Endangered and Threatened Wildlife and Plants; 12-Month Finding on a Petition To List 14 Aquatic Mollusks as Endangered or Threatened, 57921-57948 [2012-22723]
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Vol. 77
Tuesday,
No. 181
September 18, 2012
Part IV
Department of the Interior
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Fish and Wildlife Service
50 CFR Part 17
Endangered and Threatened Wildlife and Plants; 12-Month Finding on a
Petition To List 14 Aquatic Mollusks as Endangered or Threatened;
Proposed Rule
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS–R8–ES–2011–0076:
4500030113]
Endangered and Threatened Wildlife
and Plants; 12-Month Finding on a
Petition To List 14 Aquatic Mollusks as
Endangered or Threatened
Fish and Wildlife Service,
Interior.
ACTION: Notice of 12-month petition
finding.
AGENCY:
We, the U.S. Fish and
Wildlife Service (Service), announce a
12-month finding on a petition to list
the basalt juga (Juga new species (n. sp.)
2), canary duskysnail (Colligyrus
convexus), cinnamon juga (Juga n. sp.
3), Columbia duskysnail (Colligyrus n.
sp. 1), Fredenburg pebblesnail
(Fluminicola n. sp. 11), Goose Valley
pebblesnail (Fluminicola anserinus),
Hat Creek pebblesnail (Fluminicola
umbilicatus), Klamath Rim pebblesnail
(Fluminicola n. sp. 3), knobby ramshorn (Vorticifex n. sp. 1), masked
duskysnail (Colligyrus n. sp. 2), nugget
pebblesnail (Fluminicola seminalis),
Potem Creek pebblesnail (Fluminicola
potemicus), Shasta pebblesnail
(Fluminicola multifarius), and tall
pebblesnail (Fluminicola n. sp. 2) as
endangered or threatened, and to
designate critical habitat, under the
Endangered Species Act of 1973, as
amended (Act). The Fredenburg
pebblesnail and the Klamath Rim
pebblesnail were referred to in the
petition and in our 90-day finding (76
FR 61826) as the nerite pebblesnail and
the diminutive pebblesnail, respectively
(see Clarification Regarding Common
Names for Two Petitioned Aquatic
Mollusks, below). After review of the
best available scientific and commercial
information, we find that listing the
basalt juga, cinnamon juga, Columbia
duskysnail, Fredenburg pebblesnail,
Klamath Rim pebblesnail, knobby ramshorn, masked duskysnail, and tall
pebblesnail is not warranted at this time
because these snails do not constitute
listable entities under the Act (see
Listable Entity Evaluation, below). We
ask the public to submit to us new
information that becomes available
concerning the taxonomic status of
these mollusks. We find that listing the
canary duskysnail, Goose Valley
pebblesnail, Hat Creek pebblesnail,
nugget pebblesnail, Potem Creek
pebblesnail, and Shasta pebblesnail is
not warranted at this time. We ask the
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SUMMARY:
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public to submit to us new information
that becomes available concerning
threats to these mollusks.
DATES: The finding announced in this
document was made on September 18,
2012.
ADDRESSES: This finding is available on
the Internet at https://
www.regulations.gov at Docket Number
FWS–R8–ES–2011–0076. Supporting
documentation we used in preparing
this finding is available for public
inspection, by appointment, during
normal business hours at the U.S. Fish
and Wildlife Service, Sacramento Fish
and Wildlife Office, 2800 Cottage Way,
Room W–2605, Sacramento, California
95825. Please submit any new
information, materials, comments, or
questions concerning this finding to the
above address.
FOR FURTHER INFORMATION CONTACT:
Listing Coordinator, U.S. Fish and
Wildlife Service, Sacramento Fish and
Wildlife Office (see ADDRESSES); by
telephone at 916–414–6600; or by
facsimile at 916–414–6712 mailto:. If
you use a telecommunications device
for the deaf (TDD), please call the
Federal Information Relay Service
(FIRS) at 800–877–8339.
SUPPLEMENTARY INFORMATION:
List of Acronyms
To assist the reader, the following is
a partial list of acronyms that are used
in this document.
ACS = Aquatic Conservation Strategy
ANSTF = Aquatic Nuisance Species Task
Force
BNSF = Burlington Northern and Santa Fe
CAL FIRE = California Department of
Forestry and Fire Protection
CBD = Center for Biological Diversity
CDFG = California Department of Fish and
Game
CDPR = California Department of Parks and
Recreation
CNDDB = California Natural Diversity
Database
DPS = distinct population segment
FERC = Federal Energy Regulatory
Commission
FPA = Forest Practice Act
FRRCD = Fall River Resource Conservation
District
IPCC = Intergovernmental Panel on Climate
Change
NBII = National Biological Information
Infrastructure
NWP = Northwest Forest Plan
OHV = off-highway vehicle
ORNHIC = Oregon Natural Heritage and
Information Center
PDA = Public Domain Allotment
PGE = Pacific Gas and Electric Company
RCAs = Riparian Conservation Areas
SHU = Shasta–Trinity Unit
SMP = Survey and Manage Program
SNFPA = Sierra Nevada Forest Plan
Amendment
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SPR = significant portion of the range
SWRCB = State Water Resources Control
Board
THP = Timber Harvest Plan
Background
Section 4(b)(3)(B) of the Act (16
U.S.C. 1531 et seq.) requires that, for
any petition to revise the Federal Lists
of Threatened and Endangered Wildlife
and Plants that contains substantial
scientific or commercial information
that listing a species may be warranted,
we make a finding within 12 months of
the date of receipt of the petition. In this
finding, we will determine that the
petitioned action is: (1) Not warranted;
(2) warranted; or (3) warranted, but the
immediate proposal of a regulation
implementing the petitioned action is
precluded by other pending proposals to
determine whether species are
endangered or threatened, and
expeditious progress is being made to
add or remove qualified species from
the Federal Lists of Endangered and
Threatened Wildlife and Plants. Section
4(b)(3)(C) of the Act requires that we
treat a petition for which the requested
action is found to be warranted but
precluded as though resubmitted on the
date of such finding, that is, requiring a
subsequent finding to be made within
12 months. We must publish these 12month findings in the Federal Register.
Previous Federal Actions
On March 17, 2008, we received a
petition dated March 13, 2008, from five
conservation organizations: The Center
for Biological Diversity (CBD),
Conservation Northwest, the
Environmental Protection Information
Center, the Klamath-Siskiyou Wildlands
Center, and Oregon Wild. The petition
asked us to list 32 species and
subspecies of snails and slugs
(mollusks) in the Pacific Northwest as
threatened or endangered under the Act.
Additionally, the petition requested that
we designate critical habitat concurrent
with listing. The petition clearly
identified itself as a petition and
included identification information
regarding the petitioners, as required by
title 50 of the Code of Federal
Regulations (CFR) in 424.14(a). The
petition included the 14 aquatic
mollusk species addressed in this
finding, and provided supporting
information regarding the species’
taxonomy and ecology, range, present
status, and actual and potential causes
of decline.
In a June 27, 2008, letter to the
petitioners, we responded that we had
reviewed the information presented in
the petition and determined that issuing
an emergency regulation temporarily
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listing the species as per section 4(b)(7)
of the Act was not warranted. We also
stated that we could not address their
petition at that time due to court orders
and judicially approved settlement
agreements for other listing and critical
habitat determinations under the Act
that required nearly all of our listing
and critical habitat funding for fiscal
years 2008 and 2009. We indicated that
we anticipated making an initial finding
on their petition in fiscal year 2010.
On April 13, 2009, we received a
signed email from CBD providing
updated taxonomic information
regarding some of the 32 petitioned
mollusk species (Curry 2009, pp. 1–2).
The email indicated that two of the
species had been formally described,
two others had been combined into a
single species that had been formally
described, and three additional
petitioned species had been combined
into a single species that had been
formally described. The email provided
a citation to the article making the
taxonomic changes, and asked us to
consider the revised species for listing
as endangered or threatened under the
Act. We treated this email message as an
amendment to the original petition.
Therefore, the amended petition asked
us to list 29 species and subspecies of
mollusks, including the 14 aquatic
species addressed here.
We addressed the petition as funding
permitted beginning in late 2009, and
published a 90-day finding on October
5, 2011 (76 FR 61826). We found that
substantial scientific and commercial
information had been presented in the
petition and existed in our files to
indicate listing may be warranted for 26
of the 29 petitioned mollusks. Fourteen
of those 26 mollusks are aquatic and 12
are terrestrial. We have initiated a status
review of the 14 aquatic mollusks, and
present the results here. We intend to
review the status of the remaining 12
terrestrial mollusks in fiscal year 2013.
This notice constitutes our 12-month
finding on the June 27, 2008, petition
(as amended on April 13, 2009) to list
14 aquatic mollusks as endangered or
threatened.
Clarification Regarding Common Names
for Two Petitioned Aquatic Mollusks
The mollusks petitioned for listing
included the ‘‘diminutive pebblesnail
(Fluminicola n. sp. 3)’’ (CBD et al. 2008,
pp. 9, 44) and the ‘‘nerite pebblesnail
(Fluminicola n. sp. 11)’’ (CBD et al.
2008, pp. 9, 46). In our 90-day finding,
which was limited in scope to
information provided by the petition
and available in our files, we noted that
these mollusks were sometimes referred
to by cited sources other than the
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petition as the Klamath Rim pebblesnail
and the Fredenburg pebblesnail,
respectively (76 FR 61836, 61843).
Information that we reviewed for this
status review indicates that the only
accepted common names for these
mollusks are the Klamath Rim
pebblesnail and the Fredenburg
pebblesnail. The only sources that refer
to these two mollusks by the common
names used in the petition are the
Oregon Natural Heritage and
Information Center (ORNHIC) (2004d, p.
1) for the diminutive pebblesnail, and
ORNHIC (2004j, p. 1) for the nerite
pebblesnail. However, these must be
incorrect rather than simply alternate
common names because Frest and
Johannes (the original discoverers of
these snails) refer to all four named
mollusks as separate species (Frest and
Johannes 1993, pp. 46, 47, 49; Frest and
Johannes 2000, pp. 181, 264, 267, 273).
They note that the Klamath Rim and
Fredenburg pebblesnails are protected
under the Survey and Manage Program
(SMP) of the Northwest Forest Plan
(NWFP) (see Generally Applicable
Federal Regulatory Mechanisms, below),
whereas the diminutive and nerite
pebblesnails ‘‘should be’’ included in
that program (Frest and Johannes 2000,
pp. 264, 265, 268, 274). The petition
only included mollusks that had been
protected under the SMP (CBD et al.
2008, p. 12). An Environmental Impact
Statement (EIS) on which we relied in
our 90-day finding for information
regarding occupied locations of various
mollusks, identifies all the petitioned
mollusks by their scientific names
alone, without providing common
names (for example, U.S. Department of
Agriculture (USDA) and U.S.
Department of the Interior (USDI) 2007,
pp. 92, 251).
In the case of these two mollusks, the
‘‘scientific names’’ were provisional and
subject to change in different documents
(Frest and Johannes 1993, pp. 46, 49;
Frest and Johannes 2000, pp. 264, 273)
(see Listable Entity Evaluation, below).
However, we have subsequently
obtained the survey protocol for aquatic
mollusk species under the SMP, and
that document identifies Fluminicola n.
sp. 3 and n. sp. 11 as the Klamath Rim
and Fredenburg pebblesnails,
respectively (Furnish et al. 1997, p. 29).
It does not mention the diminutive or
nerite pebblesnails, presumably because
they were not protected by the SMP.
Accordingly, in this document we will
refer to the petitioned mollusk
Fluminicola n. sp. 3 as the Klamath Rim
pebblesnail and to the petitioned
mollusk Fluminicola n. sp. 11 as the
Fredenburg pebblesnail, rather than as
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the diminutive and nerite pebblesnails,
respectively.
Listable Entity Evaluation
Section 3(16) of the Act defines the
term ‘‘species’’ to include ‘‘any
subspecies of fish or wildlife or plants,
and any distinct population segment
(DPS) of any species of vertebrate fish or
wildlife which interbreeds when
mature.’’ Taxonomic groups or entities
that meet the Act’s definition of a
‘‘species’’ can be considered for listing
under the Act and are, therefore,
referred to as ‘‘listable entities.’’ Listable
entities can then be listed if they are
determined to meet the definition of
either an endangered or threatened
species.
Of the 14 aquatic mollusks considered
in this review, 8 have not been formally
described as species or subspecies in a
peer-reviewed journal, or in any other
source commonly accepted by the
scientific community. This is why they
have provisional scientific names,
including ‘‘new species’’ (or ‘‘n. sp.’’)
and a number, rather than accepted
species names. Formal peer-reviewed
description, with its opportunities for
further review and comment, is the
process by which proposed new species
and subspecies become generally
recognized or rejected by the taxonomic
community. We must therefore evaluate
whether the best available scientific and
commercial information indicates that
these eight mollusks constitute valid
species, despite their lack of formal
descriptions, for the purpose of
determining whether the mollusks in
question constitute listable entities (16
U.S.C. 1533(b)(3)(A) and (B)). It is rare
for us to list entities that have not been
formally described, but we have
occasionally done so in the past.
Examples include two fish: The Hutton
tui chub (Gila bicolor ssp.) and Foskett
speckled dace (Rhinichthys osculus
ssp.) (50 FR 12302; March 28, 1985). In
those instances, there was general
agreement among biologists familiar
with these fish that they constituted
listable subspecies, and formal
descriptions of the subspecies were in
preparation. Additionally, if our
determination of the status of these fish
as valid subspecies had been incorrect,
the fish would still likely have
constituted distinct vertebrate
population segments, and thus qualified
as listable entities under section 3(16) of
the Act. Mollusk populations are not
listable entities, unless they also
constitute valid species or subspecies,
because the provision in section 3(16)
allowing DPSs to be listed only applies
to vertebrates (16 U.S.C. 1532(16)).
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The eight aquatic mollusks reviewed
here that have not been formally
described are: Basalt juga, cinnamon
juga, Columbia duskysnail, Fredenburg
pebblesnail, Klamath Rim pebblesnail,
knobby rams-horn, masked duskysnail,
and tall pebblesnail. Table 1 below
summarizes basic taxonomic and
biological information for these
purported species.
TABLE 1—BASIC BIOLOGY OF MOLLUSKS LACKING FORMAL DESCRIPTIONS
Common
name
Description
Habitat
Known sites
Basalt
juga.
Shell about 22 by 10 mm *; color bands of
yellow, brown, pink, white, or tan (Frest
and Johannes 1999, p. 85).
Small, gravelly springs with unpolluted
water (Frest and Johannes 1995a, p.
179).
Cinnamon
juga.
Shell about 15 by 8 mm; cinnamon red
but can appear black in the field (Frest
and Johannes 1999, p. 89).
Columbia
duskysnail.
Shell about 1.7 by 1.4 mm; translucent,
off-white, often with rust to black coating (Frest and Johannes 1999, p. 69).
Large cold springs and spring runs, with
sand-cobble substrate or exposed basalt bedrock (Frest and Johannes 1999,
p. 90).
Cold, shallow, well-oxygenated, slow-flowing springs and outflows with soft substrates. (Duncan 2005b, p. 10).
Fredenburg
pebblesnail.
Klamath
Rim
pebblesnail.
Knobby
ramshorn.
Shell about 3 by 2.5 mm; white with
greenish-yellow outer layer; white, sickle-shaped penis. (Frest and Johannes
1999, p. 29).
Shell about 2 by 2 mm; white with greenish-yellow outer layer; sickle-shaped
penis (Frest and Johannes 1999, p. 25).
31 sites in Hood River, Sherman, and
Wasco Counties, OR; and Klickitat and
Skamania Counties, WA (BLM 2011,
entire).
8 sites in the Shasta Springs complex,
upper Sacramento River, Siskiyou
County, CA (Frest and Johannes 1999,
p. 90).
64 sites in Clackamas, Wasco, Hood
River, and Multnomah Counties, OR;
and Skamania County, WA (USDA and
USDI 2007, p. 93).
19 sites in Jackson County, OR. (Frest
and Johannes 1999, p. 30; USDA and
USDI 2007, p. 92).
Masked
duskysnail.
Tall
pebblesnail.
Shell about 6 by 6 mm; reddish-brown
outer layer, keeled with ribs and protuberances (Frest and Johannes 1995b,
p. 57; Frest and Johannes 1999, p. 98).
Shell described as up to 2 mm long (Frest
and Johannes 1995a, p. 185) or as 3 to
5 mm long (Frest and Johannes 1999,
p. 73); mask of black pigment on neck
and around eyes (Frest and Johannes
1999, p. 73).
Shell about 4.5 by 3 mm; conical, white
with green outer layer; black body except for white, flanged penis (Frest and
Johannes 1999, p. 21).
Small, shallow, cold spring runs with cobbled substrate (Frest and Johannes
1999, p. 30).
Shady areas in small, cold, shallow spring
runs with gravel-cobble substrates and
no large water plants (Frest and Johannes 1999, p. 26).
Rocky substrates in cold, clear water with
high dissolved oxygen levels (Frest and
Johannes 1999, p. 99).
6 sites in southern OR and possibly northern CA (USDA and USDI 2007, pp. 92,
251).
Cool-water kettle lakes with oxygenated
mud substrates and aquatic plant
growth (Duncan 2005e, p. 3).
3 to 4 sites at two lakes: Curlew Lake,
Ferry County, WA, and Fish Lake, Chelan County, WA (Duncan 2005e, p. 3;
USDA and USDI 2007, p. 94). Some indications of possible additional sites in
ID and OR (ORNHIC 2004u, p. 1).
1 site at Harriman Spring, Klamath County, OR (Duncan 2005b, p. 9; USDA and
USDI 2007, p. 92).
Very cold water and cobbled substrate
(Duncan 2005b, p. 9).
2 sites in Shasta County, CA (USDA and
USDI 2007, pp. 94, 268).
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* mm = millimeter.
None of these eight aquatic mollusks
are included in databases of recognized
mollusk species, such as the Integrated
Taxonomic Information System (ITIS)
(2010), or Turgeon et al. (1998). All
eight mollusks were first proposed as
new species in an unpublished
consultation report produced in 1993
(Frest and Johannes 1993, pp. 46, 49, 50,
59, 62, 67). These eight mollusks have
been addressed in several subsequent
documents (Frest and Johannes 1999,
pp. 21–26, 29–30, 69–76, 85–90, 98–
101; Furnish and Monthey 1999,
Sections 2, 4, 5, entire; Frest and
Johannes 2000, pp. 181, 264, 273, 274;
ORNHIC 2004a, entire; ORNHIC 2004d,
entire; ORNHIC 2004j, entire; ORNHIC
2004r, entire; ORNHIC 2004s, entire;
ORNHIC 2004t, entire; ORNHIC 2004u,
entire; ORNHIC 2004v, entire; Duncan
2005b, entire; Duncan 2005e, entire;
USDA and USDI 2007, pp. 92–94, 250–
252, 257–259, 268–269), but none of
those documents provide peer-reviewed
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evidentiary support of the mollusks’
taxonomic distinctness. Although the
eight mollusks have been treated by the
U.S. Forest Service (USFS) and Bureau
of Land Management (BLM) as distinct
entities under the SMP of the Northwest
Forest Plan (see Factor D, below), that
program is not specifically restricted to
species or subspecies, as is the Act
when applied to invertebrates (16 U.S.C.
1532 (16)).
The unpublished descriptions of these
eight mollusks are all primarily based
on shell characteristics, with occasional
mention of certain characters of the
animals themselves (such as color).
Snail shell characteristics in general can
vary due to environmental influences
including elevation, calcium content of
the surrounding water, and population
density (Minton and Lydeard 2003, p.
