effects of
contaminants over time can result in
reduced feeding efficiency, reduced
growth, decreased reproduction,
changes in enzyme activity, and
behavioral changes to all mussel life
stages. Even wastewater discharges with
low ammonia levels have been shown to
negatively affect mussel populations.
Finally, water temperature plays a
critical role in the life history of
freshwater mussels. High water
temperatures can cause valve closure,
reduced reproductive output, and death.
Laboratory studies investigating the
effects of thermal stress on glochidia
and adults have indicated thermal stress
may occur at 27 °C (80.6 °F) (Bonner et
al. 2018; Khan et al. 2019, entire)).
Based on the above information, we
determine that stream reaches with the
following water quality parameters are
suitable for the Texas heelsplitter and
Louisiana pigtoe:
• Water temperature below 27 °C
(80.6 °F);
• Dissolved oxygen levels greater
than 3 mg/L;
• Low salinity (less than 2 ppt) and
total dissolved solids;
• Low total ammonia and nitrogen
(below 0.3–0.7 mg/L total ammonia
nitrogen);
• Low levels of copper, nickel, and
other trace metals;
• Low levels of pesticides, sulfate,
chloride, potassium, and other harmful
constituents; and
• Low pollutants and environmental
contaminants common to wastewater.
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Space for Individual and Population
Growth and for Normal Behavior
Most freshwater mussels, including
the Texas heelsplitter and Louisiana
pigtoe, are found in aggregations, called
mussel beds, that vary in size from
about 50 to greater than 5,000 square
meters (m2), separated by stream
reaches in which mussels are absent or
rare (Vaughn 2012, p. 983). Freshwater
mussel larvae (called glochidia) are
parasites that must attach to a host fish.
A population incorporates more than
one mussel bed; it is the collection of
mussel beds within a stream reach
between which infested host fish may
travel, allowing for ebbs and flows in
mussel bed density and abundance over
time throughout the population’s
occupied reach. Accordingly,
sufficiently resilient mussel populations
must occupy stream reaches long
enough so that stochastic events that
affect individual mussel beds do not
eliminate the entire population.
Repopulation by infested host fish from
other mussel beds within the reach can
allow the population to recover from
these events. Longer stream reaches are
more likely to support populations of
the Texas heelsplitter and Louisiana
pigtoe into the future than shorter
stream reaches. Therefore, we determine
that long stream reaches, over 50 river
miles (80.5 km), are an important
component of a riverine system with
habitat to support all life stages of the
Texas heelsplitter and Louisiana pigtoe.
Populations occupying reaches shorter
than 50 miles can still provide
population redundancy and, if habitat
factors are of sufficiently high quality,
can be an important component of the
recovery of Texas heelsplitter and
Louisiana pigtoe.
The Texas heelsplitter needs low to
moderately flowing streams, and
tolerates impoundments (lakes,
reservoirs, or pools without flow). All
life stages of the Texas heelsplitter
require substrates consisting of firm
mud, sand, finer gravels, and mixtures
of those with high organic matter
content. The Louisiana pigtoe needs
flowing water for survival and occurs in
medium- to large-sized streams and
rivers associated with riffle, run, and
sometimes larger backwater tributary
habitats. All life stages of the Louisiana
pigtoe require substrates consisting of
cobble/rock, sand/gravel/woody debris,
and runs with subdominant gravel
mixtures. River reaches with continuous
flow support all life stages of these two
species of freshwater mussels, while
those with little or no flow do not. Flow
rates needed by each species will vary
depending on the species and the river
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size, location, and substrate type.
Habitat locations must be relatively free
of fine sediments for both species such
that the mussels are not smothered.
Sites for Development of Offspring
As discussed above, freshwater
mussel larvae are parasites that must
attach to a host fish to develop into
juvenile mussels. The Texas heelsplitter
and Louisiana pigtoe use a variety of
host fish, many of which are widely
distributed throughout their ranges. The
presence of these fish species, either
singly or in combination, supports the
life-history needs of these two species of
freshwater mussels:
• Texas heelsplitter: freshwater drum
(Aplodinotus grunniens).
• Louisiana pigtoe: red shiner
(Cyprinella (=Notropis) lutrensis),
blacktail shiner (Cyprinella venusta),
and bullhead minnow (Pimephales
vigilax).
Summary of Essential Physical or
Biological Features
In summary, we derive the specific
PBFs essential to the conservation of
Texas heelsplitter and Louisiana pigtoe
from studies of these species’ habitat,
ecology, and life history as described
above. Additional information can be
found in the SSA report available on
https://www.regulations.gov under
Docket No. FWS–R2–ES–2022–0026.
Texas Heelsplitter
We have determined that the
following PBFs are essential to the
conservation of the Texas heelsplitter:
1. Water quality parameters within
the following ranges:
a. Water temperature below 27 °C
(80.6 °F);
b. Dissolved oxygen levels greater
than 3 mg/L;
c. Low salinity (less than 2 ppt) and
total dissolved solids;
d. Low total ammonia and nitrogen
(below 0.3–0.7 mg/L total ammonia
nitrogen);
e. Low levels of copper, nickel, and
other trace metals;
f. Low levels of pesticides, sulfate,
chloride, potassium, and other harmful
constituents; and
g. Low pollutants and environmental
contaminants common to wastewater.
2. Moderately flowing water rates
suitable to prevent excess sedimentation
but not so high as to dislodge
individuals or sediment; or no water
flow, if in an impoundment (lake,
reservoir, or pool without flow).
3. Substrate including bedrock and
boulder crevices, point bars, and
vegetated run habitat comprising sand,
gravel, and larger cobbles.
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4. Freshwater drum (Aplodinotus
grunniens) present.
Louisiana Pigtoe
We have determined that the
following PBFs are essential to the
conservation of the Louisiana pigtoe:
1. Water quality parameters within
the following ranges:
a. Water temperature below 27 °C
(80.6 °F);
b. Dissolved oxygen levels greater
than 3 mg/L;
c. Low salinity (less than 2 ppt) and
total dissolved solids;
d. Low total ammonia and nitrogen
(below 0.3–0.7 mg/L total ammonia
nitrogen);
e. Low levels of copper, nickel, and
other trace metals;
f. Low levels of pesticides, sulfate,
chloride, potassium, and other harmful
constituents; and
g. Low pollutants and environmental
contaminants common to wastewater.
2. Moderately flowing water rates
suitable to prevent excess sedimentation
but not so high as to dislodge
individuals or sediment.
3. Stable bank and riffle habitats with
bedrock and boulder crevices, point
bars, and vegetated run habitat
comprising sand, gravel, and larger
cobbles.
4. Red shiner (Cyprinella (=Notropis)
lutrensis), blacktail shiner (Cyprinella
venusta), and bullhead minnow
(Pimephales vigilax) present.
Special Management Considerations or
Protection
When designating critical habitat, we
assess whether the specific areas within
the geographical area occupied by the
species at the time of listing contain
features which are essential to the
conservation of the species and which
may require special management
considerations or protection. The
features essential to the conservation of
the Texas heelsplitter and Louisiana
pigtoe may require special management
considerations or protections to reduce
the following threats: increased fine
sediment, changes in water quality
impairment, altered hydrology from
both inundation and flow loss/scour,
predation and collection, and barriers to
fish movement.
Management activities that could
ameliorate these threats include, but are
not limited to: Use of best management
practices (BMPs) designed to reduce
sedimentation, erosion, and bank side
destruction; protection of riparian
corridors and retention of sufficient
canopy cover along banks; exclusion of
livestock and nuisance wildlife (feral
hogs, exotic ungulates); moderation of
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surface and ground water withdrawals
to maintain natural flow regimes;
increased use of stormwater
management and reduction of
stormwater flows into the systems; use
of highest water quality standards for
wastewater and other return flows; and
reduction of other watershed and
floodplain disturbances that release
sediments, pollutants, or nutrients into
the water.
In summary, we find that the
occupied areas we are proposing to
designate as critical habitat contain the
PBFs that are essential to the
conservation of the species and that may
require special management
considerations or protection. Special
management considerations or
protection may be required of the
Federal action agency to eliminate, or to
reduce to negligible levels, the threats
affecting the PBFs of each unit.
Criteria Used To Identify Critical
Habitat
As required by section 4(b)(2) of the
Act, we use the best scientific data
available to designate critical habitat. In
accordance with the Act and our
implementing regulations at 50 CFR
424.12(b), we review available
information pertaining to the habitat
requirements of the species and identify
specific areas within the geographical
area occupied by the species at the time
of listing and any specific areas outside
the geographical area occupied by the
species to be considered for designation
as critical habitat. We are not currently
proposing to designate any areas outside
the geographical area occupied by the
Texas heelsplitter and Louisiana pigtoe
because we have determined that the
occupied areas are sufficient to conserve
the species.
We anticipate that recovery will
require conserving the genetic diversity
of extant populations across the species’
current ranges and maintaining and,
where necessary, improving habitat and
habitat connectivity to ensure the longterm viability of the Texas heelsplitter
and Louisiana pigtoe. This proposed
critical habitat designation delineates
the habitat that is physically occupied
and used by the species rather than
delineating all land or aquatic areas that
influence the species. We recognize that
there may be additional occupied areas
outside of the proposed areas designated
as critical habitat that we are not aware
of at the time of this designation that
may be necessary for the conservation of
the species. We have determined that
the areas currently occupied by the
Texas heelsplitter and Louisiana pigtoe
would maintain each species’ resiliency,
redundancy, and representation and are
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sufficient to conserve these two species.
Therefore, we are not currently
proposing to designate any areas outside
the geographical area occupied by the
species.
Sources of data for this proposed
critical habitat include multiple
databases maintained by universities
and State agencies, scientific and agency
reports, and numerous survey reports on
streams throughout the species’ range
(Service 2022, pp. 16–24).
Areas Occupied at the Time of Listing
The proposed critical habitat
designations do not include all rivers
and streams known to have been
occupied by the species historically;
instead, they focus on rivers and
streams occupied at the time of listing
that have retained the necessary PBFs
that will allow for the maintenance and
expansion of existing populations. A
stream reach may not have all of the
PBFs to be included as proposed critical
habitat; in such reaches, our goal is to
recover the species by restoring the
missing PBFs. We defined ‘‘occupied’’
units as stream channels with
observations of one or more live
individuals. Specific habitat areas were
delineated based on reports of live
individuals and recently dead shells.
We include ‘‘recent dead shell material’’
to delineate the boundaries of a unit
because recently dead shell material at
a site indicates the species is present in
that area. Recently dead shells have
tissue remaining on the shells or have
retained a shiny nacre, indicating the
animal died within days or weeks of
finding the shell. It is highly unlikely
that a dead individual represents the
last remaining individual of the
population, and recently dead shells are
an accepted indicator of a species’
presence (e.g., Howells 1996, pp. ii, 4;
Randklev et al. 2011, p. 17).
We are relying on evidence of
occupancy from data collected in 2000
to the present. This is because
freshwater mussels may be difficult to
detect, and some sites are not visited
multiple times. Additionally, these
species live at least 15 to 20 years.
Because adults are less sensitive to
habitat changes than juveniles, changes
in population sizes usually occur over
decades rather than years. As a result,
areas where individuals were collected
within the last 20 years are expected to
remain occupied now. Additionally, any
areas that were surveyed around 20
years ago and do not have subsequent
surveys were reviewed for any largescale habitat changes (i.e., major flood
or scour event, drought) to confirm that
general habitat characteristics remained
constant over this time. None of the
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relatively few areas without more recent
survey information had experienced
changes to general habitat
characteristics. Therefore, data from
around 2000 would be considered a
strong indicator a species remains
extant at a site if general habitat
characteristics have remained constant
over that time.
For areas proposed as critical habitat,
we delineated critical habitat unit
boundaries using the following
criterion: Evaluate habitat suitability of
stream segments within the geographic
area occupied at the time of listing, and
retain those segments that contain some
or all of the PBFs to support life-history
functions essential for conservation of
the species. Humanmade reservoirs are
not considered natural habitat for either
species and may not contain all of the
PBFs; therefore, they were not
delineated as critical habitat for Texas
heelsplitter, which occurs in some
reservoirs. The recovery vision for Texas
heelsplitter will not be focused on
enhancing the species in these areas.
As a final step, we evaluated those
occupied stream segments retained
through the above analysis and refined
the starting and ending points by
evaluating the presence or absence of
appropriate PBFs. We selected upstream
and downstream cutoff points to
reference existing easily recognizable
geopolitical features including
confluences, highway crossings, and
county lines. Using these features as end
points allows the public to clearly
understand the boundaries of critical
habitat. Unless otherwise specified, any
stream beds located directly beneath
bridge crossings or other landmark
features used to describe critical habitat
spatially, such as stream confluences,
are considered to be wholly included
within the critical habitat unit. Critical
habitat stream segments were then
mapped using ArcMap version 10.6.1
(ESRI, Inc.), a Geographic Information
Systems program.
We consider the following streams
and rivers to be occupied by the Texas
heelsplitter at the time of proposed
listing: Neches River, Sabine River, and
Trinity River.
We consider the following streams
and rivers to be occupied by the
Louisiana pigtoe at the time of proposed
listing: Angelina River, Big Cypress
Bayou, Calcasieu River, Cossatot River,
Little River, Neches River, Pearl River,
Rolling Fork, Sabine River, Saline River,
San Jacinto River, and Sulphur River.
General Information on the Maps of the
Proposed Critical Habitat Designations
When determining proposed critical
habitat boundaries, we made every
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effort to avoid including developed
areas such as lands covered by
buildings, pavement, and other
structures because such lands lack
physical or biological features necessary
for the Texas heelsplitter and Louisiana
pigtoe. Critical habitat for these mussels
includes only stream channels up to
bankfull height, where the stream base
flow is contained within the channel.
The scale of the maps we prepared
under the parameters for publication
within the Code of Federal Regulations
may not reflect the exclusion of such
developed lands. Any such lands
inadvertently left inside critical habitat
boundaries shown on the maps of this
proposed rule have been excluded by
text in the proposed rule and are not
proposed for designation as critical
habitat. Therefore, if the critical habitat
is finalized as proposed, a Federal
action involving these lands would not
trigger section 7 consultation with
respect to critical habitat and the
requirement of no adverse modification
unless the specific action would affect
the physical or biological features in the
adjacent critical habitat.
We are proposing to designate as
critical habitat three units for the Texas
heelsplitter and six units for the
Louisiana pigtoe based on one or more
of the PBFs being present to support the
Texas heelsplitter’s or Louisiana
pigtoe’s life-history processes. Some
units contain all of the identified
physical or biological features and
support multiple life-history processes.
Some units contain only some of the
PBFs necessary to support the Texas
heelsplitter’s or Louisiana pigtoe’s
particular use of that habitat.
The proposed critical habitat
designation is defined by the map or
maps, as modified by any accompanying
regulatory text, presented at the end of
this document under Proposed
Regulation Promulgation. We include
more detailed information on the
boundaries of the critical habitat
designation in the preamble of this
document. We will make the
coordinates or plot points or both on
which each map is based available to
the public on https://
www.regulations.gov at Docket No.
FWS–R2–ES–2022–0026, on our
internet site https://www.fws.gov/office/
arlington-ecological-services.
Proposed Critical Habitat Designation
We are proposing to designate
approximately 832 river mi (1,339 km)
in three units as critical habitat for
Texas heelsplitter and approximately
1,028 river mi (1,654 km) in six units for
the Louisiana pigtoe. The critical habitat
areas we describe below constitute our
current best assessment of areas that
meet the definition of critical habitat for
Texas heelsplitter and Louisiana pigtoe.
All units are occupied by their
respective species. The three areas we
propose as critical habitat for Texas
heelsplitter are all in Texas and are: (1)
Trinity River, (2) Sabine River, and (3)
Neches River. The six areas we propose
as critical habitat for Louisiana pigtoe
are: (1) Little River (Arkansas/
Oklahoma), (2) Sabine River (Louisiana/
Texas), (3) Neches River (Texas), (4) San
Jacinto River (Texas), (5) Calcasieu River
(Louisiana), and (6) Pearl River
(Louisiana/Mississippi). One proposed
Louisiana pigtoe critical habitat subunit,
LAPT–1a (Upper Little River,
Oklahoma; 25.7 river miles (41.4 km)),
is located within the Choctaw
Reservation, but not on any lands held
in trust for the Tribe, or owned or
managed by the Tribe. Tables 5 and 6
show the proposed critical habitat units,
the adjacent riparian area ownership,
and the approximate area of each unit.
TABLE 5—PROPOSED CRITICAL HABITAT UNITS FOR THE TEXAS HEELSPLITTER
River miles
(kilometers)
Unit
Subunit
Riparian ownership
Occupied?
TXHS–1: Trinity River ...................
TXHS–1a: Trinity River .................
TXHS–1b: Bedias Creek ..............
Private, State ................................
Private ...........................................
Yes .................
Yes .................
212.8 (342.4)
28.9 (46.5)
Unit Total ...............................
.......................................................
.......................................................
........................
241.7 (388.9)
TXHS–2: Sabine River ..................
TXHS–2a: Upper Sabine River ....
TXHS–2b: Lake Fork Creek .........
TXHS–2c: Patroon Bayou ............
Private, State, Local, Federal .......
Private ...........................................
Private, Federal ............................
Yes .................
Yes .................
Yes .................
237.4 (382.0)
13.8 (22.2)
19.9 (32.0)
Unit Total ...............................
.......................................................
.......................................................
........................
271.1 (436.2)
TXHS–3: Neches River .................
TXHS–3a: Upper Neches River ...
TXHS–3b: Lower Angelina River
TXHS–3c: Lower Neches River ...
Private, Federal ............................
Private, Federal ............................
Private, State, Federal ..................
Yes .................
Yes .................
Yes .................
227.9 (366.7)
14.7 (23.7)
76.3 (122.8)
Unit Total ...............................
.......................................................
.......................................................
........................
318.9 (513.1)
Total ................................
.......................................................
.......................................................
........................
831.8 (1,338.6)
Note: Lengths may not accurately sum due to rounding.
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TABLE 6—PROPOSED CRITICAL HABITAT UNITS FOR THE LOUISIANA PIGTOE
Subunit
Riparian ownership
LAPT–1: Little River ......................
LAPT–1a: Upper Little River ........
LAPT–1b: Rolling Fork .................
LAPT–1c: Cossatot River .............
LAPT–1d: Saline River .................
Private, State, Federal, Tribal ......
Private ...........................................
Private, Federal ............................
Private ...........................................
Yes
Yes
Yes
Yes
.................
.................
.................
.................
88.0 (141.6)
29.9 (47.9)
47.2 (75.9)
42.6 (68.5)
Unit Total ...............................
.......................................................
.......................................................
........................
207.7 (334.2)
LAPT–2: Sabine River ..................
LAPT–2a: Upper Sabine River .....
Private, State, Federal ..................
Yes .................
110.1 (177.2)
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(kilometers)
Unit
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TABLE 6—PROPOSED CRITICAL HABITAT UNITS FOR THE LOUISIANA PIGTOE—Continued
Unit
River miles
(kilometers)
Subunit
Riparian ownership
Occupied?
LAPT–2b: Anacoco Bayou ...........
Private ...........................................
Yes .................
12.2 (19.6)
Unit Total ...............................
.......................................................
.......................................................
........................
122.3 (196.8)
LAPT–3: Neches River .................
LAPT–3a: Upper Neches River ....
LAPT–3b: Upper Angelina River ..
LAPT–3c: Lower Neches River ....
LAPT–3d: Village Creek ...............
LAPT–3e: Big Sandy Creek .........
Private,
Private,
Private,
Private,
Private,
Yes
Yes
Yes
Yes
Yes
.................
.................
.................
.................
.................
200.4 (322.4)
67.4 (108.4)
76.2 (122.6)
54.9 (88.3)
43.7 (70.3)
Unit Total ...............................
.......................................................
.......................................................
........................
442.6 (712.1)
LAPT–4: East Fork San Jacinto
River.
.......................................................
Private ...........................................
Yes .................
23.3 (37.5)
Unit Total ...............................
.......................................................
.......................................................
........................
23.3 (37.5)
LAPT–5: Calcasieu River ..............
LAPT–5a: Upper Calcasieu River
LAPT–5b: Whisky Chitto Creek ....
LAPT–5c: Tenmile Creek .............
Private, Federal ............................
Private, State ................................
Private, State ................................
Yes .................
Yes .................
Yes .................
92.0 (148.0)
21.7 (34.9)
32.0 (51.5)
Unit Total ...............................
.......................................................
.......................................................
........................
145.7 (234.4)
LAPT–6: Pearl River .....................
.......................................................
Private, State, Federal ..................
Yes .................
86.6 (139.3)
Unit Total ...............................
.......................................................
.......................................................
........................
86.6 (139.3)
Total ................................
.......................................................
.......................................................
........................
1,028.2 (1,654.3)
Federal ............................
Federal ............................
State, Federal ..................
State, Federal ..................
Federal ............................
Note: Lengths may not accurately sum due to rounding.
We present brief descriptions of all
units, and reasons why they meet the
definition of critical habitat for the
Texas heelsplitter (TXHS) or Louisiana
pigtoe (LAPT) below.
Texas Heelsplitter
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Unit TXHS–1: Trinity River
Subunit TXHS–1a: Trinity River. The
Trinity River Subunit includes 212.8
river mi (342.4 km) in Anderson, Ellis,
Freestone, Henderson, Houston,
Kaufman, Leon, Madison, and Navarro
Counties, Texas. The subunit begins at
Lake Livingston (estimated from the
State Highway 24 bridge located 4.7 mi
(7.6 km) northeast of Midway, Texas)
and continues upstream to the State
Highway 34 bridge, located 2.5 miles (4
km) southwest of Rosser, Texas.
Ownership of adjacent riparian areas is
95 percent private and 5 percent State.
Although this reach is approximately 20
mi (32.2 km) southeast and downstream
of the Dallas-Fort Worth Metroplex,
activities occurring across the Metroplex
continue to affect both water quality and
quantity downstream, including in this
subunit, even though it is located in a
largely rural area and predominately
within riparian woodlands and
agricultural lands. The Trinity River
Subunit is occupied by the Texas
heelsplitter and contains all the PBFs
essential to the conservation of the
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species most of the year. However,
hydrologic conditions have been
significantly altered by wastewater
return flows, and flooding in the Trinity
River can be extreme, causing the
species to experience a variety of
environmental stressors that degrade
habitat quality, such as shear stress,
scouring, erosion, sediment deposition
and siltation, and bank collapse.
The Trinity River Subunit is being
affected by impoundments, wastewater
return flows, ongoing agricultural
activities, and development resulting in
excessive sedimentation, water quality
degradation, ground water withdrawals,
and surface water diversions. Therefore,
special management considerations may
be required to reduce sedimentation,
improve water quality, maintain
adequate flows, and improve habitat
connectivity. There is no overlap with
any designated critical habitat for other
listed species.
Subunit TXHS–1b: Bedias Creek. The
Bedias Creek Subunit is comprised of
28.9 river mi (46.5 km) in Grimes,
Madison, and Walker Counties, Texas.
The subunit continues upstream from
Livingston Lake, as estimated from the
Farm to Market Road 247 bridge located
9.2 mi (14.8 km) south-southeast of
Midway, Texas, to the State Highway 90
bridge located approximately 6.3 mi
(10.1 km) south-southwest of
Madisonville, Texas. Adjacent riparian
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areas are privately owned. This reach is
largely rural and predominately within
riparian woodlands and agricultural
lands. The Bedias Creek Subunit is
occupied by the Texas heelsplitter and
contains all the PBFs essential to the
conservation of the species most of the
year. However, fluctuating drought
conditions and flooding in Bedias Creek
can cause the species to experience
either extreme low-flow conditions with
related reduced water quality or extreme
high flows that mobilize substrates,
erode habitat, or deposit sediment on
Texas heelsplitter populations.
The Bedias Creek Subunit is
influenced by drought, low flows, and
flooding (leading to scour), and the
subunit is being affected by ongoing
agricultural activities and development
resulting in excessive sedimentation,
water quality degradation, ground water
withdrawals, and surface water
diversions. Therefore, special
management may be required to reduce
sedimentation, improve water quality,
maintain adequate flows, and improve
habitat connectivity. There is no overlap
with any designated critical habitat for
other listed species.
Unit TXHS–2: Sabine River
Subunit TXHS–2a: Upper Sabine
River. The Upper Sabine River Subunit
includes 237.4 river mi (382 km) in
Gregg, Harrison, Panola, Rains, Rusk,
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Smith, Upshur, Van Zandt, and Wood
Counties, Texas. The subunit extends
upstream from the Louisiana/Texas
State line, located approximately 2.4 mi
(3.9 km) north-northeast of Joaquin,
Texas, to a utility easement
approximately 0.9 river mile (1.4 km)
below Tawakoni Lake dam. Ownership
of adjacent riparian areas is
approximately 93 percent private, 4
percent State, 1 percent local, and 2
percent Federal. This reach is mostly
rural and predominately within riparian
woodlands bordered by agricultural
lands. The Upper Sabine River Subunit
is occupied by the Texas heelsplitter
and contains all the PBFs essential to
the conservation of the species most of
the year. However, drought conditions
and flooding in the Sabine River can be
significant, resulting in either extreme
low-flow conditions with related
reduced water quality or high flows that
mobilize substrates, erode habitat, or
deposit sediment on Texas heelsplitter
populations. The City of Longview,
Texas, is located north of the subunit
approximately mid-reach. Industrial and
municipal wastewater associated with
this urban area are discharged into the
Sabine River Basin, negatively affecting
water quality in some areas
downstream.
The Upper Sabine River Subunit is
influenced by drought, low flows, and
flooding (leading to scour), and the
subunit is being affected by
impoundments, ongoing agricultural
activities, and development resulting in
excessive sedimentation, water quality
degradation, ground water withdrawals,
and surface water diversions. Therefore,
special management considerations may
be required to reduce sedimentation,
improve water quality, maintain
adequate flows, and improve habitat
connectivity. There is an overlap of
110.05 river mi (177.11 km) of this unit
with proposed critical habitat for the
Louisiana pigtoe.
Subunit TXHS–2b: Lake Fork Creek.
The Lake Fork Creek Subunit consists of
13.8 river mi (22.2 km) in Wood County,
Texas. The subunit extends upstream
from its confluence with the Sabine
River to the FM 49 bridge, located
approximately 5 mi (8 km) northeast of
Mineola, Texas. Adjacent riparian areas
are privately owned. This reach is
mostly rural and predominately within
riparian woodlands bordered by
agricultural lands. The Lake Fork Creek
Subunit is occupied by the Texas
heelsplitter and contains all the PBFs
essential to the conservation of the
species most of the year. However,
drought conditions and flooding in the
Lake Fork Creek can cause the species
to experience either extreme low-flow
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conditions with related reduced water
quality or high flows that mobilize
substrates, erode habitat, or deposit
sediment on Texas heelsplitter
populations.
The Lake Fork Creek Subunit is
influenced by drought, low flows, and
flooding (leading to scour), and the
subunit is being affected by
impoundments, ongoing agricultural
activities, and development resulting in
excessive sedimentation, water quality
degradation, ground water withdrawals,
and surface water diversions. Therefore,
special management considerations may
be required to reduce sedimentation,
improve water quality, maintain
adequate flows, and improve habitat
connectivity. There is no overlap with
any designated critical habitat for other
listed species.
Subunit TXHS–2c: Patroon Bayou.
The Patroon Bayou Subunit includes
19.9 river mi (32 km) in Sabine and
Shelby Counties, Texas. This subunit
begins at the mouth of Patroon Bayou
(location estimated at the Reeves Road
bridge, approximately 7 mi (11.3 km)
north of Milam, Texas) and continues
upstream to the State Highway 87 bridge
located 11.3 mi (18.2 km) southeast of
Shelbyville, Texas. Ownership of
adjacent riparian areas are 93 percent
private and 7 percent Federal. The
Patroon Bayou Subunit is occupied by
the Texas heelsplitter and contains all
the PBFs essential to the conservation of
the species most of the year. However,
drought conditions and flooding in the
Patroon Bayou can cause low-flow
conditions with related reduced water
quality or high flows that mobilize
substrates, erode habitat, or deposit
sediment on Texas heelsplitter
populations.
The Patroon Bayou Subunit is
influenced by drought, low flows, and
flooding (leading to scour), and the
subunit is being affected by ongoing
agricultural activities and development
resulting in excessive sedimentation,
water quality degradation, ground water
withdrawals, and surface water
diversions. Therefore, special
management considerations may be
required to reduce sedimentation,
improve water quality, maintain
adequate flows, and improve habitat
connectivity. There is no overlap with
any designated critical habitat for other
listed species.
Unit TXHS–3: Neches River
Subunit TXHS–3a: Upper Neches
River. The Upper Neches River Subunit
includes 227.9 river mi (366.7 km) of
stream in Anderson, Angelina,
Cherokee, Houston, Jasper, Polk,
Trinity, and Tyler Counties, Texas. The
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subunit originates at B.A. Steinhagen
Lake (estimated at a point located
approximately 13 mi (20.9 km) east of
Colmesneil, Texas) and continues
upstream to a transmission line right-ofway (ROW) located approximately 1.1
river mi (1.8 km) below Palestine Lake
Dam. Ownership of adjacent riparian
areas is approximately 88 percent
private and 12 percent Federal. This
reach is rural and predominately within
riparian woodlands bordered by
agricultural lands. The Upper Neches
River Subunit is occupied by the Texas
heelsplitter and contains all the PBFs
essential to the conservation of the
species most of the year. However,
drought conditions and flooding in the
Neches River can cause either extreme
low-flow conditions with related
reduced water quality or high flows that
mobilize substrates, erode habitat, or
deposit sediment on Texas heelsplitter
populations.
The Upper Neches River Subunit is
influenced by drought, low flows, and
flooding (leading to scour), and the
subunit is being affected by
impoundments, ongoing agricultural
activities, and development resulting in
excessive sedimentation, water quality
degradation, ground water withdrawals,
and surface water diversions. Therefore,
special management considerations may
be required to reduce sedimentation,
improve water quality, maintain
adequate flows, and improve habitat
connectivity. There is an overlap of
200.38 river mi (322.48 km) of this unit
with proposed critical habitat for the
Louisiana pigtoe.
Subunit TXHS–3b: Lower Angelina
River. The Lower Angelina River
Subunit consists of 14.7 river mi (23.7
km) in Jasper County, Texas. The
subunit extends upstream from B.A.
Steinhagen Lake, estimated at a point
located approximately 5.7 mi (9.2 km)
west of Curtis, Texas, to a transmission
line ROW located approximately 0.3
mile (0.5 km) below Sam Rayburn
Reservoir. Ownership of adjacent
riparian areas is approximately 89
percent private and 11 percent Federal.
This reach is rural and predominately
within riparian woodlands bordered by
agricultural lands. The Lower Angelina
River Subunit is occupied by the Texas
heelsplitter and contains all the
necessary PBFs essential to the
conservation of the species most of the
year. However, drought conditions and
flooding in the Angelina River can be
compounded by hydroelectric dam
operations at Sam Rayburn Reservoir,
causing the species to experience either
extreme low-flow conditions with
related reduced water quality or extreme
high flows that mobilize substrates,
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erode habitat, or deposit sediment on
Texas heelsplitter populations.
The Lower Angelina River Subunit is
influenced by drought, low flows, and
flooding (leading to scour), and the
subunit is being affected by
impoundments, ongoing agricultural
activities, and development resulting in
excessive sedimentation, water quality
degradation, ground water withdrawals,
and surface water diversions. Therefore,
special management considerations may
be required to reduce sedimentation,
improve water quality, maintain
adequate flows, and improve habitat
connectivity. There is no overlap with
any designated critical habitat for other
listed species.
Subunit TXHS–3c: Lower Neches
River. The Lower Neches River Subunit
occupies 76.3 river mi (122.8 km) in
Hardin, Jasper, Jefferson, Orange, and
Tyler Counties, Texas. The subunit
extends upstream from the Lower
Neches Valley Authority weir, located
north of Beaumont, Texas, to the Walnut
Run confluence, which is approximately
2.6 mi (4.2 km) southeast of the B.A.
Steinhagen Dam. The Lower Neches
River Subunit is hydrologically isolated
from the Upper Neches River Subunit
by B.A. Steinhagen Lake. Ownership of
adjacent riparian areas is approximately
88 percent private, 7 percent State, and
5 percent Federal. This reach is mostly
rural and predominately within riparian
woodlands bordered by agricultural
lands. The Lower Neches River Subunit
is occupied by the Texas heelsplitter
and contains all the PBFs essential to
the conservation of the species most of
the year. However, drought conditions
and flooding in the Neches River can
cause low-flow conditions with related
reduced water quality or high flows that
mobilize substrates, erode habitat, or
deposit sediment on Texas heelsplitter
populations.
The Lower Neches River Subunit is
influenced by drought, low flows, and
flooding (leading to scour); and the
subunit is being affected by
impoundments, ongoing agricultural
activities, and development resulting in
excessive sedimentation, water quality
degradation, groundwater withdrawals,
and surface water diversions. Therefore,
special management considerations may
be required to reduce sedimentation,
improve water quality, maintain
adequate flows, and improve habitat
connectivity. There is an overlap of
76.35 river mi (122.87 km) of this unit
with proposed critical habitat for the
Louisiana pigtoe.
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Louisiana Pigtoe
Unit LAPT–1: Little River
Subunit LAPT–1a: Upper Little River.
The Upper Little River Subunit consists
of approximately 88.0 river mi (141.6
km) of the mainstem Little River
upstream of Millwood Lake, Arkansas,
occupying portions of Little River and
Sevier Counties, Arkansas, and
McCurtain County, Oklahoma. This
subunit extends upstream from the U.S.
Highway 69/71 bridge near Millwood
Lake, Arkansas, to the Glover River
confluence, located 2.6 mi (4.2 km)
west-southwest of Golden, Oklahoma.
This subunit is hydrologically
connected to the Rolling Fork Subunit
(Subunit LAPT–1b). Ownership of
adjacent riparian areas is approximately
42 percent private, 1 percent State, 26
percent Federal, and 23 percent private
land within the Choctaw Reservation,
but not any lands held in trust for the
Tribe, or owned or managed by the
Tribe. This reach is entirely rural, with
long sections of intact riparian
woodlands bordered by agricultural
lands. The Upper Little River Subunit is
occupied by the Louisiana pigtoe and
contains all the PBFs essential to the
conservation of the species most of the
year.
Drought conditions and flooding in
the Little River are seldom extreme;
however, this subunit is affected by
hydroelectric dam-related cold water
releases in the Mountain Fork from
Broken Bow Reservoir and ongoing
agricultural activities, resulting in
excessive sedimentation, water quality
degradation, ground water withdrawals,
and surface water diversions. Therefore,
special management considerations may
be required to reduce sedimentation,
improve water quality, maintain
adequate flows, and improve habitat
connectivity. The Upper Little River
Subunit is occupied by four federally
listed freshwater mussels, the
endangered pink mucket (Lampsilis
abrupta), the threatened rabbitsfoot
(Theliderma cylindrica, listed as
Quadrula cylindrica cylindrica), the
endangered winged mapleleaf
(Quadrula fragosa), and the endangered
Ouachita rock pocketbook (Arcidens
wheeleri, listed as Arkansia wheeleri).
There is overlap of 88.3 river mi (142.1
km) of this unit with designated critical
habitat for rabbitsfoot (see 50 CFR
17.95(f) and 80 FR 24692, April 30,
2015).
Subunit LAPT–1b: Rolling Fork. The
Rolling Fork Subunit consists of
approximately 29.9 river mi (47.9 km) in
Sevier County, Arkansas. The subunit
extends upstream from the Little River
confluence to the falls/bedrock ledge
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located approximately 0.5 river mile
(0.8 km) downstream of DeQueen Lake
Dam. Ownership of adjacent riparian
areas is privately held. This reach is
entirely rural, and predominately
agricultural lands and riparian
woodlands. The Rolling Fork Subunit is
occupied by the Louisiana pigtoe and
contains all the PBFs essential to the
conservation of the species most of the
year.
Drought conditions and flooding in
Rolling Fork are seldom extreme;
however, this subunit is affected by
impoundments and ongoing agricultural
activities, resulting in excessive
sedimentation, water quality
degradation, ground water withdrawals,
and surface water diversions. Therefore,
special management considerations may
be required to reduce sedimentation,
improve water quality, maintain
adequate flows, and improve habitat
connectivity. There is no overlap with
any designated critical habitat for other
listed species.
Subunit LAPT–1c: Cossatot River. The
Cossatot River Subunit consists of
approximately 47.2 river mi (75.9 km) of
stream located within Sevier County,
Arkansas. This subunit extends
upstream from the U.S. Highway 69/71
bridge near Millwood Lake, Arkansas, to
the Howard/Sevier County line in
southeast Arkansas. Ownership of
adjacent riparian areas is approximately
85 percent private and 15 percent
Federal. This reach is entirely rural, and
predominately riparian woodlands
bordered by agricultural lands. The
Cossatot River Subunit is occupied by
the Louisiana pigtoe and contains all the
PBFs essential to the conservation of the
species most of the year.
Drought conditions and flooding in
the Cossatot River are seldom extreme;
however, this subunit is affected by
impoundments and ongoing agricultural
activities, resulting in excessive
sedimentation, water quality
degradation, ground water withdrawals,
and surface water diversions. Therefore,
special management considerations may
be required to reduce sedimentation,
improve water quality, maintain
adequate flows, and improve habitat
connectivity. There is no overlap with
any designated critical habitat for other
listed species.
Subunit LAPT–1d: Saline River. The
Saline River Subunit consists of
approximately 42.6 river mi (68.5 km) of
stream located along the Howard/Sevier
County line in southeast Arkansas. This
subunit extends upstream from the
Bright Star Road bridge, which is
located immediately north of Millwood
Lake, to the Thirty Thousand Road
(County Road 80) bridge located
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approximately 3.8 mi (6.1 km) westnorthwest of Dierks, Arkansas. Adjacent
riparian areas are privately owned. This
reach is entirely rural, and
predominately riparian woodlands
bordered by agricultural lands. The
Saline River Subunit is occupied by the
Louisiana pigtoe and contains all the
PBFs essential to the conservation of the
species most of the year.
Drought conditions and flooding in
the Saline River are seldom extreme;
however, this subunit is affected by
impoundments and ongoing agricultural
activities, resulting in excessive
sedimentation, water quality
degradation, ground water withdrawals,
and surface water diversions. Therefore,
special management considerations may
be required to reduce sedimentation,
improve water quality, maintain
adequate flows, and improve habitat
connectivity. There is no overlap with
any designated critical habitat for other
listed species.
Unit LAPT–2: Sabine River
Subunit LAPT–2a: Upper Sabine
River. The Upper Sabine River Subunit
consists of 110.1 river mi (177.2 km)
occupying portions of Gregg, Harrison,
Panola, Rusk, Smith, Upshur, and Wood
Counties, Texas. This subunit continues
upstream from the State Highway 43
bridge, which is 5 mi (8 km) northeast
of Tatum, Texas, and terminates at the
Farm-to-Market Road 1804 bridge
located 3.3 mi (5.3 km) southeast of
Mineola, Texas. Ownership of adjacent
riparian areas is approximately 96
percent private, 2 percent State, and 2
percent Federal. This reach is mostly
rural and predominately within riparian
woodlands bordered by agricultural
lands.
The Upper Sabine River Subunit is
occupied by the Louisiana pigtoe and
contains all the PBFs essential to the
conservation of the species most of the
year. However, drought conditions and
flooding in the Sabine River can be
extreme, causing the species to
experience either extreme low-flow
conditions with associated reduced
water quality or extreme high flows that
mobilize substrates, erode habitat, or
deposit sediment on Louisiana pigtoe
populations. The City of Longview,
Texas, is located north of the subunit at
approximately one-third of the reach
length upstream from the downstream
terminus. Industrial and municipal
wastewater associated with this urban
area are discharged into the Sabine
River Basin. The Upper Sabine River
Subunit is influenced by drought, low
flows, and flooding (leading to scour),
and the subunit is being affected by
impoundments, ongoing agricultural
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activities, and development resulting in
excessive sedimentation, water quality
degradation, ground water withdrawals,
and surface water diversions. Therefore,
special management considerations may
be required to reduce sedimentation,
improve water quality, maintain
adequate flows, and improve habitat
connectivity. There is an overlap of
110.05 river mi (177.11 km) of this unit
with proposed critical habitat for the
Texas heelsplitter.
Subunit LAPT–2b: Anacoco Bayou.
The Anacoco Bayou Subunit consists of
12.2 river mi (19.6 km) in Vernon
Parish, Louisiana. The subunit extends
upstream from the Beauregard/Vernon
parish line, situated approximately 8 mi
(12.9 km) northwest of DeRidder,
Louisiana, and terminates at the Hawks
Road bridge, located approximately 4.8
mi (7.7 km) northwest of Rosepine,
Louisiana. Adjacent riparian areas are
privately owned. This reach is mostly
rural and predominately within riparian
woodlands. The Anacoco Bayou
Subunit is occupied by the Louisiana
pigtoe and contains all the PBFs
essential to the conservation of the
species most of the year. However,
drought conditions and flooding in
Anacoco Bayou can be extreme, causing
the species to experience either extreme
low-flow conditions with associated
reduced water quality or extreme high
flows that mobilize substrates, erode
habitat, or deposit sediments on
Louisiana pigtoe populations.
Three sand and gravel mining
operations and one paper mill that exist
adjacent to this subunit likely negatively
affect water quality from activities that
generate point and non-point source
pollution. Wastewater and storm water
runoff associated with these activities
are discharged into Anacoco Bayou
drainage. The Anacoco Bayou Subunit
is influenced by drought, low flows, and
flooding (leading to scour), and the
subunit is being affected by
impoundments, as well as ongoing
mining and industrial activities
resulting in excessive sedimentation,
water quality degradation, ground water
withdrawals, and surface water
diversions. Therefore, special
management considerations may be
required to reduce sedimentation,
improve water quality, maintain
adequate flows, and improve habitat
connectivity. There is no overlap with
any designated critical habitat for other
listed species.
Unit LAPT–3: Neches River
Subunit LAPT–3a: Upper Neches
River. The Upper Neches River Subunit
extends for 200.4 river mi (322.4 km)
through parts of Anderson, Angelina,
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Cherokee, Houston, Polk, Trinity, and
Tyler Counties, Texas. The downstream
boundary corresponds to U.S. Highway
59 bridge, approximately 4 mi (6.4 km)
south of Diboll, Texas, and the upstream
boundary is located at a transmission
line ROW approximately 1.1 river mi
(1.8 km) below Palestine Lake Dam.
Ownership of adjacent riparian areas is
approximately 89 percent private and 11
percent Federal. This reach is mostly
rural and predominately within riparian
woodlands bordered by agricultural
lands. The Upper Neches River Subunit
is occupied by the Louisiana pigtoe and
contains all the PBFs essential to the
conservation of the species most of the
year. However, drought conditions and
flooding in the Neches River can be
significant, causing the species to
experience either extreme low-flow
conditions with associated reduced
water quality or extreme high flows that
mobilize substrates, erode habitat, or
deposit sediment on Louisiana pigtoe
populations.
The Upper Neches River Subunit is
influenced by drought, low flows, and
flooding (leading to scour), and the
subunit is being affected by
impoundments, ongoing agricultural
activities, and development resulting in
excessive sedimentation, water quality
degradation, ground water withdrawals,
and surface water diversions. Therefore,
special management considerations may
be required to reduce sedimentation,
improve water quality, maintain
adequate flows, and improve habitat
connectivity. The entire subunit
overlaps with proposed critical habitat
for the Texas heelsplitter.
Subunit LAPT–3b: Upper Angelina
River. The Upper Angelina River
Subunit includes 67.4 river mi (108.4
km) in Angelina, Cherokee, and
Nacogdoches Counties, Texas. The
subunit extends upstream from the
Union Pacific Railroad crossing, located
approximately 3.7 mi (6 km) northnorthwest of Redland, Texas, to the
State Highway 204 bridge located 1.6 mi
(2.6 km) west of Sacul, Texas. This
subunit is hydrologically isolated from
the Upper Neches River Subunit by Sam
Rayburn Reservoir. Ownership of
adjacent riparian areas is approximately
50 percent private and 50 percent
Federal. This reach is mostly rural and
predominately within riparian
woodlands bordered by agricultural
lands. The Upper Angelina River
Subunit is occupied by the Louisiana
pigtoe and contains all the PBFs
essential to the conservation of the
species most of the year. However,
drought conditions and flooding in the
Angelina River can result in either
extreme low-flow conditions with
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associated reduced water quality or
extreme high flows that mobilize
substrates, erode habitat, or deposit
sediments on Louisiana pigtoe
populations.
The Upper Angelina River Subunit is
influenced by drought, low flows, and
flooding (leading to scour); the subunit
is being affected by impoundments,
ongoing agricultural activities, and
development resulting in excessive
sedimentation, water quality
degradation, ground water withdrawals,
and surface water diversions. Therefore,
special management considerations may
be required to reduce sedimentation,
improve water quality, maintain
adequate flows, and improve habitat
connectivity. There is no overlap with
any designated critical habitat for other
listed species.
Subunit LAPT–3c: Lower Neches
River. The Lower Neches River Subunit
occupies 76.2 river mi (122.6 km) in
Hardin, Jasper, Jefferson, Orange, and
Tyler Counties, Texas. The subunit
extends upstream from the Lower
Neches Valley Authority weir, located
north of Beaumont, Texas, to the Walnut
Run confluence, which is approximately
2.6 mi (4.2 km) southeast of the B.A.
Steinhagen Dam. The Lower Neches
River Subunit is hydrologically isolated
from the Upper Neches River Subunit
by B.A. Steinhagen Lake. Ownership of
adjacent riparian areas is approximately
88 percent private, 7 percent State, and
5 percent Federal. This reach is mostly
rural and predominately within riparian
woodlands bordered by agricultural
lands. The Lower Neches River Subunit
is occupied by the Louisiana pigtoe and
contains all the PBFs essential to the
conservation of the species most of the
year. However, drought conditions and
flooding in the Neches River can cause
the species to experience either extreme
low-flow conditions with associated
reduced water quality or extreme high
flows that mobilize substrates, erode
habitat, or deposit sediments on
Louisiana pigtoe populations.
The Lower Neches River Subunit is
influenced by drought, low flows, and
flooding (leading to scour); the subunit
is being affected by impoundments,
ongoing agricultural activities, and
development resulting in excessive
sedimentation, water quality
degradation, groundwater withdrawals,
and surface water diversions. Therefore,
special management considerations may
be required to reduce sedimentation,
improve water quality, maintain
adequate flows, and improve habitat
connectivity. The entire subunit
overlaps with proposed critical habitat
for the Texas heelsplitter.
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Subunit LAPT–3d: Village Creek. The
Village Creek Subunit includes 54.9
river mi (88.3 km) of stream in Hardin
County, Texas. The subunit originates at
the Village Creek confluence with the
Neches River, located approximately 1.6
mi (2.6 km) north-northwest of
Lakeview, Texas, and continues up
Village Creek to its terminus at the
confluence of Big Sandy and Kimball
creeks, located approximately 1.6 mi
(2.6 km) south-southeast of Wildwood,
Texas. Ownership of adjacent riparian
areas is approximately 20 percent
private, 2 percent State, and 78 percent
Federal. Although some urban
encroachment occurs in the lower half
of the reach, it is mostly rural and
predominately within riparian
woodlands bordered by agricultural
lands. The Village Creek Subunit is
occupied by the Louisiana pigtoe and
contains all the PBFs essential to the
conservation of the species most of the
year. However, drought conditions and
flooding in Village Creek can be
extreme, causing the species to
experience either extreme low-flow
conditions with associated reduced
water quality or extreme high flows that
mobilize substrates, erode habitat, or
deposit sediments on Louisiana pigtoe
populations.
The Village Creek Subunit is
influenced by drought, low flows, and
flooding (leading to scour); the subunit
is being affected by impoundments,
ongoing agricultural activities, and
development resulting in excessive
sedimentation, water quality
degradation, ground water withdrawals,
and surface water diversions. Therefore,
special management considerations may
be required to reduce sedimentation,
improve water quality, maintain
adequate flows, and improve habitat
connectivity. There is no overlap with
any designated critical habitat for other
listed species.
Subunit LAPT–3e: Big Sandy Creek.
The Big Sandy Creek Subunit consists of
43.7 river mi (70.3 km) of stream in
Hardin, Polk, and Tyler Counties, Texas.
The subunit continues upstream from
its confluence with Kimball Creek,
located approximately 1.6 mi (2.6 km)
south-southeast of Wildwood, Texas, to
the Alabama-Coushatta Reservation
boundary. This boundary is 1.4 river mi
(2.25 km) southeast of the U.S. Highway
190 bridge, which is located
approximately 12.8 mi (20.6 km) east of
Livingston, Texas. Ownership of
adjacent riparian areas is approximately
5 percent private and 95 percent
Federal. This reach is mostly rural and
predominately within riparian
woodlands bordered by agricultural
lands. The Big Sandy Creek Subunit is
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16809
occupied by the Louisiana pigtoe and
contains all the PBFs essential to the
conservation of the species most of the
year. However, drought conditions and
flooding in Big Sandy Creek can be
significant, resulting in low-flow
conditions with associated reduced
water quality or high flows that
mobilize substrates, erode habitat, or
deposit sediments on Louisiana pigtoe
populations.