76; Chak 2007, p. 3). The informal
descriptions lack genetic data, data
regarding microscopic anatomical
features such as the radula (tongue), and
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photographs or drawings of anatomical
features other than the shell. Such data
are often highly distinctive, and are of
key importance in formal descriptions
(for example, Hershler et al. 2003, pp.
278–282; Hershler et al. 2007, pp. 407–
419).
At the time the petition to list these
aquatic mollusks was first submitted,
only one of the petitioned mollusks (the
nugget pebblesnail) had been formally
described (CBD et al. 2008, p. 9). Since
then, an additional five mollusks have
been formally described and thereby
established in the scientific community
as valid species. These are the canary
duskysnail, Goose Valley pebblesnail,
Hat Creek pebblesnail, Potem Creek
pebblesnail, and Shasta pebblesnail
(Hershler et al. 2003, p. 278; Hershler et
al. 2007, pp. 407, 409, 412, 415). For
three of these recently described species
(the canary duskysnail, Goose Valley
pebblesnail, and Potem Creek
pebblesnail), the formal descriptions
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simply confirm the informal species
designations under which they had been
petitioned. However, the formal
description of the Hat Creek pebblesnail
combined into one species two of the
petitioned mollusks that had previously
been informally described as separate
species (the umbilicate pebblesnail
(Fluminicola n. sp. 19) and the Lost
Creek pebblesnail (Fluminicola n. sp.
20). Similarly, the formal description of
the Shasta pebblesnail combined four
mollusks that had previously been
informally described as separate species
(Hershler et al. 2007, p. 419)). Three of
those had been petitioned for listing
(CBD et al. 2008, p. 9): the flat-top,
Shasta Springs, and disjunct
pebblesnails (identified as Fluminicola
n. sp. 3, 4, and 5 in Frest and Johannes
1995b, pp. 43, 44; but as Fluminicola n.
sp. 15, 16, and 17 in Frest and Johannes
1999, pp. 39, 43, 47 and in CBD et al.
2008, p. 9). The fourth, the Sacramento
pebblesnail (Fluminicola n. sp. 1) (Frest
and Johannes 1995b, p. 42) had not been
petitioned for listing and was not
protected by the SMP (USDA and USDI
2007, pp. 92–94). In describing the
Shasta pebblesnail, the authors noted
the ‘‘[m]arked shell variation’’ of the
species (Hershler et al. 2007, p. 419).
The primary reason for combining
multiple informally described mollusks
in the formal descriptions of the Hat
Creek and Shasta pebblesnails was that
new genetic comparisons had shown
those informally described mollusks
were not genetically divergent or
phylogenetically independent (Hershler
et al. 2007, p. 383). Such genetic
comparisons have not yet been
published for the remaining
undescribed mollusks. This suggests the
remaining but undescribed mollusks
may also be determined by future
taxonomic analyses to represent
populations of larger-ranging species or
subspecies. New taxonomic analyses are
currently being conducted for a large
number of provisionally identified
species in the Fluminicola genus
(Johannes 2011, p. 1). Additionally, the
establishment of the Shasta pebblesnail
as a single species, despite the marked
differences in shell morphology among
its various populations, indicates that
shell morphology is a relatively poor
indicator of species status for at least
some of these mollusks.
Accordingly, we conclude that the
eight mollusks that have not been
formally described (as listed in Table 1,
above) cannot be considered to be
listable entities under the Act at this
time, and, therefore, we will not further
evaluate the status of these entities.
These include the Basalt juga, cinnamon
juga, Columbia duskysnail, Fredenburg
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pebblesnail, Klamath Rim pebblesnail,
knobby rams-horn, masked duskysnail,
and tall pebblesnail. We, therefore,
restrict the remainder of our listing
status review to the six mollusks
constituting listable entities under the
Act. These are the canary duskysnail,
the Goose Valley pebblesnail, the Hat
Creek pebblesnail, the nugget
pebblesnail, the Potem Creek
pebblesnail, and the Shasta pebblesnail.
Generally Applicable Federal
Regulatory Mechanisms
The Northwest Forest Plan
The Northwest Forest Plan (NWFP) is
a set of amendments to the resource
management plans for USFS and BLM
lands within the range of the northern
spotted owl (Strix occidentalis caurina)
in western Washington, Oregon, and
northwestern California (referred to
below as NWFP lands) (USDA and USDI
1994a, pp. 11, 12). The NWFP was
established to protect species commonly
occurring in late-successional and oldgrowth forests, while also allowing for
sustainable timber production (USDA
and USDI 1994a, p. 3). The NWFP
established several categories of land
allocations and, with minor exceptions,
restricted timber production to those
areas designated as Matrix Lands (16
percent of the total) and to certain
Adaptive Management Areas (6 percent
of the total) (USDA and USDI 1994a, pp.
6, 7). The NWFP includes two
subprograms designed to provide
additional protections to specific
resources on NWFP lands. The first
subprogram is the Aquatic Conservation
Strategy (ACS), which protects aquatic
and riparian habitat. The second
subprogram is the SMP, which protects
numerous rare species associated with
late-successional or old-growth forests
that are not adequately protected by
other provisions of the NWFP (USDA
and USDI 1994a, pp. 9, 10; Olson et al.
2007, pp. 1, 2). The ACS and SMP are
particularly applicable, in varying
degrees, to the six listable aquatic
mollusks considered here, and are
discussed in more detail below.
The Aquatic Conservation Strategy
The ACS was established to protect
and restore aquatic ecosystems on
NWFP lands (USDA and USDI 1994b, p.
B–11; Reeves et al. 2006, p. 320). The
ACS includes four components:
Riparian reserves, key watersheds,
watershed analysis, and watershed
restoration (USDA and USDI 1994a, pp.
9, 10). Of these, riparian reserves are the
most significant conservation tool for
the aquatic mollusks considered here.
Riparian reserves include all aquatic
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habitat (perennial and seasonal streams,
lakes, ponds, and wetlands) on NWFP
lands. Riparian reserves are managed to
maintain and restore water quality,
aquatic ecosystem physical integrity,
instream flows, habitat connectivity,
and other natural features of the
protected riparian and aquatic habitat
(USDA and USDI 1994b, pp. B–11, B–
13). Activities with the potential to
negatively affect natural features, such
as logging, road construction and
maintenance, grazing, recreation,
mineral management, and fire
management are closely regulated
within the reserves (USDA and USDI
1994a, p. 9; USDA and USDI 1994b, pp.
C–31—C–38).
Riparian reserves incorporate buffers
of 100 to 300 feet (ft) (30.5 to 91.4
meters (m)) around these aquatic
features (except for wetlands of less
than 1 acre (ac) (0.4 hectares (ha)),
which have buffers that extend to the
limit of the associated riparian
vegetation). The six listable aquatic
mollusks considered in this review all
occupy springs (including those forming
lakes or ponds) and perennial streams,
sometimes fish-bearing and sometimes
not (a stream is considered fish bearing
if it supports any species of fish for any
duration of time) (USDA and USDI
1994b, p. B–14). When any of these six
mollusks are on NWFP lands in lakes,
ponds, or fish-bearing streams, they are
protected by buffers extending outward
300 ft (91.4 m) from the streambanks, to
the limit of riparian vegetation or to a
distance equal to the height of two sitepotential trees, whichever is greater
(USDA and USDI 1994a, p. 9). ‘‘Sitepotential tree height’’ refers to the
expected height attainable by a mature
conifer growing in the area (Kier
Associates 2011a, p. 2). Average sitepotential tree height for much of the
Pacific Northwest is about 170 ft (51.8
m). When present in non-fish-bearing
streams on NWFP lands, the six
mollusks are protected by buffers of 150
ft (45.7 m) or equal to the height of one
site-potential tree, whichever is greater.
These boundaries may be modified
based on subsequent watershed analysis
(USDA and USDI 1994a, p. 10; USDA
and USDI 1994b, p. B–13)).
The second component of the ACS,
key watersheds, establishes specific
watersheds to be given the highest
priority in watershed restoration efforts
(USDA and USDI 1994b, p. B–19). None
of the key watersheds identified under
the ACS are in the known current range
of, or upstream from, any of the six
aquatic mollusks that qualify as listable
entities (REO 2006, p. 5). Accordingly,
the key watersheds provision of the ACS
does not affect the conservation of those
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six mollusks, except if new locations of
those species are identified within key
watersheds in the future.
The third component of the ACS,
watershed analysis, is a systematic
procedure to collect information on and
characterize watersheds on NWFP lands
(USDA and USDI 1994b, pp. B–20—B–
31). Watershed analysis must be
conducted in key watersheds and
roadless areas prior to management
activities, in riparian reserves prior to
changing reserve widths, and in any
watershed prior to restoration efforts.
Watershed analysis is recommended for
all watersheds, and has been conducted
on an ongoing basis since its inclusion
in the NWFP (USDA 2009, p. 1).
Analyses have been conducted for
portions of the upper Sacramento River
and lower McCloud River watersheds,
which support occupied sites of the
Shasta pebblesnail and nugget
pebblesnail, respectively.
The final component of the ACS,
watershed restoration, focuses primarily
on restoring watershed aquatic habitat
through the prevention of road-related
runoff, restoration of riparian
vegetation, and restoration of instream
habitat complexity (USDA and USDI
1994b, p. B–31). The Shasta-Trinity and
Lassen National Forests are currently
planning or implementing several such
watershed restoration projects (USDA
2012a, pp. 4, 5; USDA 2012b, pp. 3, 5),
although none of the currently active
projects involve locations near sites
occupied by the mollusks addressed in
this status review at the present time.
practicality of conducting
predisturbance surveys (surveys
conducted prior to habitat-disturbing
projects) (Molina et al. 2006, p. 311,
312). Rare species for which
predisturbance surveys are practical are
in Category A. Thirteen of the 14
petitioned aquatic mollusks fall into this
category, including all six of the listable
mollusks (USDA and USDI 2007, pp.
92–94). The one exception among the
petitioned aquatic mollusks is the
knobby rams-horn (see Table 1, above),
which is in Category E (rare, practicality
of predisturbance surveys
undetermined) (Molina et al. 2006, p.
312; USDA and USDI 2007, p. 94).
For Category A species, the SMP
requires predisturbance, strategic
surveys (conducted in areas not
currently under consideration for
habitat-disturbing projects),
management of all known sites to
support species persistence, and annual
species reviews (Molina et al. 2006, p.
312; Olson et al. 2007, abstract).
Numerous such surveys and several
annual reviews have been completed
(Molina et al. 2006, pp. 312–315; USDA
and USDI 2001, entire; USDA and USDI
2002, entire; USDA and USDI 2003,
entire). The process of continually
collecting information through surveys,
and of summarizing and updating the
information in annual reviews,
produces an adaptive management
approach to guide conservation and
mitigation measures for rare species
associated with late-successional or oldgrowth forests (Olson et al. 2007, p. 2).
The Survey and Manage Program
The SMP, like the ACS, was
established under the NWFP and is
particularly applicable, in varying
degrees, to the six listable aquatic
mollusks considered here. The six
mollusks were protected under the SMP
(when on Federal lands subject to the
NWFP), but the SMP program was
discontinued in 2007 (USDA and USDI
2007, pp. xii, xiii; CBD et al. 2008, p.
5). The SMP was subsequently
reinstated in accordance with a courtapproved settlement agreement in 2011
(Conservation Northwest v. Sherman
2011, C08–1067–JCC, p. 2), and is being
implemented in accordance with the
2001 Record of Decision. All of the
aquatic mollusks petitioned in 2008
(both formally described and otherwise)
are protected where they occur on
NWFP lands (Conservation Northwest v.
Sherman 2011, C08–1067–JCC,
Document 81–2, pp. 6, 7). Refinements
to the SMP in 2001 established six
species categories with differing
mitigation requirements based on the
species’ conservation status and on the
Summary of Procedures for
Determining the Listing Status of
Species
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Review of Status Based on Five Factors
Section 4 of the Act (16 U.S.C. 1533)
and implementing regulations (50 CFR
part 424) set forth procedures for adding
species to, removing species from, or
reclassifying species on the Federal
Lists of Endangered and Threatened
Wildlife and Plants. Under section
4(a)(1) of the Act, a species may be
determined to be endangered or
threatened based on any of the
following 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.
In making these findings, we discuss
information below pertaining to each
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species in relation to the five factors
provided in section 4(a)(1) of the Act. In
considering what factors might
constitute threats to a species, we must
look beyond the simple exposure of the
species to a particular factor. Instead we
must evaluate whether the species may
respond to the factor in a way that
causes actual impacts to the species. If
there is exposure to a factor and the
species responds negatively, the factor
may be a threat and, during the status
review, we attempt to determine how
significant a threat it is. The threat is
significant if it drives or contributes to
the risk of extinction of the species such
that the species warrants listing as
endangered or threatened as those terms
are defined by the Act. However, the
identification of factors that could
impact a species negatively may not be
sufficient to compel a finding that the
species warrants listing. The
information must include evidence
sufficient to suggest that the potential
threat has the capacity (is of sufficient
magnitude and extent) to affect the
species’ status such that it meets the
definition of endangered or threatened
under the Act.
Distinct Population Segments
After considering the five factors, we
assess whether each species is
endangered or threatened throughout all
of its range. Generally, we next consider
in our findings whether a DPS or any
significant portion of the species’ range
meets the definition of endangered or is
likely to become endangered in the
foreseeable future (threatened). The
inclusion of DPSs in the definition of
species under paragraph 3(16) of the Act
only applies to vertebrate fish or
wildlife. Therefore, our Policy
Regarding the Recognition of Distinct
Vertebrate Population Segments Under
the Endangered Species Act (DPS
Policy) (61 FR 4722; February 7, 1996)
is not applicable to mollusks and no
population segments under review
could qualify as a DPS under the Act.
Although our DPS Policy is not
applicable to mollusks, we do determine
in our findings whether a mollusk
species is endangered or threatened in
a significant portion of its range.
Significant Portion of the Range
Under the Act and our implementing
regulations, a species may warrant
listing if it is endangered or threatened
throughout all or a significant portion of
its range. The Act defines ‘‘endangered
species’’ as any species which is ‘‘in
danger of extinction throughout all or a
significant portion of its range,’’ and
‘‘threatened species’’ as any species
which is ‘‘likely to become an
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endangered species within the
foreseeable future throughout all or a
significant portion of its range.’’ The
definition of ‘‘species’’ is also relevant
to this discussion. The Act defines
‘‘species’’ as follows: ‘‘The term
‘species’ includes any subspecies of fish
or wildlife or plants, and any DPS of
any species of vertebrate fish or wildlife
which interbreeds when mature.’’ The
phrase ‘‘significant portion of its range’’
(SPR) is not defined by the statute, and
we have never addressed in our
regulations: (1) The consequences of a
determination that a species is either
endangered or likely to become so
throughout a significant portion of its
range, but not throughout all of its
range; or (2) what qualifies a portion of
a range as ‘‘significant.’’
Two recent district court decisions
have addressed whether the SPR
language allows the Service to list or
protect less than all members of a
defined ‘‘species’’: Defenders of Wildlife
v. Salazar, 729 F. Supp. 2d 1207 (D.
Mont. 2010), concerning the Service’s
delisting of the Northern Rocky
Mountain gray wolf (74 FR 15123, April
2, 2009); and WildEarth Guardians v.
Salazar, 2010 U.S. Dist. LEXIS 105253
(D. Ariz. September 30, 2010),
concerning the Service’s 2008 finding
on a petition to list the Gunnison’s
prairie dog (73 FR 6660, February 5,
2008). The Service had asserted in both
of these determinations that it had
authority, in effect, to protect only some
members of a ‘‘species,’’ as defined by
the Act (i.e., species, subspecies, or
DPS), under the Act. Both courts ruled
that the determinations were arbitrary
and capricious on the grounds that this
approach violated the plain and
unambiguous language of the Act. The
courts concluded that reading the SPR
language to allow protecting only a
portion of a species’ range is
inconsistent with the Act’s definition of
‘‘species.’’ The courts concluded that
once a determination is made that a
species (i.e., species, subspecies, or
DPS) meets the definition of
‘‘endangered species’’ or ‘‘threatened
species,’’ it must be placed on the list
in its entirety and the Act’s protections
applied consistently to all members of
that species (subject to modification of
protections through special rules under
sections 4(d) and 10(j) of the Act).
Consistent with that interpretation,
and for the purposes of this finding, we
interpret the phrase ‘‘significant portion
of its range’’ in the Act’s definitions of
‘‘endangered species’’ and ‘‘threatened
species’’ to provide an independent
basis for listing; thus there are two
situations (or factual bases) under which
a species would qualify for listing: a
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species may be endangered or
threatened throughout all of its range; or
a species may be endangered or
threatened in only a significant portion
of its range. If a species is in danger of
extinction throughout a significant
portion of its range, the species is an
‘‘endangered species.’’ The same
analysis applies to ‘‘threatened species.’’
Based on this interpretation and
supported by existing case law, the
consequence of finding that a species is
endangered or threatened in only a
significant portion of its range is that the
entire species shall be listed as
endangered or threatened, respectively,
and the Act’s protections shall be
applied across the species’ entire range.
We conclude, for the purposes of this
finding, that interpreting the significant
portion of its range phrase as providing
an independent basis for listing is the
best interpretation of the Act because it
is consistent with the purposes and the
plain meaning of the key definitions of
the Act; it does not conflict with
established past agency practice (i.e.,
prior to the 2007 Solicitor’s Opinion), as
no consistent, long-term agency practice
has been established; and it is consistent
with the judicial opinions that have
most closely examined this issue.
Having concluded that the phrase
‘‘significant portion of its range’’
provides an independent basis for
listing and protecting the entire species,
we next turn to the meaning of
‘‘significant’’ to determine the threshold
for when such an independent basis for
listing exists.
Although there are potentially many
ways to determine whether a portion of
a species’ range is ‘‘significant,’’ we
conclude, for the purposes of this
finding, that the significance of the
portion of the range should be
determined based on its biological
contribution to the conservation of the
species. For this reason, we describe the
threshold for ‘‘significant’’ in terms of
an increase in the risk of extinction for
the species. We conclude that a
biologically based definition of
‘‘significant’’ best conforms to the
purposes of the Act, is consistent with
judicial interpretations, and best
ensures species’ conservation. Thus, for
the purposes of this finding, and as
explained further below, a portion of the
range of a species is ‘‘significant’’ if its
contribution to the viability of the
species is so important that without that
portion, the species would be in danger
of extinction.
We evaluate biological significance
based on the principles of conservation
biology using the concepts of
redundancy, resiliency, and
representation. Resiliency describes the
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characteristics of a species and its
habitat that allow it to recover from
periodic disturbance. Redundancy
(having multiple populations
distributed across the landscape) may be
needed to provide a margin of safety for
the species to withstand catastrophic
events. Representation (the range of
variation found in a species) ensures
that the species’ adaptive capabilities
are conserved. Redundancy, resiliency,
and representation are not independent
of each other, and some characteristic of
a species or area may contribute to all
three. For example, distribution across a
wide variety of habitat types is an
indicator of representation, but it may
also indicate a broad geographic
distribution contributing to redundancy
(decreasing the chance that any one
event affects the entire species), and the
likelihood that some habitat types are
less susceptible to certain threats,
contributing to resiliency (the ability of
the species to recover from disturbance).
None of these concepts is intended to be
mutually exclusive, and a portion of a
species’ range may be determined to be
‘‘significant’’ due to its contributions
under any one or more of these
concepts.
For the purposes of this finding, we
determine if a portion’s biological
contribution is so important that the
portion qualifies as ‘‘significant’’ by
asking whether without that portion, the
representation, redundancy, or
resiliency of the species would be so
impaired that the species would have an
increased vulnerability to threats to the
point that the overall species would be
in danger of extinction (i.e., would be
‘‘endangered’’). Conversely, we would
not consider the portion of the range at
issue to be ‘‘significant’’ if there is
sufficient resiliency, redundancy, and
representation elsewhere in the species’
range that the species would not be in
danger of extinction throughout its
range if the population in that portion
of the range in question became
extirpated (extinct locally).
We recognize that this definition of
‘‘significant’’ (a portion of the range of
a species is ‘‘significant’’ if its
contribution to the viability of the
species is so important that, without
that portion, the species would be in
danger of extinction) establishes a
threshold that is relatively high. On the
one hand, given that the consequences
of finding a species to be endangered or
threatened in a significant portion of its
range would be listing the species
throughout its entire range, it is
important to use a threshold for
‘‘significant’’ that is robust. It would not
be meaningful or appropriate to
establish a very low threshold whereby
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a portion of the range can be considered
‘‘significant’’ even if only a negligible
increase in extinction risk would result
from its loss. Because nearly any portion
of a species’ range can be said to
contribute some increment to a species’
viability, use of such a low threshold
would require us to impose restrictions
and expend conservation resources
disproportionately to conservation
benefit: listing would be rangewide,
even if only a portion of the range of
minor conservation importance to the
species is imperiled. On the other hand,
it would be inappropriate to establish a
threshold for ‘‘significant’’ that is too
high. This would be the case if the
standard were, for example, that a
portion of the range can be considered
‘‘significant’’ only if threats in that
portion result in the entire species being
currently endangered or threatened.
Such a high bar would not give the
significant portion of its range phrase
independent meaning, as the Ninth
Circuit held in Defenders of Wildlife v.
Norton, 258 F.3d 1136 (9th Cir. 2001).
The definition of ‘‘significant’’ used in
this finding carefully balances these
concerns. By setting a relatively high
threshold, we minimize the degree to
which restrictions will be imposed or
resources expended that do not
contribute substantially to species
conservation. But we have not set the
threshold so high that the phrase ‘‘in a
significant portion of its range’’ loses
independent meaning. Specifically, we
have not set the threshold as high as it
was under the interpretation presented
by the Service in the Defenders
litigation. Under that interpretation, the
portion of the range would have to be
so important that current imperilment
there would mean that the species
would be currently imperiled
everywhere. Under the definition of
‘‘significant’’ used in this finding, the
portion of the range need not rise to
such an exceptionally high level of
biological significance. (We recognize
that if the species is imperiled in a
portion that rises to that level of
biological significance, then we should
conclude that the species is in fact
imperiled throughout all of its range,
and that we would not need to rely on
the significant portion of its range
language for such a listing.) Rather,
under this interpretation we ask
whether the species would be
endangered everywhere without that
portion, i.e., if that portion were
completely extirpated. In other words,
the portion of the range need not be so
important that even the species being in
danger of extinction in that portion
would be sufficient to cause the species
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in the remainder of the range to be
endangered; rather, the complete
extirpation (in a hypothetical future) of
the species in that portion would be
required to cause the species in the
remainder of the range to be
endangered.
The range of a species can
theoretically be divided into portions in
an infinite number of ways. However,
there is no purpose to analyzing
portions of the range that have no
reasonable potential to be significant or
to analyzing portions of the range in
which there is no reasonable potential
for the species to be endangered or
threatened. To identify only those
portions that warrant further
consideration, we determine whether
there is substantial information
indicating that: (1) The portions may be
‘‘significant,’’ and (2) the species may be
in danger of extinction there or likely to
become so within the foreseeable future.
Depending on the biology of the species,
its range, and the threats it faces, it
might be more efficient for us to address
the significance question first or the
status question first. Thus, if we
determine that a portion of the range is
not ‘‘significant,’’ we do not need to
determine whether the species is
endangered or threatened there; if we
determine that the species is not
endangered or threatened in a portion of
its range, we do not need to determine
if that portion is ‘‘significant.’’ In
practice, a key part of the determination
that a species is in danger of extinction
in a significant portion of its range is
whether the threats are geographically
concentrated in some way. If the threats
to the species are essentially uniform
throughout its range, no portion is likely
to warrant further consideration.
Moreover, if any concentration of
threats to the species occurs only in
portions of the species’ range that
clearly would not meet the biologically
based definition of ‘‘significant,’’ such
portions will not warrant further
consideration.
Evaluation of the Status of Each of the
Six Mollusk Species That Are Listable
Entities
For each of the six listable aquatic
mollusk species considered, we provide
a description of the species and its life
history and habitat, an evaluation of
listing factors, and our finding as to
whether the petitioned action is
warranted throughout its range. We then
address whether the species may be
considered endangered or threatened in
any significant portion of its range.
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Canary Duskysnail (Colligyrus
convexus)
Species Information for the Canary
Duskysnail
Taxonomy and Species Description
The canary duskysnail was formally
named and described in 2003 (Hershler
et al. 2003, p. 278). Prior to that it was
referred to as ‘‘Lyogyrus n. sp. 3’’ (Frest
and Johannes 1999, pp. 77–78; Hershler
et al. 2003, p. 278; USDA and USDI
2007, pp. 93, 169), and also as
‘‘Lyogyrus n. sp. 1’’ (Frest and Johannes
1995b, p. 50). Although the canary
duskysnail was considered to be in the
Hydrobiidae family by earlier authors
(Frest and Johannes 1995b, p. 50; Frest
and Johannes 1999, p. 13), and was
referred to as such in the listing petition
(CBD et al. 2008, p. 9), it was placed in
the family Amnicolidae when it was
formally described (Hershler et al. 2003,
p. 278). It is a small (1.4 to 1.9
millimeters (mm) 0.06 to 0.07 inches
(in)), aquatic snail with a yellowish
shell, sometimes with weakly striped
markings on the whorls. It is
distinguishable from the other two
species in its genus by its smaller size,
the highly convex whorls on the main
part of its shell, and the waviness of the
shell near the opening (Hershler et al.
2003, p. 278).
Distribution
The canary duskysnail is known from
a total of 21 sites in Shasta County,
California, including 9 along the lower
Pit River (California Natural Diversity
Database (CNDDB) 2012, pp. 1–5;
Johannes 2012a, pp. 2–7; Pacific Gas
and Electric Company (PGE) 2011, pp.
26, 37; Johannes 2012b, p. 11; PGE 2012,
p. 27). Of those 21 sites, 7 are on Federal
land covered by the NWFP, 1 is on an
Indian Public Domain Allotment (PDA),
3 are in State parks, and 10 are on
privately owned lands. Repeat site
monitoring at eight of those sites (see
Factor A, below) shows large shifts in
population density and in presence or
absence of canary duskysnails at any
given site. Site locations fall into three
broad areas: The lower Pit River and
nearby Burney Creek (11 sites), Hat
Creek (2 sites), and the upper Fall and
Tule River area (8 sites).
Habitat and Biology
The canary duskysnail typically
occurs in shallow water on the
undersides of boulders and cobbles in
pond springs and wetted areas near
streambeds (the hyporheic zone)
(Hershler et al. 2003, pp. 280, 284). It is
most likely a grazer on perilithon, the
community of small organisms such as
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algae, protozoa, and bacteria growing
underwater on stones (Frest and
Johannes 1995b, p. 81; Furnish and
Monthey 1999, Sect. 4, p. 9). It is most
commonly found in areas lacking cover
from aquatic plants, often in association
with the Shasta crayfish (Pacifastacus
fortis). It is found in, and is likely
dependent on, water that is cold, clear,
well-oxygenated, and unpolluted (Frest
and Johannes 1995b, p. 3). It is often
found in spring flows or in springinfluenced streams (Service 1998, p. 20;
Frest and Johannes 1999, p. 78). The
canary duskysnail is a short-lived
species (1 to occasionally 2 years) that
only reproduces once before dying
(Frest and Johannes 1995b, p. 4; Furnish
and Monthey 1999, Sect. 4, p. 7). Eggs
are likely laid in the spring and hatch
in 2 to 4 weeks (Furnish and Monthey
1999, Sect. 4, p. 7).
Five-Factor Evaluation of Threats for the
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Factor A. The Present or Threatened
Destruction, Modification, or
Curtailment of Its Habitat or Range
Impoundments
Nine of the 21 occupied sites are in
or along the lower Pit River below Lake
Britton (PGE 2011, pp. 26, 37; Johannes
2012b, p. 11; PGE 2012 p. 27). PGE
maintains three dams in this area: Pit 3,
4, and 5 (PGE 2010, p. 5). Each dam
sends water from its associated reservoir
through tunnels to power-generating
stations located just above the reservoirs
of the next dam downstream. Flows in
the natural river channel below each
dam (referred to as the Pit 3, 4, and 5
reaches) have in the past consisted
primarily of water from springs and
minor tributaries emptying below each
dam. In 2007, however, the Pit 3, 4, and
5 dams were issued a new operating
license that required increased releases
of surface water from the reservoirs into
their associated reaches (PGE 2010, p.
2). These releases have the potential to
negatively impact the canary duskysnail
because reservoir surface water tends to
be warmer than spring or creek water
(Ellis 2012, p. 1). Because the dams
initially lacked the infrastructure to
release the required amounts of
instream water, the required amounts
were not achieved until 2011 (PGE
2012, p. 1). In accordance with a
facilities modification plan, interim
flow releases of approximately half the
required amounts were authorized for
2008 through 2010 while the flow
release structures of the dams were
improved (PGE 2010, pp. 1, 2).
PGE was also required by the
relicensing requirements to conduct
mollusk surveys in 2009, in 2011–2015,
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in 2018, and every 4 years thereafter
until the expiration of the license in
2043 (PGE 2012, p. 1). Following
monitoring in 2009, PGE decided to
monitor for mollusks in 2010 as well
(PGE 2010, p. 54; PGE 2011, p. 1).
Accordingly, we now have 3 years of
survey data (2009–2011) for a total of 12
sites in the Pit River (four sites
downstream of each dam) (PGE 2011,
pp. 26, 37; PGE 2012, p. 27). The
surveys found canary duskysnails at 8 of
those 12 sites (as well as nugget
pebblesnails at all 12 sites, as discussed
below). A ninth site in the Pit River
with canary duskysnails (as mentioned
above) was not in a monitored location
(Hershler et al. 2003, p. 280; CNDDB
2012, p. 2; Johannes 2012a, p. 2).
Four of the eight monitored occupied
sites are in the Pit 3 reach, which is the
farthest upstream (PGE 2011, pp. 26, 37;
PGE 2012, p. 27). During 2009, that
reach also showed the lowest average
water discharge rates, lowest average
water temperatures, and produced the
highest average densities of canary
duskysnails, thus tending to support the
idea that canary duskysnails benefit
from lower discharge rates from the
dams (PGE 2010, p. 35; PGE 2011, pp.
26, 37; PGE 2012, p. 27). However, as
average water discharge rates increased
in the Pit 3 reach from 150 cubic ft per
second (cfs) in 2009 to 350 cfs in 2011,
and as average water temperatures
increased as well from approximately 60
to about 63 degrees Fahrenheit (°F) (15.4
to 17.2 degrees Celsius (°C)), canary
duskysnail densities rose from 20 to 53
snails per square meter (16.7 to 44.3
snails per square yard) at one location
(their highest density in the study), and
dropped from 50 to 0 snails per square
meter (41.8 to 0 snails per square yard)
at another location. The populations
thus showed strong fluctuations, with
widely differing responses to increasing
flows. Similarly, in the Pit 5 reach, 37
snails per square meter (30.9 snails per
square yard) were found in 2011 (the
year of highest flows) at a location that
had supported no snails in the 2
previous years. All other occupied
locations had comparatively low
population densities, and only one of
those showed a clear drop in population
density over the 3-year monitoring
period (from 4 to 0 snails per square
meter (3.3 to 0 snails per square yard)).
Therefore, we conclude there are no
clear trends in observed survey data
attributable to changes in flow releases
from dams.
The only other occupied site
potentially affected by an impoundment
is at Baum Lake (CNDDB 2012, p. 4;
Johannes 2012a, pp. 4, 5), a PGE-owned
reservoir on Hat Creek, just north of the
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town of Cassel (Service 1998, pp. 20,
43). Abundant canary duskysnails were
found at the site in 2001, under cobbles
near the outflow of Crystal Lake, a
spring-fed water body that abuts and
empties into Baum Lake (CNDDB 2012,
p. 4; Johannes 2012a, pp. 4, 5). Although
the best available information does not
indicate the fate of that population, its
presence in 2001 and the abundant
number of individual snails found at
that time suggest the impoundment of
Baum Lake does not constitute a threat.
Three other occupied sites (identified in
the source material as locations 102,
412, and 514) are located on the margins
of spring-fed natural lakes in water
bodies draining into the Fall River
(Johannes 2012a pp. 3, 6), so the species
is capable of surviving in slow-moving
lake waters fed by nearby springs.
Water Quality
The Pit River is considered a waterquality limited segment for 198
kilometers (km) (123 miles (mi))
upstream of Shasta Lake; including the
locations of all nine canary duskysnail
sites known from the Pit River (State
Water Resources Control Board
(SWRCB) 2010a, p. 164). Nutrients from
cattle defecation and fertilizers applied
in the course of agriculture enter the Pit
River, where they promote algal growth
that decreases oxygen levels and
increases water temperature. However,
as discussed above with respect to
impoundments, the only population
trend data available for the canary
duskysnail does not show clearly
decreasing populations, despite any
temperature increases or oxygen
decreases that may be attributable to
water quality.
PGE will continue to monitor mollusk
populations annually as discussed
above (PGE 2012, p. 1), so if impacts
from Pit water quality or from the
releases themselves do develop, they
should be detected. The operating
license for the dams includes an
adaptive management plan for
responding to negative impacts detected
by the monitoring program (PGE 2008,
pp. 3–6). The Service serves on the
Technical Review Group which
recommends specific adaptive
management responses (PGE 2008, p. 2),
and so will remain informed of the
effectiveness of those responses. Seven
of the nine occupied locations on the Pit
River are on Federal land (either ShastaTrinity National Forest or Lassen
National Forest) within the area covered
by the NWFP. Activities on those lands
with the potential to affect water quality
(or to affect the populations directly)
would have to meet the requirements of
the SMP and the ACS, as discussed
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above. For instance, logging or road
construction in the vicinity of the Pit
River or its tributaries (on Federal lands
within the NWFP area) would be subject
to buffers for riparian reserves
established under the ACS as well as
predisturbance surveys and mitigation
as required by the SMP.
There are no locations occupied by
canary duskysnails on the Pit River
upstream of the Pit 3 dam at Lake
Britton. However, there are two
locations each on Burney Creek and Hat
Creek, which both flow into Lake
Britton. The remaining eight canary
duskysnail locations are in the Fall
River drainage, generally at the
headwater springs (Service 2012a, p. 1).
Neither Burney Creek nor Hat Creek is
considered water-quality limited
(SWRCB 2010a, entire; SWRCB 2010b,
entire; SWRCB 2010c, entire). However,
the Fall River is affected by
sedimentation extending far enough
upstream to reach the southernmost of
the eight sites in the drainage occupied
by canary duskysnails (SWRCB 2010a,
p. 148; SWRCB 2011, p. 2). The
sedimentation was caused by historical
land management activities, and is not
likely to constitute a threat to the other
sites (Fall River Resource Conservation
District (FRRCD) 2005, pp. 1–3; SWRCB
2010a, p. 148).
A final area with impaired water
quality is Eastman Lake, at the
headwaters of the Little Tule River, a
tributary of the Fall River (SWRCB
2010a, p. 148; SWRCB 2011, p. 1). One
canary duskysnail site (514) is located at
the lake, while two others (102, 263) are
just upstream of the inlet (Johannes
2012a, pp. 3, 4, 6). At an average pH of
8.64, the lake water is slightly more
alkaline than the established water
quality objective range of 6.5 to 8.5
(SWRCB 2010d, pp. 6, 7). The reason for
the increased alkalinity is unknown, as
is the optimal pH range for the canary
duskysnail. However, acidic waters (pH
5 and below) can interfere with shell
production, so freshwater snails are
generally found in waters that are at
least somewhat alkaline (Wyoming
Game and Fish Department (WGFD)
2005, p. 548).
Other Habitat-Related Impacts
Grazing, spring diversions, road
construction, and railroad construction
have all been mentioned as possible
threats to the canary duskysnail
(Furnish and Monthey 1999, Sect. 4, p.
14; Service 2011, p. 61831). However,
since the time of Furnish and Monthey’s
conclusions in 1999, the number of
known locations has increased from 2 to
21, 10 of which are on protected State
or Federal lands (Furnish and Monthey
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1999, Sect. 4, pp. 10, 11; Johannes
2012a, pp. 2–7; Johannes 2012b, p. 11;
PGE 2011, pp. 26, 37; PGE 2012 p. 27).
The SMP (discussed above) has also
been reinstated on Federal lands subject
to the NWFP. Various habitat
improvement measures have been
carried out in the upper Fall River
drainage, where the majority of
occupied sites on private land are
located (FRRCD 2005, pp. 1–3). Habitat
improvements include exclusion
fencing to keep cattle from streambanks,
bank stabilization projects, and the
replacement and upgrade of a railroad
crossing that had collapsed twice in the
past (producing extensive siltation on
those occasions) (FRRCD 2005, p. 2;
Ellis and Haley 2012, p. 1). Landowners
also took steps to reduce the potential
for serious wildfires and to prevent
erosion of sediment from a nearby
meadow (FRRCD 2005, p. 3). In Hat
Creek, grazing has been eliminated in
the general vicinity of the PGE dams
since 2001 (Stewardship Council 2007,
Vol. 2, p. PM–31). Grazing has also been
eliminated from lands surrounding the
two privately owned sites occupied by
canary duskysnails in the lower Pit
River. Forestry has been eliminated in
areas near those sites conducted in
accordance with a conservation plan
developed and implemented by a
nonprofit land-management corporation
(see Grazing and Logging under Nugget
Pebblesnail, below) (Stewardship
Council, Vol. 2, pp. PM 38, 40, 41, 48,
50).
The Shasta crayfish is a federally
endangered species that shares
essentially the same native range and
habitat requirements as the canary
duskysnail (Service 2009, pp. 4–6). The
two species often co-occur at the same
locations (Hershler et al. 2003, p. 280).
When we listed the Shasta crayfish in
1988, we identified grazing, pollution,
and water use for residential
development as threats to the species
(Service 1988, p. 38463). In our 2009
review of the species’ status, however,
we determined those practices no longer
constitute significant impacts to the
species (Service 2009, p. 9).
Summary of Factor A
In summary, no clear population
trends in response to habitat
modifications are evident at any of the
sites occupied by canary duskysnails,
including the eight sites monitored by
PGE. The release of additional Pit River
waters from the dams under PGE’s new
licensing agreements does not appear to
have resulted in adverse effects on
downstream canary duskysnail
populations. We also know of no
occupied sites that have been
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permanently lost due to habitat
modifications, although population
fluctuations at some of the monitored
sites included densities of zero during
some years. No cause of the fluctuations
at the monitored sites was evident. We
therefore conclude, based on the best
available scientific and commercial
data, that the present or threatened
destruction, modification or curtailment
of its habitat or range does not
constitute a significant threat to the
species now or in the future.
Factor B. Overutilization for
Commercial, Recreational, Scientific, or
Educational Purposes
Our review of the best available
scientific and commercial information
yielded nothing to indicate that
overutilization for commercial,
recreational, scientific, or educational
purposes is occurring at this time or is
likely to occur in the future. We
therefore conclude such overutilization
does not constitute a threat to the canary
duskysnail.