The Big Sandy Creek Subunit is
influenced by drought, low flows, and
flooding (leading to scour), and the
subunit is being affected by ongoing
agricultural activities and development
resulting in excessive sedimentation,
water quality degradation, ground water
withdrawals, and surface water
diversions. Therefore, special
management considerations may be
required to reduce sedimentation,
improve water quality, maintain
adequate flows, and improve habitat
connectivity. There is no overlap with
any designated critical habitat for other
listed species.
Unit LAPT–4: East Fork San Jacinto
River
The East Fork San Jacinto River Unit
includes 23.3 river mi (37.5 km) of the
East Fork San Jacinto River in Liberty
and Montgomery Counties, Texas. The
downstream boundary of this unit is
located at the FM 1485 bridge
approximately 1 mile (1.6 km) east of
Lake Houston Wilderness Park. The
upstream boundary coincides with the
Low Water Bridge Road (FM 388) bridge
approximately 1.6 mi (2.6 km)
northwest of Cleveland, Texas. Adjacent
riparian areas are privately owned.
Although located 10 mi northwest of the
Houston metropolitan area, this reach is
mostly rural and predominately within
riparian woodlands, but it is bordered
by developed areas. Four sand and
gravel mining operations are located
adjacent to this unit. The East Fork San
Jacinto River Unit is occupied by the
Louisiana pigtoe and contains all the
PBFs essential to the conservation of the
species most of the year. However,
drought conditions and flooding in the
East Fork San Jacinto River can be
extreme, causing the species to
experience either extreme low-flow
conditions with associated reduced
water quality or extreme high flows that
mobilize substrates, erode habitat, or
deposit sediments on Louisiana pigtoe
populations.
The East Fork San Jacinto River Unit
is influenced by drought, low flows, and
flooding (leading to scour), and the unit
is being affected by ongoing agricultural
activities and development resulting in
excessive sedimentation, water quality
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degradation, ground water withdrawals,
and surface water diversions. Therefore,
special management considerations may
be required to reduce sedimentation,
improve water quality, maintain
adequate flows, and improve habitat
connectivity. There is no overlap with
any designated critical habitat for other
listed species.
Unit LAPT–5: Calcasieu River
Subunit LAPT–5a: Upper Calcasieu
River. The Upper Calcasieu River
Subunit includes 92.0 river mi (148.0
km) located in Allen and Rapides
parishes, Louisiana. The subunit
originates at the Union Pacific Railroad
crossing located south of U.S. Highway
190 approximately 4 mi (6.4 km) west
of Kinder, Louisiana, and continues
upstream to the Price Road bridge,
located 3.1 mi (5 km) northwest of
Hineston, Louisiana. Ownership of
adjacent riparian areas is 78 percent
private and 22 percent Federal. This
reach is rural and predominately within
riparian woodlands. The Upper
Calcasieu River Subunit is occupied by
the Louisiana pigtoe and contains all the
PBFs essential to the conservation of the
species most of the year. However,
drought conditions and flooding in the
Calcasieu River can be extreme, causing
the species to experience either extreme
low-flow conditions with related
reduced water quality or extreme high
flows that mobilize substrates, erode
habitat, or deposit sediment on
Louisiana pigtoe populations.
The Upper Calcasieu River Subunit is
influenced by drought, low flows, and
flooding (leading to scour), and the
subunit is being affected by ongoing
agricultural activities and development
resulting in excessive sedimentation,
water quality degradation, ground water
withdrawals, and surface water
diversions. Therefore, special
management considerations may be
required to reduce sedimentation,
improve water quality, maintain
adequate flows, and improve habitat
connectivity. There is no overlap with
any designated critical habitat for other
listed species.
Subunit LAPT–5b: Whisky Chitto
Creek. The Whisky Chitto Creek Subunit
includes 21.7 river mi (34.9 km) located
in Allen Parish, Louisiana. The subunit
extends from its confluence with
Calcasieu River to the Tenmile Creek
confluence, which is located
approximately 0.7 mi (1.1 km) northeast
of Mittie, Louisiana. Ownership of
adjacent riparian areas is 1 percent
private and 99 percent State. This reach
is rural and predominately within
riparian woodlands. The Whisky Chitto
Creek Subunit is occupied by the
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Louisiana pigtoe and contains all the
PBFs essential to the conservation of the
species most of the year. However,
drought conditions and flooding in the
Whisky Chitto Creek can be extreme,
causing the species to experience either
extreme low-flow conditions with
related reduced water quality or extreme
high flows that mobilize substrates,
erode habitat, or deposit sediment on
Louisiana pigtoe populations.
The Whisky Chitto Creek Subunit is
influenced by drought, low flows, and
flooding (leading to scour), and the
subunit is being affected by ongoing
agricultural activities and development
resulting in excessive sedimentation,
water quality degradation, ground water
withdrawals, and surface water
diversions. Therefore, special
management considerations may be
required to reduce sedimentation,
improve water quality, maintain
adequate flows, and improve habitat
connectivity. There is no overlap with
any designated critical habitat for other
listed species.
Subunit LAPT–5c: Tenmile Creek. The
Tenmile Creek Subunit consists of 32.0
river mi (51.5 km) in Allen, Rapides,
and Vernon parishes, Louisiana. The
Tenmile Creek Subunit continues
upstream from the Whisky Chitto Creek
confluence located 0.7 mi (1.1 km)
northeast of Mittie, Louisiana, to the 10
Mile Road bridge located approximately
5 mi (8 km) north of Elizabeth,
Louisiana. Ownership of adjacent
riparian areas is 98 percent private and
2 percent State. This reach is rural and
predominately within riparian
woodlands. The Tenmile Creek Subunit
is occupied by the Louisiana pigtoe and
contains all the PBFs essential to the
conservation of the species most of the
year. However, drought conditions and
flooding in the Tenmile Creek can be
extreme, causing the species to
experience either extreme low-flow
conditions with related reduced water
quality or extreme high flows that
mobilize substrates, erode habitat, or
deposit sediment on Louisiana pigtoe
populations.
The Tenmile Creek Subunit is
influenced by drought, low flows, and
flooding (leading to scour), and the
subunit is being affected by ongoing
agricultural activities and development
resulting in excessive sedimentation,
water quality degradation, ground water
withdrawals, and surface water
diversions. Therefore, special
management considerations may be
required to reduce sedimentation,
improve water quality, maintain
adequate flows, and improve habitat
connectivity. There is no overlap with
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any designated critical habitat for other
listed species.
Unit LAPT–6: Pearl River
The Pearl River Unit consists of 86.6
river mi (139.3 km) in St. Tammany and
Washington parishes, Louisiana, and
Marion and Pearl River Counties,
Mississippi. The Pearl River splits into
two significant channels within Bogue
Chitto National Wildlife Refuge, and a
navigation channel is associated with
the west channel. Proposed critical
habitat river mileage is calculated from
the east channel only, but the Pearl
River Unit does include the west
channel by definition. The navigation
channel is excluded from the unit.
Following the east channel, the Pearl
River Unit extends upstream along the
Louisiana/Mississippi State line from
the I–59 bridge located 1 mile (1.6 km)
south of Nicholson, Mississippi, to
where the Pearl River enters Louisiana
from Mississippi, which is located 3.9
mi (6.3 km) southeast of Sandy Hook,
Mississippi. The west channel extends
from the I–59 bridge located 0.9 mi (1.4
km) northeast of Pearl River, Louisiana,
and continues upstream to its
confluence with the east channel, which
is located approximately 2.7 mi (4.3 km)
west of Industrial, Mississippi.
Ownership of adjacent riparian areas is
44 percent private, 14 percent State, and
42 percent Federal. This reach is largely
rural and predominately within riparian
woodlands. The Pearl River Unit is
occupied by the Louisiana pigtoe and
contains all the PBFs essential to the
conservation of the species most of the
year. However, drought conditions and
flooding in the Pearl River can be
extreme, causing the species to
experience either extreme low-flow
conditions with related reduced water
quality or extreme high flows that
mobilize substrates, erode habitat, or
deposit sediment on Louisiana pigtoe
populations.
The Pearl River Unit is influenced by
drought, low flows, and flooding
(leading to scour), and the subunit is
being affected by impoundments,
ongoing agricultural activities, and
development resulting in excessive
sedimentation, water quality
degradation, ground water withdrawals,
and surface water diversions. Therefore,
special management considerations may
be required to reduce sedimentation,
improve water quality, maintain
adequate flows, and improve habitat
connectivity. The entire subunit
overlaps with critical habitat for the
federally listed Gulf sturgeon (Acipenser
oxyrinchus (=oxyrhynchus) desotoi) (see
50 CFR 17.95(e)).
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Effects of Critical Habitat Designation
Section 7 Consultation
Section 7(a)(2) of the Act requires
Federal agencies, including the Service,
to ensure that any action they fund,
authorize, or carry out is not likely to
jeopardize the continued existence of
any endangered species or threatened
species or result in the destruction or
adverse modification of designated
critical habitat of such species. In
addition, section 7(a)(4) of the Act
requires Federal agencies to confer with
the Service on any agency action which
is likely to jeopardize the continued
existence of any species proposed to be
listed under the Act or result in the
destruction or adverse modification of
proposed critical habitat.
We published a final rule revising the
definition of destruction or adverse
modification on August 27, 2019 (84 FR
44976). Destruction or adverse
modification means a direct or indirect
alteration that appreciably diminishes
the value of critical habitat as a whole
for the conservation of a listed species.
If a Federal action may affect a listed
species or its critical habitat, the
responsible Federal agency (action
agency) must enter into consultation
with us. Examples of actions that are
subject to the section 7 consultation
process are actions on State, Tribal,
local, or private lands that require a
Federal permit (such as a permit from
the U.S. Army Corps of Engineers under
section 404 of the Clean Water Act (33
U.S.C. 1251 et seq.) or a permit from the
Service under section 10 of the Act) or
that involve some other Federal action
(such as funding from the Federal
Highway Administration, Federal
Aviation Administration, or the Federal
Emergency Management Agency).
Federal actions not affecting listed
species or critical habitat—and actions
on State, Tribal, local, or private lands
that are not federally funded,
authorized, or carried out by a Federal
agency—do not require section 7
consultation.
Compliance with the requirements of
section 7(a)(2) is documented through
our issuance of:
(1) A concurrence letter for Federal
actions that may affect, but are not
likely to adversely affect, listed species
or critical habitat; or
(2) A biological opinion for Federal
actions that may affect, and are likely to
adversely affect, listed species or critical
habitat.
When we issue a biological opinion
concluding that a project is likely to
jeopardize the continued existence of a
listed species and/or destroy or
adversely modify critical habitat, we
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provide reasonable and prudent
alternatives to the project, if any are
identifiable, that would avoid the
likelihood of jeopardy and/or
destruction or adverse modification of
critical habitat. We define ‘‘reasonable
and prudent alternatives’’ (at 50 CFR
402.02) as alternative actions identified
during consultation that:
(1) Can be implemented in a manner
consistent with the intended purpose of
the action,
(2) Can be implemented consistent
with the scope of the Federal agency’s
legal authority and jurisdiction,
(3) Are economically and
technologically feasible, and
(4) Would, in the Service Director’s
opinion, avoid the likelihood of
jeopardizing the continued existence of
the listed species and/or avoid the
likelihood of destroying or adversely
modifying critical habitat.
Reasonable and prudent alternatives
can vary from slight project
modifications to extensive redesign or
relocation of the project. Costs
associated with implementing a
reasonable and prudent alternative are
similarly variable.
Regulations at 50 CFR 402.16 set forth
requirements for Federal agencies to
reinitiate consultation on previously
reviewed actions. These requirements
apply when the Federal agency has
retained discretionary involvement or
control over the action (or the agency’s
discretionary involvement or control is
authorized by law) and, subsequent to
the previous consultation: (a) if the
amount or extent of taking specified in
the incidental take statement is
exceeded; (b) if new information reveals
effects of the action that may affect
listed species or critical habitat in a
manner or to an extent not previously
considered; (c) if the identified action is
subsequently modified in a manner that
causes an effect to the listed species or
critical habitat that was not considered
in the biological opinion or written
concurrence; or (d) if a new species is
listed or critical habitat designated that
may be affected by the identified action.
In such situations, Federal agencies
sometimes may need to request
reinitiation of consultation with us, but
Congress also enacted some exceptions
in 2018 to the requirement to reinitiate
consultation on certain land
management plans on the basis of a new
species listing or new designation of
critical habitat that may be affected by
the subject Federal action. See 2018
Consolidated Appropriations Act,
Public Law 115–141, Div, O, 132 Stat.
1059 (2018).
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Application of the ‘‘Destruction or
Adverse Modification’’ Standard
The key factor related to the
destruction or adverse modification
determination is whether
implementation of the proposed Federal
action directly or indirectly alters the
designated critical habitat in a way that
appreciably diminishes the value of the
critical habitat as a whole for the
conservation of the listed species. As
discussed above, the role of critical
habitat is to support physical or
biological features essential to the
conservation of a listed species and
provide for the conservation of the
species.
Section 4(b)(8) of the Act requires us
to briefly evaluate and describe, in any
proposed or final regulation that
designates critical habitat, activities
involving a Federal action that may
violate section 7(a)(2) of the Act by
destroying or adversely modifying such
habitat, or that may be affected by such
designation.
Activities that we may, during a
consultation under section 7(a)(2) of the
Act, consider likely to destroy or
adversely modify critical habitat
include, but are not limited to, actions
that would: (1) Alter the minimum flow
or the existing flow regime (for example,
impoundment, channelization, water
diversion, water withdrawal, or
hydropower generation); (2)
significantly alter water chemistry or
temperature (for example, release of
chemicals, biological pollutants, or
heated effluents into surface water or
connected groundwater at a point
source or by dispersed release (nonpoint
source)); (3) significantly increase
sediment deposition within the stream
channel (for example, excessive
sedimentation from livestock grazing;
road construction; channel alteration;
timber harvest; off-road vehicle use;
agricultural, industrial, or urban
development; or other watershed and
floodplain disturbances); and (4)
significantly alter channel morphology
or geometry (for example,
channelization, impoundment, road and
bridge construction, mining, dredging,
or destruction of riparian vegetation).
These activities may lead to changes in
water flows and levels that would
degrade or eliminate the mussel or its
fish host and/or their habitats. These
actions can also lead to increased
sedimentation and degradation in water
quality to levels that are beyond the
tolerances of the mussels or their fish
hosts.
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Application of Section 4(a)(3) of the Act
Section 4(a)(3)(B)(i) of the Act (16
U.S.C. 1533(a)(3)(B)(i)) provides that the
Secretary shall not designate as critical
habitat any lands or other geographical
areas owned or controlled by the
Department of Defense (DoD), or
designated for its use, that are subject to
an integrated natural resources
management plan (INRMP) prepared
under section 101 of the Sikes Act
Improvement Act of 1997 (16 U.S.C.
670a), if the Secretary determines in
writing that such plan provides a benefit
to the species for which critical habitat
is proposed for designation. No DoD
lands with a completed INRMP are
within the proposed critical habitat
designations.
Consideration of Impacts Under Section
4(b)(2) of the Act
Section 4(b)(2) of the Act states that
the Secretary shall designate and make
revisions to critical habitat on the basis
of the best available scientific data after
taking into consideration the economic
impact, national security impact, and
any other relevant impact of specifying
any particular area as critical habitat.
The Secretary may exclude an area from
designated critical habitat based on
economic impacts, impacts on national
security, or any other relevant impacts.
Exclusion decisions are governed by the
regulations at 50 CFR 424.19 and the
Policy Regarding Implementation of
Section 4(b)(2) of the Endangered
Species Act (hereafter, the ‘‘2016
Policy’’; 81 FR 7226, February 11, 2016),
both of which were developed jointly
with the National Marine Fisheries
Service (NMFS). We also refer to a 2008
Department of the Interior Solicitor’s
opinion entitled ‘‘The Secretary’s
Authority to Exclude Areas from a
Critical Habitat Designation under
section 4(b)(2) of the Endangered
Species Act’’ (M–37016).
In considering whether to exclude a
particular area from the designation, we
identify the benefits of including the
area in the designation, identify the
benefits of excluding the area from the
designation, and evaluate whether the
benefits of exclusion outweigh the
benefits of inclusion. If the analysis
indicates that the benefits of exclusion
outweigh the benefits of inclusion, the
Secretary may exercise discretion to
exclude the area only if such exclusion
would not result in the extinction of the
species. In making the determination to
exclude a particular area, the statute on
its face, as well as the legislative history,
are clear that the Secretary has broad
discretion regarding which factor(s) to
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use and how much weight to give to any
factor. In our final rules, we explain any
decision to exclude areas, as well as
decisions not to exclude, to demonstrate
that the decision is reasonable. We
describe below the process that we use
for taking into consideration each
category of impacts and any initial
analyses of the relevant impacts.
Consideration of Economic Impacts
Section 4(b)(2) of the Act and its
implementing regulations require that
we consider the economic impact that
may result from a designation of critical
habitat. To assess the probable
economic impacts of a designation, we
must first evaluate specific land uses or
activities and projects that may occur in
the area of the critical habitat. We then
must evaluate the impacts that a specific
critical habitat designation may have on
restricting or modifying specific land
uses or activities for the benefit of the
species and its habitat within the areas
proposed. We then identify which
conservation efforts may be the result of
the species being listed under the Act
versus those attributed solely to the
designation of critical habitat for the
particular species. The probable
economic impact of a proposed critical
habitat designation is analyzed by
comparing scenarios both ‘‘with critical
habitat’’ and ‘‘without critical habitat.’’
The ‘‘without critical habitat’’
scenario represents the baseline for the
analysis, which includes the existing
regulatory and socio-economic burden
imposed on landowners, managers, or
other resource users potentially affected
by the designation of critical habitat
(e.g., under the Federal listing as well as
other Federal, State, and local
regulations). The baseline, therefore,
represents the costs of all efforts
attributable to the listing of the species
under the Act (i.e., conservation of the
species and its habitat incurred
regardless of whether critical habitat is
designated). The ‘‘with critical habitat’’
scenario describes the incremental
impacts associated specifically with the
designation of critical habitat for the
species. The incremental conservation
efforts and associated impacts would
not be expected without the designation
of critical habitat for the species. In
other words, the incremental costs are
those attributable solely to the
designation of critical habitat, above and
beyond the baseline costs. These are the
costs we use when evaluating the
benefits of inclusion and exclusion of
particular areas from the final
designation of critical habitat should we
choose to conduct a discretionary
4(b)(2) exclusion analysis.
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For this particular designation, we
developed an incremental effects
memorandum (IEM) considering the
probable incremental economic impacts
that may result from this proposed
designations of critical habitat. The
information contained in our IEM was
then used to develop a screening
analysis of the probable effects of the
designation of critical habitat for the
Texas heelsplitter and the Louisiana
pigtoe (IEc 2021, entire). We began by
conducting a screening analysis of the
proposed designations of critical habitat
in order to focus our analysis on the key
factors that are likely to result in
incremental economic impacts. The
purpose of the screening analysis is to
filter out particular geographic areas of
critical habitat that are already subject
to such protections and are, therefore,
unlikely to incur incremental economic
impacts. In particular, the screening
analysis considers baseline costs (i.e.,
absent critical habitat designation) and
includes any probable economic
impacts where land and water use may
already be subject to conservation plans,
land management plans, best
management practices, or regulations
that protect the habitat area as a result
of the Federal listing status of the
species. Ultimately, the screening
analysis allows us to focus our analysis
on evaluating the specific areas or
sectors that may incur probable
incremental economic impacts as a
result of the designation. If the proposed
critical habitat designation contains any
unoccupied units, the screening
analysis assesses whether those units
require additional management or
conservation efforts that may incur
incremental economic impacts
(although here the proposed critical
habitat designations does not contain
any unoccupied units). This screening
analysis, combined with the information
contained in our IEM, are what we
consider our draft economic analysis
(DEA) of the proposed critical habitat
designations for the Texas heelsplitter
and Louisiana pigtoe; our DEA is
summarized in the narrative below.
Executive Orders (E.O.s) 12866 and
13563 direct Federal agencies to assess
the costs and benefits of available
regulatory alternatives in quantitative
(to the extent feasible) and qualitative
terms. Consistent with the E.O.
regulatory analysis requirements, our
effects analysis under the Act may take
into consideration impacts to both
directly and indirectly affected entities,
where practicable and reasonable. If
sufficient data are available, we assess
to the extent practicable the probable
impacts to both directly and indirectly
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affected entities. As part of our
screening analysis, we considered the
types of economic activities that are
likely to occur within the areas likely
affected by the critical habitat
designations. In our evaluation of the
probable incremental economic impacts
that may result from the proposed
designations of critical habitat for the
Texas heelsplitter and Louisiana pigtoe,
first we identified, in the IEM dated
September 1, 2021, probable
incremental economic impacts
associated with the following categories
of activities: (1) Federal lands
management (National Park Service,
National Wildlife Refuge System, U.S.
Forest Service, U.S. Army Corp of
Engineers, Natural Resources
Conservation Service, Department of the
Army); (2) industrial, municipal, and
agricultural water users and dischargers
(including wastewater treatment plants);
(3) water supply delivery and treatment;
(4) reservoir and dam operations; (5)
transportation; (6) petroleum pipelines
that may cross proposed designated
stream reaches; (7) residential,
commercial, industrial, and agricultural
development; and (8) disaster recovery
from hurricanes and flooding. We
considered each industry or category
individually. Additionally, we
considered whether their activities have
any Federal involvement. Critical
habitat designation generally will not
affect activities that do not have any
Federal involvement; under the Act,
designation of critical habitat only
affects activities conducted, funded,
permitted, or authorized by Federal
agencies. If we list these species, in
areas where the Texas heelsplitter and
Louisiana pigtoe are present, Federal
agencies would be required to consult
with the Service under section 7 of the
Act on activities they fund, permit, or
implement that may affect the species.
If, when we list the species, we also
finalize this proposed critical habitat
designation, Federal agencies would be
required to consider the effects of their
actions on the designated habitat, and if
the Federal action may affect critical
habitat, our consultations would
include an evaluation of measures to
avoid the destruction or adverse
modification of critical habitat.
In our IEM, we attempted to clarify
the distinction between the effects that
would result from the species being
listed and those attributable to the
critical habitat designation (i.e.,
difference between the jeopardy and
adverse modification standards) for the
Texas heelsplitter’s and Louisiana
pigtoe’s critical habitat. Because the
designations of critical habitat for Texas
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heelsplitter and Louisiana pigtoe are
being proposed concurrently with their
listings, it has been our experience that
it is more difficult to discern which
conservation efforts are attributable to
the species being listed and those which
will result solely from the designation of
critical habitat. However, the following
specific circumstances in this case help
to inform our evaluation: (1) The
essential physical or biological features
identified for critical habitat are the
same features essential for the life
requisites of the species, and (2) any
actions that would result in sufficient
harm or harassment to constitute
jeopardy to the Texas heelsplitter and
Louisiana pigtoe would also likely
adversely affect the essential physical or
biological features of critical habitat.
The IEM outlines our rationale
concerning this limited distinction
between baseline conservation efforts
and incremental impacts of the
designation of critical habitat for these
species. This evaluation of the
incremental effects has been used as the
basis to evaluate the probable
incremental economic impacts of these
proposed designations of critical
habitat.
The proposed critical habitat
designations for the Texas heelsplitter
and Louisiana pigtoe include a total of
nine units, all of which are occupied by
their respective species. Ownership of
riparian lands adjacent to the nine
proposed units includes 1,214 river mi
(1,954 km; 82.2 percent) in private
ownership, and 262 river mi (422 km;
17.8 percent) in public (Federal, State,
or Local) ownership. In these areas, any
actions that may affect the two species
or their habitats would also affect
designated critical habitat.
Total incremental costs of critical
habitat designation for the Texas
heelsplitter and Louisiana pigtoe are not
expected to exceed $51,800 (2021
dollars) per year. The costs are reflective
of: (1) All proposed units are considered
occupied, (2) project modifications
requested to avoid adverse modification
are likely to be the same as those
recommended to avoid jeopardy in
occupied habitat for these species, and
(3) a portion of the proposed
designations receive baseline protection
from the presence of critical habitat for
co-occurring listed mussel species with
similar habitat needs. Because
consultation would be required as a
result of the listing of the Texas
heelsplitter and Louisiana pigtoe and is
already required in some of these areas
as a result of the presence of other listed
species and critical habitats, the
economic costs of the critical habitat
designation would likely be primarily
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limited to additional administrative
efforts to consider adverse modification
for these two species in section 7
consultations.
Based on the consultation history
regarding historical projects and
activities overlapping the proposed
critical habitat areas for the Texas
heelsplitter and Louisiana pigtoe, the
number of future consultations,
including technical assistance efforts, is
likely to be no more than nine per year
across all nine units. Overall,
transportation and utilities activities are
expected to result in the largest portion
of consultations for both the Texas
heelsplitter and Louisiana pigtoe and,
therefore, to incur the highest costs. The
geographic distribution of future section
7 consultations and associated costs are
likely to be most heavily concentrated
in all three proposed units for the Texas
heelsplitter, and in proposed Units 2
and 3 for the Louisiana pigtoe. However,
even assuming consultation activity
increases substantially, incremental
administrative costs are still likely to
remain well under $100 million per
year. Therefore, based on the definition
of significance in E.O. 12866, they
would not be significant.
The entities most likely to incur
incremental costs are parties to section
7 consultations, including Federal
action agencies and, in some cases, third
parties, most frequently State agencies
or municipalities. Activities we expect
would be subject to consultations that
may involve private entities as third
parties are farms and ranches acquiring
funding through Federal agricultural
programs, oil and gas production
regulated by the Federal Energy
Regulatory Commission, and
infrastructure projects that involve
Federal funding or authorization.
However, based on coordination efforts
with State and local agencies, the cost
to private entities in these sectors is
expected to be relatively minor
(administrative costs of less than
$10,000 per consultation effort) and
would not be significant (i.e., would not
exceed $100 million in a single year).
We are soliciting data and comments
from the public on the DEA discussed
above. During the development of a
final designation, we will consider the
information presented in the DEA and
any additional information on economic
impacts we receive during the public
comment period to determine whether
any specific areas should be excluded
from the final critical habitat
designation under authority of section
4(b)(2) and our implementing
regulations at 50 CFR 424.19. We may
exclude an area from critical habitat if
we determine that the benefits of
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excluding the area outweigh the benefits
of including the area, provided the
exclusion will not result in the
extinction of this species.
Consideration of National Security
Impacts or Homeland Security Impacts
Section 4(a)(3)(B)(i) of the Act may
not cover all DoD lands or areas that
pose potential national-security
concerns (e.g., a DoD installation that is
in the process of revising its INRMP for
a newly listed species or a species
previously not covered). If a particular
area is not covered under section
4(a)(3)(B)(i), national-security or
homeland-security concerns are not a
factor in the process of determining
what areas meet the definition of
‘‘critical habitat.’’ However, the Service
must consider impacts on national
security, including homeland security,
on those lands or areas not covered by
section 4(a)(3)(B)(i) because section
4(b)(2) requires the Service to consider
those impacts whenever it designates
critical habitat. Accordingly, if DoD,
Department of Homeland Security
(DHS), or another Federal agency has
requested exclusion based on an
assertion of national-security or
homeland-security concerns, or we have
otherwise identified national-security or
homeland-security impacts from
designating particular areas as critical
habitat, we generally have reason to
consider excluding those areas.
However, we cannot automatically
exclude requested areas. When DoD,
DHS, or another Federal agency requests
exclusion from critical habitat on the
basis of national-security or homelandsecurity impacts, we must conduct an
exclusion analysis if the Federal
requester provides information,
including a reasonably specific
justification of an incremental impact
on national security that would result
from the designation of that specific
area as critical habitat. That justification
could include demonstration of
probable impacts, such as impacts to
ongoing border-security patrols and
surveillance activities, or a delay in
training or facility construction, as a
result of compliance with section 7(a)(2)
of the Act. If the agency requesting the
exclusion does not provide us with a
reasonably specific justification, we will
contact the agency to recommend that it
provide a specific justification or
clarification of its concerns relative to
the probable incremental impact that
could result from the designation. If we
conduct an exclusion analysis because
the agency provides a reasonably
specific justification or because we
decide to exercise the discretion to
conduct an exclusion analysis, we will
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defer to the expert judgment of DoD,
DHS, or another Federal agency as to:
(1) Whether activities on its lands or
waters, or its activities on other lands or
waters, have national-security or
homeland-security implications; (2) the
importance of those implications; and
(3) the degree to which the cited
implications would be adversely
affected in the absence of an exclusion.
In that circumstance, in conducting a
discretionary section 4(b)(2) exclusion
analysis, we will give great weight to
national-security and homeland-security
concerns in analyzing the benefits of
exclusion.
In preparing this proposal, we have
determined that the lands within the
proposed designations of critical habitat
for Texas heelsplitter and Louisiana
pigtoe are not owned or managed by the
DoD or DHS, and, therefore, we
anticipate no impact on national
security or homeland security.
Consideration of Other Relevant
Impacts
Under section 4(b)(2) of the Act, we
consider any other relevant impacts, in
addition to economic impacts and
impacts on national security discussed
above. To identify other relevant
impacts that may affect the exclusion
analysis, we consider a number of
factors, including whether there are
permitted conservation plans covering
the species in the area—such as HCPs,
safe harbor agreements (SHAs), or
candidate conservation agreements with
assurances (CCAAs)—or whether there
are non-permitted conservation
agreements and partnerships that may
be impaired by designation of, or
exclusion from, critical habitat. In
addition, we look at whether Tribal
conservation plans or partnerships,
Tribal resources, or government-togovernment relationships of the United
States with Tribal entities may be
affected by the designation. We also
consider any State, local, social, or other
impacts that might occur because of the
designation.
When analyzing other relevant
impacts of including a particular area in
a designation of critical habitat, we
weigh those impacts relative to the
conservation value of the particular
area. To determine the conservation
value of designating a particular area,
we consider a number of factors,
including, but not limited to, the
additional regulatory benefits that the
area would receive due to the protection
from destruction or adverse
modification as a result of actions with
a Federal nexus, the educational
benefits of mapping essential habitat for
recovery of the listed species, and any
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benefits that may result from a
designation due to State or Federal laws
that may apply to critical habitat.
In the case of the Texas heelsplitter
and Louisiana pigtoe, the benefits of
critical habitat include public awareness
of the presence of these species and the
importance of habitat protection, and,
where a Federal nexus exists, increased
habitat protection for the Texas
heelsplitter and Louisiana pigtoe due to
protection from destruction or adverse
modification of critical habitat.
Continued implementation of an
ongoing management plan that provides
conservation equal to or more than the
protections that result from a critical
habitat designation would reduce those
benefits of including that specific area
in the critical habitat designation.
We evaluate the existence of a
conservation plan when considering the
benefits of inclusion. We consider a
variety of factors, including, but not
limited to, whether the plan is finalized;
how it provides for the conservation of
the essential physical or biological
features; whether there is a reasonable
expectation that the conservation
management strategies and actions
contained in a management plan will be
implemented into the future; whether
the conservation strategies in the plan
are likely to be effective; and whether
the plan contains a monitoring program
or adaptive management to ensure that
the conservation measures are effective
and can be adapted in the future in
response to new information.
After identifying the benefits of
inclusion and the benefits of exclusion,
we carefully weigh the two sides to
evaluate whether the benefits of
exclusion outweigh those of inclusion.
If our analysis indicates that the benefits
of exclusion outweigh the benefits of
inclusion, we then determine whether
exclusion would result in extinction of
the species. If exclusion of an area from
critical habitat will result in extinction,
we will not exclude it from the
designation.
Private or Other Non-Federal
Conservation Plans Related to Permits
Under Section 10 of the Act
HCPs for incidental take permits
under section 10(a)(1)(B) of the Act
provide for partnerships with nonFederal entities to minimize and
mitigate impacts to listed species and
their habitat. In some cases, HCP
permittees agree to do more for the
conservation of the species and their
habitats on private lands than
designation of critical habitat would
provide alone. We place great value on
the partnerships that are developed
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during the preparation and
implementation of HCPs.
CCAAs and SHAs are voluntary
agreements designed to conserve
candidate and listed species,
respectively, on non-Federal lands. In
exchange for actions that contribute to
the conservation of species on nonFederal lands, participating property
owners are covered by an ‘‘enhancement
of survival’’ permit under section
10(a)(1)(A) of the Act, which authorizes
incidental take of the covered species
that may result from implementation of
conservation actions, specific land uses,
and, in the case of SHAs, the option to
return to a baseline condition under the
agreements. We also provide enrollees
assurances that we will not impose
further land-, water-, or resource-use
restrictions, or require additional
commitments of land, water, or
finances, beyond those agreed to in the
agreements.
When we undertake a discretionary
section 4(b)(2) exclusion analysis based
on permitted conservation plans such as
CCAAs, SHAs, and HCPs, we consider
the following three factors:
(i) Whether the permittee is properly
implementing the conservation plan or
agreement;
(ii) Whether the species for which
critical habitat is being designated is a
covered species in the conservation plan
or agreement; and
(iii) Whether the conservation plan or
agreement specifically addresses the
habitat of the species for which critical
habitat is being designated and meets
the conservation needs of the species in
the planning area.
In preparing this proposal, we have
determined that there are currently no
HCPs or other management plans for the
Texas heelsplitter or Louisiana pigtoe.
The proposed designation of critical
habitat for the Louisiana pigtoe includes
the Choctaw Reservation in Oklahoma,
but not any lands held in trust for the
tribe, or owned or managed by the tribe.
No Tribal lands fall within the range of
the Texas heelsplitter or the boundaries
of the proposed critical habitat
designations. Therefore the proposed
designations do not include any Tribal
lands or trust resources. We anticipate
no impact on Tribal lands, partnerships,
or HCPs from the proposed critical
habitat designations.
We are currently working with the
Sabine River Authority of Louisiana,
State of Louisiana, and Sabine River
Authority of Texas to develop CCAAs
that address activities conducted by the
River Authorities and States with
conservation measures specifically
designed to provide a net conservation
benefit to the covered species, including
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the Texas heelsplitter and Louisiana
pigtoe, in the covered area for the term
for each of the CCAAs. We are also
working with the Trinity River
Authority of Texas to develop a CCAA
that would address activities conducted
by the Trinity River Authority and State
with conservation measures specifically
designed to provide a net conservation
benefit to the covered species, including
the Texas heelsplitter, in the covered
area for the term of the CCAA. While
these agreements are not yet completed,
if and when they are, we may consider
excluding areas covered by the
completed agreements from our critical
habitat designations.
Summary of Exclusions Considered
Under Section 4(b)(2) of the Act
At this time, we are not considering
any exclusions from the proposed
designations based on economic
impacts, national security impacts, or
other relevant impacts—such as
partnerships, management, or protection
afforded by cooperative management
efforts—under section 4(b)(2) of the Act.
In preparing this proposal, we have
determined that the proposed
designation of critical habitat for the
Louisiana pigtoe includes Choctaw
Reservation in Oklahoma, but not any
lands held in trust for the Tribe, or
owned or managed by the Tribe. No
tribal lands fall within the range of the
Texas heelsplitter or the boundaries of
the proposed critical habitat
designations. Therefore we have
determined that no HCPs or other
management plans for the Texas
heelsplitter or Louisiana pigtoe
currently exist, and the proposed
designations do not include any Tribal
lands or trust resources. Therefore, we
anticipate no impact on Tribal lands,
partnerships, or HCPs from the
proposed critical habitat designations,
and, thus, as described above, we are
not considering excluding any
particular areas on the basis of the
presence of conservation agreements or
impacts to trust resources. Some areas
within the proposed designations are
included in proposed CCAAs. If
finalized, we will consider the lands
covered in the CCAAs for exclusion in
the development of the final
designations. However, we have
contacted the Choctaw Nation of
Oklahoma to request information on any
possible impacts and will include such
information in our final review.
If through the public comment period
we receive information that we
determine indicates that there are
economic, national security or other
relevant impacts from designating
particular areas as critical habitat, then
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as part of developing the final
designation of critical habitat, we will
evaluate that information and may
conduct a discretionary exclusion
analysis to determine whether to
exclude those areas under authority of
section 4(b)(2) and our implementing
regulations at 50 CFR 424.19. If we
receive a request for exclusion of a
particular area and after evaluation of
supporting information we do not
exclude, we will fully explain our
decision in the final rule for this action.
(Please see ADDRESSES, above, for
instructions on how to submit
comments).
Required Determinations
Clarity of the Rule
We are required by Executive Orders
12866 and 12988 and by the
Presidential Memorandum of June 1,
1998, to write all rules in plain
language. This means that each rule we
publish must:
(1) Be logically organized;
(2) Use the active voice to address
readers directly;
(3) Use clear language rather than
jargon;
(4) Be divided into short sections and
sentences; and
(5) Use lists and tables wherever
possible.
If you feel that we have not met these
requirements, send us comments by one
of the methods listed in ADDRESSES. To
better help us revise the rule, your
comments should be as specific as
possible. For example, you should tell
us the numbers of the sections or
paragraphs that are unclearly written,
which sections or sentences are too
long, the sections where you feel lists or
tables would be useful, etc.
Regulatory Planning and Review
(Executive Orders 12866 and 13563)
Executive Order 12866 provides that
the Office of Information and Regulatory
Affairs (OIRA) in the Office of
Management and Budget will review all
significant rules. OIRA has determined
that this proposed rule is not significant.
Executive Order 13563 reaffirms the
principles of E.O. 12866 while calling
for improvements in the nation’s
regulatory system to promote
predictability, to reduce uncertainty,
and to use the best, most innovative,
and least burdensome tools for
achieving regulatory ends. The
executive order directs agencies to
consider regulatory approaches that
reduce burdens and maintain flexibility
and freedom of choice for the public
where these approaches are relevant,
feasible, and consistent with regulatory
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objectives. E.O. 13563 emphasizes
further that regulations must be based
on the best available science and that
the rulemaking process must allow for
public participation and an open
exchange of ideas. We have developed
this proposed rule in a manner
consistent with these requirements.
Regulatory Flexibility Act (5 U.S.C. 601
et seq.)
Under the Regulatory Flexibility Act
(RFA; 5 U.S.C. 601 et seq.), as amended
by the Small Business Regulatory
Enforcement Fairness Act of 1996
(SBREFA; 5 U.S.C. 801 et seq.),
whenever an agency is required to
publish a notice of rulemaking for any
proposed or final rule, it must prepare
and make available for public comment
a regulatory flexibility analysis that
describes the effects of the rule on small
entities (i.e., small businesses, small
organizations, and small government
jurisdictions). However, no regulatory
flexibility analysis is required if the
head of the agency certifies the rule will
not have a significant economic impact
on a substantial number of small
entities. The SBREFA amended the RFA
to require Federal agencies to provide a
certification statement of the factual
basis for certifying that the rule will not
have a significant economic impact on
a substantial number of small entities.
According to the Small Business
Administration, small entities include
small organizations such as
independent nonprofit organizations;
small governmental jurisdictions,
including school boards and city and
town governments that serve fewer than
50,000 residents; and small businesses
(13 CFR 121.201). Small businesses
include manufacturing and mining
concerns with fewer than 500
employees, wholesale trade entities
with fewer than 100 employees, retail
and service businesses with less than $5
million in annual sales, general and
heavy construction businesses with less
than $27.5 million in annual business,
special trade contractors doing less than
$11.5 million in annual business, and
agricultural businesses with annual
sales less than $750,000. To determine
whether potential economic impacts to
these small entities are significant, we
considered the types of activities that
might trigger regulatory impacts under
this designation as well as types of
project modifications that may result. In
general, the term ‘‘significant economic
impact’’ is meant to apply to a typical
small business firm’s business
operations.
Under the RFA, as amended, and as
understood in light of recent court
decisions, Federal agencies are required
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to evaluate the potential incremental
impacts of rulemaking on those entities
directly regulated by the rulemaking
itself; in other words, the RFA does not
require agencies to evaluate the
potential impacts to indirectly regulated
entities. The regulatory mechanism
through which critical habitat
protections are realized is section 7 of
the Act, which requires Federal
agencies, in consultation with the
Service, to ensure that any action
authorized, funded, or carried out by the
agency is not likely to destroy or
adversely modify critical habitat.
Therefore, under section 7, only Federal
action agencies are directly subject to
the specific regulatory requirement
(avoiding destruction and adverse
modification) imposed by critical
habitat designation. Consequently, it is
our position that only Federal action
agencies would be directly regulated if
we adopt the proposed critical habitat
designations. The RFA does not require
evaluation of the potential impacts to
entities not directly regulated.
Moreover, Federal agencies are not
small entities. Therefore, because no
small entities would be directly
regulated by this rulemaking, the
Service certifies that, if made final as
proposed, the proposed critical habitat
designations will not have a significant
economic impact on a substantial
number of small entities.
In summary, we have considered
whether the proposed designations
would result in a significant economic
impact on a substantial number of small
entities. For the above reasons and
based on currently available
information, we certify that, if made
final, the proposed critical habitat
designations would not have a
significant economic impact on a
substantial number of small business
entities. Therefore, an initial regulatory
flexibility analysis is not required.
Energy Supply, Distribution, or Use—
Executive Order 13211
Executive Order 13211 (Actions
Concerning Regulations That
Significantly Affect Energy Supply,
Distribution, or Use) requires agencies
to prepare Statements of Energy Effects
when undertaking certain actions.
Facilities that provide energy supply,
distribution, or use occur within some
units of the proposed critical habitat
designations (for example, dams,
pipelines) and may potentially be
affected. We determined that
consultations, technical assistance, and
requests for species lists may be
necessary in some instances. In our
economic analysis, we did not find that
the proposed critical habitat
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designations would significantly affect
energy supplies, distribution, or use.
Therefore, this action is not a significant
energy action, and no Statement of
Energy Effects is required.
Unfunded Mandates Reform Act (2
U.S.C. 1501 et seq.)
In accordance with the Unfunded
Mandates Reform Act (2 U.S.C. 1501 et
seq.), we make the following finding:
(1) This proposed rule would not
produce a Federal mandate. In general,
a Federal mandate is a provision in
legislation, statute, or regulation that
would impose an enforceable duty upon
State, local, or Tribal governments, or
the private sector, and includes both
‘‘Federal intergovernmental mandates’’
and ‘‘Federal private sector mandates.’’
These terms are defined in 2 U.S.C.
658(5)–(7). ‘‘Federal intergovernmental
mandate’’ includes a regulation that
‘‘would impose an enforceable duty
upon State, local, or Tribal
governments’’ with two exceptions. It
excludes ‘‘a condition of Federal
assistance.’’ It also excludes ‘‘a duty
arising from participation in a voluntary
Federal program,’’ unless the regulation
‘‘relates to a then-existing Federal
program under which $500,000,000 or
more is provided annually to State,
local, and Tribal governments under
entitlement authority,’’ if the provision
would ‘‘increase the stringency of
conditions of assistance’’ or ‘‘place caps
upon, or otherwise decrease, the Federal
Government’s responsibility to provide
funding,’’ and the State, local, or Tribal
governments ‘‘lack authority’’ to adjust
accordingly. At the time of enactment,
these entitlement programs were:
Medicaid; Aid to Families with
Dependent Children work programs;
Child Nutrition; Food Stamps; Social
Services Block Grants; Vocational
Rehabilitation State Grants; Foster Care,
Adoption Assistance, and Independent
Living; Family Support Welfare
Services; and Child Support
Enforcement. ‘‘Federal private sector
mandate’’ includes a regulation that
‘‘would impose an enforceable duty
upon the private sector, except (i) a
condition of Federal assistance or (ii) a
duty arising from participation in a
voluntary Federal program.’’
The designation of critical habitat
does not impose a legally binding duty
on non-Federal Government entities or
private parties. Under the Act, the only
regulatory effect is that Federal agencies
must ensure that their actions do not
destroy or adversely modify critical
habitat under section 7. While nonFederal entities that receive Federal
funding, assistance, or permits, or that
otherwise require approval or
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authorization from a Federal agency for
an action, may be indirectly impacted
by the designation of critical habitat, the
legally binding duty to avoid
destruction or adverse modification of
critical habitat rests squarely on the
Federal agency. Furthermore, to the
extent that non-Federal entities are
indirectly impacted because they
receive Federal assistance or participate
in a voluntary Federal aid program, the
Unfunded Mandates Reform Act would
not apply, nor would critical habitat
shift the costs of the large entitlement
programs listed above onto State
governments.
(2) We do not believe that this
proposed rule would significantly or
uniquely affect small governments
because the vast majority of the lands
being proposed for critical habitat
designation are owned by the Federal
Government; States of Arkansas,
Louisiana, Mississippi, Oklahoma, and
Texas; and private individuals. These
entities do not fit the definition of
‘‘small governmental jurisdiction.’’ One
proposed unit (TXHS–2a) includes a
very small portion of land owned by the
local government, but that is only 1
percent of that one unit. Therefore, a
Small Government Agency Plan is not
required.
Takings—Executive Order 12630
In accordance with E.O. 12630
(Government Actions and Interference
with Constitutionally Protected Private
Property Rights), we have analyzed the
potential takings implications of
designating critical habitat for the Texas
heelsplitter and Louisiana pigtoe in a
takings implications assessment. The
Act does not authorize the Service to
regulate private actions on private lands
or confiscate private property as a result
of critical habitat designation.
Designation of critical habitat does not
affect land ownership, or establish any
closures, or restrictions on use of or
access to the designated areas.
Furthermore, the designation of critical
habitat does not affect landowner
actions that do not require Federal
funding or permits, nor does it preclude
development of habitat conservation
programs or issuance of incidental take
permits to permit actions that do require
Federal funding or permits to go
forward. However, Federal agencies are
prohibited from carrying out, funding,
or authorizing actions that would
destroy or adversely modify critical
habitat. A takings implications
assessment has been completed for the
proposed designation of critical habitat
for the Texas heelsplitter and the
Louisiana pigtoe, and it concludes that,
if adopted, these designations of critical
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habitat do not pose significant takings
implications for lands within or affected
by the designations.
Federalism—Executive Order 13132
In accordance with E.O. 13132
(Federalism), this proposed rule does
not have significant federalism effects.
A federalism summary impact statement
is not required. In keeping with
Department of the Interior and
Department of Commerce policy, we
requested information from, and
coordinated development of the
proposed critical habitat designations
with, appropriate State resource
agencies. From a federalism perspective,
the designation of critical habitat
directly affects only the responsibilities
of Federal agencies. The Act imposes no
other duties with respect to critical
habitat, either for States and local
governments, or for anyone else. As a
result, the proposed rule does not have
substantial direct effects either on the
States, or on the relationship between
the national government and the States,
or on the distribution of powers and
responsibilities among the various
levels of government. The proposed
designations may have some benefit to
these governments because the areas
that contain the features essential to the
conservation of the species are more
clearly defined, and the physical or
biological features of the habitat
necessary for the conservation of the
species are specifically identified. This
information does not alter where and
what federally sponsored activities may
occur. However, it may assist State and
local governments in long-range
planning because they no longer have to
wait for case-by-case section 7
consultations to occur.
Where State and local governments
require approval or authorization from a
Federal agency for actions that may
affect critical habitat, consultation
under section 7(a)(2) of the Act would
be required. While non-Federal entities
that receive Federal funding, assistance,
or permits, or that otherwise require
approval or authorization from a Federal
agency for an action, may be indirectly
impacted by the designation of critical
habitat, the legally binding duty to
avoid destruction or adverse
modification of critical habitat rests
squarely on the Federal agency.
Civil Justice Reform—Executive Order
12988
In accordance with Executive Order
12988 (Civil Justice Reform), the Office
of the Solicitor has determined that the
proposed rule would not unduly burden
the judicial system and that it meets the
requirements of sections 3(a) and 3(b)(2)
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16817
of the Order. We have proposed
designating critical habitat in
accordance with the provisions of the
Act. To assist the public in
understanding the habitat needs of the
species, this proposed rule identifies the
physical or biological features essential
to the conservation of the species. The
proposed areas of critical habitat are
presented on maps, and the proposed
rule provides several options for the
interested public to obtain more
detailed location information, if desired.
Paperwork Reduction Act of 1995 (44
U.S.C. 3501 et seq.)
This proposed rule does not contain
information collection requirements,
and a submission to the Office of
Management and Budget (OMB) under
the Paperwork Reduction Act of 1995
(44 U.S.C. 3501 et seq.) is not required.
We may not conduct or sponsor and you
are not required to respond to a
collection of information unless it
displays a currently valid OMB control
number.
National Environmental Policy Act (42
U.S.C. 4321 et seq.)
It is our position that, outside the
jurisdiction of the U.S. Court of Appeals
for the Tenth Circuit, we do not need to
prepare environmental analyses
pursuant to the National Environmental
Policy Act (NEPA; 42 U.S.C. 4321 et
seq.) in connection with regulations
adopted pursuant to section 4(a) of the
Act. We published a notice outlining
our reasons for this determination in the
Federal Register on October 25, 1983
(48 FR 49244). This position was upheld
by the U.S. Court of Appeals for the
Ninth Circuit (Douglas County v.
Babbitt, 48 F.3d 1495 (9th Cir. 1995),
cert. denied 516 U.S. 1042 (1996)).
However, when the range of the species
includes States within the Tenth
Circuit, such as that of the Louisiana
pigtoe, under the Tenth Circuit ruling in
Catron County Board of Commissioners
v. U.S. Fish and Wildlife Service, 75
F.3d 1429 (10th Cir. 1996), we
undertake a NEPA analysis for critical
habitat designation. We invite the
public to comment on the extent to
which these proposed critical habitat
designations may have a significant
impact on the human environment or
fall within one of the categorical
exclusions for actions that have no
individual or cumulative effect on the
quality of the human environment. We
will complete our analysis, in
compliance with NEPA, before making
a final determination on this proposed
rule.
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Government-to-Government
Relationship With Tribes
In accordance with the President’s
memorandum of April 29, 1994
(Government-to-Government Relations
with Native American Tribal
Governments; 59 FR 22951), Executive
Order 13175 (Consultation and
Coordination with Indian Tribal
Governments), and the Department of
the Interior’s manual at 512 DM 2, we
readily acknowledge our responsibility
to communicate meaningfully with
federally recognized Tribes on a
government-to-government basis. In
accordance with Secretarial Order 3206
of June 5, 1997 (American Indian Tribal
Rights, Federal-Tribal Trust
Responsibilities, and the Endangered
Species Act), we readily acknowledge
our responsibilities to work directly
with Tribes in developing programs for
healthy ecosystems, to acknowledge that
Tribal lands are not subject to the same
controls as Federal public lands, to
remain sensitive to Indian culture, and
Common name
*
CLAMS
References Cited
A complete list of references cited in
this rulemaking is available on the
internet at https://www.regulations.gov
and upon request from the Austin
Ecological Services Field Office (see FOR
FURTHER INFORMATION CONTACT).
Authors
The primary authors of this proposed
rule are the staff members of the Fish
and Wildlife Service’s Species
Assessment Team and the Arlington
Ecological Services Field Office.
Where listed
Status
*
E
*
Pigtoe, Louisiana .............
*
*
Pleurobema riddellii ........
*
Wherever found ..............
T
§ 17.45
*
Special rules—snails and clams.
*
*
*
*
*
(f) [Reserved]
(g) Louisiana pigtoe (Pleurobema
riddellii).
(1) Prohibitions. The following
prohibitions that apply to endangered
wildlife also apply to the Louisiana
pigtoe. Except as provided under
paragraph (g)(2) of this section and
§§ 17.4 and 17.5, it is unlawful for any
person subject to the jurisdiction of the
United States to commit, to attempt to
commit, to solicit another to commit, or
cause to be committed, any of the
following acts in regard to Louisiana
pigtoe:
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1. The authority citation for part 17
continues to read as follows:
■
Authority: 16 U.S.C. 1361–1407; 1531–
1544; and 4201–4245, unless otherwise
noted.
2. Amend § 17.11(h) by adding entries
for ‘‘Heelsplitter, Texas’’ and ‘‘Pigtoe,
Louisiana’’ to the List of Endangered
and Threatened Wildlife in alphabetical
order under CLAMS to read as follows:
■
*
Frm 00044
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*
*
*
*
*
*
[Federal Register citation when published as a
final rule]; 50 CFR 17.95(f).CH
*
*
*
[Federal Register citation when published as a
final rule]; 50 CFR 17.45(g); 4d 50 CFR
17.95(f).CH
*
Sfmt 4702
*
Listing citations and applicable rules
(i) Import or export, as set forth at
§ 17.21(b) for endangered wildlife.
(ii) Take, as set forth at § 17.21(c)(1)
for endangered wildlife.
(iii) Possession and other acts with
unlawfully taken specimens, as set forth
at § 17.21(d)(1) for endangered wildlife.
(iv) Interstate or foreign commerce in
the course of commercial activity, as set
forth at § 17.21(e) for endangered
wildlife.
(v) Sale or offer for sale, as set forth
at § 17.21(f) for endangered wildlife.
(2) Exceptions from prohibitions. In
regard to this species, you may:
(i) Conduct activities as authorized by
a permit under § 17.32.
(ii) Take, as set forth at § 17.21(c)(2)
through (4) for endangered wildlife.
(iii) Take as set forth at § 17.31(b).
(iv) Possess and engage in other acts
with unlawfully taken wildlife, as set
forth at § 17.21(d)(2) for endangered
wildlife.
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*
*
(h) * * *
*
*
Wherever found ..............
3. Further amend § 17.45, as proposed
to be amended on September 29, 2020,
at 85 FR 61384, on August 26, 2021, at
86 FR 47916, and on September 7, 2021,
at 86 FR 50010, and by adding
paragraphs (f) and (g) to read as follows:
PART 17—ENDANGERED AND
THREATENED WILDLIFE AND PLANTS
*
*
*
Potamilus amphichaenus
■
Accordingly, we propose to amend
part 17, subchapter B of chapter I, title
50 of the Code of Federal Regulations,
as set forth below:
Endangered and threatened species,
Exports, Imports, Plants, Reporting and
*
*
Proposed Regulation Promulgation
§ 17.11 Endangered and threatened
wildlife.
Scientific name
*
recordkeeping requirements,
Transportation, Wildlife.
List of Subjects in 50 CFR Part 17
*
Heelsplitter, Texas ..........
*
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to make information available to Tribes.
We have determined that no Tribal
lands fall within the boundaries of the
proposed critical habitat for the Texas
heelsplitter or Louisiana pigtoe, so no
Tribal lands would be affected by the
proposed designations.
*
*
(v) Take incidental to an otherwise
lawful activity caused by:
(A) Channel restoration projects that
create natural, physically stable,
ecologically functioning streams (or
stream and wetland systems) that are
reconnected with their groundwater
aquifers.
(B) Bioengineering methods such as
streambank stabilization using live
native stakes (live, vegetative cuttings
inserted or tamped into the ground in a
manner that allows the stake to take root
and grow), live native fascines (live
branch cuttings, usually willows, bound
together into long, cigar-shaped
bundles), or native brush layering
(cuttings or branches of easily rooted
tree species layered between successive
lifts of soil fill). These methods must not
include the sole use of quarried rock
(rip-rap) or the use of rock baskets or
gabion structures. In addition, to reduce
streambank erosion and sedimentation
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into the stream, work using these
bioengineering methods must be
performed at base-flow or low-water
conditions and when significant rainfall
is not predicted. Further, streambank
stabilization projects must keep all
equipment out of the stream channels
and water.
(C) Soil and water conservation
practices and riparian and adjacent
upland habitat management activities
that restore instream habitats for the
species, restore adjacent riparian
habitats that enhance stream habitats for
the species, stabilize degraded and
eroding stream banks to limit
sedimentation and scour of the species’
habitats, and restore or enhance nearby
upland habitats to limit sedimentation
of the species’ habitats. We recommend
that these practices and activities
comply with specifications and
technical guidelines developed by the
U.S. Department of Agriculture’s
Natural Resources Conservation Service.
■ 4. Amend § 17.95(f) by adding an
entry for ‘‘Texas Heelsplitter (Potamilus
amphichaenus)’’ after the entry for
‘‘Carolina Heelsplitter (Lasmigona
decorata)’’, and by adding an entry for
‘‘Louisiana Pigtoe (Pleurobema
riddellii)’’ after the entry for ‘‘Georgia
Pigtoe (Pleurobema hanleyianum)’’, to
read as follows:
§ 17.95
Critical habitat—fish and wildlife.
*
*
*
*
(f) Clams and Snails.
*
*
*
*
*
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*
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Texas Heelsplitter (Potamilus
amphichaenus)
(1) Critical habitat units are depicted
for Anderson, Angelina, Cherokee, Ellis,
Freestone, Gregg, Grimes, Hardin,
Harrison, Henderson, Houston, Jasper,
Jefferson, Kaufman, Leon, Madison,
Navarro, Orange, Panola, Polk, Rains,
Rusk, Sabine, Shelby, Smith, Trinity,
Tyler, Upshur, Van Zandt, Walker, and
Wood Counties, Texas, on the maps in
this entry.
(2) Within these areas, the physical or
biological features essential to the
conservation of Texas heelsplitter
consist of the following components
within impoundments and streambeds:
(i) Water quality parameters within
the following ranges:
(A) Water temperature below 27 °C
(80.6 °F);
(B) Dissolved oxygen levels greater
than 3 milligrams per liter (mg/L);
(C) Low salinity (less than 2 parts per
thousand) and total dissolved solids;
(D) Low total ammonia and nitrogen
(below 0.3–0.7 mg/L total ammonia
nitrogen);
(E) Low levels of copper, nickel, and
other trace metals;
(F) Low levels of pesticides, sulfate,
chloride, potassium, and other harmful
constituents; and
(G) Low pollutants and environmental
contaminants common to wastewater.
(ii) Moderately flowing water rates
suitable to prevent excess sedimentation
but not so high as to dislodge
individuals or sediment; or no water
flow, if in an impoundment (lake,
reservoir, or pool without flow).
(iii) Substrate including bedrock and
boulder crevices, point bars, and
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16819
vegetated run habitat comprising sand,
gravel, and larger cobbles.
(iv) Freshwater drum (Aplodinotus
grunniens) present.
(3) Critical habitat does not include
manmade structures (such as buildings,
aqueducts, runways, roads, and other
paved areas) and the land on which they
are located existing within the legal
boundaries on the effective date of the
final rule.
(4) Data layers defining map units
were created on a base of U.S.
Geological Survey digital ortho-photo
quarter-quadrangles, and critical habitat
units were then mapped using Universal
Transverse Mercator (UTM) Zone 14N
coordinates. The maps in this entry, as
modified by any accompanying
regulatory text, establish the boundaries
of the critical habitat designation. The
coordinates or plot points or both on
which each map is based are available
to the public at the Service’s internet
site at https://www.fws.gov/office/
arlington-ecological-services, at https://
www.regulations.gov at Docket No.
FWS–R2–ES–2022–0026, and at the
field office responsible for this
designation. You may obtain field office
location information by contacting one
of the Service regional offices, the
addresses of which are listed at 50 CFR
2.2.
(5) Index map of critical habitat units
for the Texas heelsplitter follows:
Figure 1 to Texas Heelsplitter
(Potamilus amphichaenus) paragraph
(5)
BILLING CODE 4333–15–P
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(6) Unit TXHS–1: Trinity River Unit;
Anderson, Ellis, Freestone, Grimes,
Henderson, Houston, Kaufman, Leon,
Madison, Navarro, and Walker Counties,
Texas.
(i) Unit TXHS–1 consists of two
subunits:
(A) Subunit TXHS–1a (Trinity River)
is comprised of 212.8 river miles (mi)
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(342.4 kilometers (km)) in Anderson,
Ellis, Freestone, Henderson, Houston,
Kaufman, Leon, Madison, and Navarro
Counties, Texas. This subunit is
composed of lands in State (5 percent)
and private (95 percent) ownership.
(B) Subunit TXHS–1b (Bedias Creek)
is comprised of 28.9 river mi (46.5 km)
in Grimes, Madison, and Walker
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Counties, Texas. All of the riparian
lands that border this subunit are in
private ownership.
(ii) Unit TXHS–1 includes stream
channel up to bankfull height.
(iii) Map of Unit TXHS–1 follows:
Figure 2 to Texas Heelsplitter
(Potamilus amphichaenus) paragraph
(6)(iii)
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(7) Unit TXHS–2: Sabine River Unit;
Gregg, Harrison, Panola, Rains, Rusk,
Sabine, Shelby, Smith, Upshur, Van
Zandt, and Wood Counties, Texas.
(i) Unit TXHS–2 consists of three
subunits:
(A) Subunit TXHS–2a (Upper Sabine
River) is comprised of 237.4 river mi
(382 km) in Gregg, Harrison, Panola,
Rains, Rusk, Smith, Upshur, Van Zandt,
and Wood Counties, Texas. The riparian
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lands that border this subunit include
Federal (2 percent), State (4 percent),
local (1 percent), and private (93
percent) ownership.
(B) Subunit TXHS–2b (Lake Fork
Creek) consists of 13.8 river mi (22.2
km) in Wood County, Texas. All of the
riparian lands that border this subunit
are in private ownership.
(C) Subunit TXHS–2c (Patroon Bayou)
includes 19.9 river mi (32 km) in Sabine
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16821
and Shelby Counties, Texas. The
riparian lands that border this subunit
are in Federal (7 percent) and private
(93 percent) ownership.
(ii) Unit TXHS–2 includes stream
channel up to bankfull height.
(iii) Map of Unit TXHS–2 follows:
Figure 3 to Texas Heelsplitter
(Potamilus amphichaenus) paragraph
(7)(iii)
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(8) Unit TXHS–3: Neches River Unit;
Anderson, Angelina, Cherokee, Hardin,
Houston, Jasper, Jefferson, Orange, Polk,
Trinity, and Tyler Counties, Texas.
(i) Unit TXHS–3 consists of three
subunits:
(A) Subunit TXHS–3a (Upper Neches
River) is comprised of 227.9 river mi
(366.7 km) of stream in Anderson,
Angelina, Cherokee, Houston, Jasper,
Polk, Trinity, and Tyler Counties, Texas.
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The riparian lands that border this
subunit are in Federal (12 percent) and
private (88 percent) ownership.
(B) Subunit TXHS–3b (Lower
Angelina River) consists of 14.7 river mi
(23.7 km) in Jasper County, Texas. The
riparian lands that border this subunit
are in Federal (11 percent) and private
(89 percent) ownership.
(C) Subunit TXHS–3c (Lower Neches
River) includes 76.3 river mi (122.8 km)
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in Hardin, Jasper, Jefferson, Orange, and
Tyler Counties, Texas. The riparian
lands that border this subunit are in
Federal (5 percent), State (7 percent),
and private (88 percent) ownership.
(ii) Unit TXHS–3 includes stream
channel up to bankfull height.
(iii) Map of Unit TXHS–3 follows:
Figure 4 to Texas Heelsplitter
(Potamilus amphichaenus) paragraph
(8)(iii)
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Louisiana Pigtoe (Pleurobema riddellii)
(1) Critical habitat units are depicted
for Howard, Little River, and Sevier
Counties, Arkansas; Allen, Beauregard,
Rapides, St. Tammany, Vernon, and
Washington parishes, Louisiana; Marion
and Pearl River Counties, Mississippi;
McCurtain County, Oklahoma; and
Anderson, Angelina, Cherokee, Gregg,
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Hardin, Harrison, Houston, Jasper,
Jefferson, Liberty, Montgomery,
Nacogdoches, Orange, Panola, Polk,
Rusk, Smith, Trinity, Tyler, Upshur, and
Wood Counties, Texas, on the maps in
this entry.
(2) Within this area, the physical or
biological features essential to the
conservation of Louisiana pigtoe consist
of the following components within
streambeds:
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(i) Water quality parameters within
the following ranges:
(A) Water temperature below 27 °C
(80.6 °F);
(B) Dissolved oxygen levels greater
than 3 milligrams per liter (mg/L);
(C) Low salinity (less than 2 parts per
thousand) and total dissolved solids;
(D) Low total ammonia and nitrogen
(below 0.3–0.7 mg/L total ammonia
nitrogen);
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(E) Low levels of copper, nickel, and
other trace metals;
(F) Low levels of pesticides, sulfate,
chloride, potassium, and other harmful
constituents; and
(G) Low pollutants and environmental
contaminants common to wastewater.
(ii) Moderately flowing water rates
suitable to prevent excess sedimentation
but not so high as to dislodge
individuals or sediment.
(iii) Stable bank and riffle habitats
with bedrock and boulder crevices,
point bars, and vegetated run habitat
comprising sand, gravel, and larger
cobbles.
(iv) Red shiner (Cyprinella
(=Notropis) lutrensis), blacktail shiner
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(Cyprinella venusta), and bullhead
minnow (Pimephales vigilax) present.
(3) Critical habitat does not include
manmade structures (such as buildings,
aqueducts, runways, roads, and other
paved areas) and the land on which they
are located existing within the legal
boundaries on the effective date of the
final rule.
(4) Data layers defining map units
were created on a base of U.S.
Geological Survey digital ortho-photo
quarter-quadrangles, and critical habitat
units were then mapped using Universal
Transverse Mercator (UTM) Zone 14N
coordinates. The maps in this entry, as
modified by any accompanying
regulatory text, establish the boundaries
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of the critical habitat designation. The
coordinates or plot points or both on
which each map is based are available
to the public at the Service’s internet
site at https://www.fws.gov/office/
arlington-ecological-services, at https://
www.regulations.gov at Docket No.
FWS–R2–ES–2022–0026, and at the
field office responsible for this
designation. You may obtain field office
location information by contacting one
of the Service regional offices, the
addresses of which are listed at 50 CFR
2.2.
(5) Index map of critical habitat units
for the Louisiana pigtoe follows:
Figure 1 to Louisiana Pigtoe
(Pleurobema riddellii) paragraph (5)
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(6) Unit LAPT–1: Little River Unit;
Howard, Little River, and Sevier
Counties, Arkansas, and McCurtain
County, Oklahoma.
(i) Unit LAPT–1 consists of four
subunits:
(A) Subunit LAPT–1a (Upper Little
River) is comprised of consists of
approximately 88 river miles (mi) (141.6
kilometers (km)) in Little River and
Sevier Counties, Arkansas, and
McCurtain County, Oklahoma. The
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riparian lands that border this subunit
are in Federal (26 percent), State (1
percent), and private (42 percent)
ownership, and private land with the
Choctaw Reservation (23 percent), but
not any lands held in trust for the Tribe,
or owned or managed by the Tribe.
(B) Subunit LAPT–1b (Rolling Fork) is
comprised of 29.9 river mi (47.9 km) in
Sevier County, Arkansas. All of the
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riparian lands that border this subunit
are in private ownership.
(C) Subunit LAPT–1c (Cossatot River)
includes 47.2 river mi (75.9 km) in
Sevier County, Arkansas. The riparian
lands that border this subunit are in
Federal (15 percent) and private (85
percent) ownership.
(D) Subunit LAPT–1d (Saline River)
consists of 42.6 river mi (68.5 km) along
the Howard/Sevier County line in
southeast Arkansas. All of the riparian
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lands in this subunit are in private
ownership.
(ii) Unit LAPT–1 includes stream
channel up to bankfull height.
(iii) Map of Unit LAPT–1 follows:
Figure 2 to Louisiana Pigtoe
(Pleurobema riddellii) paragraph
(6)(iii)
(7) Unit LAPT–2: Sabine River Unit;
Beauregard and Vernon parishes,
Louisiana, and Gregg, Harrison, Panola,
Rusk, Smith, Upshur, and Wood
Counties, Texas.
(i) Unit LAPT–2 consists of two
subunits:
(A) Subunit LAPT–2a (Upper Sabine
River) consists of 110.1 river mi (177.2
km) in Gregg, Harrison, Panola, Rusk,
Smith, Upshur, and Wood Counties,
Texas. The riparian lands that border
this subunit are in Federal (2 percent),
State (2 percent), and private (96
percent) ownership.
(B) Subunit LAPT–2b (Anacoco
Bayou) includes 12.2 river mi (19.6 km)
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in Vernon and Beauregard parishes,
Louisiana. All of the riparian lands that
border this subunit are in private
ownership.
(ii) Unit LAPT–2 includes stream
channel up to bankfull height.
(iii) Map of Unit LAPT–2 follows:
Figure 3 to Louisiana Pigtoe
(Pleurobema riddellii) paragraph
(7)(iii)
(8) Unit LAPT–3: Neches River Unit;
Anderson, Angelina, Cherokee, Hardin,
Houston, Jasper, Jefferson, Nacogdoches,
Orange, Polk, Trinity, and Tyler
Counties, Texas.
(i) Unit LAPT–3 consists of five
subunits:
(A) Subunit LAPT–3a (Upper Neches
River) consists of 200.4 river mi (322.4
km) through parts of Anderson,
Angelina, Cherokee, Houston, Polk,
Trinity, and Tyler Counties, Texas. The
riparian lands that border this subunit
are in Federal (11 percent) and private
(89 percent) ownership.
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(B) Subunit LAPT–3b (Upper
Angelina River) consists of 67.4 river mi
(108.4 km) in Angelina, Cherokee, and
Nacogdoches Counties, Texas. The
riparian lands that border this subunit
are in Federal (50 percent) and private
(50 percent) ownership.
(C) Subunit LAPT–3c (Lower Neches
River) includes 76.2 river mi (122.6 km)
in Hardin, Jasper, Jefferson, Orange, and
Tyler Counties, Texas. The riparian
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lands that border this subunit are in
Federal (5 percent), State (7 percent),
and private (88 percent) ownership.
(D) Subunit LAPT–3d (Village Creek)
consists of 54.9 river mi (88.3 km) of
stream in Hardin County, Texas. The
riparian lands that border this subunit
are in Federal (78 percent), State (2
percent), and private (20 percent)
ownership.
(E) Subunit LAPT–3e (Big Sandy
Creek) consists of 43.7 river mi (70.3
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km) of stream in Hardin, Polk, and Tyler
Counties, Texas. The riparian lands that
border this subunit are in Federal (95
percent) and private (5 percent)
ownership.
(ii) Unit LAPT–3 includes stream
channel up to bankfull height.
(iii) Map of Unit LAPT–3 follows:
Figure 4 to Louisiana Pigtoe
(Pleurobema riddellii) paragraph
(8)(iii)
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(9) Unit LAPT–4: East Fork San
Jacinto River Unit; Liberty and
Montgomery Counties, Texas.
(i) Unit LAPT–4 consists of 23.3 river
mi (37.5 km) in Liberty and
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Montgomery Counties, Texas. All of the
riparian lands that border this unit are
in private ownership.
(ii) Unit LAPT–4 includes stream
channel up to bankfull height.
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16829
(iii) Map of Unit LAPT–4 follows:
Figure 5 to Louisiana Pigtoe
(Pleurobema riddellii) paragraph
(9)(iii)
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(10) Unit LAPT–5: Calcasieu River
Unit; Allen, Rapides, and Vernon
parishes, Louisiana.
(i) Unit LAPT–5 consists of three
subunits:
(A) Subunit LAPT–5a (Upper
Calcasieu River) includes 92 river mi
(148 km) in Allen and Rapides parishes,
Louisiana. The riparian lands that
border this subunit are in Federal (22
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percent) and private (78 percent)
ownership.
(B) Subunit LAPT–5b (Whisky Chitto
Creek) includes 21.7 river mi (34.9 km)
in Allen Parish, Louisiana. The riparian
lands that border this subunit are in
State (99 percent) and private (1
percent) ownership.
(C) Subunit LAPT–5c (Tenmile Creek)
consists of 32 river mi (51.5 km) in
Allen, Rapides, and Vernon parishes,
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Louisiana. The riparian lands that
border the subunit are in State (2
percent) and private (98 percent)
ownership.
(ii) Unit LAPT–5 includes stream
channel up to bankfull height.
(iii) Map of Unit LAPT–5 follows:
Figure 6 to Louisiana Pigtoe
(Pleurobema riddellii) paragraph
(10)(iii)
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(11) Unit LAPT–6: Pearl River Unit;
St. Tammany and Washington parishes,
Louisiana, and Marion and Pearl River
Counties, Mississippi.
(i) Unit LAPT–6 consists of 86.6 river
mi (139.3 km) in St. Tammany and
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Washington parishes, Louisiana, and
Marion and Pearl River Counties,
Mississippi. The riparian lands that
border this unit are in Federal (42
percent), State (14 percent), and private
(44 percent) ownership.
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16831
(ii) Unit LAPT–6 includes stream
channel up to bankfull height.
(iii) Map of Unit LAPT–6 follows:
Figure 7 to Louisiana Pigtoe
(Pleurobema riddellii) paragraph
(11)(iii)
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Martha Williams,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 2023–05107 Filed 3–17–23; 8:45 am]
BILLING CODE 4333–15–C
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Agencies
[Federal Register Volume 88, Number 53 (Monday, March 20, 2023)]
[Proposed Rules]
[Pages 16776-16832]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-05107]
[[Page 16775]]
Vol. 88
Monday,
No. 53
March 20, 2023
Part III
Department of the Interior
-----------------------------------------------------------------------
Fish and Wildlife Service
-----------------------------------------------------------------------
50 CFR Part 17
Endangered and Threatened Wildlife and Plants; Endangered Species
Status With Critical Habitat for Texas Heelsplitter, and Threatened
Status With Section 4(d) Rule and Critical Habitat for Louisiana
Pigtoe; Proposed Rule
Federal Register / Vol. 88, No. 53 / Monday, March 20, 2023 /
Proposed Rules
[[Page 16776]]
-----------------------------------------------------------------------
DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R2-ES-2022-0026; FF09E21000 FXES1111090FEDR 234]
RIN 1018-BE46
Endangered and Threatened Wildlife and Plants; Endangered Species
Status With Critical Habitat for Texas Heelsplitter, and Threatened
Status With Section 4(d) Rule and Critical Habitat for Louisiana Pigtoe
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Proposed rule.
-----------------------------------------------------------------------
SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to
list the Texas heelsplitter (Potamilus amphichaenus) as an endangered
species and the Louisiana pigtoe (Pleurobema riddellii) as a threatened
species under the Endangered Species Act of 1973, as amended (Act).
Both species are freshwater mussels. This document serves as our 12-
month finding on a petition to list the Texas heelsplitter and
Louisiana pigtoe. For the Louisiana pigtoe, we also propose a rule
issued under section 4(d) of the Act (a ``4(d) rule'') to provide for
the conservation of the species. In addition, we propose to designate
critical habitat for the Texas heelsplitter and Louisiana pigtoe under
the Act. In total, approximately 831.8 river miles (1,338.6 river
kilometers) in 31 counties in Texas fall within the boundaries of the
proposed critical habitat designation for the Texas heelsplitter, and
approximately 1,028.2 river miles (1,654.3 river kilometers) in 3
counties in Arkansas, 6 parishes in Louisiana, 2 counties in
Mississippi, 1 county in Oklahoma, and 21 counties in Texas fall within
the boundaries of the proposed critical habitat designation for the
Louisiana pigtoe. We announce the availability of a draft economic
analysis of the proposed designation of critical habitat for the Texas
heelsplitter and Louisiana pigtoe. Finally, we announce an
informational meeting followed by a public hearing on this proposed
rule. If we finalize this rule as proposed, it would extend the Act's
protections to these species and their critical habitats.
DATES: We will accept comments received or postmarked on or before May
19, 2023. Comments submitted electronically using the Federal
eRulemaking Portal (see ADDRESSES, below) must be received by 11:59
p.m. eastern time on the closing date.
Public informational meeting and public hearing: We will hold a
public informational session from 5 p.m. to 6 p.m., central time,
followed by a public hearing from 6:30 p.m. to 8 p.m., central time, on
May 2, 2023.
ADDRESSES: You may submit comments by one of the following methods:
(1) Electronically: Go to the Federal eRulemaking Portal: https://www.regulations.gov. In the Search box, enter FWS-R2-ES-2022-0026,
which is the docket number for this rulemaking. Then, click on the
Search button. On the resulting page, in the panel on the left side of
the screen, under the Document Type heading, check the Proposed Rule
box to locate this document. You may submit a comment by clicking on
``Comment.''
(2) By hard copy: Submit by U.S. mail to: Public Comments
Processing, Attn: FWS-R2-ES-2022-0026, U.S. Fish and Wildlife Service,
MS: PRB/3W, 5275 Leesburg Pike, Falls Church, VA 22041-3803.
We request that you send comments only by the methods described
above. We will post all comments on https://www.regulations.gov. This
generally means that we will post any personal information you provide
us (see Information Requested, below, for more information).
Availability of supporting materials: For the proposed critical
habitat designation, the coordinates or plot points or both from which
the maps are generated are included in the decision file and are
available at https://www.fws.gov/southwest/es/arlingtontexas/, at
https://www.regulations.gov under Docket No. FWS-R2-ES-2022-0026, and
at the Arlington Ecological Services Field Office (see FOR FURTHER
INFORMATION CONTACT). Additional supporting information that we
developed for this critical habitat designation will be available on
the Service's website, at https://www.regulations.gov, or both.
Public informational meeting and public hearing: The public
informational meeting and the public hearing will be held virtually
using the Zoom online video platform and via teleconference. See Public
Hearing, below, for more information.
FOR FURTHER INFORMATION CONTACT: Debra Bills, Field Supervisor, U.S.
Fish and Wildlife Service, Arlington Ecological Services Field Office,
501 West Felix Street, Suite 1105, Fort Worth, Texas 76115; telephone
817-277-1100. Individuals in the United States who are deaf, deafblind,
hard of hearing, or have a speech disability may dial 711 (TTY, TDD, or
TeleBraille) to access telecommunications relay services. Individuals
outside the United States should use the relay services offered within
their country to make international calls to the point-of-contact in
the United States.
SUPPLEMENTARY INFORMATION:
Executive Summary
Why we need to publish a rule. Under the Act, a species warrants
listing if it meets the definition of an endangered species (in danger
of extinction throughout all or a significant portion of its range) or
a threatened species (likely to become endangered within the
foreseeable future throughout all or a significant portion of its
range). If we determine that a species warrants listing, we must list
the species promptly and designate the species' critical habitat to the
maximum extent prudent and determinable. We have determined that the
Texas heelsplitter meets the definition of an endangered species and
that the Louisiana pigtoe meets the definition of a threatened species;
therefore, we are proposing to list them as such and proposing a
designation of critical habitat for both species. Both listing a
species as an endangered or threatened species and designating critical
habitat can be completed only by issuing a rule through the
Administrative Procedure Act rulemaking process.
What this document does. We propose to list the Texas heelsplitter
as an endangered species and to list the Louisiana pigtoe as a
threatened species with a 4(d) rule. We also propose to designate
critical habitat for both species.
The basis for our action. Under the Act, we may determine that a
species is an endangered or threatened species because of any of five
factors: (A) The present or threatened destruction, modification, or
curtailment of its habitat or range; (B) overutilization for
commercial, recreational, scientific, or educational purposes; (C)
disease or predation; (D) the inadequacy of existing regulatory
mechanisms; or (E) other natural or manmade factors affecting its
continued existence. We have determined that habitat loss through
changes in water quality, the gradual accumulation of additional layers
of fine sediments, and altered hydrology (Factor A) are the primary
threats to these species, all of which are exacerbated by the ongoing
and expected future effects of climate change (Factor E). Additionally,
predation (Factor C) and collection (Factor B), as well as other
natural or human-induced events/activities that result in direct
mortality, are also
[[Page 16777]]
affecting those populations already experiencing low stream flow, and
reservoirs and other instream barriers to fish movement (Factor E) that
limit dispersal and prevent recolonization after stochastic events.
Section 4(a)(3) of the Act requires the Secretary of the Interior
(Secretary) to designate critical habitat concurrent with listing to
the maximum extent prudent and determinable. Section 3(5)(A) of the Act
defines critical habitat as (i) the specific areas within the
geographical area occupied by the species, at the time it is listed, on
which are found those physical or biological features (I) essential to
the conservation of the species and (II) which may require special
management considerations or protections; and (ii) specific areas
outside the geographical area occupied by the species at the time it is
listed, upon a determination by the Secretary that such areas are
essential for the conservation of the species. Section 4(b)(2) of the
Act states that the Secretary must make the designation on the basis of
the best scientific data available and after taking into consideration
the economic impact, the impact on national security, and any other
relevant impacts of specifying any particular area as critical habitat.
Information Requested
We intend that any final action resulting from this proposed rule
will be based on the best scientific and commercial data available and
be as accurate and as effective as possible. Therefore, we request
comments or information from other governmental agencies, Native
American Tribes, the scientific community, industry, or any other
interested parties concerning this proposed rule. We particularly seek
comments concerning:
(1) The species' biology, range, and population trends, including:
(a) Biological or ecological requirements of the species, including
habitat requirements for feeding, breeding, and sheltering;
(b) Genetics and taxonomy;
(c) Historical and current ranges, including distribution patterns
and the locations of any additional populations of these species;
(d) Historical and current population levels, and current and
projected trends; and
(e) Past and ongoing conservation measures for the species, their
habitats, or both.
(2) Threats and conservation actions affecting these species,
including:
(a) Factors that may affect the continued existence of the species,
which may include habitat modification or destruction, overutilization,
disease, predation, the inadequacy of existing regulatory mechanisms,
or other natural or manmade factors.
(b) Biological, commercial trade, or other relevant data concerning
any threats (or lack thereof) to these species.
(c) Existing regulations or conservation actions that may be
addressing threats to these species.
(3) Additional information concerning the historical and current
status of these species.
(4) Information on regulations that are necessary and advisable to
provide for the conservation of the Louisiana pigtoe and that we can
consider in developing a 4(d) rule for the species. We particularly
seek information concerning the extent to which we should include any
of the section 9 prohibitions in the 4(d) rule or whether we should
consider any additional exceptions from the prohibitions in the 4(d)
rule.
(5) Specific information on:
(a) The amount and distribution of Texas heelsplitter and Louisiana
pigtoe habitat;
(b) Any additional areas occurring within the range of the
Louisiana pigtoe, i.e., Howard, Little River, and Sevier Counties,
Arkansas; Allen, Beauregard, Rapides, St. Tammany, Vernon, and
Washington parishes, Louisiana; Marion and Pearl River Counties,
Mississippi; McCurtain County, Oklahoma; and Anderson, Angelina,
Cherokee, Gregg, Hardin, Harrison, Houston, Jasper, Jefferson, Liberty,
Montgomery, Nacogdoches, Orange, Panola, Polk, Rusk, Smith, Trinity,
Tyler, Upshur, and Wood Counties, Texas, and Texas heelsplitter, i.e.,
Anderson, Angelina, Cherokee, Ellis, Freestone, Gregg, Grimes, Hardin,
Harrison, Henderson, Houston, Jasper, Jefferson, Kaufman, Leon,
Madison, Navarro, Orange, Panola, Polk, Rains, Rusk, Sabine, Shelby,
Smith, Trinity, Tyler, Upshur, Van Zandt, Walker, and Wood Counties,
Texas, that should be included in the designation because they (i) are
occupied at the time of listing and contain the physical or biological
features that are essential to the conservation of the species and that
may require special management considerations, or (ii) are unoccupied
at the time of listing and are essential for the conservation of the
species; and
(c) Special management considerations or protection that may be
needed in critical habitat areas we are proposing, including managing
for the potential effects of climate change; and
(d) To evaluate the potential to include areas not occupied at the
time of listing, we particularly seek comments regarding whether
occupied areas are adequate for the conservation of the species.
Additionally, please provide specific information regarding whether or
not unoccupied areas would, with reasonable certainty, contribute to
the conservation of the species and contain at least one physical or
biological feature essential to the conservation of the species. We
also seek comments or information regarding whether areas not occupied
at the time of listing qualify as ``habitat'' for the species.
(7) Land use designations and current or planned activities in the
subject areas and their possible impacts on proposed critical habitat.
(8) Any probable economic, national security, or other relevant
impacts of designating any area that may be included in the final
designation, and the related benefits of including or excluding
specific areas.
(9) Information on the extent to which the description of probable
economic impacts in the draft economic analysis is a reasonable
estimate of the likely economic impacts and any additional information
regarding probable economic impacts that we should consider.
(10) Whether any specific areas we are proposing for critical
habitat designation should be considered for exclusion under section
4(b)(2) of the Act, and whether the benefits of potentially excluding
any specific area outweigh the benefits of including that area under
section 4(b)(2) of the Act. If you think we should exclude any
additional areas, please provide information supporting a benefit of
exclusion.
(11) Whether we could improve or modify our approach to designating
critical habitat in any way to provide for greater public participation
and understanding, or to better accommodate public concerns and
comments.
Please include sufficient information with your submission (such as
scientific journal articles or other publications) to allow us to
verify any scientific or commercial information you include.
Please note that submissions merely stating support for, or
opposition to, the action under consideration without providing
supporting information, although noted, do not provide substantial
information necessary to support a determination. Section 4(b)(1)(A) of
the Act directs that determinations as to whether any species is an
endangered or a threatened species must be made solely on the basis of
the best scientific and commercial data available and section
[[Page 16778]]
4(b)(2) of the Act directs that the Secretary shall designate critical
habitat on the basis of the best scientific information available.
You may submit your comments and materials concerning this proposed
rule by one of the methods listed in ADDRESSES. We request that you
send comments only by the methods described in ADDRESSES.
If you submit information via https://www.regulations.gov, your
entire submission--including any personal identifying information--will
be posted on the website. If your submission is made via a hardcopy
that includes personal identifying information, you may request at the
top of your document that we withhold this information from public
review. However, we cannot guarantee that we will be able to do so. We
will post all hardcopy submissions on https://www.regulations.gov.
Comments and materials we receive, as well as supporting
documentation we used in preparing this proposed rule, will be
available for public inspection on https://www.regulations.gov.
Because we will consider all comments and information we receive
during the comment period, our final determinations may differ from
this proposal. Based on the new information we receive (and any
comments on that new information), we may conclude that Texas
heelsplitter is threatened instead of endangered or that Louisiana
pigtoe is endangered instead of threatened, or we may conclude that one
or both species do not warrant listing as either an endangered species
or a threatened species. For critical habitat, our final designations
may not include all areas proposed, may include some additional areas
that meet the definition of critical habitat, or may exclude some areas
if we find the benefits of exclusion outweigh the benefits of
inclusion. In addition, we may change the parameters of the
prohibitions or the exceptions to those prohibitions in the 4(d) rule
if we conclude it is appropriate in light of comments and new
information we receive. For example, we may expand the prohibitions to
include prohibiting additional activities if we conclude that those
additional activities are not compatible with conservation of the
species. Conversely, we may establish additional exceptions to the
prohibitions in the final rule if we conclude that the activities would
facilitate or are compatible with the conservation and recovery of the
species.
Public Hearing
We have scheduled a public informational meeting and public hearing
on this proposed rule. We will hold the public informational meeting
and public hearing on the date and at the times provided above under
Public informational meeting and public hearing in DATES. We are
holding the public informational meeting and public hearing via the
Zoom online video platform and via teleconference so that participants
can attend remotely. For security purposes, registration is required.
You must register in order to listen and view the meeting and hearing
via Zoom, listen to the meeting and hearing by telephone, or provide
oral public comments at the public hearing by Zoom or telephone. For
information on how to register, or if you encounter problems joining
Zoom the day of the meeting, visit https://www.fws.gov/office/arlington-ecological-services. Registrants will receive the Zoom link
and the telephone number for the public informational meeting and
public hearing. If applicable, interested members of the public not
familiar with the Zoom platform should view the Zoom video tutorials
(https://support.zoom.us/hc/en-us/articles/206618765-Zoom-video-tutorials) prior to the public informational meeting and public
hearing.
The public hearing will provide interested parties an opportunity
to present verbal testimony (formal, oral comments) regarding this
proposed rule. The public informational meeting will be an opportunity
for dialogue with the Service. The public hearing is a forum for
accepting formal verbal testimony. In the event there is a large
attendance, the time allotted for oral statements may be limited.
Therefore, anyone wishing to make an oral statement at the public
hearing for the record is encouraged to provide a prepared written copy
of their statement to us through the Federal eRulemaking Portal, or
U.S. mail (see ADDRESSES, above). There are no limits on the length of
written comments submitted to us. Anyone wishing to make an oral
statement at the public hearing must register before the hearing
(https://www.fws.gov/office/arlington-ecological-services). The use of
a virtual public hearing is consistent with our regulations at 50 CFR
424.16(c)(3).
Previous Federal Actions
The Texas heelsplitter was identified as a category 2 candidate
species on January 6, 1989 (54 FR 554). The category 2 designation was
assigned to taxa for which information indicated that proposing to list
as endangered or threatened was possibly warranted, but for which
conclusive data on biological vulnerability and threats were not
currently available to support proposed rules. The species remained so
designated in subsequent candidate notices of review (CNORs) (56 FR
58804, November 21, 1991; 59 FR 58982, November 15, 1994). In the
February 28, 1996, CNOR (61 FR 7596), we discontinued the designation
of category 2 species as candidates; therefore, with the publication of
that CNOR, the Texas heelsplitter was no longer a candidate species.
On June 25, 2007, we were petitioned to list both the Texas
heelsplitter and Louisiana pigtoe. We published a substantial 90-day
finding for Texas heelsplitter on December 15, 2009 (74 FR 66260), and
for Louisiana pigtoe on December 16, 2009 (74 FR 66866).
This document constitutes our 12-month warranted petition finding,
our proposed listing rule, and our proposed critical habitat rule for
the Texas heelsplitter and Louisiana pigtoe.
Supporting Documents
A species status assessment (SSA) team prepared an SSA report for
the Texas heelsplitter and Louisiana pigtoe. The SSA team was composed
of Service biologists, in consultation with other species experts. The
SSA report represents a compilation of the best scientific and
commercial data available concerning the status of the species,
including the impacts of past, present, and future factors (both
negative and beneficial) affecting the species. In accordance with our
joint policy on peer review published in the Federal Register on July
1, 1994 (59 FR 34270), and our August 22, 2016, memorandum updating and
clarifying the role of peer review of listing actions under the Act, we
sought the expert opinions of 11 appropriate specialists regarding the
SSA. We received 6 responses.
I. Proposed Listing Determination
Background
General Mussel Biology
A thorough review of the taxonomy, life history, and ecology of the
Texas heelsplitter and Louisiana pigtoe is presented in the SSA report
(USFWS 2022, entire), and briefly summarized here.
Freshwater mussels, including the Texas heelsplitter and Louisiana
pigtoe, have a complex life history involving parasitic larvae, called
glochidia, which are wholly dependent on host fish. As freshwater
mussels are generally sessile (immobile), dispersal is accomplished
primarily through the behavior of host fish and their tendencies to
travel upstream and against the current in rivers and streams. Mussels
are broadcast spawners; males release
[[Page 16779]]
sperm into the water column, which is taken in by the female through
the incurrent aperture (the tubular structure used to draw water into
the body of the mussel). The developing larvae remain with the female
until they mature and are ready for release as glochidia, to attach on
the gills, head, or fins of fishes (Vaughn and Taylor 1999, p. 913;
Barnhart et al. 2008, pp. 371-373).
Glochidia die if they fail to find a host fish, attach to the wrong
species of host fish, attach to a fish that has developed immunity from
prior infestations, or attach to the wrong location on a host fish
(Neves 1991, p. 254; Bogan 1993, p. 599). Successful glochidia encyst
(enclose in a cyst-like structure) on the host's tissue, draw nutrients
from the fish, and develop into juvenile mussels (Arey 1932, pp. 214-
215). The glochidia will remain encysted for about a month through a
transformation to the juvenile stage. Once transformed, the juveniles
will excyst from the fish and drop to the substrate.
Freshwater mussel species vary in both onset and duration of
spawning, how long developing larvae are held in the marsupial gill
chambers (gills used for holding eggs and glochidia), and which fish
species serve as hosts. The mechanisms employed by mussel species to
increase the likelihood of interaction between host fish and glochidia
vary by species.
Mussels are generally immobile; their primary opportunity for
dispersal and movement within the stream comes when glochidia attach to
a mobile host fish (Smith 1985, p. 105). Upon release from the host,
newly transformed juveniles drop to the substrate on the bottom of the
stream. Those juveniles that drop in unsuitable substrates die because
their immobility prevents them from relocating to more favorable
habitat. Juvenile freshwater mussels burrow into interstitial
substrates and grow to a larger size that is less susceptible to
predation and displacement from high-flow events (Yeager et al. 1994,
p. 220). Adult mussels typically remain within the same general
location where they dropped off (excysted) from their host fish as
juveniles.
Host specificity can vary across mussel species, which may have
specialized or generalized relationships with one or more taxa of fish.
Mussels have evolved a wide variety of adaptations to facilitate
transmission of glochidia to host fish, including mantle displays
(lures) mimicking fish or invertebrates; packages of glochidia
(conglutinates) that mimic worms, insect larvae, larval fish, or fish
eggs; and release of glochidia in mucous webs that entangle fish
(Strayer et al. 2004, p. 431). Polymorphism (existence of multiple
forms) of mantle lures and conglutinates frequently exists within
mussel populations (Barnhart et al. 2008, p. 383), representing
important adaptive capacity in terms of genetic diversity and
ecological representation.
Texas Heelsplitter
The Texas heelsplitter was first described as the species Unio
amphichaenus by Frierson (1898, p. 109) from the Sabine River near
Logansport, Louisiana. The current recognized scientific name for Texas
heelsplitter is Potamilus amphichaenus (Williams et al. 2017a, pp. 35,
42). The Texas heelsplitter is a medium- to large-sized freshwater
mussel (up to 177 millimeters (mm) (7 inches (in)) shell length) that
has a tan to brown or black elliptical shell, with lighter coloration
on the beaks, and a relatively straight hinge line. Texas heelsplitters
exhibit slight sexual dimorphism; females have a broadly rounded
posterior margin and males are more pointed (Howells 2010b, p. 2). The
base of the anterior margin exhibits a long, narrow gape, while a
shorter, much wider gape is located along the posterior margin,
presumably to accommodate the incurrent and excurrent apertures (Neck
and Howells 1995, p. 4).
Although information specific to Texas heelsplitter reproduction is
unavailable, other species from the tribe Lampsilini release glochidia
in packets, called conglutinates, and are known to use mantle lures to
attract sight feeding fishes that attack and rupture the marsupium,
thereby becoming infested by glochidia (Barnhart et al. 2008, pp. 377,
380). Related species are long-term brooders (bradytictic), spawning
and becoming gravid in the fall and releasing glochidia in the spring
(Barnhart et al. 2008, p. 384). Freshwater drum (Aplodinotus grunniens)
have been confirmed as host fish for the Texas heelsplitter (Bosman et
al. 2015, p. 15).
A related freshwater mussel species, bleufer (Potamilus
purpuratus), from the southeastern United States was reported to reach
a maximum age of 9-26 years, and other related species ranged from 4-50
years with a higher growth rate compared to other species (Haag and
Rypel 2011, pp. 229, 234, 239). The Texas heelsplitter has been
reported mature at approximately 60 mm (2.4 in) (Ford et al. 2016, p.
31).
Texas heelsplitters occur in streams and rivers of the Trinity,
Neches, and Sabine drainages in east Texas and in the Sabine River at
the western border of Louisiana on substrates consisting of ``firm mud,
sand, or finer gravels bottoms, in still to moderate flows'' and
sometimes associated with fallen timber (Howells 2014, p. 69; Howells
2010b, p. 3 and table 2.3). Additionally, Texas heelsplitters can
tolerate manmade impoundments and have been found in several East Texas
reservoirs (Howells 2010b, p. 3).
Louisiana Pigtoe
The Louisiana pigtoe was originally described as the species Unio
riddellii (Lea 1862, p. 228) from the Trinity River near the City of
Dallas, Dallas County, Texas. The current recognized scientific name
for Louisiana pigtoe is Pleurobema riddellii (Williams et al. 2017a,
pp. 35, 42). The Louisiana pigtoe is a medium-sized freshwater mussel
(shell lengths to greater than 62 mm (2.4 in)) with a brown to black,
triangular to subquadrate shell without external sculpturing, sometimes
with greenish rays. For a detailed description, see Howells et al. 1996
(pp. 91-92) and Howells 2014 (p. 65). Other native mussel species
(e.g., pimpleback (Cyclonaias pustulosa), Texas pigtoe (Fusconaia
askewi), Trinity pigtoe (F. chunii), and Wabash pigtoe (F. flava)) can
easily be mistaken for Louisiana pigtoe when identified by shell
morphology alone.
Louisiana pigtoe are bradytictic (i.e., long-term brooders;
spawning occurs during the summer, and glochidia are held by the female
over winter and released the following spring); however, gravid females
have been observed in July (Marshall 2014, pp. 46-47). A closely
related congener, the rough pigtoe (Pleurobema plenum), is known to
utilize the tachytictic reproductive cycle (i.e., short-term brooders;
fertilization occurs in the spring, and glochidia are expelled during
the summer or early fall) (EPA 2007, p. 37).
The primary host fish for Louisiana pigtoe has not been confirmed.
Bullhead minnow (Pimephales vigilax), blacktail shiner (Cyprinella
venusta), and red shiner (Cyprinella lutrensis) have been suggested as
potential fish hosts based on a fish host distribution modeling effort
(Marshall 2014, pp. 59-60).
A single juvenile Louisiana pigtoe from the Neches River, Texas,
was reported to grow 15 mm (0.6 in) during its first year from an
initial shell length of 2 mm (0.08 in) (Ford et al. 2016, p. 30).