Factor C. Disease or Predation
Disease
We reviewed the best available
scientific and commercial information
regarding this species and other similar
species, and found no evidence to
indicate that disease is impacting canary
duskysnail populations.
Predation
There is the potential for increased
predation on canary duskysnails due to
the introduction of the signal crayfish
(Pacifastacus leniusculus) into the midPit River drainage in the late 1970s, and
its subsequent expansion throughout the
area during the 1990s and early 2000s
(Ellis 1999, pp. 12, 57, 58; Service 2009,
p. 10). The signal crayfish, which is
native to Oregon, Washington, and more
coastal portions of northwest California,
is a faster growing, faster reproducing
relative of the Shasta crayfish, with a
greater tolerance for warmer water (Ellis
1999, pp. 2, 9, 12, 13; Service 2009, p.
9; PGE 2011c, p. 25). The signal crayfish
now occurs in all the general locations
occupied by the canary duskysnail
(Service 2009, pp. 5, 10; PGE 2011b, pp.
4, 10, 23) and is a generalist feeder with
a diet that very likely includes aquatic
snails (Lorman and Magnuson 1978, p.
9; Ellis 1999, pp. 55, 56).
Experiments conducted with another
species of crayfish in Wisconsin
indicate that dense crayfish populations
can significantly impact prey
populations, including aquatic snails
(Lorman and Magnuson 1978, p. 9).
However, the best available scientific
and commercial information does not
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indicate how dense crayfish populations
must generally be in order to impact
populations of aquatic snails. The best
available scientific and commercial
information does not provide data on
population density trends for crayfish
and aquatic snails at the same locations.
Although PGE conducted both crayfish
and mollusk surveys at various
locations in the Pit 4 reach, the
surveyed sites did not overlap (PGE
2010, p. 7, PGE 2011b, p. 4). Crayfish
were surveyed at foothill yellow-legged
frog breeding sites, and one such site
(Canyon Creek 45.8) appears to overlap
a surveyed mollusk site referred to as
Malinda Ridge by mollusk surveyors.
However, Canyon Creek 45.8 was one of
the frog breeding sites at which
conditions did not allow crayfish
surveys (due to risk of injuring frog
eggs) (PGE 2011b, pp. 10, 21–23).
We do know that average densities of
signal crayfish remained at 3 per square
meter in the Pit 4 reach from 2008
through 2011 (PGE 2011b, p. 10, PGE
2012b, p. 9), despite increasingly large
releases of warmer surface water from
reservoirs during those years (PGE 2010,
p. 35; PGE 2011, p. 24; PGE 2011b, p.
iii; PGE 2012, p. 24) that might be
expected to have benefitted signal
crayfish (Service 2009, p. 9). Although
average densities remained steady
during the monitoring period, maximum
densities of signal crayfish decreased
from 14 to 7 per square meter (PGE
2011b. p. 10; PGE 2012b, p. 9). The
sampled averages of 3 per square meter
are very close to the average densities of
2.85 crayfish per square meter estimated
for the native Shasta crayfish at Lava
Creek (upper Fall River drainage) in
1990 (Ellis 1999, p. 58), and therefore
suggest that they are close to the native
crayfish densities with which the canary
duskysnail evolved. The crayfish
density surveys at Pit 4 reach also
provide some evidence to suggest that
signal crayfish densities are remaining
stable in that area, despite warmer water
temperatures from increased flows of
reservoir surface water.
The evidence also does not support
the possibility that, in areas occupied by
canary duskysnails, populations of
signal and Shasta crayfish might overlap
to produce unusually high combined
crayfish densities. The known range of
the Shasta crayfish does not extend into
Burney Creek or the lower Pit River
(below Lake Britton) (Service 2009, pp.
3–5), so the 11 canary duskysnail sites
in those areas are only subject to
potential impacts from signal crayfish.
Two general areas that support canary
duskysnails are known to support both
species of crayfish: The upper Fall River
drainage and the area around Baum
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Lake on Hat Creek (Service 2009, p. 9;
Johannes 2012a, pp. 2–7). Monitoring
has shown that the occupied locations
within these general areas may support
relatively high numbers of Shasta
crayfish, or of signal crayfish, but not of
both (Service 2009, p. 9). As signal
crayfish numbers increase at a given
location, the numbers of Shasta crayfish
drop dramatically (Ellis 1999, pp. 57,
58).
Hence, the available evidence does
not support the contention that signal
crayfish are present in the range of the
canary duskysnail in sufficiently high
densities to pose a predation risk to the
canary duskysnail, either by themselves
or in combination with the native
Shasta crayfish. Furthermore, the
information does not indicate any trend
in the densities of the two crayfish that
would lead us to a conclusion that the
predation risk would increase in the
future.
We therefore conclude, based on the
best available scientific and commercial
information, that neither disease nor
predation constitutes a significant threat
to the species now or in the future.
Factor D. The Inadequacy of Existing
Regulatory Mechanisms
Under this factor, we examine
whether existing regulatory mechanisms
are inadequate to address the threats to
the species discussed under the other
factors. Section 4(b)(1)(A) of the Act
requires the Service to take into account
‘‘those efforts, if any, being made by any
State or foreign nation, or any political
subdivision of a State or foreign nation,
to protect such species * * *’’. We
interpret this language to require the
Service to consider relevant Federal,
State, and Tribal laws and regulations
when developing our threat analyses.
Regulatory mechanisms, if they exist,
may preclude the need for listing if we
determine that such mechanisms
adequately address the threats to the
species such that listing is not
warranted. The analysis of threats to the
canary duskysnail under the other
factors included consideration of the
ameliorative effects of regulatory
mechanisms where applicable, such as
those discussed under Factor A and
under Generally Applicable Federal
Regulatory Mechanisms, above.
Having evaluated the significance of
the threat as mitigated by any such
conservation efforts, we analyze under
Factor D the extent to which existing
regulatory mechanisms are inadequate
to address the specific threats to the
species. We found no significant threats
to the canary duskysnail under the other
factors, therefore, the analysis of any
existing regulatory mechanisms’
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57931
adequacy to address threats is not
applicable. Consequently, after
reviewing the best available commercial
and scientific information, we conclude
that the inadequacy of existing
regulatory mechanisms is not a threat to
the canary duskysnail now or in the
future.
Factor E. Other Natural or Manmade
Factors Affecting Its Continued
Existence
Competition With Invasive Species
New Zealand mudsnails
(Potamopyrgus antipodarum) are 4 to 6
mm (0.12 to 0.24 in) aquatic snails that
are extremely prolific and can reach
densities of hundreds of thousands per
square meter in waters outside their
native New Zealand (National Biological
Information Infrastructure (NBII) 2011,
pp. 1, 2). They are carried to new areas
on boots, fishing equipment, boats, or in
the digestive systems of birds and fish,
and are capable of colonizing locations
with a wide variety of substrates,
temperatures, and currents (NBII 2011,
pp. 1–3). In the western United States,
New Zealand mudsnail populations
typically consist almost entirely of
parthenogenic (asexually reproducing)
females born with embryos already
developing in their reproductive
systems (NBII 2011, p. 4; Crosier and
Molloy, undated, p. 1).
New Zealand mudsnails typically eat
detritus (decaying organic matter),
diatoms (a type of plankton), and
periphyton (essentially the same as
perilithon except on underwater
surfaces of vascular plants rather than
rock surfaces) (Frest and Johannes
1995b, p. 81; NBII 2011, p. 4). Although
they reach their highest numbers in
areas with numerous vascular water
plants, they can also dominate areas that
lack such plants (Hall et al. 2006, pp.
1122, 1126), indicating they eat
perilithon as necessary. As discussed
above, perilithon is likely the primary
food source of the canary duskysnail
(Furnish and Monthey 1999, Sect. 4, p.
9). One study found that New Zealand
mudsnails reached higher numbers in
areas with stable hydrological flows and
relatively warm water temperatures
(averaging 18 °C (64.4 °F) as compared
to an average 6 °C (42.8 °F) in their
native New Zealand) (Hall et al. 2006,
p. 1128). As discussed below under
Changes in Precipitation and Water
Availability Due to Climate Change, the
springs with which canary duskysnails
are associated tend to be highly stable
in flow (Service 1998, p. 46). Average
summer water temperatures for 2009
through 2011 measured in the lower Pit
River near sites occupied by canary
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duskysnails ranged from 17.1 to 19.9 °C
(62.8 to 67.8 °F) (PGE 2012, p. 24). Sites
supporting canary duskysnails are thus
not ideal for New Zealand mudsnails
due to the lack of vascular plants, but
they do provide favorable flow and
temperature characteristics that could
facilitate the growth and competitive
ability of any New Zealand mudsnail
populations that became established at
those sites.
Because of their high reproductive
rate, wide habitat tolerance, and few
effective parasites or predators outside
of their native waters, New Zealand
mudsnails are capable of outcompeting
most native aquatic snails for food and
space (NBII 2011, pp. 1, 2). They are
extremely difficult to eradicate once
established (NBII 2011, pp. 3, 4).
In 2007, New Zealand mudsnails
became established at the Bridge Bay
Marina on Shasta Lake near Interstate 5
(United States Geological Survey
(USGS) 2009a, pp. 1, 2; USGS 2009b, p.
1; McAlexander 2012a, p. 1). The aerial
distance between that location and the
nearest known site occupied by the
canary duskysnail is about 48 km (30
mi). If the New Zealand mudsnail were
to colonize multiple areas occupied by
the canary duskysnail, it could become
a serious threat to the species. However,
the likelihood that such a scenario will
occur is very uncertain. In 2011, six
additional New Zealand mudsnail
locations were found in the northcentral California area, but population
levels were low and all sites were on the
Sacramento River (USGS 2009b, p. 1;
USGS 2011, p. 40; McAlexander 2012a,
p. 1). Five of those sites are downstream
of the Bridge Bay Marina, while one is
upstream at Castle Lake (USGS 2009b,
p. 1; McAlexander 2012b, p. 1). No
populations have so far been found in
any tributary rivers or streams, such as
the Pit River. The California Department
of Fish and Game (CDFG) is following
a national management and control plan
(Aquatic Nuisance Species Task Force
(ANSTF) 2007, entire) and has posted
information and brochures about the
New Zealand mudsnail on its Web site,
including printable posters and wallet
cards (CDFG undated, p. 1).
Although there is no recognized
method for assessing the risk of New
Zealand mudsnail establishment in a
given area at a given time (ANSTF 2007,
p. 17), we consider Lake Britton to be
the location within the range of the
canary duskysnail currently at greatest
danger of infestation. Lake Britton
supports a marina, boat launch, and
fishery, borders a state park, and is
easily accessed from State Highway 89
(Stewardship Council, Vol. 2, pp. PM–
37–39). In contrast, vehicle access to the
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Pit 4 reservoir is more difficult, and
boating is not currently allowed
(Stewardship Council, Vol. 2. pp. PM–
48, PM–49). Thus, if a boat
inadvertently carrying New Zealand
mudsnails were to be towed from the
Bridge Bay Marina to some body of
water in the range of the canary
duskysnail, the most likely such
location would be Lake Britton.
However, virtually the entire extent of
the canary duskysnail’s range supports
fisheries (Stewardship Council, Vol. 2.
pp. PM–21, PM–31, PM–49), so it would
be possible for New Zealand mudsnails
to be carried on fishing waders from an
infested fishing spot (presumably farther
downstream on the Sacramento River,
rather than at the Bridge Bay Marina
itself) to almost anywhere in the range
(NBII 2011, p. 3; Emery 2012, p. 1).
Once established at one location
within the range of the canary
duskysnail, the likelihood of infestation
at other such locations would increase.
However, to compete directly with
canary duskysnails, the New Zealand
mudsnail would have to establish itself
at the canary duskysnail’s occupied
locations. The New Zealand mudsnail
tends to have a spotty distribution,
apparently governed to a large extent by
where colonizing individuals are
deposited by various vectors (USGS
2009b, p. 1; Emery 2012, p. 1). For the
New Zealand mudsnail to be a threat to
the canary duskysnail, first it would
have to colonize somewhere within the
range (probably Lake Britton), then it
would have to establish so many
additional colonies that a large
percentage of canary duskysnail sites
were overlapped. Then, it would have to
outcompete the canary duskysnails at
those sites and the canary duskysnails
would have to be unable to establish
themselves at different sites. All these
stages are likely to require several years,
if they happen at all. Currently the
available information indicates there is
no infestation at Lake Britton or at any
locations occupied by the canary
duskysnail. Accordingly, we do not
consider competition from New Zealand
mudsnails to be a threat to the canary
duskysnail at this time.
Fire
A large high-severity fire could
potentially impact canary duskysnails
by removing ground cover (Robichaud
undated, pp. 2, 4), thereby allowing silt
to wash into occupied springs and
streams. Silt can degrade water quality,
cover the perilithon on which canary
duskysnails feed, and could also
smother canary duskysnail eggs
(Furnish and Monthey 1999, Sect. 4, pp.
9, 14; Robichaud undated, p. 3). For the
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nine occupied sites in the Pit River
below Lake Britton, siltation would be
expected to collect in the Pit 3, 4, and
5 reservoirs, and to wash out of the river
portions below each dam fairly quickly
due to required flow releases
established by the dam operating
requirements (see Impoundments,
above). The remaining 12 sites are
spread out over 3 major areas, with 8
sites in the upper Fall River watershed,
and 2 each in Burney Creek (in
McArthur-Burney Falls State Park), and
Hat Creek (near Cassel, CA). The closest
distances between these locations range
from 12 km (7.5 mi) (Burney Creek to
Hat Creek) to 20 km (12.4 mi) (upper
Fall River to Hat Creek). A fire would
have to be extremely large and precisely
positioned to encompass two such
areas. Additionally, the occupied sites
along the lower Pit River and in upper
Fall River watershed are likely to benefit
from fire prevention and fuel reduction
activities conducted by the ShastaTrinity National Forest (USDA 2012a,
pp. 1–15, 17–19), the Lassen National
Forest (USDA 2012b, pp. 1, 3–7, 9–12),
and by landowners in the upper Fall
River watershed (FRRCD 2005, p. 3).
Changes in Precipitation and Water
Availability Due to Climate Change
Our analyses under the Endangered
Species Act include consideration of
ongoing and projected changes in
climate. The terms ‘‘climate’’ and
‘‘climate change’’ are defined by the
Intergovernmental Panel on Climate
Change (IPCC). ‘‘Climate’’ refers to the
mean and variability of different types
of weather conditions over time, with 30
years being a typical period for such
measurements, although shorter or
longer periods also may be used (IPCC
2007, p. 78). The term ‘‘climate change’’
thus refers to a change in the mean or
variability of one or more measures of
climate (e.g., temperature or
precipitation) that persists for an
extended period, typically decades or
longer, whether the change is due to
natural variability, human activity, or
both (IPCC 2007, p. 78). Various types
of changes in climate can have direct or
indirect effects on species. These effects
may be positive, neutral, or negative and
they may change over time, depending
on the species and other relevant
considerations, such as the effects of
interactions of climate with other
variables (for example, habitat
fragmentation) (IPCC 2007, pp. 8–14,
18–19). In our analyses, we use our
expert judgment to weigh relevant
information, including uncertainty, in
our consideration of various aspects of
climate change.
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Climate change is not expected to
significantly change total precipitation
in northern California, but may affect
seasonal water availability in some areas
due to changes in snowpack melting
times and the proportion of
precipitation falling as rain rather than
snow (Dettinger et al. 2004, pp. 43, 44).
However, the water supplying springs
occupied by the canary duskysnail in
the middle Pit River drainage (including
the upper Fall River area) and in Hat
Creek are collected from wide areas in
the Medicine Lake highlands and
Lassen volcanic highlands, respectively
(Service 1998, p. 18). Rain and
snowmelt in those areas percolate
through porous volcanic rocks to collect
in large aquifers, thereby holding extra
water from seasons when rain is
plentiful and delivering it through
springs during seasons when rain is not
plentiful. Resulting spring flows are
highly stable in volume, temperature,
and clarity (Service 1998, p. 46).
Accordingly, we do not expect changes
in precipitation or water availability due
to climate change to significantly affect
the species.
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Summary of Factor E
In summary, the canary duskysnail is
protected from expected changes in
precipitation or water availability due to
climate change by the particular
characteristics of its habitat. Although
potential competition from the New
Zealand mudsnail is cause for concern,
no site currently occupied by canary
duskysnail has been colonized and there
is nothing to indicate the New Zealand
mudsnail will colonize any of the
multiple locations occupied by the
canary duskysnail. There is also no
direct evidence to show that any such
occupied locations would be extirpated
by such a colonization were it to occur.
The two species are not known to have
interacted in the past. We therefore
conclude that, based on the best
available scientific and commercial
information, that other natural or
manmade factors such as competition
from the New Zealand mudsnail,
changes in precipitation or water
availability due to climate change, or
fire do not constitute significant threats
to the canary duskysnail now or in the
future.
Finding for the Canary Duskysnail
We have carefully assessed the best
scientific and commercial information
available regarding the past, present,
and future threats faced by the canary
duskysnail. We reviewed the petition,
available published and unpublished
scientific and commercial information,
and information submitted to us during
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our status review. This finding reflects
and incorporates that information. We
also consulted with recognized
authorities on this species, and we
consulted with Federal and State
resource agencies. Although only 21
occupied sites are known for the canary
duskysnail, the best available scientific
and commercial information does not
clearly indicate that populations at any
site are in decline, or that any sites are
likely to be lost due to impoundments,
water quality, other habitat-related
impacts, overutilization, disease or
predation, the inadequacy of existing
regulatory mechanisms, competition
with invasive species, or fire, now or in
the foreseeable future. The best
available scientific and commercial
information at this time does not
indicate that there is likely to be a
change in any of these stressors in the
future. Three years of data from an
ongoing monitoring study found
extreme fluctuations in population
density numbers at certain sites, but did
not indicate the fluctuations were in
response to threats, or likely to lead to
permanent local extirpation. New
Zealand mudsnails could be a threat to
canary duskysnails if they become
established in their range, but we have
no information to indicate whether that
will happen in the foreseeable future or
the extent of New Zealand mudsnail
impact if they do become established in
the range of the canary duskysnail.
Based on our review of the best
available scientific and commercial
information pertaining to the five
factors, we find that the threats as
described above, either alone or in
combination are not of sufficient
imminence, intensity, or magnitude to
indicate that the canary duskysnail is in
danger of extinction (endangered) or
likely to become endangered within the
foreseeable future (threatened),
throughout all of its range.
Significant Portion of the Range
Having determined that the canary
duskysnail is not endangered or
threatened throughout all of its range,
we must next consider whether there
are any significant portions of the range
where the canary duskysnail is in
danger of extinction or is likely to
become endangered in the foreseeable
future. See Significant Portion of the
Range under Summary of Procedures for
Determining the Listing Status of
Species.
We evaluated the current range of the
canary duskysnail to determine if there
is any apparent geographic
concentration of potential threats for the
species. The canary duskysnail is highly
restricted in its range and the threats
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occur throughout its range. We
considered the potential threats due to
impoundments, water quality, other
habitat-related impacts, overutilization,
disease or predation, the inadequacy of
existing regulatory mechanisms,
competition with invasive species, and
fire. We found no concentration of
threats that suggests that the canary
duskysnail may be in danger of
extinction in a portion of its range. We
found no portions of its range where
potential threats are significantly
concentrated or substantially greater
than in other portions of its range.
Therefore, we find that factors affecting
the species are essentially uniform
throughout its range, indicating no
portion of the range of the species
warrants further consideration of
possible endangered or threatened
status under the Act.
We find that the canary duskysnail is
not in danger of extinction now, nor is
likely to become endangered within the
foreseeable future, throughout all or a
significant portion of its range.
Therefore, listing the canary duskysnail
as endangered or threatened under the
Act is not warranted at this time.