Sexual maturity is achieved at shell lengths around 40 mm (1.6 in)
(Ford et al. 2016, pp. 28, 30), and Louisiana pigtoe could reach
maturity in 3 to 4 years. Based on egg production, sexually mature
females were estimated by external annuli to be between 4 and 12 years
of age with shell lengths ranging
[[Page 16780]]
from 29-59 mm (1.1-2.3 in) (Hinkle 2018, p. 19).
Louisiana pigtoes occur in medium- to large-sized streams
throughout portions of east Texas, Louisiana, west Mississippi,
southeast Oklahoma, and southwest Arkansas (Vidrine 1993, p. 66;
Howells et al. 1997, p. 22; Randklev et al. 2013, p. 269; Randklev
2018, entire) in flowing waters (0.3-1.4 meters per second (m/s)) over
substrates of cobble and rock or sand, gravel, cobble, and woody
debris; they are often associated with riffle, run, and sometimes
larger backwater tributary habitats (Ford et al. 2016, pp. 42, 52;
Howells 2010a, pp. 3-4; Williams et al. 2017b, p. 21). Specimens are
typically found in shallower waters (0.1-1.2 m (0.3-3.9 feet (ft) in
depth; Howells 2010a, p. 3)); however, recent surveys found Louisiana
pigtoe as deep as 3.33 m (10.9 ft) in the lower Neches River (Corbett
2020, pp. 2, 4).
Regulatory and Analytical Framework
Regulatory Framework
Section 4 of the Act (16 U.S.C. 1533) and the implementing
regulations in title 50 of the Code of Federal Regulations set forth
the procedures for determining whether a species is an endangered
species or a threatened species, issuing protective regulations for
threatened species, and designating critical habitat for endangered and
threatened species. In 2019, jointly with the National Marine Fisheries
Service, the Service issued a final rule that revised the regulations
in 50 CFR part 424 regarding how we add, remove, and reclassify
endangered and threatened species and the criteria for designating
listed species' critical habitat (84 FR 45020; August 27, 2019). On the
same day, the Service also issued final regulations that, for species
listed as threatened species after September 26, 2019, eliminated the
Service's general protective regulations automatically applying to
threatened species the prohibitions that section 9 of the Act applies
to endangered species (84 FR 44753; August 27, 2019).
The Act defines an ``endangered species'' as a species that is in
danger of extinction throughout all or a significant portion of its
range, and a ``threatened species'' as a species that is likely to
become an endangered species within the foreseeable future throughout
all or a significant portion of its range. The Act requires that we
determine whether any species is an endangered species or a threatened
species because of any of the following factors:
(A) The present or threatened destruction, modification, or
curtailment of its habitat or range;
(B) Overutilization for commercial, recreational, scientific, or
educational purposes;
(C) Disease or predation;
(D) The inadequacy of existing regulatory mechanisms; or
(E) Other natural or manmade factors affecting its continued
existence.
These factors represent broad categories of natural or human-caused
actions or conditions that could have an effect on a species' continued
existence. In evaluating these actions and conditions, we look for
those that may have a negative effect on individuals of the species, as
well as other actions or conditions that may ameliorate any negative
effects or may have positive effects.
We use the term ``threat'' to refer in general to actions or
conditions that are known to or are reasonably likely to negatively
affect individuals of a species. The term ``threat'' includes actions
or conditions that have a direct impact on individuals (direct
impacts), as well as those that affect individuals through alteration
of their habitat or required resources (stressors). The term ``threat''
may encompass--either together or separately--the source of the action
or condition or the action or condition itself.
However, the mere identification of any threat(s) does not
necessarily mean that the species meets the statutory definition of an
``endangered species'' or a ``threatened species.'' In determining
whether a species meets either definition, we must evaluate all
identified threats by considering the expected response by the species,
and the effects of the threats--in light of those actions and
conditions that will ameliorate the threats--on an individual,
population, and species level. We evaluate each threat and its expected
effects on the species, then analyze the cumulative effect of all of
the threats on the species as a whole. We also consider the cumulative
effect of the threats in light of those actions and conditions that
will have positive effects on the species, such as any existing
regulatory mechanisms or conservation efforts. The Secretary determines
whether the species meets the definition of an ``endangered species''
or a ``threatened species'' only after conducting this cumulative
analysis and describing the expected effect on the species now and in
the foreseeable future.
The Act does not define the term ``foreseeable future,'' which
appears in the statutory definition of ``threatened species.'' Our
implementing regulations at 50 CFR 424.11(d) set forth a framework for
evaluating the foreseeable future on a case-by-case basis. The term
``foreseeable future'' extends only so far into the future as the
Services can reasonably determine that both the future threats and the
species' responses to those threats are likely. In other words, the
foreseeable future is the period of time in which we can make reliable
predictions. ``Reliable'' does not mean ``certain''; it means
sufficient to provide a reasonable degree of confidence in the
prediction. Thus, a prediction is reliable if it is reasonable to
depend on it when making decisions.
It is not always possible or necessary to define foreseeable future
as a particular number of years. Analysis of the foreseeable future
uses the best scientific and commercial data available and should
consider the timeframes applicable to the relevant threats and to the
species' likely responses to those threats in view of its life-history
characteristics. Data that are typically relevant to assessing the
species' biological response include species-specific factors such as
lifespan, reproductive rates or productivity, certain behaviors, and
other demographic factors.
Analytical Framework
The SSA report documents the results of our comprehensive
biological review of the best scientific and commercial data regarding
the status of the species, including an assessment of the potential
threats to the species. The SSA report does not represent a decision by
the Service on whether the species should be proposed for listing as an
endangered or threatened species under the Act. It does, however,
provide the scientific basis that informs our regulatory decisions,
which involve the further application of standards within the Act and
its implementing regulations and policies. The following is a summary
of the key results and conclusions from the SSA report; the full SSA
report can be found at Docket No. FWS-R2-ES-2022-0026 on https://www.regulations.gov.
To assess the viability of the Texas heelsplitter and Louisiana
pigtoe, we used the three conservation biology principles of
resiliency, redundancy, and representation (Shaffer and Stein 2000, pp.
306-310). Briefly, resiliency supports the ability of the species to
withstand environmental and demographic stochasticity (for example, wet
or dry, warm or cold years), redundancy supports the ability of the
species to withstand catastrophic events (for example, droughts, large
pollution events), and representation supports the
[[Page 16781]]
ability of the species to adapt over time to long-term changes in the
environment (for example, climate changes). In general, the more
resilient and redundant a species is and the more representation it
has, the more likely it is to sustain populations over time, even under
changing environmental conditions. Using these principles, we
identified the species' ecological requirements for survival and
reproduction at the individual, population, and species levels, and
described the beneficial and risk factors influencing the species'
viability.
The SSA process can be categorized into three sequential stages.
During the first stage, we evaluated each individual species' life-
history needs. The next stage involved an assessment of the historical
and current condition of each species' demographics and habitat
characteristics, including an explanation of how the species arrived at
its current condition. The final stage of the SSA involved making
predictions about each species' responses to positive and negative
environmental and anthropogenic influences. Throughout all of these
stages, we used the best available information to characterize
viability as the ability of a species to sustain populations in the
wild over time. We use this information to inform our regulatory
decision.
Summary of Biological Status and Threats
In this discussion, we review the biological condition of the
species and their resources, and the threats that influence the
species' current and future condition, in order to assess the species'
overall viability and the risks to that viability. We analyze these
factors both individually and cumulatively to determine the current
condition of the species and project the future condition of the
species under several plausible future scenarios.
Using various timeframes and the current and projected future
resiliency, redundancy, and representation, we describe the species'
levels of viability over time. For the Texas heelsplitter and Louisiana
pigtoe to maintain viability, their populations or some portion thereof
must be sufficiently resilient. A number of factors influence the
resiliency of their populations, including occupied stream length,
abundance, and recruitment. Elements of the species' habitat that
determine whether Texas heelsplitter and Louisiana pigtoe populations
can grow to maximize habitat occupancy influence those factors, thereby
increasing the resiliency of populations. These resiliency factors and
habitat elements are discussed in detail in the SSA report and
summarized here.
Species Needs
Occupied Stream Length
Most freshwater mussels, including the Texas heelsplitter and
Louisiana pigtoe, are found in aggregations called mussel beds that
vary in size from about 50 to over 5,000 square meters (m\2\),
separated by stream reaches in which mussels are absent or rare (Vaughn
2012, p. 2). Mussel populations in streams are highly patchy,
especially at a small scale (less than 100 stream meters) (Strayer
1999, p. 468). We define a mussel population at a larger scale than a
single mussel bed; it is the collection or series of mussel beds within
a stream reach between that infested host fish may travel, allowing for
ebbs and flows in mussel bed density and abundance over time throughout
the population's occupied reach. Therefore, adequately resilient mussel
populations must occupy stream reaches that are long enough such that
stochastic events that adversely affect individual mussel beds do not
eliminate the entire population. Repopulation by glochidia-infested
fish from other mussel beds within the reach, if present and connected,
allow the population to recover from the temporary loss of individuals
due to occasional disruptive events.
For our analysis, we consider populations extending greater than 50
river miles (river mi) (80 kilometers (km)) to have a high probability
of persistence to stochastic events because a single event is unlikely
to affect the entire population. Populations occupying reaches between
20 and 50 river mi (32 and 80 km) have moderate resiliency to
stochastic events, while populations occupying reaches less than 20 mi
(32.19 km) have low resiliency. Note that we define populations
occupying a stream length at or approaching zero miles as being
functionally extirpated (populations with abundance that is currently
at such low levels that we expect them to become extirpated in the near
future) or extirpated.
Abundance
Populations require a minimum number of individuals to ensure
stability and persistence. This threshold is often referred to as the
minimum viable population and is generally calculated through a
population viability analysis that estimates extinction risk given a
number of input variables. There are no published minimum viable
population estimates for the Texas heelsplitter or Louisiana pigtoe;
therefore, it is unknown how many individuals are required to sustain
populations of these mussels. However, population health is dependent
on species abundance as well as water availability and the ability for
mussels to meet life-history needs within their habitats, which were
evaluated as part of the SSA.
It is important to recognize that Louisiana pigtoe observations
used to determine abundance in the SSA report may include misidentified
individuals. Without genetic confirmation, identification of Louisiana
pigtoe in the field based on shell morphology is questionable, with
seasoned experts accurately identifying the species only 76 percent of
the time (Inoue 2018, p. 1). Unfortunately, genetic testing was not
available for the majority of reported Louisiana pigtoe historical
observations, which relied solely on shell morphological
characteristics for species identification (Randklev 2018, entire).
Since there is no way to know the margin of error or to otherwise
account for potential misidentifications, we determined abundance for
Louisiana pigtoe based on reported observations (as is) and did not
adjust or modify the survey data to compensate for potential
misidentifications. We do not consider misidentification to be an issue
for Texas heelsplitter observations, since they are recognizable based
on morphological characteristics observed in the field and not easily
confused with other species.
Mussel abundance in a given stream reach is a product of the number
of mussel beds and the density of mussels within those beds. For
populations of Texas heelsplitter and Louisiana pigtoe to be healthy
(i.e., adequately resilient), mussel beds of sufficient number and
density must be present to allow recovery from natural and local
stochastic events, allowing the mussel bed to persist and the overall
local population to survive within a stream reach. Mussel abundance is
indicated by the number of individuals found during a sample event.
Mussel surveys are rarely a complete census of the population, but
density can be estimated by the number of individuals found during a
survey effort using various statistical techniques (i.e., estimate the
total population from a subset of surveyed individuals). Population
estimates are not available for all Texas heelsplitter and Louisiana
pigtoe populations, and techniques for available surveys are not always
directly comparable (i.e., same area size searched, similar search
time, etc.). When available, we used the number of
[[Page 16782]]
individuals captured relative to the amount of time surveys were
conducted to estimate population abundance, hereafter referred to as
overall catch per unit effort (CPUE). Although overall CPUE was the
preferred metric to estimate population abundance, when overall CPUE
was not available, the number of individuals detected during the most
recent comprehensive survey effort was used as a surrogate metric.
Calculation of abundance in this manner is intended to be an estimate
and is considered the best available information when population trend
data do not exist and precise population abundance cannot be
determined. Using CPUE, we are able to estimate if the species is
currently (since year 2000) common or rare within populations.
Abundance for each population is rated from ``high'' to ``low'' (or
functionally extirpated/extirpated) based on overall CPUE (or number of
individuals found when survey effort is not reported) according to live
or recent dead found during surveys since the year 2000, as follows:
``high'' is overall CPUE of greater than or equal to 4.0 (or 100 or
more individuals); ``moderate'' is overall CPUE greater than or equal
to 2.0 and less than 4.0 (or between 25 individuals and 99
individuals); ``low'' is overall CPUE greater than or equal to 0.5 and
less than 2.0 (or between 3 and 24 individuals); and ``functionally
extirpated/extirpated'' is overall CPUE less than 0.5 (or fewer than 3
individuals).
Reproduction/Recruitment
Sufficiently resilient Texas heelsplitter and Louisiana pigtoe
populations must also be reproducing and recruiting young individuals
into the population to replace individuals lost to old age, disease, or
predation. Population size and abundance are a reflection of habitat
conditions, environmental stressors, and other past influences on the
population. The ability of populations to successfully reproduce and
recruit will determine if a population may be stable, increasing, or
decreasing over time. For example, a large, dense mussel population
that contains mostly old individuals is not likely to remain large and
dense into the future if there are few young individuals to sustain the
population over time (i.e., death rates exceed birth rates resulting in
negative population growth). Conversely, a population that is less
dense but has many young and/or gravid individuals is likely to grow,
becoming more densely populated in the future (i.e., birth rates, and
subsequent recruitment of reproductive adults, exceed death rates,
resulting in positive population growth). Detection rates of very young
juvenile mussels during routine abundance and distribution surveys are
extremely low due to sampling bias because sampling involves tactile
searches and mussels less than 35 mm (1.4 in) can be difficult to
detect (Strayer and Smith 2003, pp. 47-48). For this evaluation, we
concluded there was evidence of reproduction/recruitment for a
population when surveys detected small-sized individuals (near the low
end of the detectable range or approximately 35 mm (1.4 in) in size)
since the year 2000 or gravid females (eggs and/or glochidia visible)
were observed during the reproductively active time of year.
Risk Factors for Texas Heelsplitter and Louisiana Pigtoe
We reviewed the potential risk factors (i.e., threats, stressors)
that could be affecting the Texas heelsplitter and Louisiana pigtoe now
and in the future. In this proposed rule, we will discuss only those
factors in detail that could meaningfully impact the status of the
species. Many of the threats and risk factors are the same or similar
for both species. Where the effects are expected to be similar, we
present one discussion that applies to both species. Where the effects
may be unique to one species, we will address that specifically. The
primary risk factors (i.e., threats) affecting the status of the Texas
heelsplitter and Louisiana pigtoe all fall under Factor A of the Act
and are: (1) Water quality changes, (2) altered hydrology, (3) changes
to habitat structure and substrate, and (4) habitat fragmentation.
These factors are all exacerbated by the ongoing and expected effects
of climate change (Factor E). Additionally, predation (Factor C) and
collection (Factor B), as well as other natural or human induced
events/activities that result in direct mortality, are also affecting
those populations already experiencing low stream flow, and reservoirs
and instream barriers to fish movement (Factor E) limit dispersal and
prevent recolonization after stochastic events.
Changes to Water Quality
Freshwater mussels require water in sufficient quantity and quality
on a consistent basis to complete their life cycles and those of their
host fishes. Water quality can be degraded through contamination or
alteration of water chemistry. Environmental contaminants include a
broad array of natural, synthetic, and chemical substances introduced
to the environment that can be hazardous to living organisms. Chemical
contaminants are ubiquitous throughout the environment and are a major
contributor to the current declining status of freshwater mussel
species nationwide (Augspurger et al. 2007, p. 2025). Contaminants
enter the environment through both point (e.g., hazardous spills,
industrial wastewater, municipal effluents) and non-point (e.g., urban
stormwater and agricultural runoff) sources. These sources contribute
organic compounds, trace metals, pesticides, plastics, petroleum
hydrocarbons, flame retardants, and a wide variety of emerging
contaminants (e.g., pharmaceuticals and personal care products).
Ammonia is of particular concern below wastewater treatment plant
outfalls because freshwater mussels have been shown to be particularly
sensitive to increases in ammonia levels (Augspurger et al. 2003, p.
2569). The extent to which environmental contaminants adversely affect
aquatic biota can vary depending on many site-specific variables, but
species diversity and abundance consistently ranks lower in waters that
are known to be polluted or otherwise impaired by contaminants. For
example, freshwater mussels are not generally found for many miles
downstream of municipal wastewater treatment plants (treatment plants)
(Gillis et al. 2017, p. 460; Goudreau et al. 1993, p. 211; Horne and
McIntosh 1979, p. 119).
There are approximately 386 treatment plant discharge permits
issued for the Trinity River Basin from its headwaters above the
Dallas-Fort Worth metroplex down to the Gulf of Mexico (Texas
Commission on Environmental Quality (TCEQ) 2018, entire). The San
Jacinto Basin, although geographically smaller than most other basins
in Texas, has approximately 1,052 treatment plant outfalls, while the
Neches and Sabine rivers have 218 and 191 outfalls, respectively. In
addition, some industrial permits can discharge millions of gallons per
day and have ammonia limits that exceed levels that inhibited growth in
juvenile fatmucket (Lampsilis siliquoidea) and rainbow mussel (Villosa
iris) during 28-day chronic tests (Wang et al. 2007, entire). Immature
mussels (juveniles and glochidia) are especially sensitive to water
quality degradation and contaminants (Cope et al. 2008, p. 456; Wang et
al. 2017, pp. 791-792; Wang et al. 2018, p. 3041).
An additional type of water quality impairment is the alteration of
water quality parameters such as dissolved oxygen, temperature, total
dissolved solids (TDS), and salinity levels. Dissolved oxygen levels
may be reduced from increased nutrients in the water
[[Page 16783]]
from runoff or wastewater effluent, and juveniles seem to be
particularly sensitive to low dissolved oxygen (Sparks and Strayer
1998, pp. 132-133). Increases in water temperature from water
diversions, climate change, or low flows during droughts can exacerbate
low dissolved oxygen levels as well as have its own effects on juvenile
and adult mussels.
Total dissolved solids, a measure of the mineral content of water
(i.e., inorganic salts, metals, cations, or anions dissolved in water,
including calcium, magnesium, potassium, sodium, bicarbonates,
chlorides, and sulfates), is commonly elevated in watersheds impacted
by a variety of industrial, commercial, urban, and agricultural
activities and has been associated with acute and chronic toxicity to
aquatic organisms. Watersheds with increasing trends in conductivity or
TDS are experiencing declines in water quality that can be harmful to
mussels and other aquatic organisms. Increasing trends in TDS are
common in watersheds impacted by anthropogenic activities.
Contaminant spills are also a concern. Texas leads the nation in
crude oil and natural gas production, and various chemicals, refined
fuels, and wastewater related to oil and natural gas exploration are
routinely transported along highways. These facilities and equipment
used for extraction, transportation, and refinement of hazardous
materials are all potential sources of hazardous spills, and can
originate from human error, equipment failure, or catastrophic events
like industrial accidents, fires, or floods. Although spills are
relatively short-term events and may be localized, water resources
nearby can be severely impacted and degraded for years after the
incident along with the biological resources that inhabit the area. A
reduction in surface flow drought, instream diversions, or groundwater
extraction serve to concentrate contaminant and salinity levels,
increases water temperatures in streams, and exacerbates effects to
Texas heelsplitter and Louisiana pigtoe.
Poor water quality affects most Texas heelsplitter and Louisiana
pigtoe populations currently to some degree, and future water quality
is expected to decrease due to decreasing stream flow and increasing
temperatures. We foresee threats to water quality increasing into the
future due to the effects of climate change as demand and competition
for limited water resources grows (USFWS 2022, pp. 61-62).
Altered Hydrology
Altered hydrology, through changes to historical flow regimes,
leads to inundation, or low- or high-flow conditions that may reduce
the quality of affected habitats to the point where they are no longer
suitable for freshwater mussels. While Texas heelsplitter and Louisiana
pigtoe have adapted to survive natural fluctuations in flows,
populations that experience sustained higher than normal flows,
prolonged flooding, or unnatural fluctuations in the frequency or
intensity of high/low flows or extended (or repeated) drying events
will not persist. Virtually every watershed within the range of these
two freshwater mussels has experienced some level of alteration, a
trend that has continued into the 21st century, particularly in areas
with rapid population growth.
Inundation of previously free-flowing rivers and streams by
impoundments has arguably had the single largest human-related impact
on the distribution of freshwater mussels. The construction of
reservoirs and other impoundments permanently alters the hydrology and,
hence, the ecology of rivers, often with deleterious effects to water
quality, water quantity, host fish movement, and dispersal of mussel
glochidia, nutrient cycling, sediment deposition, fate and transport of
contaminants, and numerous other changes to the physical, chemical, and
biological characteristics of affected areas (upstream and downstream).
The close relationship of flow to mussels makes them uniquely
vulnerable to hydrology changes.
Both mussel species are adapted to flowing water (lotic habitats)
rather than standing water (lentic habitats). Louisiana pigtoe require
free-flowing water to survive. The Texas heelsplitter has also been
observed in lentic habitats and appears to be tolerant of reservoir
conditions; this species may occur in higher densities in areas of
reservoirs that are influenced by stream inflows where conditions more
closely resemble their preferred riverine habitat (Whisenant 2019, p.
1; Neck and Howells 1995, p. 15).
Inundation of mussel habitat has primarily occurred upstream of
dams, including major flood control and water supply reservoirs, such
as Toledo Bend Reservoir, and smaller structures like low water vehicle
crossings and diversion dams typically found along tributaries on
privately owned land. These structures alter the hydrology of rivers by
slowing, impeding, or diverting normal flow patterns, and increasing
deposition in some areas and eliminating the interstitial spaces that
juvenile Texas heelsplitters and Louisiana pigtoes inhabit.
Large reservoirs that release water from the hypolimnion, the
deeper water is cold and often devoid of oxygen and necessary
nutrients, can adversely affect mussel survival, as cold water can
stunt mussel growth and delay or hinder spawning (Vaughn and Taylor
1999, p. 917). Cold water releases from reservoirs like Broken Bow Lake
in southeast Oklahoma can affect water temperatures for miles
downstream. These cold releases create an extinction gradient, where
freshwater mussels are absent or presence is low near the dam, and
abundance does not rebound until some distance downstream where ambient
conditions raise the water temperature to within the tolerance limits
of mussels (Davidson et al. 2014, p. 29; Vaugh and Taylor 1999, pp.
915, 916).
The construction of dams for flood control and drinking water
supply, and the subsequent management of water releases from those
reservoirs (e.g., timing, intensity, and duration), often resulting in
higher base flows and peak flows of reduced intensity but longer
duration, has significant impacts on the natural function and hydrology
of rivers and streams. The additional shear stress caused by these
sustained high base flows can incise channels, erode river banks, scour
mussel beds, and remove substrate preferred by mussels. Over time, the
physical force of these higher base flows can dislodge mussels from the
sediment and permanently alter the geomorphology of rivers.
During flood events, along with water, rivers transport sediment,
mostly as solids, suspended in the water column. The increase in
flooding severity results in greater sediment transport, with important
effects to substrate stability and benthic habitats for freshwater
mussels, as well as other organisms that are dependent on stable
benthic habitats. Further, water released by dams is usually clear due
to reduced sediment load and results in incision (downcutting of the
bed) and coarsening of the bed material until a new equilibrium is
reached (Kondolf 1997, p. 535). The extent to which downcutting and
erosion occurs as a result of dam releases varies, but in some cases
leads to bank collapse, burial of mussel beds, and mortality.
Conversely, depending on how dam releases are conducted, reduced flood
peaks can lead to accumulations of fine sediment in the river bed
(i.e., loss of flushing flows; Kondolf 1997, pp. 535, 548).
Operation of reservoirs for flood control, water supply, and
recreation results in altered hydrologic regimes,
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including an attenuation of both high- and low-flow events. The changes
to flood flows alters sediment dynamics, as sediments are trapped above
and scoured below major impoundments, and negatively affect freshwater
mussels and their habitats (Gascho Landis and Stoeckel 2016, p. 234;
Ford 2013, p. 3). Evidence that the Texas heelsplitter is able to
tolerate reservoir conditions leads us to believe the overall impacts
of reservoirs may be more pronounced for the Louisiana pigtoe (Howells
2010b, p. 3).
Very low flows and low water levels are also detrimental to Texas
heelsplitter and Louisiana pigtoe populations. Droughts that occurred
in the recent past led to extremely low flows in several east Texas
rivers. Some rivers, or portions thereof, are resilient to drought
because they are spring-fed (Calcasieu, Neches rivers), contain large
volumes of water (Trinity River), have large reservoirs in the upper
reaches that release water for downstream users (all, excluding
Calcasieu River), or have significant return flows (Pearl, Sabine,
Trinity rivers); however, drought in combination with increasing trends
in groundwater extraction may lead to lower river flows of longer
duration than previously recorded. Reservoir releases can be managed to
some extent, but in many cases dam operators must stop releases during
droughts to conserve water and protect water supplies, or to maximize
flood releases during major floods to protect public safety and
property, both can negatively affect mussels downstream.
Streamflow and overall discharge for rivers inhabited by the Texas
heelsplitter and Louisiana pigtoe are expected to decline due to
climate change and projected increases in temperatures and evaporation
rates, resulting in more frequent and intense droughts (Lafontaine et
al. 2019, entire) (Factor E). Return flows, consisting primarily of
treated municipal wastewater, are projected to continue to increase in
areas with population growth and may serve to ameliorate some of the
effects of climate change downstream of metropolitan areas, albeit with
notable impacts to water quality; however, these benefits may become
less significant as municipalities increase wastewater reuse as a
conservation measure. The Trinity River, for example, has been a
significantly modified, highly controlled, and highly regulated system
since the 1960s, with low flows steadily increasing as the population
has grown, resulting in base flows that are significantly higher
compared to historical flows (Clark and Mangham 2019, p. 9). The
increase in base flows can be attributed to substantial return flows
from Dallas/Fort Worth metropolitan area wastewater treatment plants
and are projected to continue to increase in the future. Surface and
alluvial aquifer groundwater withdrawals will likely increase in the
future due to the effects of more intense droughts, with reductions in
stream flows putting an additional strain on aquatic resources.
However, with the exception of stream segments where municipal effluent
return flows supplement base flows, most streams experience lower base
flows and reduced high-flow events after major reservoirs are
constructed (U.S. Geological Survey (USGS) 2008, pp. 964, 966).
Many streams within the range of these two freshwater mussel
species receive significant groundwater inputs from multiple springs
associated with aquifers. As spring flows decline due to drought,
climate change, or groundwater pumping, habitat for freshwater mussels
in affected streams is reduced and could eventually cease to exist.
While the Texas heelsplitter and Louisiana pigtoe may survive short
periods of low flow, as low flows persist, mussels can be subjected to
oxygen deprivation, increased water temperature, stranding, increased
predation, and, ultimately, desiccation which leads to reduced
survivorship, reproduction, and recruitment to the population. High-
flow events can lead to increased risk of mortality through physical
removal, transport, or burial of mussels as unstable substrates are
transported downstream by flood waters (entrainment) and dislodged
mussels are later redeposited in locations that may not be suitable
habitat.
The distribution of mussel communities and their habitats is
affected by large floods returning at least once during the typical
life span of an individual mussel (generally from 3-30 years), as
mediated by the presence of flow refuges, where shear stress is
relatively low, sediments are relatively stable, and mussels must
either tolerate high-frequency disturbances or be eliminated and can
colonize only areas that are infrequently disturbed between events
(Strayer 1999, pp. 468-469). Shear stress and relative shear stress are
limiting to mussel abundance and species richness (Randklev et al.
2017, p. 7), and riffle habitats may be more resilient to high-flow
events than bank habitats.
The Texas heelsplitter and Louisiana pigtoe undoubtedly evolved in
the presence of extreme hydrological conditions, including severe
droughts leading to dewatering, and heavy rains leading to damaging
scour events and movement of mussels and substrate, although the
frequency, duration, and intensity of these events may be different
from what is observed today. These same patterns led to the development
of flood control and storage reservoirs throughout Texas in the 20th
century. The increasing variability, frequency, and severity of extreme
weather events is a contributing factor to the contraction of
populations for both species.
Another source of alteration to hydrology is from sand and gravel
mining directly from rivers or from adjacent alluvial deposits (Kondolf
1997, p. 541). Instream mining directly impacts river habitats by
removal of substrates used by mussels, and can indirectly affect river
habitats through channel incision, bed coarsening, and lateral channel
instability (Kondolf 1997, p. 541). Excavation of pits in or near to
the channel can create a knickpoint, which can contribute to erosion
(and mobilization of substrate) associated with head cutting (Kondolf
1997, p. 541). Pits associated with off-channel mining of the
floodplain can become involved during floods, such that the pits become
hydrologically connected, and thus can affect sediment dynamics in the
stream or river (Kondolf 1997, p. 545). Sand and gravel mines occurred
historically and continue to operate in some basins throughout the
ranges of the Texas heelsplitter and Louisiana pigtoe.
Specifically, a change to the number of days with zero flow was
limiting for the Louisiana pigtoe, and the number of high pulses was
limiting for the Texas heelsplitter. In summary, results to date
indicate natural flow regimes have been altered in east Texas rivers,
as was expected, which has led to modification of instream habitats and
contributed to declines in freshwater mussels (Khan and Randklev 2019,
entire). These findings agree with the estimate of many experts, who
based on their research believe: (1) Portions of the Trinity River have
been significantly modified and may no longer support mussels
(particularly in the upper basin where stream hydrology and
geomorphology have been permanently altered), and (2) the Neches River
is the least altered and has some of the best remaining mussel habitat,
along with the most abundant and diverse mussel populations, in east
Texas.
Changes to Habitat Structure/Substrate
Texas heelsplitters and Louisiana pigtoes inhabit microhabitat
along river stream beds that have abundant
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interstitial spaces or small openings in an otherwise closed matrix of
stable substrates created by gravel, cobble, boulders, bedrock
crevices, tree roots, and other vegetation, with some amount of fine
sediment (i.e., clay and silt) necessary to provide appropriate
shelter. Excessive amounts of fine sediments can reduce available
microhabitat by filling in these interstitial spaces, effectively
smothering mussels in place. Interstitial spaces provide essential
habitat for juvenile mussels, offering protection from predation and
vital nutrients. While adult mussels can be physically buried by
excessive sediment, the main impacts of excess sedimentation on
freshwater mussels are often sublethal and include interference with
feeding mediated by valve closure (Box and Mossa 1999, p. 101).
Under a natural flow regime, sediments are naturally washed away
from one microhabitat to another, the amount of sediment in the
substrate is relatively stable, and different reaches within a river or
stream may be aggrading or degrading sediment at any given time (Poff
et al. 1997, pp. 770-772). Current (and past) human activities often
result in enhanced sedimentation in river systems, including legacy
sediment from past land disturbances and reservoir construction. These
activities continue in many basins occupied by the Texas heelsplitter
and Louisiana pigtoe, and influence river processes and sediment
dynamics (Wohl 2015, pp. 31, 39), with legacy effects that can result
in degradation of mussel habitat. Sediments deposited by large-scale
flooding or other disturbance may persist for several years until
adequate cleansing flows can redistribute that sediment downstream.
Conversely, when water velocity decreases from reduced streamflow or
inundation, water loses its ability to carry sediment in suspension and
sediment falls to the substrate, eventually smothering mussels not
adapted to soft substrates (Watters 2000, p. 263).
Sediment accumulation can be exacerbated when there is a
simultaneous increase in the sources of fine sediments in a watershed,
including streambank erosion from development, agricultural activities,
livestock and wildlife grazing, in-channel disturbances, roads, and
crossings, among others (Poff et al. 1997, p. 773). In areas with
ongoing development, runoff can transport substantial amounts of
sediment from ground disturbance related to construction activities
with inadequate or absent sedimentation controls. While these
construction impacts can be transient (lasting only during the
construction phase), the long-term effects of development on water
quantity and quality are long lasting and can result in hydrological
alterations as increased impervious cover increases run off and
resulting shear stress causes streambank instability and additional
sedimentation.
Habitat Fragmentation
Historically, the Texas heelsplitter and Louisiana pigtoe were
likely distributed in areas with suitable habitat throughout the river
basins described above under Background. Today, the remaining Texas
heelsplitter and Louisiana pigtoe populations are isolated from one
another by major reservoirs, habitat alterations, and de-watering
events, prolonged drought, among other reasons, such that natural
recolonization of areas previously extirpated is extremely unlikely, if
not impossible, due to barriers to host fish movement. With the
exception of the Louisiana pigtoe populations in the Red River Basin in
Arkansas and Oklahoma, there is currently no opportunity for
substantial interaction among extant Texas heelsplitter and Louisiana
pigtoe populations, resulting in genetic isolation.
The impacts of reservoirs are significant, causing permanent
changes to fish movement, water quality, and hydrology, with cascading
effects to river ecology and aquatic species that utilize areas
downstream. Small populations are more affected by limited host fish
immigration potential because they are susceptible to genetic drift
(random loss of genetic diversity) and inbreeding depression. At the
species level, populations that are eliminated due to stochastic events
cannot be recolonized naturally, leading to reduced overall redundancy
and representation.
The confirmed or assumed primary host fish species for both the
Texas heelsplitter and Louisiana pigtoe are known to be common and
widespread throughout the range of both mussel species and are
therefore not believed to be a limiting factor to dispersal at this
time (Nico and Sturtevant 2022, entire; Nico et al. 2022, entire; Nico
and Fuller 2022, entire; Fuller et al. 2022, entire). Each of the
identified fish hosts are known to tolerate lake environments and may
utilize impoundments as corridors to facilitate migration between
hydrologically connected tributaries, thus aiding mussel dispersal. If
fish host species are indeed abundant, existing dams, the construction
of new major dams and reservoirs, and other barriers to fish movement
are the primary mechanism through which remaining populations are
isolated. Furthermore, reservoir impacts to river ecosystems can be
difficult and costly to manage or minimize.
Most reservoirs function primarily to provide water supply and/or
flood control, and meeting those objectives typically involves holding
on to as much water as possible (i.e., not releasing); this may limit
the ability of reservoir managers to modify releases for the purpose of
meeting wildlife conservation or recovery goals. Although dams have
been managed to allow fish passage for spawning, to our knowledge, fish
passage has not been facilitated specifically to allow movement of host
fish for the benefit of freshwater mussels, nor would this be cost-
effective considering host fish for the Texas heelsplitter and
Louisiana pigtoe are believed to be abundant. Nevertheless, reservoirs
represent a permanent barrier to freshwater mussel dispersal. The
overall impact of reservoirs is believed to be greater for the
Louisiana pigtoe than for the Texas heelsplitter, which is able to
persist in reservoir conditions although questions remain about their
reproductive success in lake environments.
Direct Mortality
Direct mortality includes any activity or event, whether human-
induced or natural, that results in the death of mussels within a
localized area due to removal, crushing, burying, consumption,
desiccation, or poisoning. Potential activities or events causing
direct mortality include, but are not limited to, development projects
(such as bridge replacement, stream channelization, and impoundment
construction), undeveloped low-water crossings with vehicular traffic
that intersect mussel beds, bank collapse, accidental release of
hazardous materials, predation, vandalism, and collection (whether for
scientific purposes or recreation) (USFWS 2022, pp. 57-58). The
frequency, intensity, and magnitude of these impacts likely vary in
time and by location and are difficult to quantify with any certainty
other than to acknowledge that they exist and negatively affect mussel
survival to some degree.
Predation on freshwater mussels is a natural ecological
interaction. Raccoons, feral hogs, muskrats, snapping turtles, and fish
are known to prey upon mussels (East et al. 2013, p. 692; Walters and
Ford 2013, p. 480; Kaller et al. 2007, p. 174; Neves and Odom 1989, p.
939). Under natural conditions, the level of predation occurring is not
likely to pose
[[Page 16786]]
a significant risk to any given population; however, during periods of
low flow, terrestrial predators have increased access to portions of
the river that are otherwise too deep under normal flow conditions,
resulting in unnaturally high levels of predation that can decimate
mussel populations. Predation during drought has been observed for the
Texas heelsplitter on the Sabine River (Walters and Ford 2013, p. 479).
Drought, low-flow conditions, and reductions in minimum summer base
flows are predicted to occur more often and for longer periods due to
the effects of future climate change; therefore, the tributaries and
upper portions of focal areas for the Texas heelsplitter and Louisiana
pigtoe are expected to experience increased predation pressure into the
future (Lafontaine et al. 2019, entire).
Additionally, certain mussel beds within some populations, due to
ease of access, are vulnerable to over-collection and vandalism. These
areas have well known and well documented mussel beds that are often
sampled multiple times annually by various researchers for various
scientific projects. Populations subjected to repeated sampling or
monitoring may experience increased stress or higher rates of
mortality. Mortality may also occur in areas where local fishing
enthusiasts have been observed using freshwater mussels as bait. The
risk of direct mortality from recreation or over-collection for
scientific purposes are compounded by the additional stressors
discussed in this section, which can influence mussel survival in a
cumulative manner. Because collection of Louisiana pigote is localized
and could affect populations, we carried this risk factor forward as a
population-level threat. Service biologists recently hosted a meeting
with State biologists, consultants, and academia who are involved in
mussel research to discuss ongoing monitoring and scientific
collections and to reduce the likelihood of over-harvesting mussels
from any given population (USFWS 2018, p. 1), and we anticipate this
collaboration among researchers will continue into the future with
ongoing coordination and annual meetings.
Invasive Species
Invasive species, such as Asian clam (Corbicula fluminea), zebra
mussel (Dreissena polymorpha), feral hog (Sus scrofa), floating water
hyacinth (Eichhornia crassipes), giant salvinia (Salvinia molesta), and
hydrilla (Hydrilla verticillata), occur throughout the ranges of the
Texas heelsplitter and Louisiana pigtoe and can negatively impact
mussel survival. These impacts include predation (feral hog), habitat
destruction or modification (feral hog, floating water hyacinth, giant
salvinia, hydrilla), changes to water quality (feral hog, zebra
mussel), increased resource competition (Asian clam, zebra mussel), or
physical impairment (zebra mussel, hydrilla) (Kaller and Kelso 2006,
pp. 172-174; Howells 2010a, p. 13; Howells 2010b, pp. 14-15).
Although zebra mussel infestations occur in several Texas
reservoirs, including Lewisville Lake and Lake Livingston, populations
have not yet become established in nearby river habitats occupied by
the Texas heelsplitter and Louisiana pigtoe (Ford et al. 2016, p. 47;
Texas Parks and Wildlife Department (TPWD) 2019, entire; USGS 2019e,
entire).
Feral hogs occur throughout the range of both mussel species and
are known to engage in a variety of activities that cause bank and
streambed damage, contribute to erosion and increased sedimentation,
and their presence appears to cause native mussel diversity and
abundance to decrease through organic enrichment of the water and
unfavorable changes to microbial community composition (Kaller et al.
2007, p. 174; Howells 2010b, p. 10).
Invasive macrophyte infestations of floating water hyacinth,
hydrilla, and giant salvinia negatively impact native mussels and their
host fish throughout the southern half of the ranges of the Texas
heelsplitter and Louisiana pigtoe by creating hypoxic conditions
through respiration and during decay (Karatayev and Burlakova 2007, p.
298; USGS 2019b, entire; USGS 2019c, entire; USGS 2019d, entire). Dense
mats of hydrilla can also impede native mussel movement during periods
of fluctuating surface water levels, leaving them stranded as water
levels recede.
Climate Change
Climate change in the form of the change in timing and amount of
precipitation and air temperature increase is occurring, and continued
greenhouse gas emissions at or above current rates will cause further
warming (Intergovernmental Panel on Climate Change (IPCC) 2021, pp. 1-
13-1-15). Warming in Texas is expected to be greatest in the summer
(Maloney et al. 2014, p. 2236, figure 3), with the number of extremely
hot days (high temperatures exceeding 35 [deg]C (95 [deg]F)) projected
to double by around 2050 (Kinniburgh et al. 2015, p. 83). Changes in
stream temperatures are expected to reflect changes in air temperature,
at a rate of an approximately 0.6-0.8 [deg]C (33 [deg]F) increase in
stream water temperature for every 1 [deg]C (33 [deg]F) increase in air
temperature (Morrill et al. 2005, pp. 1-2, 15), with implications for
temperature-dependent water quality parameters such as dissolved oxygen
and ammonia toxicity. Given that freshwater mussels in Texas exist at
or near the ecophysiological edge of climate and habitat gradients of
freshwater mussel biogeography in North America, they may be
particularly vulnerable to future climate changes in combination with
current and future stressors (Burlakova et al. 2011a, pp. 156, 161,
163; Burlakova et al. 2011b, pp. 395, 403).
While projected changes to rainfall in Texas may seem relatively
small (U.S. Global Change Research Program (USGCRP) 2017, p. 217),
higher temperatures caused by anthropogenic activity will lead to
increased soil water deficits because of higher rates of
evapotranspiration. In turn, higher evapotranspiration rates will
likely result in increasing drought severity in future climate
scenarios, and the warming atmosphere is projected to continue across
the United States (USGCRP 2017, p. 231). Even if precipitation and
groundwater recharge remain at current levels, increased groundwater
pumping and resulting aquifer shortages due to increased temperatures
are nearly certain (Loaiciga et al. 2000, p. 193; Mace and Wade 2008,
pp. 662, 664-665; Taylor et al. 2013, p. 3).
Effects of climate change, such as changes to seasonal rainfall
patterns, air temperature increases, and increases in drought frequency
and intensity, have been shown to be occurring throughout the ranges of
the Texas heelsplitter and Louisiana pigtoe (Andreadis and Lettenmaier
2006, p. 3; USGCRP 2017, p. 188); these effects are expected to
exacerbate several of the stressors discussed above, such as water
temperature and flow loss (Wuebbles et al. 2013, p. 16). A recent
review of future climate projections for Texas concludes that both
droughts and floods could become more common in east Texas, with
droughts like 2011 (the driest on record) becoming commonplace by the
year 2100 (Mullens and McPherson 2017, pp. 3, 6). This trend of more
frequent droughts is driven by increases in hot temperatures (e.g.,
daily maximum) and the number of days projected to be at or above 37.8
[deg]C (100 [deg]F), which is set to ``increase in both consecutive
events and the total number of days'' (Mullens and McPherson 2017, pp.
14-15). Similarly, floods and extreme runoff are projected to become
more common and severe in the 21st century as the frequency,
[[Page 16787]]
magnitude, and intensity of heavy precipitation events increase
(Mullens and McPherson 2017, p. 20; USGCRP 2017, p. 224).
In the analysis of the future condition for the Texas heelsplitter
and Louisiana pigtoe, climate change is considered further under
various plausible future scenarios, serving to exacerbate already
deteriorating conditions through an increase of fine sediments, changes
to water quality, loss of flowing water, and predation, among others.
Summary of Risk Factors for Texas Heelsplitter and Louisiana Pigtoe
Our analysis of the past, current, and future influences on the
needs of the Texas heelsplitter and Louisiana pigtoe for long-term
viability revealed that there are four that pose the greatest impact on
current condition and future viability: degradation of water quality,
altered hydrology, substrate changes, and habitat fragmentation, all of
which are exacerbated by climate change.
Conservation Efforts and Regulatory Mechanisms
The level of interest among stakeholders, regulatory agencies, and
partners to better understand the status, threats, and conservation of
freshwater mussels in Texas has increased significantly since 2017,
when the Service initiated reviews of several Texas mussel species for
possible listing under the Act. This led to improved communication
among interested parties and multiple partnerships seeking to conduct
research and improve our understanding of the health and distribution
of mussel populations across Texas, as well as increased efforts to
protect and conserve known populations. Although there are currently no
formal conservation agreements in place designed to specifically
provide benefits to the Texas heelsplitter or Louisiana pigtoe, we are
in discussions with multiple stakeholders who are interested in
strengthening partnerships to conserve rare species, including several
river authorities that are in the process of developing candidate
conservation agreements with assurances (CCAAs). The CCAAs, if
finalized, would implement voluntary conservation actions in river
basins that would result in a net conservation benefit for the species.
Additionally, several stakeholders have voluntarily funded research to
ensure that we have the best available information upon which to base a
listing decision, and we commend them for their efforts to improve the
science of freshwater mussels in Texas. Interested stakeholders and
potential future conservation partners include the Trinity River
Authority, Lower Neches Valley Authority, North Texas Municipal Water
District, Sabine River Authority, the Cities of Dallas and Fort Worth,
Tarrant Regional Water District, Texas Department of Transportation,
Texas Parks and Wildlife Department, U.S. Army Corps of Engineers,
Texas Comptroller of Public Accounts, Texas A&M University, Texas State
University, and others.
With regard to silvicultural operations that occur on forested
areas across the range of the species, we recognize that private timber
companies routinely implement State-approved best management practices
(BMPs; as reviewed by Cristan et al. 2018, entire). Adherence to these
BMPs, such as citing river crossings away from sensitive areas and
leaving intact habitat as buffers for areas adjacent to streams,
broadly protects water quality by reducing timber harvest-related
impacts, particularly erosion and sedimentation (as reviewed by Cristan
et al. 2018; Warrington et al. 2017, entire; and Schilling et al. 2021,
entire). However, it is important to recognize that while BMPs reduce
timber harvest impacts, they do not eliminate impacts; therefore,
sensitive species and their habitats may still be impacted even when
BMP guidelines are followed.
Some voluntary habitat restoration projects have been completed on
private lands within the river basins currently known to be occupied by
one or both species. These restoration projects include upland and
riparian habitat enhancements coordinated by our State, Federal, and
nongovernmental partners, as well as our Partners for Fish and Wildlife
Program. There are also regulatory mechanisms in place to protect water
quality and quantity, such as protections afforded by the Clean Water
Act (33 U.S.C. 1251 et seq.), that are implemented by the States with
oversight by the EPA. While these regulations are in place and provide
some level of protection, population declines continue to be documented
in some species of freshwater mussels, indicating that existing
regulations may not be sufficient to prevent extinction.
Species Condition
Here we discuss the current and future condition of each known
population, taking into account the risks to those populations that are
currently occurring, as well as management actions that are currently
occurring to address those risks. We consider climate change to be
currently occurring, resulting in changes to the timing and amount of
rainfall affecting streamflow, which can alter stream characteristics
such as an increase in stream temperatures, erosion, and the
accumulation of fine sediments. The current condition of each species
and population is based upon the cumulative effects of these factors.
In the SSA report, for each species and population, we developed and
assigned condition categories for three population factors (occupied
stream length, abundance, reproduction/recruitment; see Species Needs,
above) and three habitat factors (habitat structure/substrate,
hydrological regime, and water quality; see Risk Factors for Texas
Heelsplitter and Louisiana Pigtoe, above) that are important for the
viability of each species. The summation of all six condition scores
assigned to each factor were then used to determine the overall
condition of each population: high (healthy), moderate (moderately
healthy), low (unhealthy), or functionally extirpated/extirpated. All
six factors were weighted equally in importance except abundance, which
was viewed as the most relevant and direct measure of current
biological condition; therefore, overall condition was capped by the
abundance score such that no population's overall condition could
exceed the abundance score. These overall conditions translate to our
presumed probability of persistence of each population, with healthy
populations having the highest probability of persistence over 20 years
(greater than 90 percent), moderately healthy populations having a
probability of persistence that falls between 60 and 90 percent,
unhealthy populations having the lowest probability of persistence
(between 10 and 60 percent). Functionally extirpated populations (less
than 10 percent) are not expected to persist over 20 years or are
already extirpated.
Texas Heelsplitter
There are five remaining Texas heelsplitter populations, occurring
in three adjacent river basins (Neches, Sabine, and Trinity River
basins) in east Texas and on the Sabine River to the western border of
Louisiana. Historically, populations likely occurred throughout the
entirety of each basin where connectivity was not an issue and
conditions were suitable. Based on our analysis, three populations are
considered to have a low current condition, and two populations are
considered functionally extirpated/extirpated (see Table 1, below).
Neches River Basin: There are two Texas heelsplitter populations in
the
[[Page 16788]]
Neches River Basin, one in the Neches River/B.A. Steinhagen Reservoir
and the other in the Lower Neches River; these populations are
fragmented and isolated from each other by the dam that forms B.A.
Steinhagen Reservoir. The Neches River/B.A. Steinhagen Reservoir
population occurs in habitat on a fairly long reach (240.9 river mi
(387.6 km)) of the Neches River that extends from just below Lake
Palestine to B.A. Steinhagen Reservoir and includes the portion of
mainstem Angelina River between B.A. Steinhagen and Sam Rayburn
reservoirs. This population is characterized by low abundance and a
lack of evidence of reproductive success, resulting in low recruitment
of new individuals. Further, water quality in tributaries and segments
of the occupied habitat is affected by a variety of point and non-point
source pollution, and infrequent but substantial drawdowns of the B.A.