Goose Valley Pebblesnail (Fluminicola
anserinus)
Species Information for the Goose
Valley Pebblesnail
Taxonomy and Species Description
The Goose Valley pebblesnail was
formally named and described in 2007
(Hershler et al. 2007, p. 409). Prior to
2007, it was referred to as the globular
pebblesnail, ‘‘Fluminicola n. sp. 18’’
(Frest and Johannes 1993, p. 52; Frest
and Johannes 1999, pp. 51–52; Furnish
and Monthey 1999, Sect. 2, p. 6; CBD et
al. 2008, p. 49). It was assigned a
different provisional scientific name
(‘‘Fluminicola n. sp. 6’’) by Frest and
Johannes (1995b, p. 44), although it
remained the ‘‘globular pebblesnail’’ as
referred to in that source. Although
pebblesnails in general (Fluminicola
genus) had previously been considered
part of the Hydrobiidae family (Hershler
et al. 2003, p. 275), they have since been
reassigned to the Lithoglyphidae family
(Hershler et al. 2007, p. 371).
The Goose Valley pebblesnail is a
small aquatic snail, roughly 2 to 3.5 mm
(0.08 to 0.14 in) tall, with about 3.25 to
3.75 major whorls (Hershler et al. 2007,
pp. 372, 410–412). Its head is dark
brown, while the periostracum (outer
layer) is tan or light green. It is similar
in appearance to the Potem Creek
pebblesnail (described below), but has a
larger shell aperture with a more
reinforced periphery (among other
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differences) (Furnish et al. 1997, p. 48;
Hershler et al. 2007, pp. 409, 410).
Five-Factor Evaluation of Threats to the
Goose Valley Pebblesnail
Distribution
Factor A. The Present or Threatened
Destruction, Modification, or
Curtailment of Its Habitat or Range
The Goose Valley pebblesnail is
known from a total of 13 locations, 2 in
the upper Sacramento River drainage in
Siskiyou County, California (Frest and
Johannes 1995b, pp. T12, A6, B24), and
11 (after accounting for overlap from
different sources) in the lower Pit River
drainage, Shasta County, California
(Frest and Johannes 1995b, pp. T13, A7;
Hershler et al. 2007, pp. 376, 409, 410;
Haley 2012a, p. 3). Further review has
indicated that the Siskiyou County sites
must be considered unconfirmed
(Johannes 2012c, pp. 1–4).
The type locality for the Goose Valley
pebblesnail is a spring on the west side
of Goose Valley, about 10 km (6.3 mi)
east of the crossing of Highways 89 and
299, and about 6.5 km (4 mi) from the
Pit River (Hershler et al. 2007, p. 409).
All other occupied sites in the drainage
are in the valley formed by the Pit River
itself. Nine sites are in springs along the
Pit 4 reach (below Pit 4 dam) on ShastaTrinity National Forest land in the
NWFP area (Hershler et al. 2007, pp.
376, 409, 410; Haley 2012a, p. 3). The
11th site is upstream, in a spring on
private land near Lake Britton (Hershler
et al. 2007, pp. 376, 409, 410). The
unconfirmed sites in the upper
Sacramento River drainage are located
in springs somewhat east of the river
and north of Mossbrae Falls Frest and
Johannes 1995b, pp. T12, A6, B24).
Those sites also support Shasta
pebblesnails (discussed below).
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Habitat and Biology
The Goose Valley pebblesnail occurs
in springs and spring-fed habitats,
generally on the sides and undersides of
stones in shaded areas with few water
plants (Frest and Johannes 1999, p. 52;
Spring Rivers 2001, p. 22). It is likely to
be a perilithon grazer (Furnish et al.
1997, p. 31; Frest and Johannes 1999, p.
52). We have no specific information
regarding the reproduction of this
species, but members of the Fluminicola
genus typically live a single year and
breed only once (Furnish and Monthey
1999, Sect. 2, p. 5; ORNHIC 2004, p. 2).
They generally lay eggs in the spring,
which hatch in 2 to 4 weeks. They are
not known to disperse widely, and are
highly sensitive to water pollution,
decreases in dissolved oxygen, elevated
temperatures, and sedimentation
(Furnish and Monthey 1999, Sect. 2, pp.
5, 7; Hershler et al. 2007, p. 372).
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Impoundments
Although 9 of the 11 known occupied
sites are downstream of the Pit 4 dam,
the sites consist of springs or spring-fed
creeks near the Pit River and thus
physically removed from any warmer
high-water flows released by the dams
(Hershler et al. 2007, pp. 376, 409, 410;
Haley 2012a, p. 3). A tenth occupied site
is near Lake Britton, at 878 m (2,880 ft)
elevation (Hershler et al. 2007, p. 409).
The lake surface is lower than 841 m
(2,759 ft) when full, and we are not
aware of any plans to raise the level of
the lake. The final occupied location, at
Goose Valley, is not influenced by
dams. Therefore, we conclude the
habitat of the Goose Valley pebblesnail
is not currently at risk of modification
due to impoundments nor do we expect
it to be so in the future.
Agriculture
The type locality is a spring on the
edge of Goose Valley, the floor of which
is completely converted to agriculture.
The site is within 50 m (164 ft) of
converted land, but it is separated by
Goose Valley Road, and is on sloped
and forested terrain. The limits of the
converted land have not changed since
at least 2001, and the occupied site is on
land zoned as unclassified, whereas the
valley floor is zoned as exclusive
agriculture and agricultural preserve
(Shasta County 2003, p. 1; Shasta
County 2012, p. 1). The best available
scientific and commercial information
does not indicate that the quality of the
site has been damaged by its proximity
to converted agricultural lands over the
past decade, nor is there any indication
that the location of the spring itself is
likely to be converted to agriculture.
None of the other occupied locations are
near agricultural lands.
Diversions and Grazing
In our 90-day finding, we indicated
that diversions of spring water for
agricultural and other uses, and grazing
in and around occupied locations, were
potential threats. However, these
conclusions were largely based on
generalized information for the mid and
lower Pit River area (Hershler et al.
2003, p. 277) and the upper Sacramento
River (ORNHIC 2004e, p. 2), where we
now know no occupied locations exist
(see Distribution, above). Nine of the 11
known sites in the Pit River drainage are
within the NWFP area on the ShastaTrinity National Forest and, as such, are
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protected by the SMP and ACS (see
Generally Applicable Federal
Regulatory Mechanisms, above).
Proposed diversions or grazing practices
at those locations would have to take
into account the buffer requirements
established by the ACS riparian
reserves, as well as the survey and
mitigation requirements of the SMP. We
are not aware of evidence suggesting
any such practices are occurring on
Shasta-Trinity National Forest land.
In summary, although the type
locality is close to agricultural land,
most occupied locations are near flows
influenced by dams, and diversions and
grazing occur within the larger
geographic area occupied by the species,
a review of the best available scientific
and commercial information does not
indicate that any of these factors are
negatively impacting any populations of
Goose Valley pebblesnails. We therefore
conclude that the present or threatened
destruction, modification or curtailment
of its habitat or range does not
constitute a significant threat to the
species now or in the future.
Factor B. Overutilization for
Commercial, Recreational, Scientific, or
Educational Purposes
Our review of the best available
scientific and commercial information
yielded nothing to indicate that
overutilization for commercial,
recreational, scientific, or educational
purposes is occurring at this time or is
likely to occur in the future. We
therefore conclude such overutilization
does not constitute a threat to the Goose
Valley pebblesnail.
Factor C. Disease or Predation
Disease
We reviewed the best available
scientific and commercial information
regarding this species and other similar
species, and found no evidence to
indicate that disease is impacting Goose
Valley pebblesnail populations.
Predation
There is a potential for increased
predation on Goose Valley pebblesnails
due to the establishment of the signal
crayfish in the mid and lower Pit River
drainage (Ellis 1999, pp. 12, 57, 58;
Service 2009, p. 10). As discussed above
with regard to the canary duskysnail,
signal crayfish predation can
significantly impact mollusk
populations when the crayfish are at
high densities (Lorman and Magnuson
1978, p. 9). The known Goose Valley
pebblesnail sites do not overlap the
current range of the Shasta crayfish, so
only the signal crayfish poses a
potential predation impact. The only
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information we have regarding crayfish
densities applies to the Pit 4 reach and
does not indicate that crayfish densities
at that location are either particularly
high (as compared to populations of
native crayfish at other locations) or
increasing (Ellis 1999, p. 58; PGE 2011b,
pp. iii, 10; PGE 2012b, p. 9). Hence, the
available evidence does not support the
contention that signal crayfish are
present in the range of the Goose Valley
pebblesnail in sufficiently high
densities to pose a predation risk to the
Goose Valley pebblesnail. Furthermore,
the information does not indicate any
trend in the densities of the signal
crayfish that would lead us to a
conclusion that the predation risk
would increase in the future.
We therefore conclude, based on the
best available scientific and commercial
information, that neither disease nor
predation constitutes a significant threat
to the species now or in the future.
Factor D. The Inadequacy of Existing
Regulatory Mechanisms
Under this factor, we examine
whether existing regulatory mechanisms
are inadequate to address the threats to
the species discussed under the other
factors. Section 4(b)(1)(A) of the Act
requires the Service to take into account
‘‘those efforts, if any, being made by any
State or foreign nation, or any political
subdivision of a State or foreign nation,
to protect such species * * *’’. We
interpret this language to require the
Service to consider relevant Federal,
State, and Tribal laws and regulations
when developing our threat analyses.
Regulatory mechanisms, if they exist,
may preclude the need for listing if we
determine that such mechanisms
adequately address the threats to the
species such that listing is not
warranted. The analysis of threats to the
Goose Valley pebblesnail under the
other factors included consideration of
the ameliorative effects of regulatory
mechanisms where applicable, such as
those discussed under Factor A and
under Generally Applicable Federal
Regulatory Mechanisms, above.
Having evaluated the significance of
the threat as mitigated by any such
conservation efforts, we analyze under
Factor D the extent to which existing
regulatory mechanisms are inadequate
to address the specific threats to the
species. We found no significant threats
to the Goose Valley pebblesnail under
the other factors, therefore, the analysis
of any existing regulatory mechanisms’
adequacy to address threats is not
applicable. Consequently, after
reviewing the best available commercial
and scientific information, we conclude
that the inadequacy of existing
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regulatory mechanisms is not a threat to
the Goose Valley pebblesnail now or in
the future.
Factor E. Other Natural or Manmade
Factors Affecting Its Continued
Existence
Competition With Invasive Species
An invasion by the New Zealand
mudsnail into the lower Pit River
drainage could constitute a serious
threat to the Goose Valley pebblesnail
due to competition for food and space
(see canary duskysnail, above).
However, we found no information to
indicate New Zealand mudsnails are
currently in the lower Pit River, nor did
we find specific information to indicate
the likelihood of an invasion by New
Zealand mudsnails in the near future.
Additionally, the occupied spring at
Goose Valley would be less likely to be
colonized by the New Zealand mudsnail
because it drains into Goose Valley,
where it is used for agriculture, rather
than into the Pit River, which is visited
by boaters and fishermen who may
inadvertently transport the mudsnail
from previously visited sites.
Changes in Precipitation and Water
Availability Due to Climate Change
See our discussion of climate change
in general in the Changes in
Precipitation and Water Availability
Due to Climate Change section under
‘‘Factor A’’ in Five-Factor Evaluation of
Threats for the Canary Duskysnail.
Climate change is not expected to
significantly change total precipitation
in northern California, but may affect
seasonal water availability in some areas
due to changes in snowpack melting
times and the proportion of
precipitation falling as rain rather than
snow (Dettinger et al. 2004, pp. 43, 44).
However, the water supplying springs
occupied by the Goose Valley
pebblesnail in the middle Pit River
drainage is collected from wide areas in
the Medicine Lake highlands (Service
1998, p. 18). Rain and snowmelt in
those areas percolate through porous
volcanic rocks to collect in large
aquifers, thereby holding extra water
from seasons when rain is plentiful and
delivering it through springs during
seasons when it is not. Resulting spring
flows are highly stable in volume,
temperature, and clarity (Service 1998,
p. 46). Similarly, the size of the aquifer
that supplies the water for the Goose
Valley spring is estimated at
approximately 18 square km (7 square
mi) (CDWR 2003, p. 1). All occupied
locations of the Goose Valley
pebblesnail are in springs or small
spring-fed streams, rather than in the
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57935
main current of the Pit River, and so are
likely to be protected from temperature
and flow variations by the springs’
stable flows. Accordingly, we do not
expect changes in precipitation or water
availability due to climate change to
significantly affect the species.
Fire
Fire could potentially affect Goose
Valley pebblesnails by increased
siltation due to the accumulation of ash
or subsequent erosional deposition of
soil in their springs or streams.
However, most siltation should clear
relatively quickly from the four
occupied locations in the lower Pit
River drainage, because the flow rates
for those locations are high (Haley
2012b, p. 1). Biologists working on
mollusk surveys in the lower Pit River
both before and after the Shasta-Trinity
Unit (SHU) Lightning Complex Fire of
early August 2009 (PGE 2010, p. 13) did
not consider the impacts to nearby
springs and streams to be serious or
lasting (Ellis and Haley 2012, p. 1). A
search of fire data archived by the
California Department of Forestry and
Fire Protection (CAL FIRE) and
extending back to 2003, indicates that
the SHU Lightning Complex Fire, at
17,623 ac (7,132 ha) (CAL FIRE 2009, p.
1) was the largest in Shasta County on
record (Service 2012, p. 1). Future
Shasta County fires are therefore likely
to be smaller than the SHU Lightning
Complex Fire, and to have smaller
impacts (such as less siltation from the
accumulation of ash). Since the SHU
Lightning Complex fire did not produce
serious impacts to Goose Valley
pebblesnail habitats, smaller fires would
not be expected to either.
Summary of Factor E
In summary, the Goose Valley
pebblesnail is protected from likely
impacts of climate change and fire by
the particular characteristics of its
habitat. Although potential competition
from the New Zealand mudsnail is
cause for concern, no site currently
occupied by Goose Valley pebblesnail
has been colonized, and there is nothing
to indicate the New Zealand mudsnail
will colonize multiple locations
occupied by the Goose Valley
pebblesnail. There is also no direct
evidence to show that any such
occupied locations would be extirpated
by such a colonization, were it to occur.
The two species are not known to have
interacted in the past. We therefore
conclude, based on the best available
scientific and commercial information,
that other natural or manmade factors
such as competition from the New
Zealand mudsnail, changes in
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precipitation or water availability due to
climate change, or fire do not constitute
significant threats to the Goose Valley
pebblesnail now or in the future.
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Finding for the Goose Valley Pebblesnail
We have carefully assessed the best
scientific and commercial information
available regarding the past, present,
and future threats faced by the Goose
Valley pebblesnail. We reviewed the
petition, available published and
unpublished scientific and commercial
information, and information submitted
to us during our status review. This
finding reflects and incorporates that
information. We also consulted with
recognized authorities on this species
and Federal and State resource agencies.
Although only 11 occupied sites are
known for the Goose Valley pebblesnail,
a review of the best available
information does not indicate that
populations at any site are in decline, or
that any sites are likely to be lost due
to impoundments, agriculture,
diversions and grazing, overutilization,
disease or predation, the inadequacy of
existing regulatory mechanisms,
competition with invasive species,
changes in precipitation and water
availability due to climate change, or
fire, now or in the foreseeable future.
The best available scientific and
commercial information at this time
does not indicate that there is likely to
be a change in any of these stressors in
the future.
Based on our review of the best
available scientific and commercial
information pertaining to the five
factors, we find that the threats as
described above, either alone or in
combination, are not of sufficient
imminence, intensity, or magnitude to
indicate that the Goose Valley
pebblesnail is in danger of extinction
(endangered) or likely to become
endangered within the foreseeable
future (threatened), throughout all of its
range.
Significant Portion of the Range
Having determined that the Goose
Valley pebblesnail is not endangered or
threatened throughout all of its range,
we must next consider whether there
are any significant portions of the range
where the Goose Valley pebblesnail is in
danger of extinction or is likely to
become endangered in the foreseeable
future. See Significant Portion of the
Range under Summary of Procedures for
Determining the Listing Status of
Species.
We evaluated the current range of the
Goose Valley pebblesnail to determine if
there is any apparent geographic
concentration of potential threats for the
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species. The Goose Valley pebblesnail is
highly restricted in its range and the
threats occur throughout its range. We
considered the potential threats due to
impoundments, agriculture, diversions
and grazing, overutilization, disease or
predation, the inadequacy of existing
regulatory mechanisms, competition
with invasive species, changes in
precipitation and water availability due
to climate change, and fire. We found no
concentration of threats that suggests
that the Goose Valley pebblesnail may
be in danger of extinction in a portion
of its range. We found no portions of its
range where potential threats are
significantly concentrated or
substantially greater than in other
portions of its range. Therefore, we find
that factors affecting the species are
essentially uniform throughout its
range, indicating no portion of the range
of the species warrants further
consideration of possible endangered or
threatened status under the Act.
We find that the Goose Valley
pebblesnail is not in danger of
extinction now, nor is likely to become
endangered within the foreseeable
future, throughout all or a significant
portion of its range. Therefore, listing
the Goose Valley pebblesnail as
endangered or threatened under the Act
is not warranted at this time.
Hat Creek Pebblesnail (Fluminicola
umbilicatus)
Species Information for the Hat Creek
Pebblesnail
Taxonomy and Species Description
The Hat Creek pebblesnail is an
aquatic snail that was formally named
and described in 2007 (Hershler et al.
2007, p. 407). This species combines
two taxa previously considered likely
species but never formally described,
the umbilicate pebblesnail (Fluminicola
n. sp. 19) (Frest and Johannes 1999, p.
55) and the Lost Creek pebblesnail
(Fluminicola n. sp. 20) (Frest and
Johannes 1999, pp. 55, 59). The shell of
the Hat Creek pebblesnail is subglobose
(rounded top) to ovate conic (egg shaped
top), and ranges from 2.1 to 5.4 mm
(0.08 to 0.2 in) tall, with 3.25 to 4.5
major whorls (Hershler et al. 2007, p.
409). The periostracum can be tan,
brown, or light green. The head is dark
brown to almost black. Adult Hat Creek
pebblesnails are somewhat unusual
among Fluminicola species in having a
visible open space near the opening of
the shell, called an umbilicus, around
which the whorls wrap (Frest and
Johannes 1999, pp. 55, 58).
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Distribution
The Hat Creek pebblesnail is known
from five locations in the upper Hat
Creek watershed, Shasta County, close
to the intersection of State Highways 44
and 89. The locations fall into two
groups, one of which centers on Hat
Creek itself and the other on nearby Lost
Creek. Lost Creek disappears into a lava
tube, and is presumed to connect to Hat
Creek (ORNHIC 2004f, p. 1). The groups
are roughly 13 km (8 mi) apart, and the
furthest distance of occupied locations
within each group is roughly 1 km (0.6
mi). One occupied location in each
group is on Lassen National Forest land,
while the others are on private
inholdings within the general
boundaries of the National Forest.
Habitat and Biology
The Hat Creek pebblesnail appears
limited to cold water springs and spring
runs (Frest and Johannes 1999, pp. 56,
60). It occurs on sand-gravel substrates,
and on water plants such as watercress
(genus Nasturtium, formerly Rorippa)
and brooklime (Veronica sp.). It grazes
on perilithon and periphyton. We have
no specific information regarding the
reproduction of this species, but
members of the Fluminicola genus
typically live a single year and breed
only once (Furnish and Monthey 1999,
Sect. 4, p. 7 and Sect. 6, p. 4; ORNHIC
2004f, p. 2). They generally lay eggs in
the spring, which hatch in 2 to 4 weeks.