Steinhagen Reservoir have resulted in direct mortality of Texas
heelsplitters. The Lower Neches River population extends 74.2 river mi
(119.4 km) downstream from Lake B.A. Steinhagen Reservoir's Town Bluff
Dam to approximately 4.5 river mi (7.2 km) downstream of the Village
Creek confluence. This population is also characterized by low
abundance and lack of evidence of reproductive success, with subsequent
low recruitment of new individuals. Further, hydrology and water
quality in this reach are affected by water releases from the B.A.
Steinhagen Reservoir. The Neches River/B.A. Steinhagen Reservoir
population and the Lower Neches River population have a low overall
current condition, resulting in low resiliency for both populations.
Sabine River Basin: This Texas heelsplitter population occurs in a
fairly long reach (245.8 river mi (395.5 km)) of the Sabine River
Basin, that includes the Toledo Bend Reservoir, Sabine River upstream
to Lake Tawakoni's Iron Bridge Dam, a portion of Lake Fork Creek
upstream from its confluence with the Sabine River, and a portion of
Patroon Bayou upstream from its confluence with Toledo Bend Reservoir.
While the overall water quality, habitat structure/substrate, and
occupied habitat reach length are in high condition, construction of
Lake Tawakoni and Toledo Bend Reservoir have altered the natural
hydrologic conditions through dam releases causing substrate scouring
and elimination of habitat downstream. Due to lack of evidence of
reproduction and recruitment, as well as extremely low abundance (CPUE
= 0.14) based on 99 surveys since 2000, this population of Texas
heelsplitter is considered functionally extirpated/extirpated.
Trinity River Basin: There are two populations of the Texas
heelsplitter in the Trinity River Basin, one within Grapevine Lake and
another within the Trinity River/Lake Livingston, that are
hydrologically isolated from one another by the dam that forms
Grapevine Lake. The habitat structure/substrate rating for the
Grapevine Lake population is in high condition, with stormwater runoff
and the discharge of municipal wastewater and associated pollutants
limiting water quality to moderate condition. Reservoir-related changes
to natural flow regimes likewise limited the hydrology rating to
moderate condition. However, with only two individuals found during
population surveys, abundance is extremely low, this combined with the
lack of juveniles and gravid females, the Grapevine Lake population is
considered to be functionally extirpated. The Trinity River population
is characterized by high current condition for the relatively large
habitat reach length currently occupied, while habitat structure/
substrate is affected by unnaturally elevated base flows and is in
moderate current condition. Large daily volumes of municipal wastewater
discharge and associated pollutants are impacting water quality and
hydrology, which are in low current condition. This population is also
characterized by low abundance and lack of evidence of reproductive
success, with subsequent low recruitment of new individuals. The
Trinity River/Lake Livingston population has a low overall current
condition and low resiliency.
Table 1--Estimated Current Overall Condition of Texas Heelsplitter
Populations
[USFWS 2022, pp. 40-44]
------------------------------------------------------------------------
Overall current
River basin Population condition
------------------------------------------------------------------------
Sabine.......................... Sabine River/ FE/E.\1\ \2\
Toledo Bend.
Neches.......................... Neches River/B.A. Low.\2\
Steinhagen. Low.\2\
Lower Neches River
Trinity......................... Grapevine Lake.... FE/E.\1\ \2\
Trinity River/Lake Low.\2\
Livingston.
------------------------------------------------------------------------
\1\ FE/E = Functionally extirpated/extirpated.
\2\ Indicates representation areas where overall condition was capped by
abundance.
Redundancy describes the ability of a species to withstand and
recover from catastrophic events. High redundancy is achieved through
multiple populations that serve to spread risk, thereby reducing the
impact that any one event might have in terms of overall loss to the
species. Redundancy is characterized by having multiple healthy,
resilient populations distributed across the range of the species. It
can be measured by population number, resiliency, spatial extent, and
degree of connectivity. Our analysis explored the influence of the
number, distribution, and connectivity of populations on the species'
ability to withstand catastrophic events.
Within the identified representation areas (Neches, Sabine, and
Trinity River basins), only the Neches and Trinity River basins
currently have at least one known population (the Sabine River/Toledo
Bend population in the Sabine River Basin and Grapevine Lake in the
Trinity River Basin are considered functionally extirpated). The Neches
River Basin currently has two populations (Neches River and Lower
Neches River populations); however, these populations are
hydrologically isolated, and therefore provide only minimal redundancy.
Representation describes the ability of a species to adapt to
changing environmental conditions over time. It is characterized by the
breadth of genetic and environmental diversity within and among
populations. Our analysis explores the relationship between the species
life history and the influence of genetic and ecological diversity and
the species ability to adapt to changing environmental conditions over
time.
We consider the Texas heelsplitter to have representation in the
form of genetic, geographic, and ecological diversity in the three
currently occupied river basins. Because there are no freshwater
connections between the three basins, we treated each river basin as
separate areas of representation.
Louisiana Pigtoe
Overall, there are 13 remaining populations of Louisiana pigtoe in
multiple river drainages throughout portions of east Texas (Big
Cypress-Sulphur, Neches-Angelina, Sabine, and San Jacinto river
basins), Louisiana (Calcasieu, Sabine, and Pearl river systems), west
Mississippi (Pearl River), southeast Oklahoma (Little River), and
southwest Arkansas (Cossatot, Saline, Rolling Fork, and Little rivers).
Because reported populations from the Ouachita River system in Arkansas
were determined to be phylogenetically distinct (a separate species)
from Louisiana pigtoe, they were not considered in the SSA. In 2019, an
additional population was discovered within the Lower Neches Valley
River
[[Page 16789]]
Authority canal system in Beaumont, Texas (Bio-West 2021, p. 1).
Because this population occupies artificially maintained habitat that
may not persist without active operational management by the Lower
Neches Valley River Authority, it was not considered for analysis in
the SSA.
Historically, the Louisiana pigtoe likely occurred throughout each
basin wherever conditions were suitable and connectivity was not an
issue, with populations connected by fish migration; however, due
primarily to impoundments, the populations are currently isolated from
one another, and repopulation of functionally extirpated/extirpated
locations is unlikely to occur without human assistance. Two
populations are currently considered to be in high condition, four
populations are in moderate condition, five populations are in low
condition, and two populations are considered functionally extirpated/
extirpated (see Table 2, below).
Big Cypress-Sulphur Basin: Although Louisiana pigtoes have not been
genetically confirmed and observations may be misidentified as Wabash
pigtoe (Fusconaia flava), past surveys indicated Louisiana pigtoe
presence (Randklev 2018, entire) in this basin. Therefore, we included
this population in this assessment. The Louisiana pigtoe population in
Big Cypress Bayou includes approximately 32.0 river mi (51.5 km) of Big
Cypress Bayou and Little Cypress Bayou upstream of their confluence.
This population is characterized by moderate condition for occupied
habitat stream length, abundance, habitat structure/substrate,
hydrology, and water quality; the habitat factors are influenced by a
variety of anthropogenic activities that vary by watershed, including
stormwater runoff and discharges from multiple wastewater treatments
plants. However, there has been a lack of reported juveniles or gravid
females, so this population is in low condition for reproduction and
recruitment.
Calcasieu River Basin: Louisiana pigtoe has a single population in
the Calcasieu-Mermentau Basin that occurs along an approximately 134-
river-mi (216-km) section of hydrologically connected portions of the
mainstem Calcasieu River, and the Whisky Chitto and Tenmile creeks
located in Allen, Rapides, and Vernon parishes, Louisiana. This
population is characterized as being in high condition for occupied
habitat reach length and habitat structure/substrate, while hydrology
and water quality are in moderate condition due to fluctuations in flow
rates and municipal wastewater effluent discharges, among other sources
of pollution. However, abundance, reproduction, and recruitment are in
low condition, which corresponds to low resiliency.
Neches River Basin: The Neches River Basin in Texas has three
populations of Louisiana pigtoe, one each in the Angelina (above Sam
Rayburn Reservoir), Neches (above B.A. Steinhagen Reservoir), and Lower
Neches rivers (below B.A. Steinhagen Reservoir). These three
populations combined extend over 400 river mi (644 km) in a basin that
many experts believe contains some of the best remaining habitat and
most diverse populations of freshwater mussels in Texas. The Neches
River and Lower Neches River populations are hydrologically isolated
from each other by the Town Bluff Dam that forms B.A. Steinhagen
Reservoir, and the Angelina River population is isolated from the
Neches River population by Sam Rayburn Dam and Reservoir. The Neches
River population's current condition is characterized as high condition
for the occupied habitat reach length (203 river mi (326.7 km)),
abundance, habitat structure/substrate, and hydrology, and moderate
condition for reproduction/recruitment and water quality. The Lower
Neches River population is characterized by high current condition for
occupied habitat reach length (160.4 river mi (258.1 km)) and habitat
structure/substrate, and a moderate current condition for hydrology,
water quality, and reproduction/recruitment due to the impacts of
fluctuating stream flows, pollution loading from point and non-point
sources, and few reports of gravid females or juvenile mussels. In
addition, few individuals have been observed, resulting in a low
current condition for population abundance. The Angelina River
population is in high condition for occupied habitat reach length (53.2
river mi (85.6 km)), habitat structure/substrate, and hydrology;
however, water quality impacts such as elevated bacteria, fecal
coliform, and ammonia resulted in a moderate current condition for
water quality. Like the Lower Neches River population, due to the few
numbers of individuals observed and a lack of juvenile or gravid female
presence, abundance and reproduction/recruitment are in low condition
for the Angelina River population. The Neches River population has a
high overall current condition, and the Lower Neches River and Angelina
River populations have a low overall current condition (primarily due
to being capped by low abundance).
Pearl River Basin: The Pearl River Basin in Louisiana and
Mississippi has a single population of the Louisiana pigtoe within the
main stem that extends approximately 280 river mi (450 km) below Ross
Barnett Dam near Jackson to Picayune, Mississippi (upstream of
Interstate 59). A new impoundment proposed by the Rankin-Hinds Pearl
River Flood and Drainage Control District, located 9 mi (14.5 km)
downstream of Ross Barnett Reservoir, intended for flood control, is
still under review. For the Pearl River population, we determined that
occupied habitat reach length is in high condition, and habitat
structure/substrate, hydrology, and water quality are in moderate
condition due to erratic flows and pollutants from urban areas and
industry wastewater discharge. Because few individuals have been
reported and there is a lack of juvenile or gravid female presence,
abundance and reproduction/recruitment are in low condition. The Pearl
River population has an estimated overall low current condition and low
resiliency.
Red River Basin: The Red River Basin contains four distinct
populations of the Louisiana pigtoe that extend along 88.3 river mi
(142.1 km) within the Little River drainage in Arkansas and Oklahoma,
including populations in the Cossatot River, Little River/Rolling Fork,
Lower Little River, and Saline River. Millwood Lake, located in
southwest Arkansas, hydrologically separates the Cossatot River, Saline
River, and Little River/Rolling Fork populations from the Lower Little
River population. The current condition evaluation for the Cossatot
River population determined that abundance, reproduction/recruitment,
and habitat structure/substrate are in high condition, and occupied
habitat reach length, hydrology, and water quality are in moderate
condition due to fluctuations of stream flows from Gillham Lake, as
well as pollutant discharges from agriculture and other sources. No
habitat or population factors are determined to be in low condition.
The Little River/Rolling Fork population's current condition evaluation
determined occupied habitat reach length and reproduction/recruitment
are in high condition. All other population and habitat factors are in
moderate condition due to lower abundance, fluctuations in instream
flow (which affect benthic habitat, substrate, and stream hydrology),
and increased levels of zinc, lead, and salinity (among other
pollutants), leading to moderate water quality. The Saline River
population's current condition evaluation found
[[Page 16790]]
occupied habitat reach length, abundance, hydrology, and water quality
in moderate condition caused by prolonged high water levels and low
levels of dissolved oxygen. Due to the lack of evidence of reproductive
success and subsequent recruitment of new individuals, and altered flow
conditions downstream of Dierks Lake, reproduction/recruitment and
habitat structure/substrate are in low condition. The Lower Little
River population's current condition evaluation determined that
reproduction/recruitment and all habitat factors are in low condition
primarily because of its short reach length (8.5 river mi (14.16 km)),
altered flow regime, and paucity of survey data. This population is
located downstream of Millwood Lake and Dam, a flood control reservoir,
and is subject to altered hydrology that further impacts habitat
structure and substrates during flood events. Agricultural runoff
associated with the lower section of this reach impacts water quality.
Due to the extremely low numbers of individuals observed (abundance),
this population is considered functionally extirpated/extirpated. In
summary, the Cossatot River population has a high overall current
condition and high resiliency, the Little River/Rolling Fork and Saline
River populations have a moderate overall current condition and
moderate resiliency, and the Lower Little River population is
considered functionally extirpated/extirpated.
Sabine River: There are two known populations of the Louisiana
pigtoe within the Sabine River, one located along 87 river mi (140 km)
between Hawkins and Tatum, Texas, and a second population within a 9-
river-mi (15-km) segment of Bayou Anacoco in Louisiana. These
populations are hydrologically separated by Toledo Bend Dam and
Reservoir. The Sabine River population's current condition evaluation
determined that occupied habitat reach length and habitat structure/
substrate are in high condition. Dam releases from Lake Tawakoni and
Toledo Bend Reservoir, wastewater releases, and water quality
degradation (including elevated levels of bacteria) are primary causes
for moderate current conditions for hydrology and water quality. Due to
an extremely low number of individuals detected during surveys, and the
lack of juveniles or gravid females observed, abundance and
reproduction/recruitment are in low condition, and this population is
considered functionally extirpated/extirpated. The Bayou Anacoco
population's current condition evaluation found habitat structure/
substrate is high condition, and abundance, hydrology, and water
quality are in moderate condition. However, the occupied habitat reach
length and reproduction/recruitment are in low condition due to the
distribution of observed individuals and lack of reported juveniles or
gravid females. The Bayou Anacoco population is in moderate current
overall condition and has moderate resiliency.
East Fork San Jacinto River: There is one known population of
Louisiana pigtoe that occurs within a short (1.3-river-mi (2-km))
segment of the East Fork San Jacinto River near Plum Grove, Texas. The
population's current condition evaluation determined that hydrology and
water quality are in moderate condition, whereas sand and gravel mining
are affecting the habitat structure/substrate, which is in low
condition. Due to a low number of individuals detected and lack of
juveniles or gravid females observed, population abundance and
reproduction/recruitment are in low condition. The East Fork San
Jacinto River population is determined to be in overall low condition
and has low resiliency.
Table 2--Estimated Current Overall Condition of Known Louisiana Pigtoe
Populations
[USFWS 2022, pp. 34-40]
------------------------------------------------------------------------
Overall current
River basin Population condition
------------------------------------------------------------------------
Red............................. Little River/ Moderate.
Rolling Fork. High.
Cossatot River.... Moderate.
Saline River...... FE/E. \1\ \2\
Lower Little River
Big Cypress-Sulphur............. Big Cypress Bayou. Moderate.
Calcasieu-Mermentau............. Calcasieu River... Low. \2\
Pearl........................... Pearl River....... Low. \2\
Sabine.......................... Sabine River...... FE/E. \1\ \2\
Bayou Anacoco..... Moderate.
Neches.......................... Angelina River.... Low. \2\
Neches River...... High.
Lower Neches River Low.\2\
San Jacinto..................... East Fork San Low.
Jacinto River.
------------------------------------------------------------------------
\1\ FE/E = Functionally extirpated/extirpated.
\2\ Indicates representation areas where overall condition was capped by
abundance.
Within identified representation areas, the Big Cypress-Sulphur,
Calcasieu-Mermentau, Pearl, and San Jacinto River basins each have only
one known current population, and therefore lack redundancy should
catastrophic events occur that cause extirpation of one or a few
populations. The Sabine River Basin has two separate populations
(Sabine River and Bayou Anacoco populations) but lacks redundancy due
to the Sabine River population being functionally extirpated. The
Neches and Red River basins each currently have three known populations
(the Lower Little River population in the Red River Basin is considered
functionally extirpated), however each population is hydrologically
isolated within their respective river basins and are, therefore,
considered to provide only limited redundancy.
We consider Louisiana pigtoe to have representation in the form of
genetic, ecological, and geographical diversity between each of seven
river basins: Big Cypress-Sulphur, Calcasieu-Mermentau, Neches, Pearl,
Red, Sabine, and San Jacinto. Because there are no un-impounded,
freshwater connections that allow movement between the seven basins,
each river was considered a separate area of representation.
Future Conditions
As part of the SSA, we developed multiple future condition
scenarios to capture the range of uncertainties
[[Page 16791]]
regarding future threats and the projected responses by the Texas
heelsplitter and Louisiana pigtoe. Our scenarios included a status quo
scenario, which incorporated the current risk factors continuing on the
same trajectory that they are on now. We also evaluated two future
scenarios that incorporated varying levels of increasing risk factors
with elevated negative effects on Texas heelsplitter and Louisiana
pigtoe populations. However, because we determined that the current
condition of the Texas heelsplitter is consistent with an endangered
species (see Texas Heelsplitter: Determination of Status, below), we
are not presenting the results of the future scenarios in this proposed
rule. Please refer to the SSA report (Service 2022) for the full
analysis of future scenarios.
We forecasted the Louisiana pigtoe's responses to two plausible
future scenarios of environmental conditions projected across the next
10, 25, and 50 years. Ten years represents one to two generations of
mussels, assuming an average reproductive life span of five to 10
years. Twenty-five years similarly represents at least two to four
mussel generations and 50 years represents at least five or more
generations of mussels. The scenarios project the threats into the
future and consider the impacts those threats could have on the
viability of the Louisiana pigtoe. We apply the concepts of resiliency,
redundancy, and representation to the future scenarios to describe
possible future conditions of the Louisiana pigtoe. The scenarios
described in the SSA report represent only two possible future
conditions. Uncertainty is inherent in any projection of future
condition, so we must consider plausible scenarios to make our
determinations. When assessing the future, viability is not a specific
state, but rather a continuous measure of the likelihood that the
species will sustain populations over time.
We included climate change in our future scenarios as a factor that
would add to the negative impacts of the primary threats on the
species' habitat. Climate change is expected to alter the natural flow
regime through increased drought and flooding worsening desiccation,
scour, and sedimentation. Global climate models project changes in
global temperature and other associated climatic changes based on
potential future scenarios of greenhouse gas concentrations in the
atmosphere (i.e., Representative Concentration Pathways, or RCPs). RCP
4.5 assumes major near-future cuts to carbon dioxide emissions, and RCP
8.5 assumes that current emissions practices continue with no
significant change (Terando et al. 2020, p. 10). Thus, these RCPs
represent conditions in the upper and lower ends of the range of what
can reasonably be expected for the future effects of climate change
(Terando et al. 2020, p. 17).
Scenario 1 assesses the species' responses to moderate increases in
stressors influencing Louisiana pigtoe populations. Scenario 1 is based
on RCP 4.5 emission trajectory and associated model projections, and
represents medium-term increases in emissions followed by a decline
through the rest of the century. Scenario 2 assesses the species'
responses to severe increases in stressors and is based on RCP 8.5
projections. Scenario 2 also includes anthropogenic actions, such as
the construction of new reservoirs, wastewater treatment plants, and
other currently proposed projects, and manifests as a future where the
hydrological conditions of many of the rivers and streams currently
occupied by Louisiana pigtoe are altered such that base flows are
diminished, floods are more severe if not more frequent, and mussels
and their habitats are adversely affected through degradation of water
quality and quantity. These altered hydrological conditions are
primarily caused by a combination of increasing anthropogenic stressors
and climate change. Due to a lack of resolution of the available data,
we were unable to distinguish any meaningful difference between a
moderate increase in stressors and a moderate decrease in stressors. As
a result, we limited the future forecasts to these two scenarios, which
we projected over a 50-year period. We restricted our evaluation to 50
years primarily due to limitations projecting non-modeled, extrapolated
future conditions for water quality, road density, and habitat
fragmentation. Fifty years encompasses about 5 generations of the
Louisiana pigtoe; additionally, projected human population growth and
the limitations of existing resources are expected to increase and
interact with climate effects to exacerbate the effects of drought
which is likely to impact water quality and quantity (i.e., the ability
to provide the minimum flow needed by the Louisiana pigtoe). A full
description of the future scenarios and our methods is available in the
SSA report (USFWS 2022, pp. 63-73).
Under Scenario 1, populations of the Louisiana pigtoe decline in
resiliency, redundancy, and representation over time as conditions
moderately decline from current conditions. One population will remain
in moderate condition, seven in low condition, and five functionally
extirpated in 50 years. This species will lose two areas of
representation, diminishing the overall adaptive capacity to future
environmental change in the next 50 years (see Table 3).
Table 3--Future Condition of Louisiana Pigtoe Populations With a Moderate Increase in Stressors
[Scenario 1]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Scenario 1 future condition
Species River basin Population --------------------------------------------------------------------
10 years 25 years 50 years
--------------------------------------------------------------------------------------------------------------------------------------------------------
Louisiana Pigtoe................... Red Little River/ Moderate.............. Low.................. Low..................
Rolling Fork. High.................. High................. Moderate.............
Cossatot River........ Moderate.............. Moderate............. Low..................
Saline River.......... FE/E \1\.............. FE/E \1\............. FE/E.\1\.............
Lower Little River....
Big Cypress-Sulphur... Big Cypress Bayou..... Moderate............. Moderate............. Low.
Calcasieu............. Calcasieu River....... Low.................. Low.................. FE/E.\1\
Pearl................. Pearl River........... Low.................. Low.................. Low.
Sabine................ Sabine River.......... FE/E \1\............. FE/E \1\............. FE/E.\1\
Bayou Anacoco......... Low.................. Moderate............. Low.
Neches................ Angelina River........ Low.................. Low.................. FE/E.\1\
Neches River.......... High................. Low.................. Low.
Lower Neches River.... Low.................. Low.................. Low.
[[Page 16792]]
San Jacinto........... East Fork San Jacinto Low.................. Low.................. FE/E. \1\
River.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ FE/E = Functionally extirpated/extirpated.
Under Scenario 2, populations of the Louisiana pigtoe further
decline in resiliency, redundancy, and representation over time as the
effects of climate change impact populations through extremely low
stream flows, severe increases in sedimentation, reductions in water
quality, and an increase in potential for desiccation of habitat. Eight
populations of Louisiana pigtoe are expected to become either
functionally extirpated or extirpated within 50 years, with the
remaining five populations in low condition. The Louisiana pigtoe is
projected to lose four of the seven current representation areas in 50
years, with eight populations remaining or becoming extirpated;
therefore, the adaptive capacity of this species is projected to be
severely reduced in the future (see Table 4).
Table 4--Future Condition of Louisiana Pigtoe Populations With a Severe Increase in Stressors
[Scenario 2]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Scenario 2 future condition
Species River basin Population --------------------------------------------------------------------
10 years 25 years 50 years
--------------------------------------------------------------------------------------------------------------------------------------------------------
Louisiana Pigtoe................... Red................... Little River/Rolling Moderate............. Low.................. Low.
Fork. High................. High................. Low.
Cossatot River........ Moderate............. Low.................. Low.
Saline River.......... FE/E \1\............. FE/E \1\............. FE/E.\1\
Lower Little River....
Big Cypress-Sulphur... Big Cypress Bayou..... Moderate............. Moderate............. Low.
Calcasieu-Mermentau... Calcasieu River....... Low.................. Low.................. FE/E.\1\
Pearl................. Pearl River........... Low.................. Low.................. FE/E.\1\
Sabine................ Sabine River.......... FE/E \1\............. FE/E \1\............. FE/E.\1\
Bayou Anacoco......... Low.................. Moderate............. FE/E.\1\
Neches................ Angelina River........ Low.................. Low.................. FE/E.\1\
Neches River.......... High................. Low.................. Low
Lower Neches River.... Low.................. Low.................. FE/E.\1\
San Jacinto........... East Fork San Jacinto Low.................. FE/E \1\............. FE/E.\1\
River.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ FE/E = Functionally extirpated/extirpated.
We note that, by using the SSA framework to guide our analysis of
the scientific information documented in the SSA report, we have not
only analyzed individual effects on the species, but we have also
analyzed their potential cumulative effects. We incorporate the
cumulative effects into our SSA analysis when we characterize the
current and future condition of the species. To assess the current and
future condition of the species, we undertake an iterative analysis
that encompasses and incorporates the threats individually and then
accumulates and evaluates the effects of all the factors that may be
influencing the species, including threats and conservation efforts.
Water quality degradation, altered hydrology, changes to habitat
structure/substrate, habitat fragmentation, invasive species, climate
change, and collecting are all factors that influence or could
influence the viability of these two freshwater mussel species. These
factors also have the potential to act cumulatively to impact Texas
heelsplitter and Louisiana pigtoe viability and their cumulative
impacts were considered in our characterization of the species' current
and future condition in the SSA. Because the SSA framework considers
not just the presence of the factors, but to what degree they
collectively influence risk to the entire species, our assessment
integrates the cumulative effects of the factors and replaces a
standalone cumulative effects analysis.
Determination of Status
Section 4 of the Act (16 U.S.C. 1533) and its implementing
regulations (50 CFR part 424) set forth the procedures for determining
whether a species meets the definition of an endangered species or a
threatened species. The Act defines an ``endangered species'' as a
species in danger of extinction throughout all or a significant portion
of its range, and a ``threatened species'' as a species likely to
become an endangered species within the foreseeable future throughout
all or a significant portion of its range. The Act requires that we
determine whether a species meets the definition of an endangered
species or a threatened species because of any of the following
factors: (A) The present or threatened destruction, modification, or
curtailment of its habitat or range; (B) overutilization for
commercial, recreational, scientific, or educational purposes; (C)
disease or predation; (D) the inadequacy of existing regulatory
mechanisms; or (E) other natural or manmade factors affecting its
continued existence.
Status Throughout All of Its Range
After evaluating threats to the Texas heelsplitter and Louisiana
pigtoe and
[[Page 16793]]
assessing the cumulative effect of the threats under the Act's section
4(a)(1) factors, we found that both species of freshwater mussels have
declined significantly in overall distribution and abundance. At
present, most of the known populations exist in very low abundances and
show limited evidence of recruitment. Furthermore, existing available
habitats are reduced in quality and quantity, relative to historical
conditions. Our analysis revealed six primary threats that caused these
declines and pose a meaningful risk to the viability of the species.
These threats are primarily related to habitat changes (Factor A):
impairment of water quality, altered hydrology, the accumulation of
fine sediments, and habitat fragmentation, all of which are exacerbated
by the effects of climate change (Factor E). Predation (Factor C) and
collection (Factor B), as well as other natural or human-induced
events/activities that result in direct mortality, are also affecting
those populations already experiencing low stream flow, and reservoirs
and instream barriers to fish movement (Factor E) limit dispersal and
prevent recolonization after stochastic events.
Populations of the Texas heelsplitter and Louisiana pigtoe are
faced with a myriad of stressors from natural and anthropogenic sources
that pose a risk to their survival in both large and small river
segments. Climate change has the noteworthy distinction of being able
to directly or indirectly exacerbate the most relevant stressors to
freshwater mussels wherever they occur. Climate projections suggest
persistent droughts over the continental United States that are longer,
cover more area, and are more intense than what has been experienced in
the 20th century (APA 2019, p. 4; Terando et al. 2018, p. 786; Wehner
et al. 2017, p. 237). Humans are likely to respond to climate change in
predictable ways to meet their needs, such as increased groundwater
pumping and surface water diversions, and increased use of reverse
osmosis to treat sources of water that are of poor quality (thereby
generating increasing volumes of wastewater). These activities will
increase overall demand for freshwater resources at a time when those
very resources are strained and less abundant (reviewed in Banner et
al. 2010, entire). We expect climate change impacts to occur throughout
the range of both the Texas heelsplitter and the Louisiana pigtoe.
The threats to the species, acting alone or in combination with
each other and climate change, could result in the extirpation of
additional mussel populations, further reducing the overall redundancy
and representation of the Texas heelsplitter and Louisiana pigtoe.
Historically, each species, bolstered by large, interconnected
populations (i.e., with meta-population dynamics), would have been more
resilient to stochastic events such as drought, excessive
sedimentation, and scouring floods. As locations became extirpated by
catastrophic events, they could be recolonized over time by dispersal
from nearby surviving populations, facilitated by movements of host
fish. This connectivity across potential habitats made for highly
resilient species overall, as evidenced by the long and successful
evolutionary history of freshwater mussels as a taxonomic group, and in
North America in particular. However, under current conditions,
restoration of that connectivity on a regional scale is not feasible.
Because of these current conditions, the viability of the Texas
heelsplitter and Louisiana pigtoe now primarily depends on maintaining
the remaining isolated populations and potentially restoring new
populations where feasible.
Texas Heelsplitter: Status Throughout All of Its Range
The Texas heelsplitter has declined significantly in overall
distribution and abundance over the past 100 or more years. Most known
populations of the Texas heelsplitter are isolated and currently exist
in very low numbers (low abundance), have limited evidence of
recruitment, and are believed to occupy much less habitat than in the
past (range contraction). Of the five remaining populations of Texas
heelsplitter, three are small in abundance and have low resiliency, and
two are considered functionally extirpated/extirpated. While the three
low resiliency populations (Neches River/B.A. Steinhagen Reservoir,
Lower Neches River, and Trinity River/Lake Livingston) have habitat in
high or moderate current condition, all three have very little evidence
of reproduction and are therefore likely to decline due to a lack of
young individuals joining the population as the population ages. Low
abundance, combined with the lack of evidence of reproduction and
recruitment, results in populations with very little population
resiliency. Overall, these low levels of resiliency, redundancy, and
representation currently result in the Texas heelsplitter having a high
risk of extinction.
Our analysis of the species' current condition, as well as the
conservation efforts discussed above, show that the Texas heelsplitter
is in danger of extinction throughout all of its range due to the
severity and immediacy of threats currently impacting their
populations. The risk of extinction is high because the remaining
fragmented populations have a high risk of extirpation, are isolated,
and have limited potential for recolonization. We find that a
threatened species status is not appropriate for the Texas heelsplitter
because its current range is already contracted, all populations are
fragmented and isolated from one another, the threats are occurring
across the entire range of this species, and the species currently
exhibits low resiliency, redundancy, and representation. Because these
conditions place the species already in danger of extinction throughout
its range, a threatened status is not appropriate.
Texas Heelsplitter: Status Throughout a Significant Portion of Its
Range
Under the Act and our implementing regulations, a species may
warrant listing if it is in danger of extinction or likely to become so
in the foreseeable future throughout all or a significant portion of
its range. We have determined that the Texas heelsplitter is in danger
of extinction throughout all of its range and accordingly did not
undertake an analysis of any significant portion of its range. Because
the Texas heelsplitter warrants listing as endangered throughout all of
its range, our determination does not conflict with the decision in
Center for Biological Diversity v. Everson, 2020 WL 437289 (D.D.C. Jan.
28, 2020), because that decision related to significant portion of the
range analyses for species that warrant listing as threatened, not
endangered, throughout all of their range.
Texas Heelsplitter: Determination of Status
Our review of the best available scientific and commercial
information indicates that the Texas heelsplitter meets the Act's
definition of an endangered species. Therefore, we propose to list the
Texas heelsplitter as an endangered species in accordance with sections
3(6) and 4(a)(1) of the Act.
Louisiana Pigtoe: Status Throughout All of Its Range
Many Louisiana pigtoe populations are relatively abundant, but
populations are isolated from one another; therefore, the species is
unable to recolonize following stochastic events that may reduce or
eliminate populations. Additionally, many populations occur in degraded
habitats. Although some
[[Page 16794]]
conservation efforts are underway, they are not sufficient to prevent
the decline of the species. Thirteen populations of Louisiana pigtoe
remain. Two populations are in high condition, four in moderate
condition, five are in low condition, and two are functionally
extirpated/extirpated. The Red River Basin has four populations, and
only one is in high condition (Cossatot River), two are in moderate
overall condition, and one (Lower Little River) is functionally
extirpated/extirpated. The Neches River is the only other population
with a high overall current condition. Only two populations, Little
River/Rolling Fork and Cossatot River (both within the Red River
Basin), have strong evidence of reproduction and recruitment as
indicated by presence of fish hosts, juveniles, and gravid females; two
(Neches and Lower Neches rivers) have moderate evidence of reproduction
and recruitment; the remaining nine populations have low evidence of
reproduction and recruitment. Two populations have high abundance
(Cossatot and Neches rivers) four populations have moderate abundance
(Little River/Rolling Rock, Saline River, Big Cypress Bayou, and Bayou
Anacoco), and five populations have extremely low abundance (Calcasieu,
Pearl, Angelina, Lower Neches, and East Fork San Jacinto rivers), and
population abundance is too low to support resiliency of two
populations (Lower Little River (tributary to the Red River) and Sabine
River), which are functionally extirpated/extirpated
We considered whether the Louisiana pigtoe is presently in danger
of extinction throughout all of its range and determined that
endangered status is not appropriate. The current conditions as
assessed in the SSA report show two of the populations in two of the
representative units are in high current condition, and four are in
moderate current condition; they are not currently subject to declining
flows or extreme flow events. While threats are currently acting on the
species and many of those threats are expected to continue into the
future, we did not find that the species is currently in danger of
extinction throughout all of its range.
In the future, as extreme flow events become more frequent as
rainfall patterns change, and increased urbanization results in reduced
groundwater levels, we expect even these populations to be at an
increased risk of extirpation. Given the likelihood of climate change
and other anthropogenic effects in the foreseeable future, within 50
years we estimate at least five populations will become (or remain)
functionally extirpated/extirpated, seven will be in low condition, and
one population will be in moderate condition. In the future, we
anticipate that the Louisiana pigtoe will have reduced viability, with
no highly resilient populations and limited representation and
redundancy.
According to our assessment of plausible future scenarios in the
SSA report, the species is likely to become an endangered species in
the foreseeable future of 50 years throughout all of its range. Fifty
years encompasses about 5 generations of the Louisiana pigtoe;
additionally, projected human population growth and the limitations of
existing resources are expected to increase and interact with climate
effects to exacerbate the effects of drought on surface water resources
throughout all of its range. These effects are likely to impact the
ability to provide the minimum flow needed by the Louisiana pigtoe. As
a result, we expect increased incidences of low flows followed by scour
events, as well as persistent decreased water quality, to be occurring
in 50 years.
After evaluating threats to the species and assessing the
cumulative effect of the threats under the Act's section 4(a)(1)
factors, we find that the Louisiana pigtoe populations will continue to
decline over the next 50 years so that this species is likely to become
in danger of extinction throughout all of its range within the
foreseeable future due to increased frequency of drought and extremely
high-flow events, decreased water quality, and decreased substrate
suitability.
Thus, after assessing the best available information, we determine
that the Louisiana pigtoe is not currently in danger of extinction but
is likely to become in danger of extinction within the foreseeable
future throughout all of its range.
Louisiana Pigtoe: Status Throughout a Significant Portion of Its Range
Under the Act and our implementing regulations, a species may
warrant listing if it is in danger of extinction or likely to become so
in the foreseeable future throughout all or a significant portion of
its range. The court in Center for Biological Diversity v. Everson,
2020 WL 437289 (D.D.C. Jan. 28, 2020) (Everson), vacated the aspect of
the Final Policy on Interpretation of the Phrase ``Significant Portion
of Its Range'' in the Endangered Species Act's Definitions of
``Endangered Species'' and ``Threatened Species'' (Final Policy) (79 FR
37578; July 1, 2014) that provided that the Service does not undertake
an analysis of significant portions of a species' range if the species
warrants listing as threatened throughout all of its range. Therefore,
we proceed to evaluating whether the species is endangered in a
significant portion of its range--that is, whether there is any portion
of the species' range for which both (1) the portion is significant;
and (2) the species is in danger of extinction in that portion.
Depending on the case, it might be more efficient for us to address the
``significance'' question or the ``status'' question first. We can
choose to address either question first. Regardless of which question
we address first, if we reach a negative answer with respect to the
first question that we address, we do not need to evaluate the other
question for that portion of the species' range.
Following the court's holding in Everson, we now consider whether
there are any significant portions of the species' range where the
species is in danger of extinction now (i.e., endangered). In
undertaking this analysis for the Louisiana pigtoe, we choose to
address the status question first--we consider information pertaining
to the geographic distribution of both the species and the threats that
the species faces to identify any portions of the range where the
species may be endangered.
For the Louisiana pigtoe, we consider abundance to be the most
direct measure of the health and status of the species (see Species
Condition, above). Measures like water quality and hydrology may rank
moderate or high, indicating higher quality habitat--but that does not
necessarily indicate the presence of Louisiana pigtoe, only presence of
suitable habitat. All six factors were weighted equally in importance
except abundance, which was viewed as the most relevant and direct
measure of current biological condition; therefore, overall condition
was capped by the abundance score such that no population's overall
condition could exceed the abundance score. By capping abundance, we
ensured that the overall current condition score is based on species-
specific information. There are five populations that are considered to
be in low overall current condition (with between 3-25 individuals
found per population survey) and two that are considered functionally
extirpated/extirpated (with less than 3 individuals found per
population survey). In addition to low abundance, there was a lack of
evidence of reproduction in 9 of the 13 populations; these two
population factors are similar in scope, scale, and distribution across
the range of the species (See Reproduction/
[[Page 16795]]
Recruitment in Species Needs above). We then considered whether these
populations that are at higher risk of extirpation are geographically
concentrated in any portion of the species' range at a biologically
meaningful scale.
We examined the range of Louisiana pigtoe for biologically
meaningful portions that may be at higher risk of extirpation, as
reflected by current population resiliency. The range of Louisiana
pigtoe is relatively large, and populations are distributed in varying
conditions across the range. Therefore, we examined the range based on
accepted mussel faunal provinces (i.e., Haag 2010, p. 18), which
reflect phylogenetic relationships as well as physiogeographical
differences in stream habitat. The faunal provinces germane to the
range of the Louisiana pigtoe are Interior Highlands (includes the
Little River and tributaries), Mississippi Embayment (includes Big
Cypress Bayou), Sabine-Trinity (includes Upper Calcasieu, Sabine,
Angelina, Neches, and East Fork San Jacinto Rivers, and Bayou Anacoco),
and Pontchartrain-Pearl-Pascagoula (includes Pearl River). Of these
faunal provinces, the Interior Highlands, Sabine-Trinity, and
Pontchartrain-Pearl-Pascagoula faunal provinces contain populations in
low condition or that are functionally extirpated and therefore are at
higher risk of extirpation.
The Interior Highlands faunal province is characterized by upland
streams in the Ozark and Ouachita mountains. This province has numerous
endemic aquatic species of both fish and freshwater mussels, due to the
isolation of the river systems within the province from each other and
from other upland river systems (Haag 2012, pp. 82-83). In this faunal
province, the Lower Little River is functionally extirpated, with the
remaining populations in moderate (Little River and Saline River) or
high (Cossatot River) condition. While the populations in this faunal
province are subject to threats such as erratic flows capable of
causing bed movement or dislocation of mussels, increased
sedimentation, altered water chemistry (e.g., low temperatures), and
decreased water quality due to higher pollutant loads from urban areas
and industrial wastewater discharges, the threats are primarily
occurring in the future. Under a moderate increase in stressors based
on the lower greenhouse gas emissions trajectory (RCP 4.5), model
projections expect an increase in global mean surface temperatures that
will alter precipitation events resulting in drought and flooding in
the next 25-50 years, this combined with future human demand for water
resources indicate an overall decline in populations in the future.
Louisiana pigtoe within the Interior Highlands faunal province are not
currently in danger of extinction; therefore, they do not have a
different status from the remainder of the species' range.
The Sabine-Trinity faunal province is located in the central Gulf
Coast of Texas, and characterized by lowland streams and rivers, with
lentic and wetland habitats bordering the main channels (Haag 2012, pp.
86-87). In this faunal province, the Upper Calcasieu River, Angelina
River, Lower Neches River, and the East Fork San Jacinto River are in
low condition, the Sabine River is functionally extirpated, with the
remaining populations in moderate (Big Cypress Bayou) or high condition
(Neches River). While the populations in this faunal province are being
affected by impoundments resulting in threats such as excessive
sedimentation and water quality degradation, as well as ongoing
agricultural activities, groundwater withdrawals, and surface water
diversions, these threats are primarily occurring in the future. Under
a moderate increase in stressors based on the lower greenhouse gas
emissions trajectory (RCP 4.5), model projections expect an increase in
global mean surface temperatures that will alter precipitation events
resulting in more extreme drought and flooding conditions that reduces
water quality, mobilizes substrates, eroded habitat or deposits
sentiments on Louisiana pigtoe populations in the next 25-50 years. The
Sabine-Trinity faunal province are not currently in danger of
extinction; therefore, they do not have a different status from the
remainder of the species' range.
The Pontchartrain-Pearl-Pascagoula faunal province lies entirely
within the Coastal Plain and is characterized by lowland streams filled
with sandy and fine sediments, with lentic and wetland habitats
alongside the main stream channels (Haag 2012, p. 87.). This province
has numerous endemic aquatic species of both fish and freshwater
mussels, the majority of which are shared with the Mobile Basin
province (Haag 2012, pp. 87-89), and includes the Pearl River
population in an overall low condition. The Pearl River population in
this faunal province is subject to threats such as erratic flows from
water releases from the Ross Barrett Dam that are capable of causing
bed movement or dislocation of mussels, increased sedimentation, and
altered water chemistry (e.g., low temperatures), the threats are
primarily occurring in the future. Under a moderate greenhouse gas
emission trajectory (RCP 4.5), model projections no changes from
current condition are expected within 10-years. Within 25-years,
hydrologic conditions would be negatively affected by the construction
of a flood control reservoir proposed for the upper portion of the
focal area, resulting in a moderate decline in substrate condition as
sediments accumulate on mussel beds from a lack or cleansing flows, and
water quality degradation. Although these threats are not unique to
this area, they may be acting at a greater intensity here, either
individually or in combination, than elsewhere in the range, given the
low abundance of Louisiana pigtoe in this reach. The small size of this
population, coupled with the current condition information in the SSA
report suggesting the population in this area has low resiliency,
indicates the populations in the Pontchartrain-Pearl-Pascagoula faunal
province may be in danger of extinction now.
We evaluated the available information about this portion of the
range of Louisiana pigtoe that occupies the upper Pearl River in this
context, assessing its biological significance in terms of the three
habitat criteria (habitat/structure, hydrology, and water quality; see
Species Condition) used to assign the current condition of Louisiana
Pigtoe populations, and determined the information did not indicate it
may be significant. Louisiana pigtoe in this population exhibit similar
habitat and host fish use to Louisiana pigtoe in the remainder of its
range; thus, there is no unique observable environmental usage or
behavioral characteristics attributable to just this area's population.
The Pearl River is not essential to any specific life-history function
of the Louisiana pigtoe that is not found elsewhere in the range.
Further, the habitat in the Pearl River does not contain higher quality
or higher value than the remainder of the species' range of the
Louisiana pigtoe (see Table 3). Additionally, this population does not
interact with other populations of the species. Overall, we found no
substantial information that would indicate the population in the Pearl
River may be significant. While this reach provides some contribution
to the species' overall ability to withstand catastrophic or stochastic
events (redundancy and resiliency, respectively), the species has
larger populations in adjacent faunal provinces. The best scientific
and commercial information available indicate that this populations'
contribution is very limited in scope
[[Page 16796]]
due to small population size and isolation from other populations.
Therefore, because we could not answer both the status and significance
questions in the affirmative, we conclude that the Pearl River does not
warrant further consideration as a significant portion of the range of
the Louisiana pigtoe.
Therefore, no portion of the species' range provides a basis for
determining that the species is in danger of extinction in a
significant portion of its range, and we determine that the species is
likely to become in danger of extinction within the foreseeable future
throughout all of its range. This does not conflict with the courts'
holdings in Desert Survivors v. Department of the Interior, 321 F.
Supp. 3d 1011, 1070-74 (N.D. Cal. 2018), and Center for Biological
Diversity v. Jewell, 248 F. Supp. 3d, 946, 959 (D. Ariz. 2017) because,
in reaching this conclusion, we did not need to consider whether any
portions are significant and, therefore, did not apply the aspects of
the Final Policy's definition of ``significant'' that those court
decisions held were invalid.
Louisiana Pigtoe: Determination of Status
Our review of the best available scientific and commercial
information indicates that the Louisiana pigtoe meets the Act's
definition of a threatened species. Therefore, we propose to list the
Louisiana pigtoe as a threatened species in accordance with sections
3(20) and 4(a)(1) of the Act.
Available Conservation Measures
Conservation measures provided to species listed as endangered or
threatened species under the Act include recognition as a listed
species, planning and implementation of recovery actions, requirements
for Federal protection, and prohibitions against certain practices.
Recognition through listing results in public awareness, and
conservation by Federal, State, Tribal, and local agencies, private
organizations, and individuals. The Act encourages cooperation with the
States and other countries and calls for recovery actions to be carried
out for listed species. The protection required by Federal agencies,
including the Service, and the prohibitions against certain activities
are discussed, in part, below.
The primary purpose of the Act is the conservation of endangered
and threatened species and the ecosystems upon which they depend. The
ultimate goal of such conservation efforts is the recovery of these
listed species, so that they no longer need the protective measures of
the Act. Section 4(f) of the Act calls for the Service to develop and
implement recovery plans for the conservation of endangered and
threatened species. The goal of this process is to restore listed
species to a point where they are secure, self-sustaining, and
functioning components of their ecosystems.
The recovery planning process begins with development of a recovery
outline made available to the public soon after a final listing
determination. The recovery outline guides the immediate implementation
of urgent recovery actions while a recovery plan is being developed.
Recovery teams (composed of species experts, Federal and State
agencies, nongovernmental organizations, and stakeholders) may be
established to develop and implement recovery plans. The recovery
planning process involves the identification of actions that are
necessary to halt and reverse the species' decline by addressing the
threats to its survival and recovery. The recovery plan identifies
recovery criteria for review of when a species may be ready for
reclassification from endangered to threatened (``downlisting'') or
removal from protected status (``delisting''), and methods for
monitoring recovery progress. Recovery plans also establish a framework
for agencies to coordinate their recovery efforts and provide estimates
of the cost of implementing recovery tasks. Revisions of the plan may
be done to address continuing or new threats to the species, as new
substantive information becomes available. The recovery outline, draft
recovery plan, final recovery plan, and any revisions will be available
on our website as they are completed (https://www.fws.gov/program/endangered-species).
Implementation of recovery actions generally requires the
participation of a broad range of partners, including other Federal
agencies, States, Tribes, nongovernmental organizations, businesses,
and private landowners. Examples of recovery actions include habitat
restoration (e.g., restoration of native vegetation), research, captive
propagation and reintroduction, and outreach and education. The
recovery of many listed species cannot be accomplished solely on
Federal lands because their ranges may occur primarily or solely on
non-Federal lands. To achieve recovery of these species requires
cooperative conservation efforts on private, State, and Tribal lands.
If these species are listed, funding for recovery actions will be
available from a variety of sources, including Federal budgets, State
programs, and cost-share grants for non-Federal landowners, the
academic community, and nongovernmental organizations. In addition,
pursuant to section 6 of the Act, the States of Arkansas, Oklahoma,
Louisiana, Mississippi, and Texas would be eligible for Federal funds
to implement management actions that promote the protection or recovery
of the Texas heelsplitter and Louisiana pigtoe. Information on our
grant programs that are available to aid species recovery can be found
at: https://www.fws.gov/service/financial-assistance.
Although the Texas heelsplitter and Louisiana pigtoe are only
proposed for listing under the Act at this time, please let us know if
you are interested in participating in recovery efforts for these
species. Additionally, we invite you to submit any new information on
these species whenever it becomes available and any information you may
have for recovery planning purposes (see FOR FURTHER INFORMATION
CONTACT).
Section 7(a) of the Act requires Federal agencies to evaluate their
actions with respect to any species that is proposed or listed as an
endangered or threatened species and with respect to its critical
habitat, if any is designated. Regulations implementing this
interagency cooperation provision of the Act are codified at 50 CFR
part 402. Section 7(a)(4) of the Act requires Federal agencies to
confer with the Service on any action that is likely to jeopardize the
continued existence of a species proposed for listing or result in
destruction or adverse modification of proposed critical habitat. If a
species is listed subsequently, section 7(a)(2) of the Act requires
Federal agencies to ensure that activities they authorize, fund, or
carry out are not likely to jeopardize the continued existence of the
species or destroy or adversely modify its critical habitat. If a
Federal action may affect a listed species or its critical habitat, the
responsible Federal agency must enter into consultation with the
Service.
Federal agency actions within the species' habitat that may require
conference or consultation or both as described in the preceding
paragraph include management and any other landscape-altering
activities on Federal lands administered by the Federal Emergency
Management Agency (related to disaster recovery projects), National
Park Service, Natural Resources Conservation Service, National Wildlife
Refuge System, U.S. Army, U.S. Army Corps of Engineers, and the U.S.
Forest Service.
[[Page 16797]]
The Act and its implementing regulations set forth a series of
general prohibitions and exceptions that apply to endangered wildlife.
The prohibitions of section 9(a)(1) of the Act, codified at 50 CFR
17.21, make it illegal for any person subject to the jurisdiction of
the United States to take (which includes harass, harm, pursue, hunt,
shoot, wound, kill, trap, capture, or collect; or to attempt any of
these) endangered wildlife within the United States or on the high
seas. In addition, it is unlawful to import; export; deliver, receive,
carry, transport, or ship in interstate or foreign commerce in the
course of commercial activity; or sell or offer for sale in interstate
or foreign commerce any species listed as an endangered species. It is
also illegal to possess, sell, deliver, carry, transport, or ship any
such wildlife that has been taken illegally. Certain exceptions apply
to employees of the Service, the National Marine Fisheries Service,
other Federal land management agencies, and State conservation
agencies.
We may issue permits to carry out otherwise prohibited activities
involving endangered wildlife under certain circumstances. Regulations
governing permits are codified at 50 CFR 17.22. With regard to
endangered wildlife, a permit may be issued for the following purposes:
For scientific purposes, to enhance the propagation or survival of the
species, and for incidental take in connection with otherwise lawful
activities. The statute also contains certain exemptions from the
prohibitions, which are found in sections 9 and 10 of the Act.
It is our policy, as published in the Federal Register on July 1,
1994 (59 FR 34272), to identify to the maximum extent practicable at
the time a species is listed, those activities that would or would not
constitute a violation of section 9 of the Act. The intent of this
policy is to increase public awareness of the effect of a proposed
listing on proposed and ongoing activities within the range of the
species proposed for listing. The Act allows the Secretary to
promulgate protective regulations for threatened species pursuant to
section 4(d) of the Act. The discussion in the following section,
Proposed Rule Issued Under Section 4(d) of the Act, regarding
protective regulations under section 4(d) of the Act for the Louisiana
pigtoe complies with our policy.
For the Texas heelsplitter, based on the best available
information, the following actions are unlikely to result in a
violation of section 9, if these activities are carried out in
accordance with existing regulations and permit requirements; this list
is not comprehensive:
(1) Normal agricultural and silvicultural practices, including
herbicide and pesticide use, that are carried out in accordance with
any existing regulations, permit and label requirements, and best
management practices; and
(2) Normal residential landscaping activities.
Based on the best available information, the following activities
may potentially result in a violation of section 9 of the Act, if they
are not authorized in accordance with applicable law; this list is not
comprehensive:
(1) Unauthorized handling or collecting of the species;
(2) Unauthorized destruction or alteration of Texas heelsplitter
habitat by dredging, channelization, impoundment, diversion,
recreational vehicle operation within the stream channel, sand or
gravel removal, or other activities that result in the destruction or
significant degradation of channel or bank stability, streamflow/water
quantity, substrate composition, and water quality used by the species
for foraging, cover, and reproduction;
(3) Modification of the channel or water flow of any stream,
including the withdrawal (decrease) or supplementation (increase) of
surface or ground waters where the Texas heelsplitter is known to
occur;
(4) Livestock grazing that results in direct or indirect
destruction of riparian or instream habitat; and
(5) Unauthorized discharge of chemicals (including pesticides and
fertilizers in violation of label restrictions), household waste, silt,
sediments, fill material, or other pollutants (e.g., sewage, oil and
gasoline, heavy metals), into any waters or their adjoining riparian
areas where the Texas heelsplitter is known to occur.
Questions regarding whether specific activities would constitute a
violation of section 9 of the Act should be directed to the Arlington
Ecological Services Field Office (see FOR FURTHER INFORMATION CONTACT).
II. Proposed Rule Issued Under Section 4(d) of the Act
Background
Section 4(d) of the Act contains two sentences. The first sentence
states that the Secretary shall issue such regulations as she deems
necessary and advisable to provide for the conservation of species
listed as threatened. The U.S. Supreme Court has noted that statutory
language similar to the language in section 4(d) of the Act authorizing
the Secretary to take action that she ``deems necessary and advisable''
affords a large degree of deference to the agency (see Webster v. Doe,
486 U.S. 592 (1988)). Conservation is defined in the Act to mean the
use of all methods and procedures which are necessary to bring any
endangered species or threatened species to the point at which the
measures provided pursuant to the Act are no longer necessary.
Additionally, the second sentence of section 4(d) of the Act states
that the Secretary may by regulation prohibit with respect to any
threatened species any act prohibited under section 9(a)(1), in the
case of fish or wildlife, or section 9(a)(2), in the case of plants.
Thus, the combination of the two sentences of section 4(d) provides the
Secretary with wide latitude of discretion to select and promulgate
appropriate regulations tailored to the specific conservation needs of
the threatened species. The second sentence grants particularly broad
discretion to the Service when adopting the prohibitions under section
9.
The courts have recognized the extent of the Secretary's discretion
under this standard to develop rules that are appropriate for the
conservation of a species. For example, courts have upheld, as a valid
exercise of agency authority, rules developed under section 4(d) that
included limited prohibitions against takings (see Alsea Valley
Alliance v. Lautenbacher, 2007 U.S. Dist. Lexis 60203 (D. Or. 2007);
Washington Environmental Council v. National Marine Fisheries Service,
2002 WL 511479 (W.D. Wash. 2002)). Courts have also upheld 4(d) rules
that do not address all of the threats a species faces (see State of
Louisiana v. Verity, 853 F.2d 322 (5th Cir. 1988)). As noted in the
legislative history when the Act was initially enacted, ``once an
animal is on the threatened list, the Secretary has an almost infinite
number of options available to [her] with regard to the permitted
activities for those species. [She] may, for example, permit taking,
but not importation of such species, or [she] may choose to forbid both
taking and importation but allow the transportation of such species''
(H.R. Rep. No. 412, 93rd Cong., 1st Sess. 1973).
The provisions of this proposed 4(d) rule would promote
conservation of the Louisiana pigtoe by encouraging riparian landscape
conservation while also meeting the conservation needs of the Louisiana
pigtoe. By streamlining those projects that follow best management
practices and improve instream habitat (such as streambank
[[Page 16798]]
stabilization, instream channel restoration, and upland restoration
that improves instream habitat), conservation is more likely to occur
for Louisiana pigtoe, improving the condition of populations in those
reaches. The provisions of this proposed rule are several of many tools
that we would use to promote the conservation of the Louisiana pigtoe.
This proposed 4(d) rule would apply only if and when we make final the
listing of the Louisiana pigtoe as a threatened species.
As mentioned previously in Available Conservation Measures, section
7(a)(2) of the Act requires Federal agencies, including the Service, to
ensure that any action they fund, authorize, or carry out is not likely
to jeopardize the continued existence of any endangered species or
threatened species or result in the destruction or adverse modification
of designated critical habitat of such species. In addition, section
7(a)(4) of the Act requires Federal agencies to confer with the Service
on any agency action that is likely to jeopardize the continued
existence of any species proposed to be listed under the Act or result
in the destruction or adverse modification of proposed critical
habitat.
If a Federal action may affect a listed species or its critical
habitat, the responsible Federal agency (action agency) must enter into
consultation with us. Examples of Federal actions that are subject to
the section 7 consultation process are actions on State, Tribal, local,
or private lands that require a Federal permit (such as a permit from
the U.S. Army Corps of Engineers under section 404 of the Clean Water
Act (33 U.S.C. 1251 et seq.) or a permit from the Service under section
10 of the Act) or that involve some other Federal action (such as
funding from the Federal Highway Administration, Federal Aviation
Administration, or the Federal Emergency Management Agency). Federal
actions not affecting listed species or critical habitat--and actions
on State, Tribal, local, or private lands that are not federally
funded, authorized, or carried out by a Federal agency--do not require
section 7 consultation.
These requirements are the same for a threatened species with a
species-specific 4(d) rule. For example, a Federal agency's
determination that an action is ``not likely to adversely affect'' a
threatened species will require the Service's written concurrence.
Similarly, a Federal agency's determination that an action is ``likely
to adversely affect'' a threatened species will require formal
consultation and the formulation of a biological opinion.
Provisions of the Proposed 4(d) Rule
Exercising the Secretary's authority under section 4(d) of the Act,
we have developed a proposed rule that is designed to address the
Louisiana pigtoe's specific conservation needs. As discussed previously
in Summary of Biological Status and Threats, we have concluded that the
Louisiana pigtoe is likely to become in danger of extinction within the
foreseeable future primarily due to habitat changes such as the
accumulation of fine sediments, altered hydrology, and impairment of
water quality; predation and collection; and barriers to fish movement.
Section 4(d) requires the Secretary to issue such regulations as she
deems necessary and advisable to provide for the conservation of each
threatened species and authorizes the Secretary to include among those
protective regulations any of the prohibitions that section 9(a)(2) of
the Act prescribes for endangered species. We find that, if finalized,
the protections, prohibitions, and exceptions in this proposed rule as
a whole satisfy the requirement in section 4(d) of the Act to issue
regulations deemed necessary and advisable to provide for the
conservation of the Louisiana pigtoe.
The protective regulations we are proposing for the Louisiana
pigtoe incorporate prohibitions from section 9(a)(1) to address the
threats to the species. Section 9(a)(1) prohibits the following
activities for endangered wildlife: importing or exporting; take;
possession and other acts with unlawfully taken specimens; delivering,
receiving, transporting, or shipping in interstate or foreign commerce
in the course of commercial activity; or selling or offering for sale
in interstate or foreign commerce. This protective regulation includes
most of these prohibitions for the Louisiana pigtoe because the
Louisiana pigtoe is at risk of extinction in the foreseeable future and
putting these prohibitions in place will help to preserve the species'
remaining populations, slow its rate of decline, and decrease
synergistic, negative effects from other stressors.
In particular, this proposed 4(d) rule would provide for the
conservation of the Louisiana pigtoe by prohibiting the following
activities, unless they fall within specific exceptions or are
otherwise authorized or permitted: Importing or exporting; take;
possession and other acts with unlawfully taken specimens; delivering,
receiving, transporting, or shipping in interstate or foreign commerce
in the course of commercial activity; or selling or offering for sale
in interstate or foreign commerce.
Under the Act, ``take'' means to harass, harm, pursue, hunt, shoot,
wound, kill, trap, capture, or collect, or to attempt to engage in any
such conduct. Some of these provisions have been further defined in
regulations at 50 CFR 17.3. Take can result knowingly or otherwise, by
direct and indirect impacts, intentionally or incidentally. Regulating
incidental and intentional take would help preserve the species'
remaining populations, slow their rate of decline, and decrease
synergistic, negative effects from other stressors. Therefore, we
propose to prohibit take of the Louisiana pigtoe, except for take
resulting from those actions and activities specifically excepted by
the 4(d) rule.
Exceptions to the prohibition on take would include most of the
general exceptions to the prohibition against take of endangered
wildlife, as set forth in 50 CFR 17.21 and certain other specific
activities that we propose for exception, as described below.
The proposed 4(d) rule would also provide for the conservation of
the species by allowing exceptions that incentivize conservation
actions or that, while they may have some minimal level of take of the
Louisiana pigtoe, are not expected to rise to the level that would have
a negative impact (i.e., would have only de minimis impacts) on the
species' conservation. The proposed exceptions to these prohibitions
include the following activities that are expected to have negligible
impacts to the Louisiana pigtoe and its habitat:
(1) Channel restoration projects that create natural, physically
stable (streambanks and substrate remaining relatively unchanging over
time), ecologically functioning streams or stream and wetland systems
(containing an assemblage of fish, mussels, other invertebrates, and
plants) that are reconnected with their groundwater aquifers. These
projects can be accomplished using a variety of methods, but the
desired outcome is a natural channel with low shear stress (force of
water moving against the channel); bank heights that enable
reconnection to the floodplain; a reconnection of surface and
groundwater systems, resulting in perennial flows in the channel;
riffles and pools composed of existing soil, rock, and wood instead of
large imported materials; low compaction of soils within adjacent
riparian areas; and inclusion of riparian wetlands and woodland
buffers. This exception to the
[[Page 16799]]
proposed 4(d) rule for incidental take would promote conservation of
Louisiana pigtoe by creating stable stream channels that are less
likely to scour during high-flow events, thereby increasing population
resiliency.
(2) Bioengineering methods such as streambank stabilization using
live native stakes (live, vegetative cuttings inserted or tamped into
the ground in a manner that allows the stake to take root and grow),
live native fascines (live branch cuttings, usually willows, bound
together into long, cigar-shaped bundles), or native brush layering
(cuttings or branches of easily rooted tree species layered between
successive lifts of soil fill). These methods must not include the sole
use of quarried rock (rip-rap) or the use of rock baskets or gabion
structures. In addition, to reduce streambank erosion and sedimentation
into the stream, work using these bioengineering methods must be
performed at base flow or low water conditions and when significant
rainfall is not predicted. Further, streambank stabilization projects
must keep all equipment out of the stream channels and water. Similar
to channel restoration projects, this exception to the proposed 4(d)
rule for incidental take would promote conservation of Louisiana pigtoe
by creating stable stream channels that are less likely to scour during
high-flow events, thereby increasing population resiliency.
(3) Soil and water conservation practices and riparian and adjacent
upland habitat management activities that restore instream habitats for
the species, restore adjacent riparian habitats that enhance stream
habitats for the species, stabilize degraded and eroding stream banks
to limit sedimentation and scour of the species' habitats, and restore
or enhance nearby upland habitats to limit sedimentation of the
species' habitats. We recommend that these practices and activities
comply with specifications and technical guidelines developed by the
U.S. Department of Agriculture's Natural Resources Conservation Service
(NRCS), as soil and water conservation practices and aquatic species
habitat restoration projects associated with NRCS conservation plans
are designed to improve water quality and enhance fish and aquatic
species habitats. This exception to the proposed 4(d) rule for
incidental take would promote conservation of Louisiana pigtoe by
creating stable stream channels and reducing sediment inputs to the
stream, thereby increasing population resiliency.
We include other standard exceptions to the prohibitions in the
proposed 4(d) rule for the Louisiana pigtoe.
Despite these prohibitions regarding threatened species, we may
under certain circumstances issue permits to carry out one or more
otherwise-prohibited activities, including those described above. The
regulations that govern permits for threatened wildlife state that the
Director may issue a permit authorizing any activity otherwise
prohibited with regard to threatened species. These include permits
issued for the following purposes: for scientific purposes, to enhance
propagation or survival, for economic hardship, for zoological
exhibition, for educational purposes, for incidental taking, or for
special purposes consistent with the purposes of the Act (50 CFR
17.32). The statute also contains certain exemptions from the
prohibitions, which are found in sections 9 and 10 of the Act.
We recognize the special and unique relationship with our State
natural resource agency partners in contributing to conservation of
listed species. State agencies often possess scientific data and
valuable expertise on the status and distribution of endangered,
threatened, and candidate species of wildlife and plants. State
agencies, because of their authorities and their close working
relationships with local governments and landowners, are in a unique
position to assist us in implementing all aspects of the Act. In this
regard, section 6 of the Act provides that we must cooperate to the
maximum extent practicable with the States in carrying out programs
authorized by the Act. Therefore, any qualified employee or agent of a
State conservation agency that is a party to a cooperative agreement
with us in accordance with section 6(c) of the Act, who is designated
by his or her agency for such purposes, would be able to conduct
activities designed to conserve Louisiana pigtoe that may result in
otherwise prohibited take without additional authorization.
Nothing in this proposed 4(d) rule would change in any way the
recovery planning provisions of section 4(f) of the Act, the
consultation requirements under section 7 of the Act, or our ability to
enter into partnerships for the management and protection of the
Louisiana pigtoe. However, interagency cooperation may be further
streamlined through planned programmatic consultations for the species
between us and other Federal agencies, where appropriate. We ask the
public, particularly State agencies and other interested stakeholders
that may be affected by the proposed 4(d) rule, to provide comments and
suggestions regarding additional guidance and methods that we could
provide or use, respectively, to streamline the implementation of this
proposed 4(d) rule (see Information Requested, above).
III. Critical Habitat
Background
Critical habitat is defined in section 3 of the Act as:
(1) The specific areas within the geographical area occupied by the
species, at the time it is listed in accordance with the Act, on which
are found those physical or biological features
(a) Essential to the conservation of the species, and
(b) Which may require special management considerations or
protection; and
(2) Specific areas outside the geographical area occupied by the
species at the time it is listed, upon a determination that such areas
are essential for the conservation of the species.
Our regulations at 50 CFR 424.02 define the geographical area
occupied by the species as an area that may generally be delineated
around species' occurrences, as determined by the Secretary (i.e.,
range). Such areas may include those areas used throughout all or part
of the species' life cycle, even if not used on a regular basis (e.g.,
migratory corridors, seasonal habitats, and habitats used periodically,
but not solely by vagrant individuals).
Conservation, as defined under section 3 of the Act, means to use
and the use of all methods and procedures that are necessary to bring
an endangered or threatened species to the point at which the measures
provided pursuant to the Act are no longer necessary. Such methods and
procedures include, but are not limited to, all activities associated
with scientific resources management such as research, census, law
enforcement, habitat acquisition and maintenance, propagation, live
trapping, and transplantation, and, in the extraordinary case where
population pressures within a given ecosystem cannot be otherwise
relieved, may include regulated taking.
Critical habitat receives protection under section 7 of the Act
through the requirement that Federal agencies ensure, in consultation
with the Service, that any action they authorize, fund, or carry out is
not likely to result in the destruction or adverse modification of
critical habitat. The designation of critical habitat does not affect
land
[[Page 16800]]
ownership or establish a refuge, wilderness, reserve, preserve, or
other conservation area. Such designation also does not allow the
government or public to access private lands. Such designation does not
require implementation of restoration, recovery, or enhancement
measures by non-Federal landowners. Where a landowner requests Federal
agency funding or authorization for an action that may affect a listed
species or critical habitat, the Federal agency would be required to
consult with the Service under section 7(a)(2) of the Act. However,
even if the Service were to conclude that the proposed activity would
likely result in destruction or adverse modification of the critical
habitat, the Federal action agency and the landowner are not required
to abandon the proposed activity, or to restore or recover the species;
instead, they must implement ``reasonable and prudent alternatives'' to
avoid destruction or adverse modification of critical habitat.
Under the first prong of the Act's definition of critical habitat,
areas within the geographical area occupied by the species at the time
it was listed are included in a critical habitat designation if they
contain physical or biological features (1) which are essential to the
conservation of the species and (2) which may require special
management considerations or protection. For these areas, critical
habitat designations identify, to the extent known using the best
scientific and commercial data available, those physical or biological
features that are essential to the conservation of the species (such as
space, food, cover, and protected habitat).
Under the second prong of the Act's definition of critical habitat,
we can designate critical habitat in areas outside the geographical
area occupied by the species at the time it is listed, upon a
determination that such areas are essential for the conservation of the
species.
Section 4 of the Act requires that we designate critical habitat on
the basis of the best scientific data available. Further, our Policy on
Information Standards Under the Endangered Species Act (published in
the Federal Register on July 1, 1994 (59 FR 34271)), the Information
Quality Act (section 515 of the Treasury and General Government
Appropriations Act for Fiscal Year 2001 (Pub. L. 106-554; H.R. 5658)),
and our associated Information Quality Guidelines provide criteria,
establish procedures, and provide guidance to ensure that our decisions
are based on the best scientific data available. They require our
biologists, to the extent consistent with the Act and with the use of
the best scientific data available, to use primary and original sources
of information as the basis for recommendations to designate critical
habitat.
When we are determining which areas should be designated as
critical habitat, our primary source of information is generally the
information from the SSA report and information developed during the
listing process for the species. Additional information sources may
include any generalized conservation strategy, criteria, or outline
that may have been developed for the species; the recovery plan for the
species; articles in peer-reviewed journals; conservation plans
developed by States and counties; scientific status surveys and
studies; biological assessments; other unpublished materials; or
experts' opinions or personal knowledge.
Habitat is dynamic, and species may move from one area to another
over time. We recognize that critical habitat designated at a
particular point in time may not include all of the habitat areas that
we may later determine are necessary for the recovery of the species.
For these reasons, a critical habitat designation does not signal that
habitat outside the designated area is unimportant or may not be needed
for recovery of the species. Areas that are important to the
conservation of the species, both inside and outside the critical
habitat designation, will continue to be subject to: (1) Conservation
actions implemented under section 7(a)(1) of the Act; (2) regulatory
protections afforded by the requirement in section 7(a)(2) of the Act
for Federal agencies to ensure their actions are not likely to
jeopardize the continued existence of any endangered or threatened
species; and (3) the prohibitions found in section 9 of the Act.
Federally funded or permitted projects affecting listed species outside
their designated critical habitat areas may still result in jeopardy
findings in some cases. These protections and conservation tools will
continue to contribute to recovery of this species. Similarly, critical
habitat designations made on the basis of the best available
information at the time of designation will not control the direction
and substance of future recovery plans, habitat conservation plans
(HCPs), or other species conservation planning efforts if new
information available at the time of these planning efforts calls for a
different outcome.
Prudency Determination
Section 4(a)(3) of the Act, as amended, and implementing
regulations (50 CFR 424.12) require that, to the maximum extent prudent
and determinable, the Secretary shall designate critical habitat at the
time the species is determined to be an endangered or threatened
species. Our regulations (50 CFR 424.12(a)(1)) state that the Secretary
may, but is not required to, determine that a designation would not be
prudent in the following circumstances:
(i) The species is threatened by taking or other human activity and
identification of critical habitat can be expected to increase the
degree of such threat to the species;
(ii) The present or threatened destruction, modification, or
curtailment of a species' habitat or range is not a threat to the
species, or threats to the species' habitat stem solely from causes
that cannot be addressed through management actions resulting from
consultations under section 7(a)(2) of the Act;
(iii) Areas within the jurisdiction of the United States provide no
more than negligible conservation value, if any, for a species
occurring primarily outside the jurisdiction of the United States;
(iv) No areas meet the definition of critical habitat; or
(v) The Secretary otherwise determines that designation of critical
habitat would not be prudent based on the best scientific data
available.
As discussed earlier in this document, there are well documented
beds of Louisiana pigtoe that are sampled for scientific projects, and
to a lesser degree collected by fishing enthusiasts for use as bait.
Because these areas are already well known, and they are not being
collected for private collections, there is currently no additional
imminent threat of collection or vandalism identified under Factor B
for these species, and identification and mapping of critical habitat
is not expected to initiate any such threat. In our SSA and proposed
listing determination for the Texas heelsplitter and Louisiana pigtoe,
we determined that the present or threatened destruction, modification,
or curtailment of habitat or range is a threat to these species and
that those threats in some way can be addressed by section 7(a)(2)
consultation measures. These species occur wholly in the jurisdiction
of the United States, and we are able to identify areas that meet the
definition of critical habitat. Therefore, because none of the
circumstances enumerated in our regulations at 50 CFR 424.12(a)(1) have
been met and because
[[Page 16801]]
the Secretary has not identified other circumstances for which this
designation of critical habitat would be not prudent, we have
determined that the designation of critical habitat is prudent for the
Texas heelsplitter and Louisiana pigtoe.
Critical Habitat Determinability
Having determined that designation is prudent, under section
4(a)(3) of the Act we must find whether critical habitat for the Texas
heelsplitter and Louisiana pigtoe is determinable. Our regulations at
50 CFR 424.12(a)(2) state that critical habitat is not determinable
when one or both of the following situations exist:
(i) Data sufficient to perform required analyses are lacking, or
(ii) The biological needs of the species are not sufficiently well
known to identify any area that meets the definition of ``critical
habitat.'' When critical habitat is not determinable, the Act allows
the Service an additional year to publish a critical habitat
designation (16 U.S.C. 1533(b)(6)(C)(ii)).
We reviewed the available information pertaining to the biological
needs of the species and habitat characteristics where these species
are located. This and other information represent the best scientific
data available and led us to conclude that the designation of critical
habitat is determinable for the Texas heelsplitter and Louisiana
pigtoe.
Physical or Biological Features Essential to the Conservation of the
Species
In accordance with section 3(5)(A)(i) of the Act and regulations at
50 CFR 424.12(b), in determining which areas we will designate as
critical habitat from within the geographical area occupied by the
species at the time of listing, we consider the physical or biological
features that are essential to the conservation of the species and that
may require special management considerations or protection. The
regulations at 50 CFR 424.02 define ``physical or biological features
essential to the conservation of the species'' as the features that
occur in specific areas and that are essential to support the life-
history needs of the species, including, but not limited to, water
characteristics, soil type, geological features, sites, prey,
vegetation, symbiotic species, or other features. A feature may be a
single habitat characteristic or a more complex combination of habitat
characteristics. Features may include habitat characteristics that
support ephemeral or dynamic habitat conditions. Features may also be
expressed in terms relating to principles of conservation biology, such
as patch size, distribution distances, and connectivity.
For example, physical features essential to the conservation of the
species might include gravel of a particular size required for
spawning, alkaline soil for seed germination, protective cover for
migration, or susceptibility to flooding or fire that maintains
necessary early-successional habitat characteristics. Biological
features might include prey species, forage grasses, specific kinds or
ages of trees for roosting or nesting, symbiotic fungi, or a particular
level of nonnative species consistent with conservation needs of the
listed species. The features may also be combinations of habitat
characteristics and may encompass the relationship between
characteristics or the necessary amount of a characteristic essential
to support the life history of the species.
In considering whether features are essential to the conservation
of the species, we may consider an appropriate quality, quantity, and
spatial and temporal arrangement of habitat characteristics in the
context of the life-history needs, condition, and status of the
species. These characteristics include, but are not limited to, space
for individual and population growth and for normal behavior; food,
water, air, light, minerals, or other nutritional or physiological
requirements; cover or shelter; sites for breeding, reproduction, or
rearing (or development) of offspring; and habitats that are protected
from disturbance.
We derive the specific physical or biological features (PBFs)
essential for the conservation of the Texas heelsplitter and Louisiana
pigtoe from studies of these species' habitat, ecology, and life
history. The life histories of these two freshwater mussel species are
very similar--mussels need suitable water quality, flowing water,
suitable substrate, flow refuges, and appropriate host fish--and so we
will discuss their common habitat needs and then describe their
species-specific needs.
Physiological Requirements: Water Quality Requirements
Freshwater mussels, as a group, are sensitive to changes in water
quality, including parameters such as dissolved oxygen, salinity,
ammonia, and environmental pollutants (e.g., pesticides and trace
metals). Habitats with appropriate levels of these parameters that are
pollutant-free or have low levels of pollutants are considered
suitable, while those habitats with levels outside of the appropriate
ranges or that contain elevated pollutants are considered less
suitable. We have used information for the Texas heelsplitter and
Louisiana pigtoe, where available, and data from other species when
species-specific information is not available. Juvenile freshwater
mussels are particularly susceptible to low dissolved oxygen levels.
Juveniles will reduce feeding behavior when dissolved oxygen is between
2-4 milligrams per liter (mg/L), and mortality has been shown to occur
at dissolved oxygen levels below 1.3 mg/L. Increased salinity levels
may also be stressful to freshwater mussels, with some species showing
signs of stress at salinity levels of 2 ppt or higher (Bonner et al.
2018; pp. 155-156).
The release of pollutants into streams from point and nonpoint
sources have immediate impacts on water quality conditions and may make
environments unsuitable for habitation by mussels. Early life stages of
freshwater mussels are some of the most sensitive organisms of all
species to ammonia and copper (Augspurger et al. 2007, p. 2025).
Additionally, sublethal effects of contaminants over time can result in
reduced feeding efficiency, reduced growth, decreased reproduction,
changes in enzyme activity, and behavioral changes to all mussel life
stages. Even wastewater discharges with low ammonia levels have been
shown to negatively affect mussel populations.
Finally, water temperature plays a critical role in the life
history of freshwater mussels. High water temperatures can cause valve
closure, reduced reproductive output, and death. Laboratory studies
investigating the effects of thermal stress on glochidia and adults
have indicated thermal stress may occur at 27 [deg]C (80.6 [deg]F)
(Bonner et al. 2018; Khan et al. 2019, entire)).
Based on the above information, we determine that stream reaches
with the following water quality parameters are suitable for the Texas
heelsplitter and Louisiana pigtoe:
Water temperature below 27 [deg]C (80.6 [deg]F);
Dissolved oxygen levels greater than 3 mg/L;
Low salinity (less than 2 ppt) and total dissolved solids;
Low total ammonia and nitrogen (below 0.3-0.7 mg/L total
ammonia nitrogen);
Low levels of copper, nickel, and other trace metals;
Low levels of pesticides, sulfate, chloride, potassium,
and other harmful constituents; and
Low pollutants and environmental contaminants common to
wastewater.
[[Page 16802]]
Space for Individual and Population Growth and for Normal Behavior
Most freshwater mussels, including the Texas heelsplitter and
Louisiana pigtoe, are found in aggregations, called mussel beds, that
vary in size from about 50 to greater than 5,000 square meters (m\2\),
separated by stream reaches in which mussels are absent or rare (Vaughn
2012, p. 983). Freshwater mussel larvae (called glochidia) are
parasites that must attach to a host fish. A population incorporates
more than one mussel bed; it is the collection of mussel beds within a
stream reach between which infested host fish may travel, allowing for
ebbs and flows in mussel bed density and abundance over time throughout
the population's occupied reach. Accordingly, sufficiently resilient
mussel populations must occupy stream reaches long enough so that
stochastic events that affect individual mussel beds do not eliminate
the entire population. Repopulation by infested host fish from other
mussel beds within the reach can allow the population to recover from
these events. Longer stream reaches are more likely to support
populations of the Texas heelsplitter and Louisiana pigtoe into the
future than shorter stream reaches. Therefore, we determine that long
stream reaches, over 50 river miles (80.5 km), are an important
component of a riverine system with habitat to support all life stages
of the Texas heelsplitter and Louisiana pigtoe. Populations occupying
reaches shorter than 50 miles can still provide population redundancy
and, if habitat factors are of sufficiently high quality, can be an
important component of the recovery of Texas heelsplitter and Louisiana
pigtoe.
The Texas heelsplitter needs low to moderately flowing streams, and
tolerates impoundments (lakes, reservoirs, or pools without flow). All
life stages of the Texas heelsplitter require substrates consisting of
firm mud, sand, finer gravels, and mixtures of those with high organic
matter content. The Louisiana pigtoe needs flowing water for survival
and occurs in medium- to large-sized streams and rivers associated with
riffle, run, and sometimes larger backwater tributary habitats. All
life stages of the Louisiana pigtoe require substrates consisting of
cobble/rock, sand/gravel/woody debris, and runs with subdominant gravel
mixtures. River reaches with continuous flow support all life stages of
these two species of freshwater mussels, while those with little or no
flow do not. Flow rates needed by each species will vary depending on
the species and the river size, location, and substrate type. Habitat
locations must be relatively free of fine sediments for both species
such that the mussels are not smothered.
Sites for Development of Offspring
As discussed above, freshwater mussel larvae are parasites that
must attach to a host fish to develop into juvenile mussels. The Texas
heelsplitter and Louisiana pigtoe use a variety of host fish, many of
which are widely distributed throughout their ranges. The presence of
these fish species, either singly or in combination, supports the life-
history needs of these two species of freshwater mussels:
Texas heelsplitter: freshwater drum (Aplodinotus
grunniens).
Louisiana pigtoe: red shiner (Cyprinella (=Notropis)
lutrensis), blacktail shiner (Cyprinella venusta), and bullhead minnow
(Pimephales vigilax).
Summary of Essential Physical or Biological Features
In summary, we derive the specific PBFs essential to the
conservation of Texas heelsplitter and Louisiana pigtoe from studies of
these species' habitat, ecology, and life history as described above.
Additional information can be found in the SSA report available on
https://www.regulations.gov under Docket No. FWS-R2-ES-2022-0026.
Texas Heelsplitter
We have determined that the following PBFs are essential to the
conservation of the Texas heelsplitter:
1. Water quality parameters within the following ranges:
a. Water temperature below 27 [deg]C (80.6 [deg]F);
b. Dissolved oxygen levels greater than 3 mg/L;
c. Low salinity (less than 2 ppt) and total dissolved solids;
d. Low total ammonia and nitrogen (below 0.3-0.7 mg/L total ammonia
nitrogen);
e. Low levels of copper, nickel, and other trace metals;
f. Low levels of pesticides, sulfate, chloride, potassium, and
other harmful constituents; and
g. Low pollutants and environmental contaminants common to
wastewater.
2. Moderately flowing water rates suitable to prevent excess
sedimentation but not so high as to dislodge individuals or sediment;
or no water flow, if in an impoundment (lake, reservoir, or pool
without flow).
3. Substrate including bedrock and boulder crevices, point bars,
and vegetated run habitat comprising sand, gravel, and larger cobbles.
4. Freshwater drum (Aplodinotus grunniens) present.
Louisiana Pigtoe
We have determined that the following PBFs are essential to the
conservation of the Louisiana pigtoe:
1. Water quality parameters within the following ranges:
a. Water temperature below 27 [deg]C (80.6 [deg]F);
b. Dissolved oxygen levels greater than 3 mg/L;
c. Low salinity (less than 2 ppt) and total dissolved solids;
d. Low total ammonia and nitrogen (below 0.3-0.7 mg/L total ammonia
nitrogen);
e. Low levels of copper, nickel, and other trace metals;
f. Low levels of pesticides, sulfate, chloride, potassium, and
other harmful constituents; and
g. Low pollutants and environmental contaminants common to
wastewater.
2. Moderately flowing water rates suitable to prevent excess
sedimentation but not so high as to dislodge individuals or sediment.
3. Stable bank and riffle habitats with bedrock and boulder
crevices, point bars, and vegetated run habitat comprising sand,
gravel, and larger cobbles.
4. Red shiner (Cyprinella (=Notropis) lutrensis), blacktail shiner
(Cyprinella venusta), and bullhead minnow (Pimephales vigilax) present.
Special Management Considerations or Protection
When designating critical habitat, we assess whether the specific
areas within the geographical area occupied by the species at the time
of listing contain features which are essential to the conservation of
the species and which may require special management considerations or
protection. The features essential to the conservation of the Texas
heelsplitter and Louisiana pigtoe may require special management
considerations or protections to reduce the following threats:
increased fine sediment, changes in water quality impairment, altered
hydrology from both inundation and flow loss/scour, predation and
collection, and barriers to fish movement.
Management activities that could ameliorate these threats include,
but are not limited to: Use of best management practices (BMPs)
designed to reduce sedimentation, erosion, and bank side destruction;
protection of riparian corridors and retention of sufficient canopy
cover along banks; exclusion of livestock and nuisance wildlife (feral
hogs, exotic ungulates); moderation of
[[Page 16803]]
surface and ground water withdrawals to maintain natural flow regimes;
increased use of stormwater management and reduction of stormwater
flows into the systems; use of highest water quality standards for
wastewater and other return flows; and reduction of other watershed and
floodplain disturbances that release sediments, pollutants, or
nutrients into the water.
In summary, we find that the occupied areas we are proposing to
designate as critical habitat contain the PBFs that are essential to
the conservation of the species and that may require special management
considerations or protection. Special management considerations or
protection may be required of the Federal action agency to eliminate,
or to reduce to negligible levels, the threats affecting the PBFs of
each unit.
Criteria Used To Identify Critical Habitat
As required by section 4(b)(2) of the Act, we use the best
scientific data available to designate critical habitat. In accordance
with the Act and our implementing regulations at 50 CFR 424.12(b), we
review available information pertaining to the habitat requirements of
the species and identify specific areas within the geographical area
occupied by the species at the time of listing and any specific areas
outside the geographical area occupied by the species to be considered
for designation as critical habitat. We are not currently proposing to
designate any areas outside the geographical area occupied by the Texas
heelsplitter and Louisiana pigtoe because we have determined that the
occupied areas are sufficient to conserve the species.
We anticipate that recovery will require conserving the genetic
diversity of extant populations across the species' current ranges and
maintaining and, where necessary, improving habitat and habitat
connectivity to ensure the long-term viability of the Texas
heelsplitter and Louisiana pigtoe. This proposed critical habitat
designation delineates the habitat that is physically occupied and used
by the species rather than delineating all land or aquatic areas that
influence the species. We recognize that there may be additional
occupied areas outside of the proposed areas designated as critical
habitat that we are not aware of at the time of this designation that
may be necessary for the conservation of the species. We have
determined that the areas currently occupied by the Texas heelsplitter
and Louisiana pigtoe would maintain each species' resiliency,
redundancy, and representation and are sufficient to conserve these two
species. Therefore, we are not currently proposing to designate any
areas outside the geographical area occupied by the species.
Sources of data for this proposed critical habitat include multiple
databases maintained by universities and State agencies, scientific and
agency reports, and numerous survey reports on streams throughout the
species' range (Service 2022, pp. 16-24).
Areas Occupied at the Time of Listing
The proposed critical habitat designations do not include all
rivers and streams known to have been occupied by the species
historically; instead, they focus on rivers and streams occupied at the
time of listing that have retained the necessary PBFs that will allow
for the maintenance and expansion of existing populations. A stream
reach may not have all of the PBFs to be included as proposed critical
habitat; in such reaches, our goal is to recover the species by
restoring the missing PBFs. We defined ``occupied'' units as stream
channels with observations of one or more live individuals. Specific
habitat areas were delineated based on reports of live individuals and
recently dead shells. We include ``recent dead shell material'' to
delineate the boundaries of a unit because recently dead shell material
at a site indicates the species is present in that area. Recently dead
shells have tissue remaining on the shells or have retained a shiny
nacre, indicating the animal died within days or weeks of finding the
shell. It is highly unlikely that a dead individual represents the last
remaining individual of the population, and recently dead shells are an
accepted indicator of a species' presence (e.g., Howells 1996, pp. ii,
4; Randklev et al. 2011, p. 17).
We are relying on evidence of occupancy from data collected in 2000
to the present. This is because freshwater mussels may be difficult to
detect, and some sites are not visited multiple times. Additionally,
these species live at least 15 to 20 years. Because adults are less
sensitive to habitat changes than juveniles, changes in population
sizes usually occur over decades rather than years. As a result, areas
where individuals were collected within the last 20 years are expected
to remain occupied now. Additionally, any areas that were surveyed
around 20 years ago and do not have subsequent surveys were reviewed
for any large-scale habitat changes (i.e., major flood or scour event,
drought) to confirm that general habitat characteristics remained
constant over this time. None of the relatively few areas without more
recent survey information had experienced changes to general habitat
characteristics. Therefore, data from around 2000 would be considered a
strong indicator a species remains extant at a site if general habitat
characteristics have remained constant over that time.
For areas proposed as critical habitat, we delineated critical
habitat unit boundaries using the following criterion: Evaluate habitat
suitability of stream segments within the geographic area occupied at
the time of listing, and retain those segments that contain some or all
of the PBFs to support life-history functions essential for
conservation of the species. Humanmade reservoirs are not considered
natural habitat for either species and may not contain all of the PBFs;
therefore, they were not delineated as critical habitat for Texas
heelsplitter, which occurs in some reservoirs. The recovery vision for
Texas heelsplitter will not be focused on enhancing the species in
these areas.
As a final step, we evaluated those occupied stream segments
retained through the above analysis and refined the starting and ending
points by evaluating the presence or absence of appropriate PBFs. We
selected upstream and downstream cutoff points to reference existing
easily recognizable geopolitical features including confluences,
highway crossings, and county lines. Using these features as end points
allows the public to clearly understand the boundaries of critical
habitat. Unless otherwise specified, any stream beds located directly
beneath bridge crossings or other landmark features used to describe
critical habitat spatially, such as stream confluences, are considered
to be wholly included within the critical habitat unit. Critical
habitat stream segments were then mapped using ArcMap version 10.6.1
(ESRI, Inc.), a Geographic Information Systems program.
We consider the following streams and rivers to be occupied by the
Texas heelsplitter at the time of proposed listing: Neches River,
Sabine River, and Trinity River.
We consider the following streams and rivers to be occupied by the
Louisiana pigtoe at the time of proposed listing: Angelina River, Big
Cypress Bayou, Calcasieu River, Cossatot River, Little River, Neches
River, Pearl River, Rolling Fork, Sabine River, Saline River, San
Jacinto River, and Sulphur River.
General Information on the Maps of the Proposed Critical Habitat
Designations
When determining proposed critical habitat boundaries, we made
every
[[Page 16804]]
effort to avoid including developed areas such as lands covered by
buildings, pavement, and other structures because such lands lack
physical or biological features necessary for the Texas heelsplitter
and Louisiana pigtoe. Critical habitat for these mussels includes only
stream channels up to bankfull height, where the stream base flow is
contained within the channel. The scale of the maps we prepared under
the parameters for publication within the Code of Federal Regulations
may not reflect the exclusion of such developed lands. Any such lands
inadvertently left inside critical habitat boundaries shown on the maps
of this proposed rule have been excluded by text in the proposed rule
and are not proposed for designation as critical habitat. Therefore, if
the critical habitat is finalized as proposed, a Federal action
involving these lands would not trigger section 7 consultation with
respect to critical habitat and the requirement of no adverse
modification unless the specific action would affect the physical or
biological features in the adjacent critical habitat.
We are proposing to designate as critical habitat three units for
the Texas heelsplitter and six units for the Louisiana pigtoe based on
one or more of the PBFs being present to support the Texas
heelsplitter's or Louisiana pigtoe's life-history processes. Some units
contain all of the identified physical or biological features and
support multiple life-history processes. Some units contain only some
of the PBFs necessary to support the Texas heelsplitter's or Louisiana
pigtoe's particular use of that habitat.
The proposed critical habitat designation is defined by the map or
maps, as modified by any accompanying regulatory text, presented at the
end of this document under Proposed Regulation Promulgation. We include
more detailed information on the boundaries of the critical habitat
designation in the preamble of this document. We will make the
coordinates or plot points or both on which each map is based available
to the public on https://www.regulations.gov at Docket No. FWS-R2-ES-
2022-0026, on our internet site https://www.fws.gov/office/arlington-ecological-services.
Proposed Critical Habitat Designation
We are proposing to designate approximately 832 river mi (1,339 km)
in three units as critical habitat for Texas heelsplitter and
approximately 1,028 river mi (1,654 km) in six units for the Louisiana
pigtoe. The critical habitat areas we describe below constitute our
current best assessment of areas that meet the definition of critical
habitat for Texas heelsplitter and Louisiana pigtoe. All units are
occupied by their respective species. The three areas we propose as
critical habitat for Texas heelsplitter are all in Texas and are: (1)
Trinity River, (2) Sabine River, and (3) Neches River. The six areas we
propose as critical habitat for Louisiana pigtoe are: (1) Little River
(Arkansas/Oklahoma), (2) Sabine River (Louisiana/Texas), (3) Neches
River (Texas), (4) San Jacinto River (Texas), (5) Calcasieu River
(Louisiana), and (6) Pearl River (Louisiana/Mississippi). One proposed
Louisiana pigtoe critical habitat subunit, LAPT-1a (Upper Little River,
Oklahoma; 25.7 river miles (41.4 km)), is located within the Choctaw
Reservation, but not on any lands held in trust for the Tribe, or owned
or managed by the Tribe. Tables 5 and 6 show the proposed critical
habitat units, the adjacent riparian area ownership, and the
approximate area of each unit.
Table 5--Proposed Critical Habitat Units for the Texas Heelsplitter
----------------------------------------------------------------------------------------------------------------
River miles
Unit Subunit Riparian ownership Occupied? (kilometers)
----------------------------------------------------------------------------------------------------------------
TXHS-1: Trinity River.......... TXHS-1a: Trinity Private, State.... Yes.................. 212.8 (342.4)
River.
TXHS-1b: Bedias Private........... Yes.................. 28.9 (46.5)
Creek.
----------------------------------------
Unit Total................. .................. .................. ..................... 241.7 (388.9)
----------------------------------------------------------------------------------------------------------------
TXHS-2: Sabine River........... TXHS-2a: Upper Private, State, Yes.................. 237.4 (382.0)
Sabine River. Local, Federal.
TXHS-2b: Lake Fork Private........... Yes.................. 13.8 (22.2)
Creek.
TXHS-2c: Patroon Private, Federal.. Yes.................. 19.9 (32.0)
Bayou.
----------------------------------------
Unit Total................. .................. .................. ..................... 271.1 (436.2)
----------------------------------------------------------------------------------------------------------------
TXHS-3: Neches River........... TXHS-3a: Upper Private, Federal.. Yes.................. 227.9 (366.7)
Neches River.
TXHS-3b: Lower Private, Federal.. Yes.................. 14.7 (23.7)
Angelina River.
TXHS-3c: Lower Private, State, Yes.................. 76.3 (122.8)
Neches River. Federal.
----------------------------------------
Unit Total................. .................. .................. ..................... 318.9 (513.1)
----------------------------------------
Total.................. .................. .................. ..................... 831.8 (1,338.6)
----------------------------------------------------------------------------------------------------------------
Note: Lengths may not accurately sum due to rounding.
Table 6--Proposed Critical Habitat Units for the Louisiana Pigtoe
----------------------------------------------------------------------------------------------------------------
River miles
Unit Subunit Riparian ownership Occupied? (kilometers)
----------------------------------------------------------------------------------------------------------------
LAPT-1: Little River........... LAPT-1a: Upper Private, State, Yes.................. 88.0 (141.6)
Little River. Federal, Tribal.
LAPT-1b: Rolling Private........... Yes.................. 29.9 (47.9)
Fork.
LAPT-1c: Cossatot Private, Federal.. Yes.................. 47.2 (75.9)
River.
LAPT-1d: Saline Private........... Yes.................. 42.6 (68.5)
River.
----------------------------------------
Unit Total................. .................. .................. ..................... 207.7 (334.2)
----------------------------------------------------------------------------------------------------------------
LAPT-2: Sabine River........... LAPT-2a: Upper Private, State, Yes.................. 110.1 (177.2)
Sabine River. Federal.
[[Page 16805]]
LAPT-2b: Anacoco Private........... Yes.................. 12.2 (19.6)
Bayou.
----------------------------------------
Unit Total................. .................. .................. ..................... 122.3 (196.8)
----------------------------------------------------------------------------------------------------------------
LAPT-3: Neches River........... LAPT-3a: Upper Private, Federal.. Yes.................. 200.4 (322.4)
Neches River.
LAPT-3b: Upper Private, Federal.. Yes.................. 67.4 (108.4)
Angelina River.
LAPT-3c: Lower Private, State, Yes.................. 76.2 (122.6)
Neches River. Federal.
LAPT-3d: Village Private, State, Yes.................. 54.9 (88.3)
Creek. Federal.
LAPT-3e: Big Sandy Private, Federal.. Yes.................. 43.7 (70.3)
Creek.
----------------------------------------
Unit Total................. .................. .................. ..................... 442.6 (712.1)
----------------------------------------------------------------------------------------------------------------
LAPT-4: East Fork San Jacinto .................. Private........... Yes.................. 23.3 (37.5)
River.
----------------------------------------
Unit Total................. .................. .................. ..................... 23.3 (37.5)
----------------------------------------------------------------------------------------------------------------
LAPT-5: Calcasieu River........ LAPT-5a: Upper Private, Federal.. Yes.................. 92.0 (148.0)
Calcasieu River.
LAPT-5b: Whisky Private, State.... Yes.................. 21.7 (34.9)
Chitto Creek.
LAPT-5c: Tenmile Private, State.... Yes.................. 32.0 (51.5)
Creek.
----------------------------------------
Unit Total................. .................. .................. ..................... 145.7 (234.4)
----------------------------------------------------------------------------------------------------------------
LAPT-6: Pearl River............ .................. Private, State, Yes.................. 86.6 (139.3)
Federal.
----------------------------------------
Unit Total................. .................. .................. ..................... 86.6 (139.3)
----------------------------------------
Total.................. .................. .................. ..................... 1,028.2
(1,654.3)
----------------------------------------------------------------------------------------------------------------
Note: Lengths may not accurately sum due to rounding.
We present brief descriptions of all units, and reasons why they
meet the definition of critical habitat for the Texas heelsplitter
(TXHS) or Louisiana pigtoe (LAPT) below.
Texas Heelsplitter
Unit TXHS-1: Trinity River
Subunit TXHS-1a: Trinity River. The Trinity River Subunit includes
212.8 river mi (342.4 km) in Anderson, Ellis, Freestone, Henderson,
Houston, Kaufman, Leon, Madison, and Navarro Counties, Texas. The
subunit begins at Lake Livingston (estimated from the State Highway 24
bridge located 4.7 mi (7.6 km) northeast of Midway, Texas) and
continues upstream to the State Highway 34 bridge, located 2.5 miles (4
km) southwest of Rosser, Texas. Ownership of adjacent riparian areas is
95 percent private and 5 percent State. Although this reach is
approximately 20 mi (32.2 km) southeast and downstream of the Dallas-
Fort Worth Metroplex, activities occurring across the Metroplex
continue to affect both water quality and quantity downstream,
including in this subunit, even though it is located in a largely rural
area and predominately within riparian woodlands and agricultural
lands. The Trinity River Subunit is occupied by the Texas heelsplitter
and contains all the PBFs essential to the conservation of the species
most of the year. However, hydrologic conditions have been
significantly altered by wastewater return flows, and flooding in the
Trinity River can be extreme, causing the species to experience a
variety of environmental stressors that degrade habitat quality, such
as shear stress, scouring, erosion, sediment deposition and siltation,
and bank collapse.