They are not known to disperse widely,
and are highly sensitive to water
pollution, decreases in dissolved
oxygen, elevated temperatures, and
sedimentation (Furnish and Monthey
1999, Sect. 4, pp. 7, 8).
Five-Factor Evaluation of Threats to the
Hat Creek Pebblesnail
Factor A. The Present or Threatened
Destruction, Modification, or
Curtailment of Its Habitat or Range
Timber Production
Lassen National Forest plans to
reduce fuel loads by removing small
conifers upstream of the two
southernmost sites occupied by Hat
Creek pebblesnails (Burton 2012, p. 1).
Such operations, if not carefully
conducted, could potentially remove
shading foliage and collapse riverbanks,
thereby causing siltation and increased
water temperatures that could impact
Hat Creek pebblesnails downstream.
However, the operations will take place
in Riparian Conservation Areas (RCAs,
discussed below), and are subject to
protective regulations likely to prevent
serious habitat impacts. In keeping with
these regulations, the fuel reduction
projects will proceed with a minimum
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of disturbance, and conifers will be cut
by hand to avoid unnecessary use of
heavy machinery near the stream
(Burton 2012, p. 1).
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Timber Production—Protective
Regulatory Mechanisms
The Sierra Nevada Forest Plan
Amendment (SNFPA)—The SNFPA is a
set of amendments to the resource
management plans of national forests in
the Sierra Nevada and Modoc Plateau
areas of California (USDA 2004, p. 15).
The SNFPA applies to those portions of
the Lassen National Forest not covered
by the NWFP, including the two areas
within the National Forest occupied by
Hat Creek pebblesnails. The SNFPA
includes a sub-program called the
Aquatic Management Strategy (AMS),
which establishes RCAs around
perennial streams and other
hydrological or topographic
depressions, such as ponds and springs
(USDA 2004, pp. 32, 42). Activities
within the RCAs require site-specific
analyses to ensure the activity conforms
to several riparian conservation
objectives (USDA 2004, p. 33). Those
objectives include maintaining or
restoring geomorphic and biological
characteristics of special aquatic
features and ensuring that activities
enhance or maintain physical and
biological characteristics associated
with aquatic and riparian-dependent
species. Although they also include
provisions for improving habitat, such
improvements are subject to funding
and may take time to address situations
in which habitat has already been
impacted, such as recreational vehicle
impacts upstream of the occupied sites
on Hat Creek.
Grazing
The two occupied sites on Hat Creek
are not near grazed areas, but two of the
three occupied sites on Lost Creek are
on private land in a location that is
subject to grazing (Burton 2012, p. 1).
The third Lost Creek site is on ungrazed
land in the Lassen National Forest,
about 0.64 km (0.4 mi) downstream
from the grazed area. Cattle grazing in
and around streams can trample banks
and riparian vegetation, resulting in
wider, shallower, muddier, and less
shaded waters (Meehan and Platts 1978,
pp. 275–276; Stephenson and Street
1978, p. 152; Kauffman and Krueger
1984, p. 432). If such impacts were to
occur in the vicinity of the sites
occupied by Hat Creek pebblesnails,
they could threaten the snail
populations, which (as discussed under
Habitat and Biology, above) are highly
sensitive to water pollution, decreases
in dissolved oxygen, elevated
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temperatures, and sedimentation.
However, the stream in the area of the
occupied sites is protected from cattle
by a combination of fencing, brush, and
rocks (Suarez 2012, p. 1). Cattle are
typically driven across the stream twice
per year, but the substrate at the
crossing site is primarily rock, so the
stream bed suffers little trampling
damage.
Impoundments
The two occupied sites on Hat Creek
are not near impoundments, but the
three occupied sites on Lost Creek are
downstream of one small impoundment
and upstream from another, with
approximately 2.5 km (1.5 mi) of
perennial stream between the two
reservoirs (Burton 2012, p. 1). There is
some potential for increases in water
temperatures in the Lost Creek occupied
sites due to releases from the upper
reservoir. However, the small upstream
reservoir exposes relatively little still
surface water to the sun as compared to
the much larger Pit 3, 4, and 5
reservoirs, and so is less likely to
produce significantly higher
downstream temperatures (see
Impoundments, under Canary
Duskysnail, above). Both the upstream
reservoir and the water below it in Lost
Creek support coldwater fish such as
rainbow trout (Burton 2012, p. 1).
The downstream reservoir is over 200
m (650 ft) from the nearest occupied
location. The downstream dam includes
an overflow outlet, so the reservoir is
unlikely to back up during high flows
and inundate sites occupied by Hat
Creek pebblesnails.
Recreation
An area about 4.8 km (3 mi) long
along Hat Creek, upstream of the
occupied sites, has been heavily
impacted by off-highway vehicle (OHV)
use in and around the creek (Burton
2012, p. 1). Impacts at the OHV site
include crushed riparian vegetation and
collapsed stream banks, resulting in
increased siltation and potentially
higher temperatures. However, the
nearest site occupied by the Hat Creek
pebblesnail is a spring off the side of
Hat Creek (Hershler et al. 2007, p. 407),
while the other occupied site in the area
is farther downstream in Hat Creek,
approximately 2 km (1.2 mi) from the
edge of the recreational area and 2.6 km
(1.6 mi) from the area of primary
impact. Because of distance to the
second site, and spring flows from the
first, sediment and increased
temperatures produced by upstream
recreational use would be unlikely to
significantly affect either occupied site.
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There is no evidence of OHV impacts at
the spring.
Accordingly, although timber
management, grazing, impoundments,
and OHV use all occur in the general
vicinity of occupied sites, the best
available evidence indicates they are not
impacting occupied habitat. We
therefore conclude, based on the best
available scientific and commercial
information, that the present or
threatened destruction, modification or
curtailment of its habitat or range does
not constitute a significant threat to the
species now or in the future.
Factor B. Overutilization for
Commercial, Recreational, Scientific, or
Educational Purposes
Our review of the best available
scientific and commercial information
yielded nothing to indicate that
overutilization for commercial,
recreational, scientific, or educational
purposes is occurring at this time, or is
likely to occur in the future. We
therefore conclude such overutilization
does not constitute a threat to the Hat
Creek pebblesnail.
Factor C. Disease or Predation
Disease
We reviewed the best available
scientific and commercial information
regarding this species and other similar
species, and found no evidence to
indicate that disease is impacting Hat
Creek pebblesnail populations.
Predation
Predation by the introduced signal
crayfish could threaten Hat Creek
pebblesnail populations if the signal
crayfish were present in sufficiently
high densities (see canary duskysnail,
above). However, we have no direct
evidence that either signal or Shasta
crayfish are present in the upper
portions of Hat Creek or Lost Creek. The
closest area for which we have signal
crayfish density information is the
middle Pit River, where densities were
roughly equal to native crayfish
densities as measured in the upper Fall
River (Ellis 1999, p. 58; PGE 2011b, pp.
iii, 10; PGE 2012b, p. 9). Hence, the
available evidence does not support the
contention that signal crayfish are
present in Hat or Lost Creeks in
sufficiently high densities to pose a
predation risk to the Hat Creek
pebblesnail. Furthermore, the
information does not indicate any trend
in the densities of either crayfish that
would lead us to a conclusion that the
predation risk would increase in the
future.
We therefore conclude, based on the
best available scientific and commercial
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information, that neither disease nor
predation constitutes a significant threat
to the species now or in the future.
Factor D. The Inadequacy of Existing
Regulatory Mechanisms
Under this factor, we examine
whether existing regulatory mechanisms
are inadequate to address the threats to
the species discussed under the other
factors. Section 4(b)(1)(A) of the Act
requires the Service to take into account
‘‘those efforts, if any, being made by any
State or foreign nation, or any political
subdivision of a State or foreign nation,
to protect such species...’’. We interpret
this language to require the Service to
consider relevant Federal, State, and
Tribal laws and regulations when
developing our threat analyses.
Regulatory mechanisms, if they exist,
may preclude the need for listing if we
determine that such mechanisms
adequately address the threats to the
species such that listing is not
warranted. The analysis of threats to the
Hat Creek pebblesnail under the other
factors included consideration of the
ameliorative effects of regulatory
mechanisms where applicable, such as
those discussed under Factor A and
under Generally Applicable Federal
Regulatory Mechanisms, above.
Having evaluated the significance of
the threat as mitigated by any such
conservation efforts, we analyze under
Factor D the extent to which existing
regulatory mechanisms are inadequate
to address the specific threats to the
species. We found no significant threats
to the Hat Creek pebblesnail under the
other factors, therefore, the analysis of
any existing regulatory mechanisms’
adequacy to address threats is not
applicable. Consequently, after
reviewing the best available commercial
and scientific information, we conclude
that the inadequacy of existing
regulatory mechanisms is not a threat to
the Hat Creek pebblesnail now or in the
future.
Factor E. Other Natural or Manmade
Factors Affecting Its Continued
Existence
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Competition With Invasive Species
New Zealand mudsnails are not
currently known to occur within the
range of the Hat Creek pebblesnail (Lost
Creek and upper Hat Creek). If New
Zealand mudsnails were to become
established in those areas, they would
likely compete with Hat Creek
pebblesnails for food and space (see
canary duskysnail, above). Typically,
New Zealand mudsnails establish
themselves in new areas after being
transported on boating or angling
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equipment (ANTSF 2005, p. 1). Upper
Hat Creek and Lost Creek are popular
fishing destinations, but lack boating
facilities, so the likelihood of New
Zealand mudsnail infestation in these
areas may be somewhat lower than for
areas in the canary duskysnail’s range
that support both fishing and boating,
such as Lake Britton.
Changes in Precipitation and Water
Availability Due to Climate Change
See our discussion of climate change
in general in the Changes in
Precipitation and Water Availability
Due to Climate Change section under
‘‘Factor A’’ in Five-Factor Evaluation of
Threats for the Canary Duskysnail.
Climate change is not expected to
significantly change total precipitation
in northern California, but may affect
seasonal water availability in some areas
due to changes in snowpack melting
times and the proportion of
precipitation falling as rain rather than
snow (Dettinger et al. 2004, pp. 43, 44).
However, the water supplying springs
emptying into Lost Creek and upper Hat
Creek are collected from wide areas in
the Lassen volcanic highlands (Service
1998, p. 18). Rain and snowmelt in
those areas percolate through porous
volcanic rocks to collect in large
aquifers, thereby holding extra water
from seasons when rain is plentiful and
delivering it through springs during
seasons when it is not. Resulting spring
flows are highly stable in volume,
temperature and clarity (Service 1998,
p. 46). Accordingly, we do not expect
changes in precipitation or water
availability due to climate change to
significantly affect the species.
Catastrophic Events—Highway Spill
Spills from tank trucks carrying
chemicals, such as pesticides or
gasoline, on State Highway 44 near the
two occupied sites on Hat Creek could
potentially impact the Hat Creek
pebblesnails at those sites. Chemical
spills can eliminate pebblesnail
populations (see discussion of Chemical
Spills under Nugget Pebblesnail
(Fluminicola seminalis), below).
However, the more upstream of the two
occupied sites is in a spring near the
creek (Hershler et al. 2007, p. 407), and
the highway pulls away from the creek
upstream of that location, so a tanker
spill would have to occur directly above
that site in order to significantly impact
the pebblesnail population there. The
highway runs close to the creek from
that point to the second occupied site,
a distance of about 1.2 km (0.75 mi), so
a spill somewhere along that stretch
might impact the second site. We are
not aware of any previous spills within
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that region, however, and we consider
the likelihood of a major chemical spill
within that relatively small area to be
low.
Summary of Factor E
We find that neither highway spills,
competition with the New Zealand
mudsnail, nor changes in precipitation
or water availability due to climate
change are a threat to the Hat Creek
pebblesnail. Although a chemical spill
off the highway could potentially
impact up to two locations, the
likelihood of such an event is extremely
low. No site occupied by the Hat Creek
pebblesnail has been colonized by the
New Zealand mudsnail and the lack of
boating opportunities makes invasion by
the mudsnail less likely. The springs
supplying Hat and Lost Creeks are
resistant to the fluctuations in
temperature and water availability
associated with predicted climate
changes. We therefore conclude that,
based on the best available scientific
and commercial information, that other
natural or manmade factors as described
above, do not constitute significant
threats to the Hat Creek pebblesnail now
or in the future.
Finding for the Hat Creek Pebblesnail
We have carefully assessed the best
scientific and commercial information
available regarding the past, present,
and future threats faced by the Hat
Creek pebblesnail. We reviewed the
petition, available published and
unpublished scientific and commercial
information, and information submitted
to us during our status review. This
finding reflects and incorporates that
information. We also consulted with
recognized authorities on this species
and Federal and State resource agencies.
Although only five occupied sites are
known for the Hat Creek pebblesnail, a
review of the best available data does
not indicate that populations at any site
are in decline, or that any sites are likely
to be lost due to timber production and
management, grazing, impoundments,
recreation, overutilization, disease or
predation, the inadequacy of existing
regulatory mechanisms, competition
with invasive species, changes in
precipitation and water availability due
to climate change, or catastrophic events
such as highways spills, now or in the
foreseeable future. The best available
scientific and commercial information
at this time does not indicate that there
is likely to be a change in any of these
stressors in the future.
Based on our review of the best
available scientific and commercial
information pertaining to the five
factors, we find that the threats as
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described above, either alone or in
combination are not of sufficient
imminence, intensity, or magnitude to
indicate that the Hat Creek pebblesnail
is in danger of extinction (endangered)
or likely to become endangered within
the foreseeable future (threatened),
throughout all of its range.
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Significant Portion of the Range
Having determined that the Hat Creek
pebblesnail is not endangered or
threatened throughout all of its range,
we must next consider whether there
are any significant portions of the range
where the Hat Creek pebblesnail is in
danger of extinction or is likely to
become endangered in the foreseeable
future. See Significant Portion of the
Range under Summary of Procedures for
Determining the Listing Status of
Species.
We evaluated the current range of the
Hat Creek pebblesnail to determine if
there is any apparent geographic
concentration of potential threats for the
species. The Hat Creek pebblesnail is
highly restricted in its range and the
threats occur throughout its range. We
considered the potential threats due to
timber production and management,
grazing, impoundments, recreation,
overutilization, disease or predation, the
inadequacy of existing regulatory
mechanisms, competition with invasive
species, changes in precipitation and
water availability due to climate change,
and catastrophic events such as
highways spills. We found no
concentration of threats that suggests
that the Hat Creek pebblesnail may be
in danger of extinction in a portion of
its range. We found no portions of its
range where potential threats are
significantly concentrated or
substantially greater than in other
portions of its range. Therefore, we find
that factors affecting the species are
essentially uniform throughout its
range, indicating no portion of the range
of the species warrants further
consideration of possible endangered or
threatened status under the Act.
We find that the Hat Creek
pebblesnail is not in danger of
extinction now, nor is likely to become
endangered within the foreseeable
future, throughout all or a significant
portion of its range. Therefore, listing
the Hat Creek pebblesnail as endangered
or threatened under the Act is not
warranted at this time.
Nugget Pebblesnail (Fluminicola
seminalis)
Species Information for the Nugget
Pebblesnail
Taxonomy and Species Description
The nugget pebblesnail was first
described as Palludina seminalis in
1842 (Hershler and Frest 1996, p. 15).
After undergoing several name changes,
it was redescribed as Fluminicola
seminalis in 1996 (Hershler and Frest
1996, p. 15). It has a globose to broadly
conical shell with 4 to 4.5 whorls (Frest
and Johannes 1995b, p. 49; Hershler and
Frest 1996, p. 16). The shell can be tan,
brown, or light green, and has a large
opening. Its distinguishing features, as
compared to other pebblesnails, include
(among other features) its relatively
large size (about 6 to 8 mm (0.24 to 0.31
in), thick periostracum, and thin
parietal lip (on the side of the opening
toward the inside of the whorls)
(Hershler et al. 2007, p. 405). The snail
itself is black with a pale gray head
(Hershler and Frest 1996, p. 16).
Although pebblesnails in general
(Fluminicola genus) had previously
been considered part of the Hydrobiidae
family (Hershler et al. 2003, p. 275),
they have since been reassigned to the
Lithoglyphidae family (Hershler et al.
2007, p. 371).
Distribution
The nugget pebblesnail is known from
approximately 44 occupied sites in
Shasta, Lassen, and Tehama Counties.
The sites can be grouped into five
general areas: The mid and lower Pit
River and nearby tributaries including
Hat Creek; the upper Fall River
drainage; Ash Creek (a tributary of the
upper Pit River in Lassen County); the
McCloud River near Lake Shasta; and
Battle Creek, along the Shasta-Tehama
County boundary. The majority of
known sites (37 of 44) are in the mid
and lower Pit River and upper Fall River
areas. The local abundance of this snail
at occupied sites can be high (Frest and
Johannes 1995b, p. 50).
The nugget pebblesnail was formerly
widespread in the upper Sacramento
River above Lake Shasta, but was
apparently extirpated from the entire
region in 1991 due to the Cantara Spill,
in which a railcar containing the
herbicide metam sodium derailed and
spilled its contents into the river (Frest
and Johannes 1995b, pp. 13, 50;
Hershler and Frest 1996, p. 16; ORNHIC
2004k, p. 1).
Habitat and Biology
The nugget pebblesnail prefers gravelboulder substrate and clear, cold,
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57939
flowing water, but has been found on
soft substrate in a few very large spring
pools (Frest and Johannes 1995b, p. 50).
It is a riparian associate, apparently
grazes on perilithon and periphyton,
and possibly on fine particles of detritus
as well (Frest and Johannes 1993, p. 54;
Furnish et al. 1997, p. 31). We have no
specific information regarding the
reproduction of this species, but
members of the Fluminicola genus
typically live a single year and breed
only once (Furnish and Monthey 1999,
Sect. 3, p. 4; ORNHIC 2004f, p. 2). They
generally lay eggs in the spring, which
hatch in 2 to 4 weeks. They are not
known to disperse widely, and are
sensitive to water pollution, decreases
in dissolved oxygen, elevated
temperatures, and sedimentation
(Furnish and Monthey 1999, Sect. 3, pp.
5, 8).
Five-Factor Evaluation of Threats to the
Nugget Pebblesnail
Factor A. The Present or Threatened
Destruction, Modification, or
Curtailment of Its Habitat or Range
Impoundments
Thirteen of the 44 occupied sites are
in or along the lower Pit River below
Lake Britton (Hershler et al. 2007, p.
405; Haley 2012a, p. 3; PGE 2011, pp.
26, 37; PGE 2012 p. 27). Twelve of those
13 sites were monitored by PGE from
2009 through 2011, in accordance with
the 2007 relicensing requirements for
the Pit 3, 4, and 5 dams (see canary
duskysnail, above). Flow releases from
the dams for 2009 and 2010 were at
interim levels (higher than in previous
years but lower than the final levels
required by the relicensing agreements
(PGE 2010, pp. 1, 2). Flow releases had
reached their final required levels in
2011 and are expected to remain at
those levels thereafter.
Increased flows from dams may
negatively impact nugget pebblesnails
by raising water temperatures (see
canary duskysnail, above) (Ellis 2012, p.
1). As average flows increased from
2009 to 2011, average temperatures did
in fact go up, and average density of
nugget pebblesnails decreased at the
four locations monitored in the Pit 3
reach (PGE 2010, p. 35; PGE 2011, pp.
24, 26, 37; PGE 2012, pp. 24, 27).
Average densities of nugget pebblesnails
likewise decreased each year over the 3year period at each of four sites in the
Pit 5 reach. However, average water
temperatures in the Pit 5 reach were
highest in 2009 at one of those
locations, highest in 2010 at another
location, and remained essentially
unchanged at a third location. This may
be due to variations in air temperature
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across the 3 years (PGE 2010, p. 35; PGE
2011, p. 24; PGE 2012, p. 24). In the Pit
4 reach, there was a varied response,
with July surveys showing an overall
average increase in nugget pebblesnail
density from 2009 to 2011, and August
surveys showing a (smaller) overall
decrease. Thus, increased water
temperatures and increased flows were
closely correlated with decreased
population densities in the Pit 3 reach,
but not in the Pit 4 or 5 reaches.
Despite any decreases, nugget
pebblesnails remained common
throughout the three survey years, and
no sites were extirpated (PGE 2011, pp.
26 37; PGE 2012, p. 27). Average
densities in 2009 ranged from 240 to
4,970 snails per square meter, while in
2011 they ranged from 10 to 5,058 snails
per square meter. The nugget
pebblesnail was also the most common
aquatic snail in each of the three areas
surveyed in 2009 (PGE 2010, p. 41),
whereas, in the following 2 years it was
the most common in the Pit 3 and Pit
4 reaches, but the second-most common
in the Pit 5 reach (PGE 2011, p. 29; PGE
2012, p. 28). Accordingly, while the
current data from PGE surveys indicate
that increased flow releases may have
impacted the nugget pebblesnail in at
least some of their lower Pit River sites,
high densities of nugget pebblesnails
persist in all three reaches despite these
impacts. We therefore do not consider
the existing data to indicate that
increased flows are likely to threaten the
continued existence of the nugget
pebblesnail in the area. PGE will
continue to monitor mollusk
populations, so any significant declines
in nugget pebblesnail populations
should be detected promptly (PGE 2012,
p. 1).
Four sites in the lower Hat Creek
watershed also are potentially affected
by dams. Two of these are in Baum Lake
near the outflow of Crystal Lake, and
close to the Baum Lake location of
canary duskysnails (discussed above)
(Hershler et al. 2007, p. 405). Another
occupied site is at Crystal Lake, a
spring-fed lake that flows into Baum
Lake at its eastern end (PGE 2006, fig 1,
p. 46; Hershler et al. 2007, p. 405). A
fourth site is upstream of Baum Lake,
just below the PGE dam (Hat Creek 1)
that forms Cassel Pond. Licensing
requirements, established by the Federal
Energy Regulatory Commission (FERC)
when the two dams were relicensed in
2002 establish minimum flows of 8 cfs
in Hat Creek below the Hat Creek 1 dam
(White 2008, pp. 1, 2) and also require
PGE to maintain the surface of Baum
Lake at a constant height (FERC 2011, p.
1). Accordingly, the occupied sites in
Baum Lake are likely to be kept at a
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constant depth, and the occupied site
below the Hat Creek 1 dam is unlikely
to be left without water. The nugget
pebblesnails at those locations are
therefore unlikely to lose the cold, welloxygenated flows they require.
Two occupied sites are in the
McCloud River near Lake Shasta
(Hershler et al. 2007, p. 405; Haley
2012a, p. 3). One could potentially be
inundated by the lake if a proposal to
raise the height of Shasta dam up to 18.5
ft (5.6 m) is carried out (U.S. Bureau of
Reclamation (USBR) 2007, p. ES 6;
USBR 2011, pp. 1–6). Inundation
resulting from the higher reservoir level
made possible by raising the dam height
would likely remove necessary flows
and would extirpate the site. The best
available scientific and commercial
information does not indicate the
likelihood of the proposal being
implemented (USBR 2011, pp. 182–
184), nor the likelihood of relocating the
nugget pebblesnails or otherwise
mitigating the project’s impact.
Water Quality
The Pit River is considered a waterquality limited segment for 198 km (123
mi) upstream of Shasta Lake, due to
added nutrients from agriculture and
grazing that encourage algal growth (see
canary duskysnail above) (SWRCB
2010a, p. 164). Sixteen sites occupied by
the nugget pebblesnail are within that
area, including the 12 sites considered
above with regard to impoundments,
and an additional 4 sites upstream of
the Pit 3, 4 and 5 reaches. Although we
lack information regarding the impacts
(if any) of the impaired water quality on
the snails, snail populations at 12 of the
16 occupied sites are subject to annual
monitoring (see Impoundments). At this
point, after only 3 years of monitoring
and 1 year at the full flow releases
established by the operating license, the
data do not indicate that water quality
is a threat to nugget pebblesnail
populations in the lower Pit River.
Sediment levels in the upper Fall
River and high pH in Eastman Lake (see
canary duskysnail, above) may affect
nugget pebblesnails at three occupied
sites in those locations. Three additional
occupied sites in upper Ash Creek
(Lassen County) may also be subject to
alkalinity levels slightly above the
established water quality limit of 8.5 pH
(SWRCB 2010a, p. 137; SWRCB 2010b,
p. 1). Three water quality samples from
the area showed pH levels of 8.62, 8.53,
and 8.58 (SWRCB 2010b, p. 8).
The three occupied sites in upper Ash
Creek discussed above may also be
subject to levels of Escherichia coli (E.
coli) bacteria (an indicator of sewage
contamination) exceeding water quality
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standards (SWRCB 2010 (Ash Cr), pp. 5,
6). A single sample taken from upper
Ash Creek in 2005 showed an E. coli
density greater than three times the
water quality standard for non-contact
recreation, and greater than 5.5 times
the standard for water contact recreation
(SWRCB 2010 (Ash Cr), pp. 6, 7). The
source of contamination was not
established (SWRCB 2010(Ash Cr), p. 5),
although feces from grazing cattle is a
possibility (see below). Although nugget
pebblesnails are considered sensitive to
water pollution (Furnish and Monthey
1999, Sect. 3, pp. 5, 8), their response
to E. coli contamination is not known.
No population trend data are available
for nugget pebblesnails in Ash Creek,
therefore, it is difficult to infer any
direct response to E. coli levels at this
location.
Grazing and Logging
In the middle and lower Pit River area
(including lower Hat Creek), 7 occupied
sites are on National Forest lands in the
NWFP area, 14 are on PGE lands, and
1 is in MacArthur-Burney State Park
(Stewardship Council 2007, Vol. 2, pp.
PM–20, PM–30, PM–38, PM–58). The
sites on NWFP lands benefit from the
SMP and ACS, (see Generally
Applicable Federal Regulatory
Mechanisms, above) and so are unlikely
to be threatened by grazing or logging
taking place on those lands. Such
activities would be subject under the
SMP to predisturbance surveys and
management of known sites to support
species persistence (Molina et al. 2006,
p. 312; Olson et al. 2007, abstract).
Under the ACS they would also be
subject to close regulation within
riparian reserve buffer areas so as to
maintain water quality and aquatic
ecosystem integrity (USDA and USDI
1994a, p. 9; USDA and USDI 1994b, pp.
C–31–C–38). The site at the State Park
is also unlikely to be threatened by
grazing or logging, as the Park is
committed to maintaining its scenic
features in a natural condition
(California Department of Parks and
Recreation (CDPR) 1997, p. 46), and to
take measures to monitor and maintain
natural water quality, channel flow, and
sediment transport rates (CDPR 1997, p.
47). Although the State is considering
closing several State Parks in order to
save money, neither MacArthur-Burney
State Park, nor Ahjumawi Lava Springs
State Park (discussed below) are among
those being considered for closure
(CDPR 2012, p. 2).
Lands owned by PGE are also subject
to conservation management. Due to
bankruptcy proceedings in 2004
(Stewardship Council 2007, Vol. 1, pp.
ES–1, ES–2), PGE accepted a settlement
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agreement with the California Public
Utilities Commission (PUC) that
requires PGE to protect the lands
associated with its dams, either by
establishing conservation easements or
by donating the land to qualified
conservation managers. A nonprofit
corporation was established that
published a land conservation plan in
2007 (Stewardship Council 2007, Vol. 1,
p. ES–1). As the plan indicates, grazing
has been eliminated to protect water
quality in the areas of the Pit 3, 4, and
5 dams and associated reaches since the
late 1980s (Stewardship Council, Vol. 2,
p. PM–47). Grazing was eliminated in
the general vicinity of the PGE dams on
Hat Creek in 2001 (Stewardship Council
2007, Vol. 2, p. PM–31). Current timber
management activities on the PGE Hat
Creek and Fall River lands are restricted
to mitigating for watershed and forest
health issues (Stewardship Council
2007, Vol. 2, pp. PM–3, PM–31). A
single timber management unit of 2,499
ac (1,011 ha) exists in the vicinity of
Lake Britton and the Pit 3 reach and is
managed for multiple uses (Stewardship
Council, Vol. 2, p. PM–40). In the Pit 4
reach, six timber management units
totaling 2,123 ac (859 ha) are currently
managed for sustainable production,
with the most recent harvest in 2005
and 2006 (Stewardship Council, Vol. 2,
p. PM–50).
Timber harvest on private lands is
governed by the state Nejedly-Z’berg
Forest Practice Act (FPA). The FPA
requires timber harvesters to submit a
publicly reviewable Timber Harvest
Plan (THP) to the California Department
of Forest and Fire Protection (CAL FIRE)
(Kier Associates 2011b, p. 2) and to
maintain buffers around fish-bearing
streams of at least 75 ft (23 m) within
which at least 50 percent of overstory
and understory vegetation and 75
percent of total original vegetation must
remain uncut (CAL FIRE 2012, pp. 68–
72).
In the upper Fall River drainage, eight
occupied sites are on private land, one
is on an Indian PDA, and three are in
the Ahjumawi Lava Springs State Park.
Various habitat improvement measures
have been carried out by private
landowners in the area, including the
erection of exclusion fencing, bank
stabilization projects, and the
replacement and upgrade of a railroad
crossing that had collapsed twice in the
past (see canary duskysnail, above)
(FRRCD 2005, pp. 1–3; Ellis and Haley
2012, p. 1). Landowners also took steps
to reduce the potential for serious
wildfires and to prevent erosion of
sediment from a nearby meadow
(FRRCD 2005, p. 3).
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A general plan is not yet completed
for Ahjumawi Lava Springs State Park,
but the California State Park System
maintains a resource management
program with the general goal of
protecting, restoring, and maintaining
the natural resources within the Parks
(CDPR 2012, p. 2).
There are three occupied sites in
upper Ash Creek in Lassen County; two
occupied sites are in the Modoc
National Forest and the other is on
private land. The sites in the National
Forest are in the Ash Creek management
unit of the Round Valley grazing
allotment, where grazing is not
currently permitted (Raymond 2012, p.
1). Grazing does occur on private lands
farther upstream from the National
Forest, however (Raymond 2012, p. 1),
so it may occur in the vicinity of the
occupied site on private land. Grazing
in and around streams on private land
is not closely regulated, and can lead to
trampled vegetation, fecal matter in the
water, and a muddier and warmer
stream (Meehan and Platts 1978, p. 276;
Stephenson and Street 1978, p. 152;
Kauffman and Krueger 1984, p. 432), all
of which would negatively impact the
nugget pebblesnail. We do not have
information regarding the extent of
grazing on private lands in the area, nor
of the extent to which protective
management actions may have been
taken.
The Modoc National Forest also
expects to offer a timber sale this year
in the vicinity of Ash Creek, possibly
leading to timber removal in the spring
of 2013 (Raymond and Bryan 2012, p.
1). Timber removal would be subject to
restrictions established by the SNFPA
(see Hat Creek pebblesnail, above).
Summary of Factor A
In summary, flow rates from the Pit 3,
4, and 5 dams, as well as impaired water
quality, may be affecting occupied
locations in the lower Pit River, but the
nugget pebblesnail remains extremely
common in the area, and ongoing
monitoring will alert us if species
persistence in the area becomes
threatened. Potential water quality
issues may also apply to three sites in
the upper Fall River drainage and to
three sites at Ash Creek, but the
available data do not show that resident
nugget pebblesnail populations are, or
are likely to be, impacted by these
issues. Available data also do not
suggest that any occupied sites are
threatened by grazing or logging, and
most occupied locations along the Pit
River also receive high levels of
regulatory protection from grazing and
logging. Seven of those sites are
protected by the SMP and ACS, fourteen
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57941
are protected by conservation provisions
established for PGE lands under a
settlement agreement, and one is
protected by State Park regulations. In
the upper Fall River drainage several
habitat improvement projects have been
completed by landowners, while in the
Ash Creek drainage two occupied sites
are on un-grazed Federal land protected
by the SNFPA, and one is on grazed
private land. We conclude, based on the
best available scientific and commercial
information, that the present or
threatened destruction, modification or
curtailment of its habitat or range does
not constitute a significant threat to the
species now or in the future.
Factor B. Overutilization for
Commercial, Recreational, Scientific, or
Educational Purposes
Our review of the best available
scientific and commercial information
yielded nothing to indicate that
overutilization for commercial,
recreational, scientific, or educational
purposes is occurring at this time or is
likely to occur in the future. We
therefore conclude such overutilization
does not constitute a threat to the nugget
pebblesnail.
Factor C. Disease or Predation
Disease
We reviewed the best available
scientific and commercial information
regarding this species and other similar
species, and found no evidence to
indicate that disease is impacting nugget
pebblesnail populations.
Predation
The nugget pebblesnail occurs in the
same general areas as the canary
duskysnail, and may also be subject to
predation by the introduced signal
crayfish. Predation by dense crayfish
populations can significantly impact
aquatic snails (Lorman and Magnuson
1978, p. 9). However, our only data
regarding signal crayfish densities
indicate those densities appear to be
holding stable at levels equivalent to
those of the native Shasta crayfish,
alongside which the nugget pebblesnail
has evolved (see Canary Duskysnail,
above) (Ellis 1999, p. 58; PGE 2011b, pp.
iii, 10; PGE 2012b, p. 9). We do not
expect occupied areas within the
current range of both crayfish species to
be subject to high combined crayfish
densities, because past monitoring has
shown a strong tendency for one or the
other crayfish species to be common in
an area, but not both (Ellis 1999, pp. 57,
58; Service 2009, p. 9) (see Canary
Duskysnail, above). Hence, the available
evidence does not support the
contention that signal crayfish are
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present in the range of the nugget
pebblesnail in sufficiently high
densities to pose a predation risk to the
nugget pebblesnail. Furthermore, the
information does not indicate any trend
in the densities of the signal crayfish
that would lead us to a conclusion that
the predation risk would increase in the
future.
We therefore conclude, based on the
best available scientific and commercial
information, that neither disease nor
predation constitutes a significant threat
to the species now or in the future.
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Factor D. The Inadequacy of Existing
Regulatory Mechanisms
Under this factor, we examine
whether existing regulatory mechanisms
are inadequate to address the threats to
the species discussed under the other
factors. Section 4(b)(1)(A) of the Act
requires the Service to take into account
‘‘those efforts, if any, being made by any
State or foreign nation, or any political
subdivision of a State or foreign nation,
to protect such species * * *’’. We
interpret this language to require the
Service to consider relevant Federal,
State, and Tribal laws and regulations
when developing our threat analyses.
Regulatory mechanisms, if they exist,
may preclude the need for listing if we
determine that such mechanisms
adequately address the threats to the
species such that listing is not
warranted. The analysis of threats to the
nugget pebblesnail under the other
Factors included consideration of the
ameliorative effects of regulatory
mechanisms where applicable, such as
those discussed under Factor A and
under Generally Applicable Federal
Regulatory Mechanisms, above.
Having evaluated the significance of
the threat as mitigated by any such
conservation efforts, we analyze under
Factor D the extent to which existing
regulatory mechanisms are inadequate
to address the specific threats to the
species. We found no significant threats
to the nugget pebblesnail under the
other factors, therefore, the analysis of
any existing regulatory mechanisms’
adequacy to address threats is not
applicable. Consequently, after
reviewing the best available commercial
and scientific information, we conclude
that the inadequacy of existing
regulatory mechanisms is not a threat to
the nugget pebblesnail now or in the
future.
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Factor E. Other Natural or Manmade
Factors Affecting Its Continued
Existence
Competition With Invasive Species
The New Zealand mudsnail has the
potential to outcompete and thereby
threaten the nugget pebblesnail if it can
establish itself at a significant number of
locations that the nugget pebblesnail
currently occupies (see canary
duskysnail, above). However, the level
of threat is somewhat reduced by the
nugget pebblesnail’s greater range as
compared to the canary duskysnail. We
consider Lake Britton to be at greatest
danger of infestation within that range,
due to its ease of access, marina, boat
launch, fishery, and nearby state park
(Stewardship Council, Vol. 2, pp. PM–
37–39). As discussed above in relation
to the canary duskysnail, once the first
infestation point is established, new
infestation points could be expected to
establish themselves from that base. At
that point, if it occurs, we could
ascertain whether the New Zealand
mudsnail was spreading in a manner
likely to threaten the nugget pebblesnail
in a significant portion of its range. At
the current time, no infestations of New
Zealand mudsnail are known within the
nugget pebblesnail’s range. Accordingly,
we do not consider competition from
New Zealand mudsnails to be a threat
to the canary duskysnail at this time.
Changes in Precipitation and Water
Availability Due to Climate Change
See our discussion of climate change
in general in the Changes in
Precipitation and Water Availability
Due to Climate Change section under
‘‘Factor A’’ in Five-Factor Evaluation of
Threats for the Canary Duskysnail.
Climate change is not expected to
significantly change total precipitation
in northern California, but may affect
seasonal water availability in some areas
due to changes in snowpack melting
times and in the proportion of
precipitation falling as rain rather than
snow (Dettinger et al. 2004, pp. 43, 44).
However, the springs that support sites
occupied by the nugget pebblesnail in
the middle and lower Pit River and
upper Fall River drainages are supplied
by large aquifers of porous lava that
collect and store water from wide areas,
thereby holding extra water from
seasons when rain is plentiful and
delivering it through springs during
seasons when it is not (see canary
duskysnail, above). Resulting spring
flows are highly stable in volume,
temperature, and clarity (Service 1998,
p. 46) We lack information regarding
aquifer sizes and collection ranges for
the six occupied sites that are not in the
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middle and lower Pit River or upper
Fall River drainages, but given the
general volcanic geology of the entire
area (U.S. National Park Service
(USNPS) 2005, p. 1), we consider it
most likely that these sites also will
maintain relatively constant flow rates
and water temperatures despite climate
change.
Catastrophic Events—Chemical Spills
The nugget pebblesnail was
apparently extirpated from the upper
Sacramento River due to a catastrophic
spill of herbicide (the Cantara Spill)
from a derailed rail car in 1991 (see
Distribution, above) (Frest and Johannes
1995b, pp. 13, 50; Hershler and Frest
1996, p. 16; ORNHIC 2004k, p. 1). A rail
line owned by the McCloud River
Railroad crosses the Pit River just
upstream of Lake Britton, but freight
service on the line was discontinued in
2006 (Trainweb undated, p. 1). A rail
line owned by the Burlington Northern
and Santa Fe (BNSF) railroad crosses
the Pit River much farther upstream in
Lassen County, south of the town of
Nubieber, and runs close to the Pit River
for almost 4 km (2.5 mi) after the
crossing. However, the point where the
rail line leaves the vicinity of the Pit
River is approximately 50 km (31 mi)
upstream of the closest known occupied
site on the Pit River. Although the
Cantara spill’s effects may have reached
such a distance (Frest and Johannes
1995b, p. 73), in this case a spill from
the BNSF line would have to travel 50
km (31 mi) to affect one occupied
nugget pebblesnail site, then
approximately 6.7 km (4.2 mi) to affect
two more, then approximately 23 km
(14 mi) farther (including approximately
11 km (6.8 mi) through Lake Britton) to
the next occupied site. If a very large
spill were to occur, the most sites it
could affect would be the three Pit River
sites upstream of Lake Britton. That
would still leave 41 known occupied
sites, and so would not pose a threat to
the species.