The Trinity River Subunit is being affected by impoundments,
wastewater return flows, ongoing agricultural activities, and
development resulting in excessive sedimentation, water quality
degradation, ground water withdrawals, and surface water diversions.
Therefore, special management considerations may be required to reduce
sedimentation, improve water quality, maintain adequate flows, and
improve habitat connectivity. There is no overlap with any designated
critical habitat for other listed species.
Subunit TXHS-1b: Bedias Creek. The Bedias Creek Subunit is
comprised of 28.9 river mi (46.5 km) in Grimes, Madison, and Walker
Counties, Texas. The subunit continues upstream from Livingston Lake,
as estimated from the Farm to Market Road 247 bridge located 9.2 mi
(14.8 km) south-southeast of Midway, Texas, to the State Highway 90
bridge located approximately 6.3 mi (10.1 km) south-southwest of
Madisonville, Texas. Adjacent riparian areas are privately owned. This
reach is largely rural and predominately within riparian woodlands and
agricultural lands. The Bedias Creek Subunit is occupied by the Texas
heelsplitter and contains all the PBFs essential to the conservation of
the species most of the year. However, fluctuating drought conditions
and flooding in Bedias Creek can cause the species to experience either
extreme low-flow conditions with related reduced water quality or
extreme high flows that mobilize substrates, erode habitat, or deposit
sediment on Texas heelsplitter populations.
The Bedias Creek Subunit is influenced by drought, low flows, and
flooding (leading to scour), and the subunit is being affected by
ongoing agricultural activities and development resulting in excessive
sedimentation, water quality degradation, ground water withdrawals, and
surface water diversions. Therefore, special management may be required
to reduce sedimentation, improve water quality, maintain adequate
flows, and improve habitat connectivity. There is no overlap with any
designated critical habitat for other listed species.
Unit TXHS-2: Sabine River
Subunit TXHS-2a: Upper Sabine River. The Upper Sabine River Subunit
includes 237.4 river mi (382 km) in Gregg, Harrison, Panola, Rains,
Rusk,
[[Page 16806]]
Smith, Upshur, Van Zandt, and Wood Counties, Texas. The subunit extends
upstream from the Louisiana/Texas State line, located approximately 2.4
mi (3.9 km) north-northeast of Joaquin, Texas, to a utility easement
approximately 0.9 river mile (1.4 km) below Tawakoni Lake dam.
Ownership of adjacent riparian areas is approximately 93 percent
private, 4 percent State, 1 percent local, and 2 percent Federal. This
reach is mostly rural and predominately within riparian woodlands
bordered by agricultural lands. The Upper Sabine River Subunit is
occupied by the Texas heelsplitter and contains all the PBFs essential
to the conservation of the species most of the year. However, drought
conditions and flooding in the Sabine River can be significant,
resulting in either extreme low-flow conditions with related reduced
water quality or high flows that mobilize substrates, erode habitat, or
deposit sediment on Texas heelsplitter populations. The City of
Longview, Texas, is located north of the subunit approximately mid-
reach. Industrial and municipal wastewater associated with this urban
area are discharged into the Sabine River Basin, negatively affecting
water quality in some areas downstream.
The Upper Sabine River Subunit is influenced by drought, low flows,
and flooding (leading to scour), and the subunit is being affected by
impoundments, ongoing agricultural activities, and development
resulting in excessive sedimentation, water quality degradation, ground
water withdrawals, and surface water diversions. Therefore, special
management considerations may be required to reduce sedimentation,
improve water quality, maintain adequate flows, and improve habitat
connectivity. There is an overlap of 110.05 river mi (177.11 km) of
this unit with proposed critical habitat for the Louisiana pigtoe.
Subunit TXHS-2b: Lake Fork Creek. The Lake Fork Creek Subunit
consists of 13.8 river mi (22.2 km) in Wood County, Texas. The subunit
extends upstream from its confluence with the Sabine River to the FM 49
bridge, located approximately 5 mi (8 km) northeast of Mineola, Texas.
Adjacent riparian areas are privately owned. This reach is mostly rural
and predominately within riparian woodlands bordered by agricultural
lands. The Lake Fork Creek Subunit is occupied by the Texas
heelsplitter and contains all the PBFs essential to the conservation of
the species most of the year. However, drought conditions and flooding
in the Lake Fork Creek can cause the species to experience either
extreme low-flow conditions with related reduced water quality or high
flows that mobilize substrates, erode habitat, or deposit sediment on
Texas heelsplitter populations.
The Lake Fork Creek Subunit is influenced by drought, low flows,
and flooding (leading to scour), and the subunit is being affected by
impoundments, ongoing agricultural activities, and development
resulting in excessive sedimentation, water quality degradation, ground
water withdrawals, and surface water diversions. Therefore, special
management considerations may be required to reduce sedimentation,
improve water quality, maintain adequate flows, and improve habitat
connectivity. There is no overlap with any designated critical habitat
for other listed species.
Subunit TXHS-2c: Patroon Bayou. The Patroon Bayou Subunit includes
19.9 river mi (32 km) in Sabine and Shelby Counties, Texas. This
subunit begins at the mouth of Patroon Bayou (location estimated at the
Reeves Road bridge, approximately 7 mi (11.3 km) north of Milam, Texas)
and continues upstream to the State Highway 87 bridge located 11.3 mi
(18.2 km) southeast of Shelbyville, Texas. Ownership of adjacent
riparian areas are 93 percent private and 7 percent Federal. The
Patroon Bayou Subunit is occupied by the Texas heelsplitter and
contains all the PBFs essential to the conservation of the species most
of the year. However, drought conditions and flooding in the Patroon
Bayou can cause low-flow conditions with related reduced water quality
or high flows that mobilize substrates, erode habitat, or deposit
sediment on Texas heelsplitter populations.
The Patroon Bayou Subunit is influenced by drought, low flows, and
flooding (leading to scour), and the subunit is being affected by
ongoing agricultural activities and development resulting in excessive
sedimentation, water quality degradation, ground water withdrawals, and
surface water diversions. Therefore, special management considerations
may be required to reduce sedimentation, improve water quality,
maintain adequate flows, and improve habitat connectivity. There is no
overlap with any designated critical habitat for other listed species.
Unit TXHS-3: Neches River
Subunit TXHS-3a: Upper Neches River. The Upper Neches River Subunit
includes 227.9 river mi (366.7 km) of stream in Anderson, Angelina,
Cherokee, Houston, Jasper, Polk, Trinity, and Tyler Counties, Texas.
The subunit originates at B.A. Steinhagen Lake (estimated at a point
located approximately 13 mi (20.9 km) east of Colmesneil, Texas) and
continues upstream to a transmission line right-of-way (ROW) located
approximately 1.1 river mi (1.8 km) below Palestine Lake Dam. Ownership
of adjacent riparian areas is approximately 88 percent private and 12
percent Federal. This reach is rural and predominately within riparian
woodlands bordered by agricultural lands. The Upper Neches River
Subunit is occupied by the Texas heelsplitter and contains all the PBFs
essential to the conservation of the species most of the year. However,
drought conditions and flooding in the Neches River can cause either
extreme low-flow conditions with related reduced water quality or high
flows that mobilize substrates, erode habitat, or deposit sediment on
Texas heelsplitter populations.
The Upper Neches River Subunit is influenced by drought, low flows,
and flooding (leading to scour), and the subunit is being affected by
impoundments, ongoing agricultural activities, and development
resulting in excessive sedimentation, water quality degradation, ground
water withdrawals, and surface water diversions. Therefore, special
management considerations may be required to reduce sedimentation,
improve water quality, maintain adequate flows, and improve habitat
connectivity. There is an overlap of 200.38 river mi (322.48 km) of
this unit with proposed critical habitat for the Louisiana pigtoe.
Subunit TXHS-3b: Lower Angelina River. The Lower Angelina River
Subunit consists of 14.7 river mi (23.7 km) in Jasper County, Texas.
The subunit extends upstream from B.A. Steinhagen Lake, estimated at a
point located approximately 5.7 mi (9.2 km) west of Curtis, Texas, to a
transmission line ROW located approximately 0.3 mile (0.5 km) below Sam
Rayburn Reservoir. Ownership of adjacent riparian areas is
approximately 89 percent private and 11 percent Federal. This reach is
rural and predominately within riparian woodlands bordered by
agricultural lands. The Lower Angelina River Subunit is occupied by the
Texas heelsplitter and contains all the necessary PBFs essential to the
conservation of the species most of the year. However, drought
conditions and flooding in the Angelina River can be compounded by
hydroelectric dam operations at Sam Rayburn Reservoir, causing the
species to experience either extreme low-flow conditions with related
reduced water quality or extreme high flows that mobilize substrates,
[[Page 16807]]
erode habitat, or deposit sediment on Texas heelsplitter populations.
The Lower Angelina River Subunit is influenced by drought, low
flows, and flooding (leading to scour), and the subunit is being
affected by impoundments, ongoing agricultural activities, and
development resulting in excessive sedimentation, water quality
degradation, ground water withdrawals, and surface water diversions.
Therefore, special management considerations may be required to reduce
sedimentation, improve water quality, maintain adequate flows, and
improve habitat connectivity. There is no overlap with any designated
critical habitat for other listed species.
Subunit TXHS-3c: Lower Neches River. The Lower Neches River Subunit
occupies 76.3 river mi (122.8 km) in Hardin, Jasper, Jefferson, Orange,
and Tyler Counties, Texas. The subunit extends upstream from the Lower
Neches Valley Authority weir, located north of Beaumont, Texas, to the
Walnut Run confluence, which is approximately 2.6 mi (4.2 km) southeast
of the B.A. Steinhagen Dam. The Lower Neches River Subunit is
hydrologically isolated from the Upper Neches River Subunit by B.A.
Steinhagen Lake. Ownership of adjacent riparian areas is approximately
88 percent private, 7 percent State, and 5 percent Federal. This reach
is mostly rural and predominately within riparian woodlands bordered by
agricultural lands. The Lower Neches River Subunit is occupied by the
Texas heelsplitter and contains all the PBFs essential to the
conservation of the species most of the year. However, drought
conditions and flooding in the Neches River can cause low-flow
conditions with related reduced water quality or high flows that
mobilize substrates, erode habitat, or deposit sediment on Texas
heelsplitter populations.
The Lower Neches River Subunit is influenced by drought, low flows,
and flooding (leading to scour); and the subunit is being affected by
impoundments, ongoing agricultural activities, and development
resulting in excessive sedimentation, water quality degradation,
groundwater withdrawals, and surface water diversions. Therefore,
special management considerations may be required to reduce
sedimentation, improve water quality, maintain adequate flows, and
improve habitat connectivity. There is an overlap of 76.35 river mi
(122.87 km) of this unit with proposed critical habitat for the
Louisiana pigtoe.
Louisiana Pigtoe
Unit LAPT-1: Little River
Subunit LAPT-1a: Upper Little River. The Upper Little River Subunit
consists of approximately 88.0 river mi (141.6 km) of the mainstem
Little River upstream of Millwood Lake, Arkansas, occupying portions of
Little River and Sevier Counties, Arkansas, and McCurtain County,
Oklahoma. This subunit extends upstream from the U.S. Highway 69/71
bridge near Millwood Lake, Arkansas, to the Glover River confluence,
located 2.6 mi (4.2 km) west-southwest of Golden, Oklahoma. This
subunit is hydrologically connected to the Rolling Fork Subunit
(Subunit LAPT-1b). Ownership of adjacent riparian areas is
approximately 42 percent private, 1 percent State, 26 percent Federal,
and 23 percent private land within the Choctaw Reservation, but not any
lands held in trust for the Tribe, or owned or managed by the Tribe.
This reach is entirely rural, with long sections of intact riparian
woodlands bordered by agricultural lands. The Upper Little River
Subunit is occupied by the Louisiana pigtoe and contains all the PBFs
essential to the conservation of the species most of the year.
Drought conditions and flooding in the Little River are seldom
extreme; however, this subunit is affected by hydroelectric dam-related
cold water releases in the Mountain Fork from Broken Bow Reservoir and
ongoing agricultural activities, resulting in excessive sedimentation,
water quality degradation, ground water withdrawals, and surface water
diversions. Therefore, special management considerations may be
required to reduce sedimentation, improve water quality, maintain
adequate flows, and improve habitat connectivity. The Upper Little
River Subunit is occupied by four federally listed freshwater mussels,
the endangered pink mucket (Lampsilis abrupta), the threatened
rabbitsfoot (Theliderma cylindrica, listed as Quadrula cylindrica
cylindrica), the endangered winged mapleleaf (Quadrula fragosa), and
the endangered Ouachita rock pocketbook (Arcidens wheeleri, listed as
Arkansia wheeleri). There is overlap of 88.3 river mi (142.1 km) of
this unit with designated critical habitat for rabbitsfoot (see 50 CFR
17.95(f) and 80 FR 24692, April 30, 2015).
Subunit LAPT-1b: Rolling Fork. The Rolling Fork Subunit consists of
approximately 29.9 river mi (47.9 km) in Sevier County, Arkansas. The
subunit extends upstream from the Little River confluence to the falls/
bedrock ledge located approximately 0.5 river mile (0.8 km) downstream
of DeQueen Lake Dam. Ownership of adjacent riparian areas is privately
held. This reach is entirely rural, and predominately agricultural
lands and riparian woodlands. The Rolling Fork Subunit is occupied by
the Louisiana pigtoe and contains all the PBFs essential to the
conservation of the species most of the year.
Drought conditions and flooding in Rolling Fork are seldom extreme;
however, this subunit is affected by impoundments and ongoing
agricultural activities, resulting in excessive sedimentation, water
quality degradation, ground water withdrawals, and surface water
diversions. Therefore, special management considerations may be
required to reduce sedimentation, improve water quality, maintain
adequate flows, and improve habitat connectivity. There is no overlap
with any designated critical habitat for other listed species.
Subunit LAPT-1c: Cossatot River. The Cossatot River Subunit
consists of approximately 47.2 river mi (75.9 km) of stream located
within Sevier County, Arkansas. This subunit extends upstream from the
U.S. Highway 69/71 bridge near Millwood Lake, Arkansas, to the Howard/
Sevier County line in southeast Arkansas. Ownership of adjacent
riparian areas is approximately 85 percent private and 15 percent
Federal. This reach is entirely rural, and predominately riparian
woodlands bordered by agricultural lands. The Cossatot River Subunit is
occupied by the Louisiana pigtoe and contains all the PBFs essential to
the conservation of the species most of the year.
Drought conditions and flooding in the Cossatot River are seldom
extreme; however, this subunit is affected by impoundments and ongoing
agricultural activities, resulting in excessive sedimentation, water
quality degradation, ground water withdrawals, and surface water
diversions. Therefore, special management considerations may be
required to reduce sedimentation, improve water quality, maintain
adequate flows, and improve habitat connectivity. There is no overlap
with any designated critical habitat for other listed species.
Subunit LAPT-1d: Saline River. The Saline River Subunit consists of
approximately 42.6 river mi (68.5 km) of stream located along the
Howard/Sevier County line in southeast Arkansas. This subunit extends
upstream from the Bright Star Road bridge, which is located immediately
north of Millwood Lake, to the Thirty Thousand Road (County Road 80)
bridge located
[[Page 16808]]
approximately 3.8 mi (6.1 km) west-northwest of Dierks, Arkansas.
Adjacent riparian areas are privately owned. This reach is entirely
rural, and predominately riparian woodlands bordered by agricultural
lands. The Saline River Subunit is occupied by the Louisiana pigtoe and
contains all the PBFs essential to the conservation of the species most
of the year.
Drought conditions and flooding in the Saline River are seldom
extreme; however, this subunit is affected by impoundments and ongoing
agricultural activities, resulting in excessive sedimentation, water
quality degradation, ground water withdrawals, and surface water
diversions. Therefore, special management considerations may be
required to reduce sedimentation, improve water quality, maintain
adequate flows, and improve habitat connectivity. There is no overlap
with any designated critical habitat for other listed species.
Unit LAPT-2: Sabine River
Subunit LAPT-2a: Upper Sabine River. The Upper Sabine River Subunit
consists of 110.1 river mi (177.2 km) occupying portions of Gregg,
Harrison, Panola, Rusk, Smith, Upshur, and Wood Counties, Texas. This
subunit continues upstream from the State Highway 43 bridge, which is 5
mi (8 km) northeast of Tatum, Texas, and terminates at the Farm-to-
Market Road 1804 bridge located 3.3 mi (5.3 km) southeast of Mineola,
Texas. Ownership of adjacent riparian areas is approximately 96 percent
private, 2 percent State, and 2 percent Federal. This reach is mostly
rural and predominately within riparian woodlands bordered by
agricultural lands.
The Upper Sabine River Subunit is occupied by the Louisiana pigtoe
and contains all the PBFs essential to the conservation of the species
most of the year. However, drought conditions and flooding in the
Sabine River can be extreme, causing the species to experience either
extreme low-flow conditions with associated reduced water quality or
extreme high flows that mobilize substrates, erode habitat, or deposit
sediment on Louisiana pigtoe populations. The City of Longview, Texas,
is located north of the subunit at approximately one-third of the reach
length upstream from the downstream terminus. Industrial and municipal
wastewater associated with this urban area are discharged into the
Sabine River Basin. The Upper Sabine River Subunit is influenced by
drought, low flows, and flooding (leading to scour), and the subunit is
being affected by impoundments, ongoing agricultural activities, and
development resulting in excessive sedimentation, water quality
degradation, ground water withdrawals, and surface water diversions.
Therefore, special management considerations may be required to reduce
sedimentation, improve water quality, maintain adequate flows, and
improve habitat connectivity. There is an overlap of 110.05 river mi
(177.11 km) of this unit with proposed critical habitat for the Texas
heelsplitter.
Subunit LAPT-2b: Anacoco Bayou. The Anacoco Bayou Subunit consists
of 12.2 river mi (19.6 km) in Vernon Parish, Louisiana. The subunit
extends upstream from the Beauregard/Vernon parish line, situated
approximately 8 mi (12.9 km) northwest of DeRidder, Louisiana, and
terminates at the Hawks Road bridge, located approximately 4.8 mi (7.7
km) northwest of Rosepine, Louisiana. Adjacent riparian areas are
privately owned. This reach is mostly rural and predominately within
riparian woodlands. The Anacoco Bayou Subunit is occupied by the
Louisiana pigtoe and contains all the PBFs essential to the
conservation of the species most of the year. However, drought
conditions and flooding in Anacoco Bayou can be extreme, causing the
species to experience either extreme low-flow conditions with
associated reduced water quality or extreme high flows that mobilize
substrates, erode habitat, or deposit sediments on Louisiana pigtoe
populations.
Three sand and gravel mining operations and one paper mill that
exist adjacent to this subunit likely negatively affect water quality
from activities that generate point and non-point source pollution.
Wastewater and storm water runoff associated with these activities are
discharged into Anacoco Bayou drainage. The Anacoco Bayou Subunit is
influenced by drought, low flows, and flooding (leading to scour), and
the subunit is being affected by impoundments, as well as ongoing
mining and industrial activities resulting in excessive sedimentation,
water quality degradation, ground water withdrawals, and surface water
diversions. Therefore, special management considerations may be
required to reduce sedimentation, improve water quality, maintain
adequate flows, and improve habitat connectivity. There is no overlap
with any designated critical habitat for other listed species.
Unit LAPT-3: Neches River
Subunit LAPT-3a: Upper Neches River. The Upper Neches River Subunit
extends for 200.4 river mi (322.4 km) through parts of Anderson,
Angelina, Cherokee, Houston, Polk, Trinity, and Tyler Counties, Texas.
The downstream boundary corresponds to U.S. Highway 59 bridge,
approximately 4 mi (6.4 km) south of Diboll, Texas, and the upstream
boundary is located at a transmission line ROW approximately 1.1 river
mi (1.8 km) below Palestine Lake Dam. Ownership of adjacent riparian
areas is approximately 89 percent private and 11 percent Federal. This
reach is mostly rural and predominately within riparian woodlands
bordered by agricultural lands. The Upper Neches River Subunit is
occupied by the Louisiana pigtoe and contains all the PBFs essential to
the conservation of the species most of the year. However, drought
conditions and flooding in the Neches River can be significant, causing
the species to experience either extreme low-flow conditions with
associated reduced water quality or extreme high flows that mobilize
substrates, erode habitat, or deposit sediment on Louisiana pigtoe
populations.
The Upper Neches River Subunit is influenced by drought, low flows,
and flooding (leading to scour), and the subunit is being affected by
impoundments, ongoing agricultural activities, and development
resulting in excessive sedimentation, water quality degradation, ground
water withdrawals, and surface water diversions. Therefore, special
management considerations may be required to reduce sedimentation,
improve water quality, maintain adequate flows, and improve habitat
connectivity. The entire subunit overlaps with proposed critical
habitat for the Texas heelsplitter.
Subunit LAPT-3b: Upper Angelina River. The Upper Angelina River
Subunit includes 67.4 river mi (108.4 km) in Angelina, Cherokee, and
Nacogdoches Counties, Texas. The subunit extends upstream from the
Union Pacific Railroad crossing, located approximately 3.7 mi (6 km)
north-northwest of Redland, Texas, to the State Highway 204 bridge
located 1.6 mi (2.6 km) west of Sacul, Texas. This subunit is
hydrologically isolated from the Upper Neches River Subunit by Sam
Rayburn Reservoir. Ownership of adjacent riparian areas is
approximately 50 percent private and 50 percent Federal. This reach is
mostly rural and predominately within riparian woodlands bordered by
agricultural lands. The Upper Angelina River Subunit is occupied by the
Louisiana pigtoe and contains all the PBFs essential to the
conservation of the species most of the year. However, drought
conditions and flooding in the Angelina River can result in either
extreme low-flow conditions with
[[Page 16809]]
associated reduced water quality or extreme high flows that mobilize
substrates, erode habitat, or deposit sediments on Louisiana pigtoe
populations.
The Upper Angelina River Subunit is influenced by drought, low
flows, and flooding (leading to scour); the subunit is being affected
by impoundments, ongoing agricultural activities, and development
resulting in excessive sedimentation, water quality degradation, ground
water withdrawals, and surface water diversions. Therefore, special
management considerations may be required to reduce sedimentation,
improve water quality, maintain adequate flows, and improve habitat
connectivity. There is no overlap with any designated critical habitat
for other listed species.
Subunit LAPT-3c: Lower Neches River. The Lower Neches River Subunit
occupies 76.2 river mi (122.6 km) in Hardin, Jasper, Jefferson, Orange,
and Tyler Counties, Texas. The subunit extends upstream from the Lower
Neches Valley Authority weir, located north of Beaumont, Texas, to the
Walnut Run confluence, which is approximately 2.6 mi (4.2 km) southeast
of the B.A. Steinhagen Dam. The Lower Neches River Subunit is
hydrologically isolated from the Upper Neches River Subunit by B.A.
Steinhagen Lake. Ownership of adjacent riparian areas is approximately
88 percent private, 7 percent State, and 5 percent Federal. This reach
is mostly rural and predominately within riparian woodlands bordered by
agricultural lands. The Lower Neches River Subunit is occupied by the
Louisiana pigtoe and contains all the PBFs essential to the
conservation of the species most of the year. However, drought
conditions and flooding in the Neches River can cause the species to
experience either extreme low-flow conditions with associated reduced
water quality or extreme high flows that mobilize substrates, erode
habitat, or deposit sediments on Louisiana pigtoe populations.
The Lower Neches River Subunit is influenced by drought, low flows,
and flooding (leading to scour); the subunit is being affected by
impoundments, ongoing agricultural activities, and development
resulting in excessive sedimentation, water quality degradation,
groundwater withdrawals, and surface water diversions. Therefore,
special management considerations may be required to reduce
sedimentation, improve water quality, maintain adequate flows, and
improve habitat connectivity. The entire subunit overlaps with proposed
critical habitat for the Texas heelsplitter.
Subunit LAPT-3d: Village Creek. The Village Creek Subunit includes
54.9 river mi (88.3 km) of stream in Hardin County, Texas. The subunit
originates at the Village Creek confluence with the Neches River,
located approximately 1.6 mi (2.6 km) north-northwest of Lakeview,
Texas, and continues up Village Creek to its terminus at the confluence
of Big Sandy and Kimball creeks, located approximately 1.6 mi (2.6 km)
south-southeast of Wildwood, Texas. Ownership of adjacent riparian
areas is approximately 20 percent private, 2 percent State, and 78
percent Federal. Although some urban encroachment occurs in the lower
half of the reach, it is mostly rural and predominately within riparian
woodlands bordered by agricultural lands. The Village Creek Subunit is
occupied by the Louisiana pigtoe and contains all the PBFs essential to
the conservation of the species most of the year. However, drought
conditions and flooding in Village Creek can be extreme, causing the
species to experience either extreme low-flow conditions with
associated reduced water quality or extreme high flows that mobilize
substrates, erode habitat, or deposit sediments on Louisiana pigtoe
populations.
The Village Creek Subunit is influenced by drought, low flows, and
flooding (leading to scour); the subunit is being affected by
impoundments, ongoing agricultural activities, and development
resulting in excessive sedimentation, water quality degradation, ground
water withdrawals, and surface water diversions. Therefore, special
management considerations may be required to reduce sedimentation,
improve water quality, maintain adequate flows, and improve habitat
connectivity. There is no overlap with any designated critical habitat
for other listed species.
Subunit LAPT-3e: Big Sandy Creek. The Big Sandy Creek Subunit
consists of 43.7 river mi (70.3 km) of stream in Hardin, Polk, and
Tyler Counties, Texas. The subunit continues upstream from its
confluence with Kimball Creek, located approximately 1.6 mi (2.6 km)
south-southeast of Wildwood, Texas, to the Alabama-Coushatta
Reservation boundary. This boundary is 1.4 river mi (2.25 km) southeast
of the U.S. Highway 190 bridge, which is located approximately 12.8 mi
(20.6 km) east of Livingston, Texas. Ownership of adjacent riparian
areas is approximately 5 percent private and 95 percent Federal. This
reach is mostly rural and predominately within riparian woodlands
bordered by agricultural lands. The Big Sandy Creek Subunit is occupied
by the Louisiana pigtoe and contains all the PBFs essential to the
conservation of the species most of the year. However, drought
conditions and flooding in Big Sandy Creek can be significant,
resulting in low-flow conditions with associated reduced water quality
or high flows that mobilize substrates, erode habitat, or deposit
sediments on Louisiana pigtoe populations.
The Big Sandy Creek Subunit is influenced by drought, low flows,
and flooding (leading to scour), and the subunit is being affected by
ongoing agricultural activities and development resulting in excessive
sedimentation, water quality degradation, ground water withdrawals, and
surface water diversions. Therefore, special management considerations
may be required to reduce sedimentation, improve water quality,
maintain adequate flows, and improve habitat connectivity. There is no
overlap with any designated critical habitat for other listed species.
Unit LAPT-4: East Fork San Jacinto River
The East Fork San Jacinto River Unit includes 23.3 river mi (37.5
km) of the East Fork San Jacinto River in Liberty and Montgomery
Counties, Texas. The downstream boundary of this unit is located at the
FM 1485 bridge approximately 1 mile (1.6 km) east of Lake Houston
Wilderness Park. The upstream boundary coincides with the Low Water
Bridge Road (FM 388) bridge approximately 1.6 mi (2.6 km) northwest of
Cleveland, Texas. Adjacent riparian areas are privately owned. Although
located 10 mi northwest of the Houston metropolitan area, this reach is
mostly rural and predominately within riparian woodlands, but it is
bordered by developed areas. Four sand and gravel mining operations are
located adjacent to this unit. The East Fork San Jacinto River Unit is
occupied by the Louisiana pigtoe and contains all the PBFs essential to
the conservation of the species most of the year. However, drought
conditions and flooding in the East Fork San Jacinto River can be
extreme, causing the species to experience either extreme low-flow
conditions with associated reduced water quality or extreme high flows
that mobilize substrates, erode habitat, or deposit sediments on
Louisiana pigtoe populations.
The East Fork San Jacinto River Unit is influenced by drought, low
flows, and flooding (leading to scour), and the unit is being affected
by ongoing agricultural activities and development resulting in
excessive sedimentation, water quality
[[Page 16810]]
degradation, ground water withdrawals, and surface water diversions.
Therefore, special management considerations may be required to reduce
sedimentation, improve water quality, maintain adequate flows, and
improve habitat connectivity. There is no overlap with any designated
critical habitat for other listed species.
Unit LAPT-5: Calcasieu River
Subunit LAPT-5a: Upper Calcasieu River. The Upper Calcasieu River
Subunit includes 92.0 river mi (148.0 km) located in Allen and Rapides
parishes, Louisiana. The subunit originates at the Union Pacific
Railroad crossing located south of U.S. Highway 190 approximately 4 mi
(6.4 km) west of Kinder, Louisiana, and continues upstream to the Price
Road bridge, located 3.1 mi (5 km) northwest of Hineston, Louisiana.
Ownership of adjacent riparian areas is 78 percent private and 22
percent Federal. This reach is rural and predominately within riparian
woodlands. The Upper Calcasieu River Subunit is occupied by the
Louisiana pigtoe and contains all the PBFs essential to the
conservation of the species most of the year. However, drought
conditions and flooding in the Calcasieu River can be extreme, causing
the species to experience either extreme low-flow conditions with
related reduced water quality or extreme high flows that mobilize
substrates, erode habitat, or deposit sediment on Louisiana pigtoe
populations.
The Upper Calcasieu River Subunit is influenced by drought, low
flows, and flooding (leading to scour), and the subunit is being
affected by ongoing agricultural activities and development resulting
in excessive sedimentation, water quality degradation, ground water
withdrawals, and surface water diversions. Therefore, special
management considerations may be required to reduce sedimentation,
improve water quality, maintain adequate flows, and improve habitat
connectivity. There is no overlap with any designated critical habitat
for other listed species.
Subunit LAPT-5b: Whisky Chitto Creek. The Whisky Chitto Creek
Subunit includes 21.7 river mi (34.9 km) located in Allen Parish,
Louisiana. The subunit extends from its confluence with Calcasieu River
to the Tenmile Creek confluence, which is located approximately 0.7 mi
(1.1 km) northeast of Mittie, Louisiana. Ownership of adjacent riparian
areas is 1 percent private and 99 percent State. This reach is rural
and predominately within riparian woodlands. The Whisky Chitto Creek
Subunit is occupied by the Louisiana pigtoe and contains all the PBFs
essential to the conservation of the species most of the year. However,
drought conditions and flooding in the Whisky Chitto Creek can be
extreme, causing the species to experience either extreme low-flow
conditions with related reduced water quality or extreme high flows
that mobilize substrates, erode habitat, or deposit sediment on
Louisiana pigtoe populations.
The Whisky Chitto Creek Subunit is influenced by drought, low
flows, and flooding (leading to scour), and the subunit is being
affected by ongoing agricultural activities and development resulting
in excessive sedimentation, water quality degradation, ground water
withdrawals, and surface water diversions. Therefore, special
management considerations may be required to reduce sedimentation,
improve water quality, maintain adequate flows, and improve habitat
connectivity. There is no overlap with any designated critical habitat
for other listed species.
Subunit LAPT-5c: Tenmile Creek. The Tenmile Creek Subunit consists
of 32.0 river mi (51.5 km) in Allen, Rapides, and Vernon parishes,
Louisiana. The Tenmile Creek Subunit continues upstream from the Whisky
Chitto Creek confluence located 0.7 mi (1.1 km) northeast of Mittie,
Louisiana, to the 10 Mile Road bridge located approximately 5 mi (8 km)
north of Elizabeth, Louisiana. Ownership of adjacent riparian areas is
98 percent private and 2 percent State. This reach is rural and
predominately within riparian woodlands. The Tenmile Creek Subunit is
occupied by the Louisiana pigtoe and contains all the PBFs essential to
the conservation of the species most of the year. However, drought
conditions and flooding in the Tenmile Creek can be extreme, causing
the species to experience either extreme low-flow conditions with
related reduced water quality or extreme high flows that mobilize
substrates, erode habitat, or deposit sediment on Louisiana pigtoe
populations.
The Tenmile Creek Subunit is influenced by drought, low flows, and
flooding (leading to scour), and the subunit is being affected by
ongoing agricultural activities and development resulting in excessive
sedimentation, water quality degradation, ground water withdrawals, and
surface water diversions. Therefore, special management considerations
may be required to reduce sedimentation, improve water quality,
maintain adequate flows, and improve habitat connectivity. There is no
overlap with any designated critical habitat for other listed species.
Unit LAPT-6: Pearl River
The Pearl River Unit consists of 86.6 river mi (139.3 km) in St.
Tammany and Washington parishes, Louisiana, and Marion and Pearl River
Counties, Mississippi. The Pearl River splits into two significant
channels within Bogue Chitto National Wildlife Refuge, and a navigation
channel is associated with the west channel. Proposed critical habitat
river mileage is calculated from the east channel only, but the Pearl
River Unit does include the west channel by definition. The navigation
channel is excluded from the unit. Following the east channel, the
Pearl River Unit extends upstream along the Louisiana/Mississippi State
line from the I-59 bridge located 1 mile (1.6 km) south of Nicholson,
Mississippi, to where the Pearl River enters Louisiana from
Mississippi, which is located 3.9 mi (6.3 km) southeast of Sandy Hook,
Mississippi. The west channel extends from the I-59 bridge located 0.9
mi (1.4 km) northeast of Pearl River, Louisiana, and continues upstream
to its confluence with the east channel, which is located approximately
2.7 mi (4.3 km) west of Industrial, Mississippi. Ownership of adjacent
riparian areas is 44 percent private, 14 percent State, and 42 percent
Federal. This reach is largely rural and predominately within riparian
woodlands. The Pearl River Unit is occupied by the Louisiana pigtoe and
contains all the PBFs essential to the conservation of the species most
of the year. However, drought conditions and flooding in the Pearl
River can be extreme, causing the species to experience either extreme
low-flow conditions with related reduced water quality or extreme high
flows that mobilize substrates, erode habitat, or deposit sediment on
Louisiana pigtoe populations.
The Pearl River Unit is influenced by drought, low flows, and
flooding (leading to scour), and the subunit is being affected by
impoundments, ongoing agricultural activities, and development
resulting in excessive sedimentation, water quality degradation, ground
water withdrawals, and surface water diversions. Therefore, special
management considerations may be required to reduce sedimentation,
improve water quality, maintain adequate flows, and improve habitat
connectivity. The entire subunit overlaps with critical habitat for the
federally listed Gulf sturgeon (Acipenser oxyrinchus (=oxyrhynchus)
desotoi) (see 50 CFR 17.95(e)).
[[Page 16811]]
Effects of Critical Habitat Designation
Section 7 Consultation
Section 7(a)(2) of the Act requires Federal agencies, including the
Service, to ensure that any action they fund, authorize, or carry out
is not likely to jeopardize the continued existence of any endangered
species or threatened species or result in the destruction or adverse
modification of designated critical habitat of such species. In
addition, section 7(a)(4) of the Act requires Federal agencies to
confer with the Service on any agency action which is likely to
jeopardize the continued existence of any species proposed to be listed
under the Act or result in the destruction or adverse modification of
proposed critical habitat.
We published a final rule revising the definition of destruction or
adverse modification on August 27, 2019 (84 FR 44976). Destruction or
adverse modification means a direct or indirect alteration that
appreciably diminishes the value of critical habitat as a whole for the
conservation of a listed species.
If a Federal action may affect a listed species or its critical
habitat, the responsible Federal agency (action agency) must enter into
consultation with us. Examples of actions that are subject to the
section 7 consultation process are actions on State, Tribal, local, or
private lands that require a Federal permit (such as a permit from the
U.S. Army Corps of Engineers under section 404 of the Clean Water Act
(33 U.S.C. 1251 et seq.) or a permit from the Service under section 10
of the Act) or that involve some other Federal action (such as funding
from the Federal Highway Administration, Federal Aviation
Administration, or the Federal Emergency Management Agency). Federal
actions not affecting listed species or critical habitat--and actions
on State, Tribal, local, or private lands that are not federally
funded, authorized, or carried out by a Federal agency--do not require
section 7 consultation.
Compliance with the requirements of section 7(a)(2) is documented
through our issuance of:
(1) A concurrence letter for Federal actions that may affect, but
are not likely to adversely affect, listed species or critical habitat;
or
(2) A biological opinion for Federal actions that may affect, and
are likely to adversely affect, listed species or critical habitat.
When we issue a biological opinion concluding that a project is
likely to jeopardize the continued existence of a listed species and/or
destroy or adversely modify critical habitat, we provide reasonable and
prudent alternatives to the project, if any are identifiable, that
would avoid the likelihood of jeopardy and/or destruction or adverse
modification of critical habitat. We define ``reasonable and prudent
alternatives'' (at 50 CFR 402.02) as alternative actions identified
during consultation that:
(1) Can be implemented in a manner consistent with the intended
purpose of the action,
(2) Can be implemented consistent with the scope of the Federal
agency's legal authority and jurisdiction,
(3) Are economically and technologically feasible, and
(4) Would, in the Service Director's opinion, avoid the likelihood
of jeopardizing the continued existence of the listed species and/or
avoid the likelihood of destroying or adversely modifying critical
habitat.
Reasonable and prudent alternatives can vary from slight project
modifications to extensive redesign or relocation of the project. Costs
associated with implementing a reasonable and prudent alternative are
similarly variable.
Regulations at 50 CFR 402.16 set forth requirements for Federal
agencies to reinitiate consultation on previously reviewed actions.
These requirements apply when the Federal agency has retained
discretionary involvement or control over the action (or the agency's
discretionary involvement or control is authorized by law) and,
subsequent to the previous consultation: (a) if the amount or extent of
taking specified in the incidental take statement is exceeded; (b) if
new information reveals effects of the action that may affect listed
species or critical habitat in a manner or to an extent not previously
considered; (c) if the identified action is subsequently modified in a
manner that causes an effect to the listed species or critical habitat
that was not considered in the biological opinion or written
concurrence; or (d) if a new species is listed or critical habitat
designated that may be affected by the identified action.
In such situations, Federal agencies sometimes may need to request
reinitiation of consultation with us, but Congress also enacted some
exceptions in 2018 to the requirement to reinitiate consultation on
certain land management plans on the basis of a new species listing or
new designation of critical habitat that may be affected by the subject
Federal action. See 2018 Consolidated Appropriations Act, Public Law
115-141, Div, O, 132 Stat. 1059 (2018).
Application of the ``Destruction or Adverse Modification'' Standard
The key factor related to the destruction or adverse modification
determination is whether implementation of the proposed Federal action
directly or indirectly alters the designated critical habitat in a way
that appreciably diminishes the value of the critical habitat as a
whole for the conservation of the listed species. As discussed above,
the role of critical habitat is to support physical or biological
features essential to the conservation of a listed species and provide
for the conservation of the species.
Section 4(b)(8) of the Act requires us to briefly evaluate and
describe, in any proposed or final regulation that designates critical
habitat, activities involving a Federal action that may violate section
7(a)(2) of the Act by destroying or adversely modifying such habitat,
or that may be affected by such designation.
Activities that we may, during a consultation under section 7(a)(2)
of the Act, consider likely to destroy or adversely modify critical
habitat include, but are not limited to, actions that would: (1) Alter
the minimum flow or the existing flow regime (for example, impoundment,
channelization, water diversion, water withdrawal, or hydropower
generation); (2) significantly alter water chemistry or temperature
(for example, release of chemicals, biological pollutants, or heated
effluents into surface water or connected groundwater at a point source
or by dispersed release (nonpoint source)); (3) significantly increase
sediment deposition within the stream channel (for example, excessive
sedimentation from livestock grazing; road construction; channel
alteration; timber harvest; off-road vehicle use; agricultural,
industrial, or urban development; or other watershed and floodplain
disturbances); and (4) significantly alter channel morphology or
geometry (for example, channelization, impoundment, road and bridge
construction, mining, dredging, or destruction of riparian vegetation).
These activities may lead to changes in water flows and levels that
would degrade or eliminate the mussel or its fish host and/or their
habitats. These actions can also lead to increased sedimentation and
degradation in water quality to levels that are beyond the tolerances
of the mussels or their fish hosts.
[[Page 16812]]
Exemptions
Application of Section 4(a)(3) of the Act
Section 4(a)(3)(B)(i) of the Act (16 U.S.C. 1533(a)(3)(B)(i))
provides that the Secretary shall not designate as critical habitat any
lands or other geographical areas owned or controlled by the Department
of Defense (DoD), or designated for its use, that are subject to an
integrated natural resources management plan (INRMP) prepared under
section 101 of the Sikes Act Improvement Act of 1997 (16 U.S.C. 670a),
if the Secretary determines in writing that such plan provides a
benefit to the species for which critical habitat is proposed for
designation. No DoD lands with a completed INRMP are within the
proposed critical habitat designations.
Consideration of Impacts Under Section 4(b)(2) of the Act
Section 4(b)(2) of the Act states that the Secretary shall
designate and make revisions to critical habitat on the basis of the
best available scientific data after taking into consideration the
economic impact, national security impact, and any other relevant
impact of specifying any particular area as critical habitat. The
Secretary may exclude an area from designated critical habitat based on
economic impacts, impacts on national security, or any other relevant
impacts. Exclusion decisions are governed by the regulations at 50 CFR
424.19 and the Policy Regarding Implementation of Section 4(b)(2) of
the Endangered Species Act (hereafter, the ``2016 Policy''; 81 FR 7226,
February 11, 2016), both of which were developed jointly with the
National Marine Fisheries Service (NMFS). We also refer to a 2008
Department of the Interior Solicitor's opinion entitled ``The
Secretary's Authority to Exclude Areas from a Critical Habitat
Designation under section 4(b)(2) of the Endangered Species Act'' (M-
37016).
In considering whether to exclude a particular area from the
designation, we identify the benefits of including the area in the
designation, identify the benefits of excluding the area from the
designation, and evaluate whether the benefits of exclusion outweigh
the benefits of inclusion. If the analysis indicates that the benefits
of exclusion outweigh the benefits of inclusion, the Secretary may
exercise discretion to exclude the area only if such exclusion would
not result in the extinction of the species. In making the
determination to exclude a particular area, the statute on its face, as
well as the legislative history, are clear that the Secretary has broad
discretion regarding which factor(s) to use and how much weight to give
to any factor. In our final rules, we explain any decision to exclude
areas, as well as decisions not to exclude, to demonstrate that the
decision is reasonable. We describe below the process that we use for
taking into consideration each category of impacts and any initial
analyses of the relevant impacts.
Consideration of Economic Impacts
Section 4(b)(2) of the Act and its implementing regulations require
that we consider the economic impact that may result from a designation
of critical habitat. To assess the probable economic impacts of a
designation, we must first evaluate specific land uses or activities
and projects that may occur in the area of the critical habitat. We
then must evaluate the impacts that a specific critical habitat
designation may have on restricting or modifying specific land uses or
activities for the benefit of the species and its habitat within the
areas proposed. We then identify which conservation efforts may be the
result of the species being listed under the Act versus those
attributed solely to the designation of critical habitat for the
particular species. The probable economic impact of a proposed critical
habitat designation is analyzed by comparing scenarios both ``with
critical habitat'' and ``without critical habitat.''
The ``without critical habitat'' scenario represents the baseline
for the analysis, which includes the existing regulatory and socio-
economic burden imposed on landowners, managers, or other resource
users potentially affected by the designation of critical habitat
(e.g., under the Federal listing as well as other Federal, State, and
local regulations). The baseline, therefore, represents the costs of
all efforts attributable to the listing of the species under the Act
(i.e., conservation of the species and its habitat incurred regardless
of whether critical habitat is designated). The ``with critical
habitat'' scenario describes the incremental impacts associated
specifically with the designation of critical habitat for the species.
The incremental conservation efforts and associated impacts would not
be expected without the designation of critical habitat for the
species. In other words, the incremental costs are those attributable
solely to the designation of critical habitat, above and beyond the
baseline costs. These are the costs we use when evaluating the benefits
of inclusion and exclusion of particular areas from the final
designation of critical habitat should we choose to conduct a
discretionary 4(b)(2) exclusion analysis.
For this particular designation, we developed an incremental
effects memorandum (IEM) considering the probable incremental economic
impacts that may result from this proposed designations of critical
habitat. The information contained in our IEM was then used to develop
a screening analysis of the probable effects of the designation of
critical habitat for the Texas heelsplitter and the Louisiana pigtoe
(IEc 2021, entire). We began by conducting a screening analysis of the
proposed designations of critical habitat in order to focus our
analysis on the key factors that are likely to result in incremental
economic impacts. The purpose of the screening analysis is to filter
out particular geographic areas of critical habitat that are already
subject to such protections and are, therefore, unlikely to incur
incremental economic impacts. In particular, the screening analysis
considers baseline costs (i.e., absent critical habitat designation)
and includes any probable economic impacts where land and water use may
already be subject to conservation plans, land management plans, best
management practices, or regulations that protect the habitat area as a
result of the Federal listing status of the species. Ultimately, the
screening analysis allows us to focus our analysis on evaluating the
specific areas or sectors that may incur probable incremental economic
impacts as a result of the designation. If the proposed critical
habitat designation contains any unoccupied units, the screening
analysis assesses whether those units require additional management or
conservation efforts that may incur incremental economic impacts
(although here the proposed critical habitat designations does not
contain any unoccupied units). This screening analysis, combined with
the information contained in our IEM, are what we consider our draft
economic analysis (DEA) of the proposed critical habitat designations
for the Texas heelsplitter and Louisiana pigtoe; our DEA is summarized
in the narrative below.
Executive Orders (E.O.s) 12866 and 13563 direct Federal agencies to
assess the costs and benefits of available regulatory alternatives in
quantitative (to the extent feasible) and qualitative terms. Consistent
with the E.O. regulatory analysis requirements, our effects analysis
under the Act may take into consideration impacts to both directly and
indirectly affected entities, where practicable and reasonable. If
sufficient data are available, we assess to the extent practicable the
probable impacts to both directly and indirectly
[[Page 16813]]
affected entities. As part of our screening analysis, we considered the
types of economic activities that are likely to occur within the areas
likely affected by the critical habitat designations. In our evaluation
of the probable incremental economic impacts that may result from the
proposed designations of critical habitat for the Texas heelsplitter
and Louisiana pigtoe, first we identified, in the IEM dated September
1, 2021, probable incremental economic impacts associated with the
following categories of activities: (1) Federal lands management
(National Park Service, National Wildlife Refuge System, U.S. Forest
Service, U.S. Army Corp of Engineers, Natural Resources Conservation
Service, Department of the Army); (2) industrial, municipal, and
agricultural water users and dischargers (including wastewater
treatment plants); (3) water supply delivery and treatment; (4)
reservoir and dam operations; (5) transportation; (6) petroleum
pipelines that may cross proposed designated stream reaches; (7)
residential, commercial, industrial, and agricultural development; and
(8) disaster recovery from hurricanes and flooding. We considered each
industry or category individually. Additionally, we considered whether
their activities have any Federal involvement. Critical habitat
designation generally will not affect activities that do not have any
Federal involvement; under the Act, designation of critical habitat
only affects activities conducted, funded, permitted, or authorized by
Federal agencies. If we list these species, in areas where the Texas
heelsplitter and Louisiana pigtoe are present, Federal agencies would
be required to consult with the Service under section 7 of the Act on
activities they fund, permit, or implement that may affect the species.
If, when we list the species, we also finalize this proposed critical
habitat designation, Federal agencies would be required to consider the
effects of their actions on the designated habitat, and if the Federal
action may affect critical habitat, our consultations would include an
evaluation of measures to avoid the destruction or adverse modification
of critical habitat.
In our IEM, we attempted to clarify the distinction between the
effects that would result from the species being listed and those
attributable to the critical habitat designation (i.e., difference
between the jeopardy and adverse modification standards) for the Texas
heelsplitter's and Louisiana pigtoe's critical habitat. Because the
designations of critical habitat for Texas heelsplitter and Louisiana
pigtoe are being proposed concurrently with their listings, it has been
our experience that it is more difficult to discern which conservation
efforts are attributable to the species being listed and those which
will result solely from the designation of critical habitat. However,
the following specific circumstances in this case help to inform our
evaluation: (1) The essential physical or biological features
identified for critical habitat are the same features essential for the
life requisites of the species, and (2) any actions that would result
in sufficient harm or harassment to constitute jeopardy to the Texas
heelsplitter and Louisiana pigtoe would also likely adversely affect
the essential physical or biological features of critical habitat. The
IEM outlines our rationale concerning this limited distinction between
baseline conservation efforts and incremental impacts of the
designation of critical habitat for these species. This evaluation of
the incremental effects has been used as the basis to evaluate the
probable incremental economic impacts of these proposed designations of
critical habitat.
The proposed critical habitat designations for the Texas
heelsplitter and Louisiana pigtoe include a total of nine units, all of
which are occupied by their respective species. Ownership of riparian
lands adjacent to the nine proposed units includes 1,214 river mi
(1,954 km; 82.2 percent) in private ownership, and 262 river mi (422
km; 17.8 percent) in public (Federal, State, or Local) ownership. In
these areas, any actions that may affect the two species or their
habitats would also affect designated critical habitat.
Total incremental costs of critical habitat designation for the
Texas heelsplitter and Louisiana pigtoe are not expected to exceed
$51,800 (2021 dollars) per year. The costs are reflective of: (1) All
proposed units are considered occupied, (2) project modifications
requested to avoid adverse modification are likely to be the same as
those recommended to avoid jeopardy in occupied habitat for these
species, and (3) a portion of the proposed designations receive
baseline protection from the presence of critical habitat for co-
occurring listed mussel species with similar habitat needs. Because
consultation would be required as a result of the listing of the Texas
heelsplitter and Louisiana pigtoe and is already required in some of
these areas as a result of the presence of other listed species and
critical habitats, the economic costs of the critical habitat
designation would likely be primarily limited to additional
administrative efforts to consider adverse modification for these two
species in section 7 consultations.
Based on the consultation history regarding historical projects and
activities overlapping the proposed critical habitat areas for the
Texas heelsplitter and Louisiana pigtoe, the number of future
consultations, including technical assistance efforts, is likely to be
no more than nine per year across all nine units. Overall,
transportation and utilities activities are expected to result in the
largest portion of consultations for both the Texas heelsplitter and
Louisiana pigtoe and, therefore, to incur the highest costs. The
geographic distribution of future section 7 consultations and
associated costs are likely to be most heavily concentrated in all
three proposed units for the Texas heelsplitter, and in proposed Units
2 and 3 for the Louisiana pigtoe. However, even assuming consultation
activity increases substantially, incremental administrative costs are
still likely to remain well under $100 million per year. Therefore,
based on the definition of significance in E.O. 12866, they would not
be significant.
The entities most likely to incur incremental costs are parties to
section 7 consultations, including Federal action agencies and, in some
cases, third parties, most frequently State agencies or municipalities.
Activities we expect would be subject to consultations that may involve
private entities as third parties are farms and ranches acquiring
funding through Federal agricultural programs, oil and gas production
regulated by the Federal Energy Regulatory Commission, and
infrastructure projects that involve Federal funding or authorization.
However, based on coordination efforts with State and local agencies,
the cost to private entities in these sectors is expected to be
relatively minor (administrative costs of less than $10,000 per
consultation effort) and would not be significant (i.e., would not
exceed $100 million in a single year).
We are soliciting data and comments from the public on the DEA
discussed above. During the development of a final designation, we will
consider the information presented in the DEA and any additional
information on economic impacts we receive during the public comment
period to determine whether any specific areas should be excluded from
the final critical habitat designation under authority of section
4(b)(2) and our implementing regulations at 50 CFR 424.19. We may
exclude an area from critical habitat if we determine that the benefits
of
[[Page 16814]]
excluding the area outweigh the benefits of including the area,
provided the exclusion will not result in the extinction of this
species.
Consideration of National Security Impacts or Homeland Security Impacts
Section 4(a)(3)(B)(i) of the Act may not cover all DoD lands or
areas that pose potential national-security concerns (e.g., a DoD
installation that is in the process of revising its INRMP for a newly
listed species or a species previously not covered). If a particular
area is not covered under section 4(a)(3)(B)(i), national-security or
homeland-security concerns are not a factor in the process of
determining what areas meet the definition of ``critical habitat.''
However, the Service must consider impacts on national security,
including homeland security, on those lands or areas not covered by
section 4(a)(3)(B)(i) because section 4(b)(2) requires the Service to
consider those impacts whenever it designates critical habitat.
Accordingly, if DoD, Department of Homeland Security (DHS), or another
Federal agency has requested exclusion based on an assertion of
national-security or homeland-security concerns, or we have otherwise
identified national-security or homeland-security impacts from
designating particular areas as critical habitat, we generally have
reason to consider excluding those areas.
However, we cannot automatically exclude requested areas. When DoD,
DHS, or another Federal agency requests exclusion from critical habitat
on the basis of national-security or homeland-security impacts, we must
conduct an exclusion analysis if the Federal requester provides
information, including a reasonably specific justification of an
incremental impact on national security that would result from the
designation of that specific area as critical habitat. That
justification could include demonstration of probable impacts, such as
impacts to ongoing border-security patrols and surveillance activities,
or a delay in training or facility construction, as a result of
compliance with section 7(a)(2) of the Act. If the agency requesting
the exclusion does not provide us with a reasonably specific
justification, we will contact the agency to recommend that it provide
a specific justification or clarification of its concerns relative to
the probable incremental impact that could result from the designation.
If we conduct an exclusion analysis because the agency provides a
reasonably specific justification or because we decide to exercise the
discretion to conduct an exclusion analysis, we will defer to the
expert judgment of DoD, DHS, or another Federal agency as to: (1)
Whether activities on its lands or waters, or its activities on other
lands or waters, have national-security or homeland-security
implications; (2) the importance of those implications; and (3) the
degree to which the cited implications would be adversely affected in
the absence of an exclusion. In that circumstance, in conducting a
discretionary section 4(b)(2) exclusion analysis, we will give great
weight to national-security and homeland-security concerns in analyzing
the benefits of exclusion.
In preparing this proposal, we have determined that the lands
within the proposed designations of critical habitat for Texas
heelsplitter and Louisiana pigtoe are not owned or managed by the DoD
or DHS, and, therefore, we anticipate no impact on national security or
homeland security.
Consideration of Other Relevant Impacts
Under section 4(b)(2) of the Act, we consider any other relevant
impacts, in addition to economic impacts and impacts on national
security discussed above. To identify other relevant impacts that may
affect the exclusion analysis, we consider a number of factors,
including whether there are permitted conservation plans covering the
species in the area--such as HCPs, safe harbor agreements (SHAs), or
candidate conservation agreements with assurances (CCAAs)--or whether
there are non-permitted conservation agreements and partnerships that
may be impaired by designation of, or exclusion from, critical habitat.
In addition, we look at whether Tribal conservation plans or
partnerships, Tribal resources, or government-to-government
relationships of the United States with Tribal entities may be affected
by the designation. We also consider any State, local, social, or other
impacts that might occur because of the designation.
When analyzing other relevant impacts of including a particular
area in a designation of critical habitat, we weigh those impacts
relative to the conservation value of the particular area. To determine
the conservation value of designating a particular area, we consider a
number of factors, including, but not limited to, the additional
regulatory benefits that the area would receive due to the protection
from destruction or adverse modification as a result of actions with a
Federal nexus, the educational benefits of mapping essential habitat
for recovery of the listed species, and any benefits that may result
from a designation due to State or Federal laws that may apply to
critical habitat.
In the case of the Texas heelsplitter and Louisiana pigtoe, the
benefits of critical habitat include public awareness of the presence
of these species and the importance of habitat protection, and, where a
Federal nexus exists, increased habitat protection for the Texas
heelsplitter and Louisiana pigtoe due to protection from destruction or
adverse modification of critical habitat. Continued implementation of
an ongoing management plan that provides conservation equal to or more
than the protections that result from a critical habitat designation
would reduce those benefits of including that specific area in the
critical habitat designation.
We evaluate the existence of a conservation plan when considering
the benefits of inclusion. We consider a variety of factors, including,
but not limited to, whether the plan is finalized; how it provides for
the conservation of the essential physical or biological features;
whether there is a reasonable expectation that the conservation
management strategies and actions contained in a management plan will
be implemented into the future; whether the conservation strategies in
the plan are likely to be effective; and whether the plan contains a
monitoring program or adaptive management to ensure that the
conservation measures are effective and can be adapted in the future in
response to new information.
After identifying the benefits of inclusion and the benefits of
exclusion, we carefully weigh the two sides to evaluate whether the
benefits of exclusion outweigh those of inclusion. If our analysis
indicates that the benefits of exclusion outweigh the benefits of
inclusion, we then determine whether exclusion would result in
extinction of the species. If exclusion of an area from critical
habitat will result in extinction, we will not exclude it from the
designation.
Private or Other Non-Federal Conservation Plans Related to Permits
Under Section 10 of the Act
HCPs for incidental take permits under section 10(a)(1)(B) of the
Act provide for partnerships with non-Federal entities to minimize and
mitigate impacts to listed species and their habitat. In some cases,
HCP permittees agree to do more for the conservation of the species and
their habitats on private lands than designation of critical habitat
would provide alone. We place great value on the partnerships that are
developed
[[Page 16815]]
during the preparation and implementation of HCPs.
CCAAs and SHAs are voluntary agreements designed to conserve
candidate and listed species, respectively, on non-Federal lands. In
exchange for actions that contribute to the conservation of species on
non-Federal lands, participating property owners are covered by an
``enhancement of survival'' permit under section 10(a)(1)(A) of the
Act, which authorizes incidental take of the covered species that may
result from implementation of conservation actions, specific land uses,
and, in the case of SHAs, the option to return to a baseline condition
under the agreements. We also provide enrollees assurances that we will
not impose further land-, water-, or resource-use restrictions, or
require additional commitments of land, water, or finances, beyond
those agreed to in the agreements.
When we undertake a discretionary section 4(b)(2) exclusion
analysis based on permitted conservation plans such as CCAAs, SHAs, and
HCPs, we consider the following three factors:
(i) Whether the permittee is properly implementing the conservation
plan or agreement;
(ii) Whether the species for which critical habitat is being
designated is a covered species in the conservation plan or agreement;
and
(iii) Whether the conservation plan or agreement specifically
addresses the habitat of the species for which critical habitat is
being designated and meets the conservation needs of the species in the
planning area.
In preparing this proposal, we have determined that there are
currently no HCPs or other management plans for the Texas heelsplitter
or Louisiana pigtoe. The proposed designation of critical habitat for
the Louisiana pigtoe includes the Choctaw Reservation in Oklahoma, but
not any lands held in trust for the tribe, or owned or managed by the
tribe. No Tribal lands fall within the range of the Texas heelsplitter
or the boundaries of the proposed critical habitat designations.
Therefore the proposed designations do not include any Tribal lands or
trust resources. We anticipate no impact on Tribal lands, partnerships,
or HCPs from the proposed critical habitat designations.
We are currently working with the Sabine River Authority of
Louisiana, State of Louisiana, and Sabine River Authority of Texas to
develop CCAAs that address activities conducted by the River
Authorities and States with conservation measures specifically designed
to provide a net conservation benefit to the covered species, including
the Texas heelsplitter and Louisiana pigtoe, in the covered area for
the term for each of the CCAAs. We are also working with the Trinity
River Authority of Texas to develop a CCAA that would address
activities conducted by the Trinity River Authority and State with
conservation measures specifically designed to provide a net
conservation benefit to the covered species, including the Texas
heelsplitter, in the covered area for the term of the CCAA. While these
agreements are not yet completed, if and when they are, we may consider
excluding areas covered by the completed agreements from our critical
habitat designations.
Summary of Exclusions Considered Under Section 4(b)(2) of the Act
At this time, we are not considering any exclusions from the
proposed designations based on economic impacts, national security
impacts, or other relevant impacts--such as partnerships, management,
or protection afforded by cooperative management efforts--under section
4(b)(2) of the Act. In preparing this proposal, we have determined that
the proposed designation of critical habitat for the Louisiana pigtoe
includes Choctaw Reservation in Oklahoma, but not any lands held in
trust for the Tribe, or owned or managed by the Tribe. No tribal lands
fall within the range of the Texas heelsplitter or the boundaries of
the proposed critical habitat designations. Therefore we have
determined that no HCPs or other management plans for the Texas
heelsplitter or Louisiana pigtoe currently exist, and the proposed
designations do not include any Tribal lands or trust resources.
Therefore, we anticipate no impact on Tribal lands, partnerships, or
HCPs from the proposed critical habitat designations, and, thus, as
described above, we are not considering excluding any particular areas
on the basis of the presence of conservation agreements or impacts to
trust resources. Some areas within the proposed designations are
included in proposed CCAAs. If finalized, we will consider the lands
covered in the CCAAs for exclusion in the development of the final
designations. However, we have contacted the Choctaw Nation of Oklahoma
to request information on any possible impacts and will include such
information in our final review.
If through the public comment period we receive information that we
determine indicates that there are economic, national security or other
relevant impacts from designating particular areas as critical habitat,
then as part of developing the final designation of critical habitat,
we will evaluate that information and may conduct a discretionary
exclusion analysis to determine whether to exclude those areas under
authority of section 4(b)(2) and our implementing regulations at 50 CFR
424.19. If we receive a request for exclusion of a particular area and
after evaluation of supporting information we do not exclude, we will
fully explain our decision in the final rule for this action. (Please
see ADDRESSES, above, for instructions on how to submit comments).
Required Determinations
Clarity of the Rule
We are required by Executive Orders 12866 and 12988 and by the
Presidential Memorandum of June 1, 1998, to write all rules in plain
language. This means that each rule we publish must:
(1) Be logically organized;
(2) Use the active voice to address readers directly;
(3) Use clear language rather than jargon;
(4) Be divided into short sections and sentences; and
(5) Use lists and tables wherever possible.
If you feel that we have not met these requirements, send us
comments by one of the methods listed in ADDRESSES. To better help us
revise the rule, your comments should be as specific as possible. For
example, you should tell us the numbers of the sections or paragraphs
that are unclearly written, which sections or sentences are too long,
the sections where you feel lists or tables would be useful, etc.
Regulatory Planning and Review (Executive Orders 12866 and 13563)
Executive Order 12866 provides that the Office of Information and
Regulatory Affairs (OIRA) in the Office of Management and Budget will
review all significant rules. OIRA has determined that this proposed
rule is not significant.
Executive Order 13563 reaffirms the principles of E.O. 12866 while
calling for improvements in the nation's regulatory system to promote
predictability, to reduce uncertainty, and to use the best, most
innovative, and least burdensome tools for achieving regulatory ends.
The executive order directs agencies to consider regulatory approaches
that reduce burdens and maintain flexibility and freedom of choice for
the public where these approaches are relevant, feasible, and
consistent with regulatory
[[Page 16816]]
objectives. E.O. 13563 emphasizes further that regulations must be
based on the best available science and that the rulemaking process
must allow for public participation and an open exchange of ideas. We
have developed this proposed rule in a manner consistent with these
requirements.
Regulatory Flexibility Act (5 U.S.C. 601 et seq.)
Under the Regulatory Flexibility Act (RFA; 5 U.S.C. 601 et seq.),
as amended by the Small Business Regulatory Enforcement Fairness Act of
1996 (SBREFA; 5 U.S.C. 801 et seq.), whenever an agency is required to
publish a notice of rulemaking for any proposed or final rule, it must
prepare and make available for public comment a regulatory flexibility
analysis that describes the effects of the rule on small entities
(i.e., small businesses, small organizations, and small government
jurisdictions). However, no regulatory flexibility analysis is required
if the head of the agency certifies the rule will not have a
significant economic impact on a substantial number of small entities.
The SBREFA amended the RFA to require Federal agencies to provide a
certification statement of the factual basis for certifying that the
rule will not have a significant economic impact on a substantial
number of small entities.
According to the Small Business Administration, small entities
include small organizations such as independent nonprofit
organizations; small governmental jurisdictions, including school
boards and city and town governments that serve fewer than 50,000
residents; and small businesses (13 CFR 121.201). Small businesses
include manufacturing and mining concerns with fewer than 500
employees, wholesale trade entities with fewer than 100 employees,
retail and service businesses with less than $5 million in annual
sales, general and heavy construction businesses with less than $27.5
million in annual business, special trade contractors doing less than
$11.5 million in annual business, and agricultural businesses with
annual sales less than $750,000. To determine whether potential
economic impacts to these small entities are significant, we considered
the types of activities that might trigger regulatory impacts under
this designation as well as types of project modifications that may
result. In general, the term ``significant economic impact'' is meant
to apply to a typical small business firm's business operations.
Under the RFA, as amended, and as understood in light of recent
court decisions, Federal agencies are required to evaluate the
potential incremental impacts of rulemaking on those entities directly
regulated by the rulemaking itself; in other words, the RFA does not
require agencies to evaluate the potential impacts to indirectly
regulated entities. The regulatory mechanism through which critical
habitat protections are realized is section 7 of the Act, which
requires Federal agencies, in consultation with the Service, to ensure
that any action authorized, funded, or carried out by the agency is not
likely to destroy or adversely modify critical habitat. Therefore,
under section 7, only Federal action agencies are directly subject to
the specific regulatory requirement (avoiding destruction and adverse
modification) imposed by critical habitat designation. Consequently, it
is our position that only Federal action agencies would be directly
regulated if we adopt the proposed critical habitat designations. The
RFA does not require evaluation of the potential impacts to entities
not directly regulated. Moreover, Federal agencies are not small
entities. Therefore, because no small entities would be directly
regulated by this rulemaking, the Service certifies that, if made final
as proposed, the proposed critical habitat designations will not have a
significant economic impact on a substantial number of small entities.
In summary, we have considered whether the proposed designations
would result in a significant economic impact on a substantial number
of small entities. For the above reasons and based on currently
available information, we certify that, if made final, the proposed
critical habitat designations would not have a significant economic
impact on a substantial number of small business entities. Therefore,
an initial regulatory flexibility analysis is not required.
Energy Supply, Distribution, or Use--Executive Order 13211
Executive Order 13211 (Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use) requires
agencies to prepare Statements of Energy Effects when undertaking
certain actions. Facilities that provide energy supply, distribution,
or use occur within some units of the proposed critical habitat
designations (for example, dams, pipelines) and may potentially be
affected. We determined that consultations, technical assistance, and
requests for species lists may be necessary in some instances. In our
economic analysis, we did not find that the proposed critical habitat
designations would significantly affect energy supplies, distribution,
or use. Therefore, this action is not a significant energy action, and
no Statement of Energy Effects is required.
Unfunded Mandates Reform Act (2 U.S.C. 1501 et seq.)
In accordance with the Unfunded Mandates Reform Act (2 U.S.C. 1501
et seq.), we make the following finding:
(1) This proposed rule would not produce a Federal mandate. In
general, a Federal mandate is a provision in legislation, statute, or
regulation that would impose an enforceable duty upon State, local, or
Tribal governments, or the private sector, and includes both ``Federal
intergovernmental mandates'' and ``Federal private sector mandates.''
These terms are defined in 2 U.S.C. 658(5)-(7). ``Federal
intergovernmental mandate'' includes a regulation that ``would impose
an enforceable duty upon State, local, or Tribal governments'' with two
exceptions. It excludes ``a condition of Federal assistance.'' It also
excludes ``a duty arising from participation in a voluntary Federal
program,'' unless the regulation ``relates to a then-existing Federal
program under which $500,000,000 or more is provided annually to State,
local, and Tribal governments under entitlement authority,'' if the
provision would ``increase the stringency of conditions of assistance''
or ``place caps upon, or otherwise decrease, the Federal Government's
responsibility to provide funding,'' and the State, local, or Tribal
governments ``lack authority'' to adjust accordingly. At the time of
enactment, these entitlement programs were: Medicaid; Aid to Families
with Dependent Children work programs; Child Nutrition; Food Stamps;
Social Services Block Grants; Vocational Rehabilitation State Grants;
Foster Care, Adoption Assistance, and Independent Living; Family
Support Welfare Services; and Child Support Enforcement. ``Federal
private sector mandate'' includes a regulation that ``would impose an
enforceable duty upon the private sector, except (i) a condition of
Federal assistance or (ii) a duty arising from participation in a
voluntary Federal program.''
The designation of critical habitat does not impose a legally
binding duty on non-Federal Government entities or private parties.
Under the Act, the only regulatory effect is that Federal agencies must
ensure that their actions do not destroy or adversely modify critical
habitat under section 7. While non-Federal entities that receive
Federal funding, assistance, or permits, or that otherwise require
approval or
[[Page 16817]]
authorization from a Federal agency for an action, may be indirectly
impacted by the designation of critical habitat, the legally binding
duty to avoid destruction or adverse modification of critical habitat
rests squarely on the Federal agency. Furthermore, to the extent that
non-Federal entities are indirectly impacted because they receive
Federal assistance or participate in a voluntary Federal aid program,
the Unfunded Mandates Reform Act would not apply, nor would critical
habitat shift the costs of the large entitlement programs listed above
onto State governments.
(2) We do not believe that this proposed rule would significantly
or uniquely affect small governments because the vast majority of the
lands being proposed for critical habitat designation are owned by the
Federal Government; States of Arkansas, Louisiana, Mississippi,
Oklahoma, and Texas; and private individuals. These entities do not fit
the definition of ``small governmental jurisdiction.'' One proposed
unit (TXHS-2a) includes a very small portion of land owned by the local
government, but that is only 1 percent of that one unit. Therefore, a
Small Government Agency Plan is not required.
Takings--Executive Order 12630
In accordance with E.O. 12630 (Government Actions and Interference
with Constitutionally Protected Private Property Rights), we have
analyzed the potential takings implications of designating critical
habitat for the Texas heelsplitter and Louisiana pigtoe in a takings
implications assessment. The Act does not authorize the Service to
regulate private actions on private lands or confiscate private
property as a result of critical habitat designation. Designation of
critical habitat does not affect land ownership, or establish any
closures, or restrictions on use of or access to the designated areas.
Furthermore, the designation of critical habitat does not affect
landowner actions that do not require Federal funding or permits, nor
does it preclude development of habitat conservation programs or
issuance of incidental take permits to permit actions that do require
Federal funding or permits to go forward. However, Federal agencies are
prohibited from carrying out, funding, or authorizing actions that
would destroy or adversely modify critical habitat. A takings
implications assessment has been completed for the proposed designation
of critical habitat for the Texas heelsplitter and the Louisiana
pigtoe, and it concludes that, if adopted, these designations of
critical habitat do not pose significant takings implications for lands
within or affected by the designations.
Federalism--Executive Order 13132
In accordance with E.O. 13132 (Federalism), this proposed rule does
not have significant federalism effects. A federalism summary impact
statement is not required. In keeping with Department of the Interior
and Department of Commerce policy, we requested information from, and
coordinated development of the proposed critical habitat designations
with, appropriate State resource agencies. From a federalism
perspective, the designation of critical habitat directly affects only
the responsibilities of Federal agencies. The Act imposes no other
duties with respect to critical habitat, either for States and local
governments, or for anyone else. As a result, the proposed rule does
not have substantial direct effects either on the States, or on the
relationship between the national government and the States, or on the
distribution of powers and responsibilities among the various levels of
government. The proposed designations may have some benefit to these
governments because the areas that contain the features essential to
the conservation of the species are more clearly defined, and the
physical or biological features of the habitat necessary for the
conservation of the species are specifically identified. This
information does not alter where and what federally sponsored
activities may occur. However, it may assist State and local
governments in long-range planning because they no longer have to wait
for case-by-case section 7 consultations to occur.
Where State and local governments require approval or authorization
from a Federal agency for actions that may affect critical habitat,
consultation under section 7(a)(2) of the Act would be required. While
non-Federal entities that receive Federal funding, assistance, or
permits, or that otherwise require approval or authorization from a
Federal agency for an action, may be indirectly impacted by the
designation of critical habitat, the legally binding duty to avoid
destruction or adverse modification of critical habitat rests squarely
on the Federal agency.
Civil Justice Reform--Executive Order 12988
In accordance with Executive Order 12988 (Civil Justice Reform),
the Office of the Solicitor has determined that the proposed rule would
not unduly burden the judicial system and that it meets the
requirements of sections 3(a) and 3(b)(2) of the Order. We have
proposed designating critical habitat in accordance with the provisions
of the Act. To assist the public in understanding the habitat needs of
the species, this proposed rule identifies the physical or biological
features essential to the conservation of the species. The proposed
areas of critical habitat are presented on maps, and the proposed rule
provides several options for the interested public to obtain more
detailed location information, if desired.
Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.)
This proposed rule does not contain information collection
requirements, and a submission to the Office of Management and Budget
(OMB) under the Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et
seq.) is not required. We may not conduct or sponsor and you are not
required to respond to a collection of information unless it displays a
currently valid OMB control number.
National Environmental Policy Act (42 U.S.C. 4321 et seq.)
It is our position that, outside the jurisdiction of the U.S. Court
of Appeals for the Tenth Circuit, we do not need to prepare
environmental analyses pursuant to the National Environmental Policy
Act (NEPA; 42 U.S.C. 4321 et seq.) in connection with regulations
adopted pursuant to section 4(a) of the Act. We published a notice
outlining our reasons for this determination in the Federal Register on
October 25, 1983 (48 FR 49244). This position was upheld by the U.S.
Court of Appeals for the Ninth Circuit (Douglas County v. Babbitt, 48
F.3d 1495 (9th Cir. 1995), cert. denied 516 U.S. 1042 (1996)). However,
when the range of the species includes States within the Tenth Circuit,
such as that of the Louisiana pigtoe, under the Tenth Circuit ruling in
Catron County Board of Commissioners v. U.S. Fish and Wildlife Service,
75 F.3d 1429 (10th Cir. 1996), we undertake a NEPA analysis for
critical habitat designation. We invite the public to comment on the
extent to which these proposed critical habitat designations may have a
significant impact on the human environment or fall within one of the
categorical exclusions for actions that have no individual or
cumulative effect on the quality of the human environment. We will
complete our analysis, in compliance with NEPA, before making a final
determination on this proposed rule.
[[Page 16818]]
Government-to-Government Relationship With Tribes
In accordance with the President's memorandum of April 29, 1994
(Government-to-Government Relations with Native American Tribal
Governments; 59 FR 22951), Executive Order 13175 (Consultation and
Coordination with Indian Tribal Governments), and the Department of the
Interior's manual at 512 DM 2, we readily acknowledge our
responsibility to communicate meaningfully with federally recognized
Tribes on a government-to-government basis. In accordance with
Secretarial Order 3206 of June 5, 1997 (American Indian Tribal Rights,
Federal-Tribal Trust Responsibilities, and the Endangered Species Act),
we readily acknowledge our responsibilities to work directly with
Tribes in developing programs for healthy ecosystems, to acknowledge
that Tribal lands are not subject to the same controls as Federal
public lands, to remain sensitive to Indian culture, and to make
information available to Tribes. We have determined that no Tribal
lands fall within the boundaries of the proposed critical habitat for
the Texas heelsplitter or Louisiana pigtoe, so no Tribal lands would be
affected by the proposed designations.
References Cited
A complete list of references cited in this rulemaking is available
on the internet at https://www.regulations.gov and upon request from
the Austin Ecological Services Field Office (see FOR FURTHER
INFORMATION CONTACT).
Authors
The primary authors of this proposed rule are the staff members of
the Fish and Wildlife Service's Species Assessment Team and the
Arlington Ecological Services Field Office.
List of Subjects in 50 CFR Part 17
Endangered and threatened species, Exports, Imports, Plants,
Reporting and recordkeeping requirements, Transportation, Wildlife.
Proposed Regulation Promulgation
Accordingly, we propose to amend part 17, subchapter B of chapter
I, title 50 of the Code of Federal Regulations, as set forth below:
PART 17--ENDANGERED AND THREATENED WILDLIFE AND PLANTS
0
1. The authority citation for part 17 continues to read as follows:
Authority: 16 U.S.C. 1361-1407; 1531-1544; and 4201-4245,
unless otherwise noted.
0
2. Amend Sec. 17.11(h) by adding entries for ``Heelsplitter, Texas''
and ``Pigtoe, Louisiana'' to the List of Endangered and Threatened
Wildlife in alphabetical order under CLAMS to read as follows:
Sec. 17.11 Endangered and threatened wildlife.
* * * * *
(h) * * *
----------------------------------------------------------------------------------------------------------------
Listing citations and
Common name Scientific name Where listed Status applicable rules
----------------------------------------------------------------------------------------------------------------
* * * * * * *
Clams
* * * * * * *
Heelsplitter, Texas............. Potamilus Wherever found.... E [Federal Register
amphichaenus. citation when
published as a final
rule]; 50 CFR
17.95(f).\CH\
* * * * * * *
Pigtoe, Louisiana............... Pleurobema Wherever found.... T [Federal Register
riddellii. citation when
published as a final
rule]; 50 CFR
17.45(g); \4d\ 50 CFR
17.95(f).\CH\
* * * * * * *
----------------------------------------------------------------------------------------------------------------
0
3. Further amend Sec. 17.45, as proposed to be amended on September
29, 2020, at 85 FR 61384, on August 26, 2021, at 86 FR 47916, and on
September 7, 2021, at 86 FR 50010, and by adding paragraphs (f) and (g)
to read as follows:
Sec. 17.45 Special rules--snails and clams.
* * * * *
(f) [Reserved]
(g) Louisiana pigtoe (Pleurobema riddellii).
(1) Prohibitions. The following prohibitions that apply to
endangered wildlife also apply to the Louisiana pigtoe. Except as
provided under paragraph (g)(2) of this section and Sec. Sec. 17.4 and
17.5, it is unlawful for any person subject to the jurisdiction of the
United States to commit, to attempt to commit, to solicit another to
commit, or cause to be committed, any of the following acts in regard
to Louisiana pigtoe:
(i) Import or export, as set forth at Sec. 17.21(b) for endangered
wildlife.
(ii) Take, as set forth at Sec. 17.21(c)(1) for endangered
wildlife.
(iii) Possession and other acts with unlawfully taken specimens, as
set forth at Sec. 17.21(d)(1) for endangered wildlife.
(iv) Interstate or foreign commerce in the course of commercial
activity, as set forth at Sec. 17.21(e) for endangered wildlife.
(v) Sale or offer for sale, as set forth at Sec. 17.21(f) for
endangered wildlife.
(2) Exceptions from prohibitions. In regard to this species, you
may:
(i) Conduct activities as authorized by a permit under Sec. 17.32.
(ii) Take, as set forth at Sec. 17.21(c)(2) through (4) for
endangered wildlife.
(iii) Take as set forth at Sec. 17.31(b).
(iv) Possess and engage in other acts with unlawfully taken
wildlife, as set forth at Sec. 17.21(d)(2) for endangered wildlife.
(v) Take incidental to an otherwise lawful activity caused by:
(A) Channel restoration projects that create natural, physically
stable, ecologically functioning streams (or stream and wetland
systems) that are reconnected with their groundwater aquifers.
(B) Bioengineering methods such as streambank stabilization using
live native stakes (live, vegetative cuttings inserted or tamped into
the ground in a manner that allows the stake to take root and grow),
live native fascines (live branch cuttings, usually willows, bound
together into long, cigar-shaped bundles), or native brush layering
(cuttings or branches of easily rooted tree species layered between
successive lifts of soil fill). These methods must not include the sole
use of quarried rock (rip-rap) or the use of rock baskets or gabion
structures. In addition, to reduce streambank erosion and sedimentation
[[Page 16819]]
into the stream, work using these bioengineering methods must be
performed at base-flow or low-water conditions and when significant
rainfall is not predicted. Further, streambank stabilization projects
must keep all equipment out of the stream channels and water.
(C) Soil and water conservation practices and riparian and adjacent
upland habitat management activities that restore instream habitats for
the species, restore adjacent riparian habitats that enhance stream
habitats for the species, stabilize degraded and eroding stream banks
to limit sedimentation and scour of the species' habitats, and restore
or enhance nearby upland habitats to limit sedimentation of the
species' habitats. We recommend that these practices and activities
comply with specifications and technical guidelines developed by the
U.S. Department of Agriculture's Natural Resources Conservation
Service.
0
4. Amend Sec. 17.95(f) by adding an entry for ``Texas Heelsplitter
(Potamilus amphichaenus)'' after the entry for ``Carolina Heelsplitter
(Lasmigona decorata)'', and by adding an entry for ``Louisiana Pigtoe
(Pleurobema riddellii)'' after the entry for ``Georgia Pigtoe
(Pleurobema hanleyianum)'', to read as follows:
Sec. 17.95 Critical habitat--fish and wildlife.
* * * * *
(f) Clams and Snails.
* * * * *
Texas Heelsplitter (Potamilus amphichaenus)
(1) Critical habitat units are depicted for Anderson, Angelina,
Cherokee, Ellis, Freestone, Gregg, Grimes, Hardin, Harrison, Henderson,
Houston, Jasper, Jefferson, Kaufman, Leon, Madison, Navarro, Orange,
Panola, Polk, Rains, Rusk, Sabine, Shelby, Smith, Trinity, Tyler,
Upshur, Van Zandt, Walker, and Wood Counties, Texas, on the maps in
this entry.
(2) Within these areas, the physical or biological features
essential to the conservation of Texas heelsplitter consist of the
following components within impoundments and streambeds:
(i) Water quality parameters within the following ranges:
(A) Water temperature below 27 [deg]C (80.6 [deg]F);
(B) Dissolved oxygen levels greater than 3 milligrams per liter
(mg/L);
(C) Low salinity (less than 2 parts per thousand) and total
dissolved solids;
(D) Low total ammonia and nitrogen (below 0.3-0.7 mg/L total
ammonia nitrogen);
(E) Low levels of copper, nickel, and other trace metals;
(F) Low levels of pesticides, sulfate, chloride, potassium, and
other harmful constituents; and
(G) Low pollutants and environmental contaminants common to
wastewater.
(ii) Moderately flowing water rates suitable to prevent excess
sedimentation but not so high as to dislodge individuals or sediment;
or no water flow, if in an impoundment (lake, reservoir, or pool
without flow).
(iii) Substrate including bedrock and boulder crevices, point bars,
and vegetated run habitat comprising sand, gravel, and larger cobbles.
(iv) Freshwater drum (Aplodinotus grunniens) present.
(3) Critical habitat does not include manmade structures (such as
buildings, aqueducts, runways, roads, and other paved areas) and the
land on which they are located existing within the legal boundaries on
the effective date of the final rule.
(4) Data layers defining map units were created on a base of U.S.
Geological Survey digital ortho-photo quarter-quadrangles, and critical
habitat units were then mapped using Universal Transverse Mercator
(UTM) Zone 14N coordinates. The maps in this entry, as modified by any
accompanying regulatory text, establish the boundaries of the critical
habitat designation. The coordinates or plot points or both on which
each map is based are available to the public at the Service's internet
site at https://www.fws.gov/office/arlington-ecological-services, at
https://www.regulations.gov at Docket No. FWS-R2-ES-2022-0026, and at
the field office responsible for this designation. You may obtain field
office location information by contacting one of the Service regional
offices, the addresses of which are listed at 50 CFR 2.2.
(5) Index map of critical habitat units for the Texas heelsplitter
follows:
Figure 1 to Texas Heelsplitter (Potamilus amphichaenus) paragraph (5)
BILLING CODE 4333-15-P
[[Page 16820]]
[GRAPHIC] [TIFF OMITTED] TP20MR23.024
(6) Unit TXHS-1: Trinity River Unit; Anderson, Ellis, Freestone,
Grimes, Henderson, Houston, Kaufman, Leon, Madison, Navarro, and Walker
Counties, Texas.
(i) Unit TXHS-1 consists of two subunits:
(A) Subunit TXHS-1a (Trinity River) is comprised of 212.8 river
miles (mi) (342.4 kilometers (km)) in Anderson, Ellis, Freestone,
Henderson, Houston, Kaufman, Leon, Madison, and Navarro Counties,
Texas. This subunit is composed of lands in State (5 percent) and
private (95 percent) ownership.
(B) Subunit TXHS-1b (Bedias Creek) is comprised of 28.9 river mi
(46.5 km) in Grimes, Madison, and Walker Counties, Texas. All of the
riparian lands that border this subunit are in private ownership.
(ii) Unit TXHS-1 includes stream channel up to bankfull height.
(iii) Map of Unit TXHS-1 follows:
Figure 2 to Texas Heelsplitter (Potamilus amphichaenus) paragraph
(6)(iii)
[[Page 16821]]
[GRAPHIC] [TIFF OMITTED] TP20MR23.025
(7) Unit TXHS-2: Sabine River Unit; Gregg, Harrison, Panola, Rains,
Rusk, Sabine, Shelby, Smith, Upshur, Van Zandt, and Wood Counties,
Texas.
(i) Unit TXHS-2 consists of three subunits:
(A) Subunit TXHS-2a (Upper Sabine River) is comprised of 237.4
river mi (382 km) in Gregg, Harrison, Panola, Rains, Rusk, Smith,
Upshur, Van Zandt, and Wood Counties, Texas. The riparian lands that
border this subunit include Federal (2 percent), State (4 percent),
local (1 percent), and private (93 percent) ownership.
(B) Subunit TXHS-2b (Lake Fork Creek) consists of 13.8 river mi
(22.2 km) in Wood County, Texas. All of the riparian lands that border
this subunit are in private ownership.
(C) Subunit TXHS-2c (Patroon Bayou) includes 19.9 river mi (32 km)
in Sabine and Shelby Counties, Texas. The riparian lands that border
this subunit are in Federal (7 percent) and private (93 percent)
ownership.
(ii) Unit TXHS-2 includes stream channel up to bankfull height.
(iii) Map of Unit TXHS-2 follows:
Figure 3 to Texas Heelsplitter (Potamilus amphichaenus) paragraph
(7)(iii)
[[Page 16822]]
[GRAPHIC] [TIFF OMITTED] TP20MR23.026
(8) Unit TXHS-3: Neches River Unit; Anderson, Angelina, Cherokee,
Hardin, Houston, Jasper, Jefferson, Orange, Polk, Trinity, and Tyler
Counties, Texas.
(i) Unit TXHS-3 consists of three subunits:
(A) Subunit TXHS-3a (Upper Neches River) is comprised of 227.9
river mi (366.7 km) of stream in Anderson, Angelina, Cherokee, Houston,
Jasper, Polk, Trinity, and Tyler Counties, Texas. The riparian lands
that border this subunit are in Federal (12 percent) and private (88
percent) ownership.
(B) Subunit TXHS-3b (Lower Angelina River) consists of 14.7 river
mi (23.7 km) in Jasper County, Texas. The riparian lands that border
this subunit are in Federal (11 percent) and private (89 percent)
ownership.
(C) Subunit TXHS-3c (Lower Neches River) includes 76.3 river mi
(122.8 km) in Hardin, Jasper, Jefferson, Orange, and Tyler Counties,
Texas. The riparian lands that border this subunit are in Federal (5
percent), State (7 percent), and private (88 percent) ownership.
(ii) Unit TXHS-3 includes stream channel up to bankfull height.
(iii) Map of Unit TXHS-3 follows:
Figure 4 to Texas Heelsplitter (Potamilus amphichaenus) paragraph
(8)(iii)
[[Page 16823]]
[GRAPHIC] [TIFF OMITTED] TP20MR23.027
* * * * *
Louisiana Pigtoe (Pleurobema riddellii)
(1) Critical habitat units are depicted for Howard, Little River,
and Sevier Counties, Arkansas; Allen, Beauregard, Rapides, St. Tammany,
Vernon, and Washington parishes, Louisiana; Marion and Pearl River
Counties, Mississippi; McCurtain County, Oklahoma; and Anderson,
Angelina, Cherokee, Gregg, Hardin, Harrison, Houston, Jasper,
Jefferson, Liberty, Montgomery, Nacogdoches, Orange, Panola, Polk,
Rusk, Smith, Trinity, Tyler, Upshur, and Wood Counties, Texas, on the
maps in this entry.
(2) Within this area, the physical or biological features essential
to the conservation of Louisiana pigtoe consist of the following
components within streambeds:
(i) Water quality parameters within the following ranges:
(A) Water temperature below 27 [deg]C (80.6 [deg]F);
(B) Dissolved oxygen levels greater than 3 milligrams per liter
(mg/L);
(C) Low salinity (less than 2 parts per thousand) and total
dissolved solids;
(D) Low total ammonia and nitrogen (below 0.3-0.7 mg/L total
ammonia nitrogen);
[[Page 16824]]
(E) Low levels of copper, nickel, and other trace metals;
(F) Low levels of pesticides, sulfate, chloride, potassium, and
other harmful constituents; and
(G) Low pollutants and environmental contaminants common to
wastewater.
(ii) Moderately flowing water rates suitable to prevent excess
sedimentation but not so high as to dislodge individuals or sediment.
(iii) Stable bank and riffle habitats with bedrock and boulder
crevices, point bars, and vegetated run habitat comprising sand,
gravel, and larger cobbles.
(iv) Red shiner (Cyprinella (=Notropis) lutrensis), blacktail
shiner (Cyprinella venusta), and bullhead minnow (Pimephales vigilax)
present.
(3) Critical habitat does not include manmade structures (such as
buildings, aqueducts, runways, roads, and other paved areas) and the
land on which they are located existing within the legal boundaries on
the effective date of the final rule.
(4) Data layers defining map units were created on a base of U.S.
Geological Survey digital ortho-photo quarter-quadrangles, and critical
habitat units were then mapped using Universal Transverse Mercator
(UTM) Zone 14N coordinates. The maps in this entry, as modified by any
accompanying regulatory text, establish the boundaries of the critical
habitat designation. The coordinates or plot points or both on which
each map is based are available to the public at the Service's internet
site at https://www.fws.gov/office/arlington-ecological-services, at
https://www.regulations.gov at Docket No. FWS-R2-ES-2022-0026, and at
the field office responsible for this designation. You may obtain field
office location information by contacting one of the Service regional
offices, the addresses of which are listed at 50 CFR 2.2.
(5) Index map of critical habitat units for the Louisiana pigtoe
follows:
Figure 1 to Louisiana Pigtoe (Pleurobema riddellii) paragraph (5)
[[Page 16825]]
[GRAPHIC] [TIFF OMITTED] TP20MR23.028
(6) Unit LAPT-1: Little River Unit; Howard, Little River, and
Sevier Counties, Arkansas, and McCurtain County, Oklahoma.
(i) Unit LAPT-1 consists of four subunits:
(A) Subunit LAPT-1a (Upper Little River) is comprised of consists
of approximately 88 river miles (mi) (141.6 kilometers (km)) in Little
River and Sevier Counties, Arkansas, and McCurtain County, Oklahoma.
The riparian lands that border this subunit are in Federal (26
percent), State (1 percent), and private (42 percent) ownership, and
private land with the Choctaw Reservation (23 percent), but not any
lands held in trust for the Tribe, or owned or managed by the Tribe.
(B) Subunit LAPT-1b (Rolling Fork) is comprised of 29.9 river mi
(47.9 km) in Sevier County, Arkansas. All of the riparian lands that
border this subunit are in private ownership.
(C) Subunit LAPT-1c (Cossatot River) includes 47.2 river mi (75.9
km) in Sevier County, Arkansas. The riparian lands that border this
subunit are in Federal (15 percent) and private (85 percent) ownership.
(D) Subunit LAPT-1d (Saline River) consists of 42.6 river mi (68.5
km) along the Howard/Sevier County line in southeast Arkansas. All of
the riparian
[[Page 16826]]
lands in this subunit are in private ownership.
(ii) Unit LAPT-1 includes stream channel up to bankfull height.
(iii) Map of Unit LAPT-1 follows:
Figure 2 to Louisiana Pigtoe (Pleurobema riddellii) paragraph (6)(iii)
[GRAPHIC] [TIFF OMITTED] TP20MR23.029
(7) Unit LAPT-2: Sabine River Unit; Beauregard and Vernon parishes,
Louisiana, and Gregg, Harrison, Panola, Rusk, Smith, Upshur, and Wood
Counties, Texas.
(i) Unit LAPT-2 consists of two subunits:
(A) Subunit LAPT-2a (Upper Sabine River) consists of 110.1 river mi
(177.2 km) in Gregg, Harrison, Panola, Rusk, Smith, Upshur, and Wood
Counties, Texas. The riparian lands that border this subunit are in
Federal (2 percent), State (2 percent), and private (96 percent)
ownership.
(B) Subunit LAPT-2b (Anacoco Bayou) includes 12.2 river mi (19.6
km)
[[Page 16827]]
in Vernon and Beauregard parishes, Louisiana. All of the riparian lands
that border this subunit are in private ownership.
(ii) Unit LAPT-2 includes stream channel up to bankfull height.
(iii) Map of Unit LAPT-2 follows:
Figure 3 to Louisiana Pigtoe (Pleurobema riddellii) paragraph (7)(iii)
[GRAPHIC] [TIFF OMITTED] TP20MR23.030
(8) Unit LAPT-3: Neches River Unit; Anderson, Angelina, Cherokee,
Hardin, Houston, Jasper, Jefferson, Nacogdoches, Orange, Polk, Trinity,
and Tyler Counties, Texas.
(i) Unit LAPT-3 consists of five subunits:
(A) Subunit LAPT-3a (Upper Neches River) consists of 200.4 river mi
(322.4 km) through parts of Anderson, Angelina, Cherokee, Houston,
Polk, Trinity, and Tyler Counties, Texas. The riparian lands that
border this subunit are in Federal (11 percent) and private (89
percent) ownership.
[[Page 16828]]
(B) Subunit LAPT-3b (Upper Angelina River) consists of 67.4 river
mi (108.4 km) in Angelina, Cherokee, and Nacogdoches Counties, Texas.
The riparian lands that border this subunit are in Federal (50 percent)
and private (50 percent) ownership.
(C) Subunit LAPT-3c (Lower Neches River) includes 76.2 river mi
(122.6 km) in Hardin, Jasper, Jefferson, Orange, and Tyler Counties,
Texas. The riparian lands that border this subunit are in Federal (5
percent), State (7 percent), and private (88 percent) ownership.
(D) Subunit LAPT-3d (Village Creek) consists of 54.9 river mi (88.3
km) of stream in Hardin County, Texas. The riparian lands that border
this subunit are in Federal (78 percent), State (2 percent), and
private (20 percent) ownership.
(E) Subunit LAPT-3e (Big Sandy Creek) consists of 43.7 river mi
(70.3 km) of stream in Hardin, Polk, and Tyler Counties, Texas. The
riparian lands that border this subunit are in Federal (95 percent) and
private (5 percent) ownership.
(ii) Unit LAPT-3 includes stream channel up to bankfull height.
(iii) Map of Unit LAPT-3 follows:
Figure 4 to Louisiana Pigtoe (Pleurobema riddellii) paragraph (8)(iii)
[[Page 16829]]
[GRAPHIC] [TIFF OMITTED] TP20MR23.031
(9) Unit LAPT-4: East Fork San Jacinto River Unit; Liberty and
Montgomery Counties, Texas.
(i) Unit LAPT-4 consists of 23.3 river mi (37.5 km) in Liberty and
Montgomery Counties, Texas. All of the riparian lands that border this
unit are in private ownership.
(ii) Unit LAPT-4 includes stream channel up to bankfull height.
(iii) Map of Unit LAPT-4 follows:
Figure 5 to Louisiana Pigtoe (Pleurobema riddellii) paragraph (9)(iii)
[[Page 16830]]
[GRAPHIC] [TIFF OMITTED] TP20MR23.032
(10) Unit LAPT-5: Calcasieu River Unit; Allen, Rapides, and Vernon
parishes, Louisiana.
(i) Unit LAPT-5 consists of three subunits:
(A) Subunit LAPT-5a (Upper Calcasieu River) includes 92 river mi
(148 km) in Allen and Rapides parishes, Louisiana. The riparian lands
that border this subunit are in Federal (22 percent) and private (78
percent) ownership.
(B) Subunit LAPT-5b (Whisky Chitto Creek) includes 21.7 river mi
(34.9 km) in Allen Parish, Louisiana. The riparian lands that border
this subunit are in State (99 percent) and private (1 percent)
ownership.
(C) Subunit LAPT-5c (Tenmile Creek) consists of 32 river mi (51.5
km) in Allen, Rapides, and Vernon parishes, Louisiana. The riparian
lands that border the subunit are in State (2 percent) and private (98
percent) ownership.
(ii) Unit LAPT-5 includes stream channel up to bankfull height.
(iii) Map of Unit LAPT-5 follows:
Figure 6 to Louisiana Pigtoe (Pleurobema riddellii) paragraph (10)(iii)
[[Page 16831]]
[GRAPHIC] [TIFF OMITTED] TP20MR23.033
(11) Unit LAPT-6: Pearl River Unit; St. Tammany and Washington
parishes, Louisiana, and Marion and Pearl River Counties, Mississippi.
(i) Unit LAPT-6 consists of 86.6 river mi (139.3 km) in St. Tammany
and Washington parishes, Louisiana, and Marion and Pearl River
Counties, Mississippi. The riparian lands that border this unit are in
Federal (42 percent), State (14 percent), and private (44 percent)
ownership.
(ii) Unit LAPT-6 includes stream channel up to bankfull height.
(iii) Map of Unit LAPT-6 follows:
Figure 7 to Louisiana Pigtoe (Pleurobema riddellii) paragraph (11)(iii)
[[Page 16832]]
[GRAPHIC] [TIFF OMITTED] TP20MR23.034
* * * * *
Martha Williams,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 2023-05107 Filed 3-17-23; 8:45 am]
BILLING CODE 4333-15-C