Summary of Factor E
In summary, the nugget pebblesnail is
protected from likely impacts of changes
in precipitation or water availability due
to climate change by the particular
characteristics of its habitat. Although
potential competition from the New
Zealand mudsnail is cause for concern,
no site currently occupied by nugget
pebblesnail has been colonized and the
best available information does not
indicate it will colonize areas occupied
by the nugget pebblesnail, or that it will
threaten the nugget pebblesnail with
extinction if it does so. We conclude
that, based on the best available
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scientific and commercial information,
that other natural or manmade factors
such as competition from the New
Zealand mudsnail, changes in
precipitation or water availability due to
climate change, and chemical spills are
not a threat to the nugget pebblesnail
now or in the future.
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Finding for the Nugget Pebblesnail
We have carefully assessed the best
scientific and commercial information
available regarding the past, present,
and future threats faced by the nugget
pebblesnail. We reviewed the petition,
available published and unpublished
scientific and commercial information,
and information submitted to us during
the public comment period following
our 90-day petition finding. This finding
reflects and incorporates information we
received during the public comment
period. We also consulted with
recognized authorities on this species
and Federal and State resource agencies.
The nugget pebblesnail occupies 44
sites, and a review of the best available
information does not indicate that
populations at any site are likely to be
extirpated due to impoundments, water
quality, grazing and logging,
overutilization, disease or predation, the
inadequacy of existing regulatory
mechanisms, competition with invasive
species, changes in precipitation and
water availability due to climate change,
or catastrophic events such as chemical
spills, now or in the foreseeable future.
The best available scientific and
commercial information at this time
does not indicate that there is likely to
be a change in any of these stressors in
the future.
Based on our review of the best
available scientific and commercial
information pertaining to the five
factors, we find that the threats as
described above either alone or in
combination, are not of sufficient
imminence, intensity, or magnitude to
indicate that the nugget pebblesnail is in
danger of extinction (endangered) or
likely to become endangered within the
foreseeable future (threatened),
throughout all of its range.
Significant Portion of the Range
Having determined that the nugget
pebblesnail is not endangered or
threatened throughout all of its range,
we must next consider whether there
are any significant portions of the range
where the nugget pebblesnail is in
danger of extinction or is likely to
become endangered in the foreseeable
future. See Significant Portion of the
Range under Summary of Procedures for
Determining the Listing Status of
Species.
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We evaluated the current range of the
nugget pebblesnail to determine if there
is any apparent geographic
concentration of potential threats for the
species. The nugget pebblesnail is
highly restricted in its range and the
threats occur throughout its range. We
considered the potential threats due to
impoundments, water quality, grazing
and logging, overutilization, disease or
predation, the inadequacy of existing
regulatory mechanisms, competition
with invasive species, changes in
precipitation and water availability due
to climate change, and catastrophic
events such as chemical spills. We
found no concentration of threats that
suggests that the nugget pebblesnail may
be in danger of extinction in a portion
of its range. We found no portions of its
range where potential threats are
significantly concentrated or
substantially greater than in other
portions of its range. Therefore, we find
that factors affecting the species are
essentially uniform throughout its
range, indicating no portion of the range
of the species warrants further
consideration of possible endangered or
threatened status under the Act.
We find that the nugget pebblesnail is
not in danger of extinction now, nor is
likely to become endangered within the
foreseeable future, throughout all or a
significant portion of its range.
Therefore, listing the nugget pebblesnail
as endangered or threatened under the
Act is not warranted at this time.
Potem Creek Pebblesnail (Fluminicola
Potemicus)
Species Information for the Potem Creek
Pebblesnail
Taxonomy and Species Description
The Potem Creek pebblesnail was
formally named and described in 2007
(Hershler et al. 2007, pp. 412–415).
Prior to 2007, it was referred to as the
‘‘Potem pebblesnail (Fluminicola n. sp.
14)’’ (Frest and Johannes 1999, pp. 35–
38). It was also referred to as the ‘‘Potem
pebblesnail (Fluminicola n. sp. 2)’’ by
Frest and Johannes (1995b, pp. 42, 43)
(Hershler et al. 2007, p. 414). Although
pebblesnails in general (Fluminicola
genus) had previously been considered
part of the Hydrobiidae family (Hershler
et al. 2003, p. 275), they have since been
reassigned to the Lithoglyphidae family
(Hershler et al. 2007, p. 371).
The shell of the Potem Creek
pebblesnail is about 2.5 to 3.3 mm (0.1
to 0.13 in) tall, with 3 to 3.75 whorls.
Its periostracum is tan or light green,
and the head of the snail itself is pale
brown or gray (Hershler et al. 2007, p.
412).
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Distribution
Only one occupied site (the type
location) for the Potem Creek
pebblesnail is mentioned in the formal
description of the species (Hershler et
al. 2007, p. 412). However, that
description indicates the species was
previously referred to as Fluminicola n.
sp. 2 (Hershler et al. 2007, p. 412).
Fluminicola n. sp. 2 (common name
Potem pebblesnail) has been identified
at 11 locations (Frest and Johannes
1995b, pp. T10–T13, T17, T22, T23),
including the 1 site mentioned by
Hershler et al. (2007, p. 412) and 7 sites
in the upper Sacramento River drainage.
Subsequent communications indicate
that the snails from the upper
Sacramento River sites were likely
Shasta pebblesnails (Fluminicola
multifarius) rather than Potem
pebblesnails (Hershler 2012, pp. 2–5;
Johannes 2012c, pp. 2, 3). However, this
has not been confirmed by
reexamination of all the specimens
involved (Hershler 2012, p. 2; Johannes
2012c, p. 1). As discussed below, Shasta
pebblesnails are unusually variable in
form (Hershler et al. 2007, p. 419). Prior
to genetic tests establishing the species
identity of the Shasta and Potem Creek
pebblesnails (Hershler et al. 2007, pp.
380–382), the particular morphological
characteristics separating one from the
other may not have been clear. The
seven Potem pebblesnail sites in the
upper Sacramento River, and the three
Potem pebblesnail sites in the Pit River
drainage (other than the Potem Creek
pebblesnail type location) identified by
Frest and Johannes in 1995 (Frest and
Johannes 1995b, pp. T13, T17), are,
therefore, considered unconfirmed.
We have also received information
regarding three additional sites in the
lower Pit River drainage with snails
tentatively identified (based on shell
alone) as Potem Creek pebblesnails
(Haley 2012, pp. 1, 3). Therefore, we are
aware of 1 confirmed site (the type
location) and 13 unconfirmed sites.
Seven of the unconfirmed sites are in
the upper Sacramento River drainage,
while all of the other sites are in the
lower Pit River drainage. One of the
unconfirmed sites in the Pit River
drainage is on Shasta-Trinity National
Forest land within the NWFP area. All
other sites are on private land. The type
location is on a small private inholding
within the perimeter of the ShastaTrinity National Forest.
Habitat and Biology
The Potem Creek pebblesnail occurs
on muddy or silty substrates in small,
cold springs and spring runs (Frest and
Johannes 1995b, p. A7 (site 36); Frest
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and Johannes 1999, p. 36). It appears to
graze on partly decayed deciduous
leaves (Frest and Johannes 1999, p. 36).
We have no specific information
regarding reproduction for this species,
but members of the Fluminicola genus
typically live a single year and breed
only once (Furnish and Monthey 1999,
Sect. 2, p. 5; ORNHIC 2004, p. 2). They
generally lay eggs in the spring, which
hatch in 2 to 4 weeks. They are not
known to disperse widely, and are
highly sensitive to water pollution,
decreases in dissolved oxygen, elevated
temperatures, and sedimentation
(Furnish and Monthey 1999, Sect. 2, pp.
5, 7; Hershler et al. 2007, p. 372).
Factor A. The Present or Threatened
Destruction, Modification, or
Curtailment of Its Habitat or Range
Impoundments
All of the Potem Creek pebblesnail
occupied sites (confirmed and
unconfirmed) are in small spring ponds
or creeks (Frest and Johannes 1995b, pp.
42, A3, A4, A6–A8, A14, A22, T10–T13,
T17, T22, T23; Hershler et al. 2007, p.
412; Haley 2012, p. 3) and are thus
relatively unlikely to be affected by flow
releases from major dams. The three
unconfirmed locations found by Haley
(2012, p. 3) are very close to the edges
of the Pit 6 and Pit 7 reservoirs, but we
are not aware of any plans to raise the
surface levels of those lakes (which
could impede flows and raise
temperatures). The surface level of
Shasta Lake may be raised up to 18.5 ft
(5.6 m) if a proposal by USBR to enlarge
Shasta Dam is implemented (see nugget
pebblesnail, above), but the closest
occupied location of the Potem Creek
pebblesnail (the type location) is over
350 ft (107 m) above the current
elevation of the lake surface, and would
therefore remain unaffected. We
conclude that, based on the best
available scientific and commercial
information, that the present or
threatened destruction, modification or
curtailment of its habitat or range does
not constitute a significant threat to the
species.
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Factor B. Overutilization for
Commercial, Recreational, Scientific, or
Educational Purposes
Our review of the best available
scientific and commercial information
yielded nothing to indicate that
overutilization for commercial,
recreational, scientific, or educational
purposes is occurring at this time or is
likely to occur in the future. We
therefore conclude such overutilization
does not constitute a threat to the Potem
Creek pebblesnail.
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Factor C. Disease or Predation
Disease
We reviewed the best available
scientific and commercial information
regarding this species and other similar
species, and found no evidence to
indicate that disease is impacting Potem
Creek pebblesnail populations.
Predation
The Potem Creek pebblesnail occurs
in the same general areas as the canary
duskysnail, and may also be subject to
predation by the introduced signal
crayfish. Predation by dense crayfish
populations can significantly impact
aquatic snails (Lorman and Magnuson
1978, p. 9). However, our only data
regarding signal crayfish density
indicates those densities appear to be
holding stable at levels equivalent to
those of the native Shasta crayfish,
alongside which the Potem Creek
pebblesnail has evolved (see canary
duskysnail, above) (Ellis 1999, p. 58;
PGE 2011b, pp. iii, 10; PGE 2012b, p. 9).
None of the confirmed or unconfirmed
Potem Creek pebblesnail sites overlap
the current range of the Shasta crayfish,
so only the signal crayfish poses a
potential predation impact. Hence, the
available evidence does not support the
contention that signal crayfish are
present in the range of the Potem Creek
pebblesnail in sufficiently high
densities to pose a predation risk to the
Potem Creek pebblesnail. Furthermore,
the information does not indicate any
trend in the densities of the signal
crayfish that would lead us to a
conclusion that the predation risk
would increase in the future.
We therefore conclude, based on the
best available scientific and commercial
information, that neither disease nor
predation constitutes a significant threat
to the species now or in the future.
Factor D. The Inadequacy of Existing
Regulatory Mechanisms
Under this factor, we examine
whether existing regulatory mechanisms
are inadequate to address the threats to
the species discussed under the other
factors. Section 4(b)(1)(A) of the Act
requires the Service to take into account
‘‘those efforts, if any, being made by any
State or foreign nation, or any political
subdivision of a State or foreign nation,
to protect such species * * * ’’. We
interpret this language to require the
Service to consider relevant Federal,
State, and Tribal laws and regulations
when developing our threat analyses.
Regulatory mechanisms, if they exist,
may preclude the need for listing if we
determine that such mechanisms
adequately address the threats to the
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species such that listing is not
warranted.
Having evaluated the significance of
the threat as mitigated by any such
conservation efforts, we analyze under
Factor D the extent to which existing
regulatory mechanisms are inadequate
to address the specific threats to the
species. We found no significant threats
to the Potem Creek pebblesnail under
the other factors, therefore, the analysis
of any existing regulatory mechanisms’
adequacy to address threats is not
applicable. Consequently, after
reviewing the best available commercial
and scientific information, we conclude
that the inadequacy of existing
regulatory mechanisms is not a threat to
the Potem Creek pebblesnail now or in
the future.
Factor E. Other Natural or Manmade
Factors Affecting Its Continued
Existence
Competition with Invasive Species
The New Zealand mudsnail is a
potential threat to the Potem Creek
pebblesnail (see canary duskysnail,
above). The level of threat is
significantly reduced in the three
occupied locations (including the type
location) that are far from the Pit River.
Because New Zealand mudsnails are
transported on boats and fishing
equipment (NBII 2011, pp. 1–3), they
are less likely to become established in
smaller creeks where boating is not
possible and fishing by non-locals is
less common. The seven unconfirmed
sites in the upper Sacramento River are
at greater potential risk because New
Zealand mudsnails have been reported
at Castle Lake, which is about 5.6 km
(3.5 mi) from Siskiyou Lake
(McAlexander 2012a, p. 1; McAlexander
2012b, p. 1). If the New Zealand
mudsnail established itself in Siskiyou
Lake, it might then easily wash down
the Sacramento River, potentially
establishing anywhere along the route,
which might include any of the seven
unconfirmed occupied sites. Since the
Sacramento River occupied sites are
unconfirmed, however, and since the
available data does not indicate New
Zealand mudsnails will establish
themselves at Lake Siskiyou or points
downstream, we do not consider the
New Zealand mudsnail a threat to the
continued existence of the Potem Creek
pebblesnail.
Changes in Precipitation and Water
Availability Due to Climate Change
See our discussion of climate change
in general in the Changes in
Precipitation and Water Availability
Due to Climate Change section under
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‘‘Factor A’’ in Five-Factor Evaluation of
Threats for the Canary Duskysnail.
Climate change is not expected to
significantly change total precipitation
in northern California, but may affect
seasonal water availability in some areas
due to changes in snowpack melting
times and in the proportion of
precipitation falling as rain rather than
snow (Dettinger et al. 2004, pp. 43, 44).
However, the springs supporting sites
occupied by the Potem Creek
pebblesnail in the middle and lower Pit
River are supplied by large aquifers of
porous lava that collect and store water
from wide areas (see canary duskysnail,
above). The aquifers are therefore able to
provide water to the springs at highly
constant flow rates and temperatures,
despite fluctuations in precipitation. We
lack information regarding aquifer sizes
and collection ranges for the seven
unconfirmed sites in the upper
Sacramento River drainage, but based
on the best available scientific and
commercial information and given the
general volcanic geology of the entire
area (USNPS 2005, p. 1), we consider it
most likely that these sites also will
maintain relatively constant flow rates
and water temperatures despite climate
change.
Catastrophic Events—Fire
Siltation caused by fires would be
likely to be cleared relatively quickly by
springs in the lower Pit River area (see
Goose Valley pebblesnail, above). We do
not know the flow rate of the spring at
the type location of the Potem Creek
pebblesnail, however, so fire remains a
concern at that site. However, for a fire
at the location to threaten the species,
it would have to be serious enough to
produce extensive siltation; the flow of
the spring would have to be insufficient
to flush that siltation; the seven
unconfirmed occupied sites in the
upper Sacramento River drainage would
have to be unoccupied; and the six
unconfirmed occupied locations in the
Pit River drainage, (located at distances
of 6 to 20 km (3.7 to 12.4 mi) from the
type location) would have to be
unoccupied or similarly affected by the
fire. We consider such a combination of
circumstances unlikely. Additionally,
the Potem Creek pebblesnail occurs on
muddy or silty substrates (see Habitat
and Biology, above), and so is likely to
be less strongly affected by siltation
than other pebblesnail species.
Summary of Factor E
In summary, the Potem Creek
pebblesnail is protected from expected
changes in precipitation or water
availability due to climate change by the
particular characteristics of its habitat.
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Although potential competition from
the New Zealand mudsnail is cause for
concern, no site currently occupied by
the Potem Creek pebblesnail has been
colonized and there is nothing to
indicate the New Zealand mudsnail will
colonize any of the locations occupied
by the Potem Creek pebblesnail. There
is also no direct evidence to show that
any such occupied locations would be
extirpated by such a colonization were
it to occur. The two species are not
known to have interacted in the past.
We consider catastrophic events such as
fire to be unlikely, and the Potem Creek
pebblesnail is likely to be less strongly
affected by siltation than other
pebblesnail species. We therefore
conclude that, based on the best
available scientific and commercial
information, that other natural or
manmade factors such as competition
from the New Zealand mudsnail,
changes in precipitation or water
availability due to climate change, or
fire do not constitute significant threats
to the Potem Creek pebblesnail now or
in the future.
Finding for the Potem Creek Pebblesnail
We have carefully assessed the best
scientific and commercial information
available regarding the past, present,
and future threats faced by the Potem
Creek pebblesnail. We reviewed the
petition, available published and
unpublished scientific and commercial
information, and information submitted
to us during our status review. This
finding reflects and incorporates that
information. We also consulted with
recognized authorities on this species,
and we consulted with Federal and
State resource agencies. Although only
1 confirmed and 13 unconfirmed
occupied sites are known for the Potem
Creek pebblesnail, review of the best
available information did not indicate
that populations at any site are likely to
be extirpated due to impoundments,
overutilization, disease or predation, the
inadequacy of existing regulatory
mechanisms, competition with invasive
species, changes in precipitation and
water availability due to climate change,
or catastrophic events such as fire, now
or in the foreseeable future. The best
available scientific and commercial
information at this time does not
indicate that there is likely to be a
change in any of these stressors in the
future.
Based on our review of the best
available scientific and commercial
information pertaining to the five
factors, we find that the threats as
described above either alone or in
combination are not of sufficient
imminence, intensity, or magnitude to
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indicate that the Potem Creek
pebblesnail is in danger of extinction
(endangered) or likely to become
endangered within the foreseeable
future (threatened), throughout all of its
range.
Significant Portion of the Range
Having determined that the Potem
Creek pebblesnail is not endangered or
threatened throughout all of its range,
we must next consider whether there
are any significant portions of the range
where the Potem Creek pebblesnail is in
danger of extinction or is likely to
become endangered in the foreseeable
future. See Significant Portion of the
Range under Summary of Procedures for
Determining the Listing Status of
Species.
We evaluated the current range of the
Potem Creek pebblesnail to determine if
there is any apparent geographic
concentration of potential threats for the
species. The Potem Creek pebblesnail is
highly restricted in its range and the
threats occur throughout its range. We
considered the potential threats due to
impoundments, overutilization, disease
or predation, the inadequacy of existing
regulatory mechanisms, competition
with invasive species, changes in
precipitation and water availability due
to climate change, and catastrophic
events such as fire. We found no
concentration of threats that suggests
that the Potem Creek pebblesnail may be
in danger of extinction in a portion of
its range. We found no portions of its
range where potential threats are
significantly concentrated or
substantially greater than in other
portions of its range. Therefore, we find
that factors affecting the species are
essentially uniform throughout its
range, indicating no portion of the range
of the species warrants further
consideration of possible endangered or
threatened status under the Act.
We find that the Potem Creek
pebblesnail is not in danger of
extinction now, nor is likely to become
endangered within the foreseeable
future, throughout all or a significant
portion of its range. Therefore, listing
the Potem Creek pebblesnail as
endangered or threatened under the Act
is not warranted at this time.
Shasta Pebblesnail (Fluminicola
multifarius)
Species Information for the Shasta
Pebblesnail
Taxonomy and Species Description
The Shasta pebblesnail is an aquatic
snail that was formally named and
described in 2007 (Hershler et al. 2007,
pp. 415–419). This species combines
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four taxa previously considered likely
species, but never formally described:
The Sacramento pebblesnail
(Fluminicola n. sp. 1) (Frest and
Johannes 1995b, pp. 42, D14) and three
species discussed in Frest and Johannes
1999 (pp. 39–50), the flat top
pebblesnail (Fluminicola n. sp. 15), the
Shasta Springs pebblesnail (Fluminicola
n. sp. 16), and the disjunct pebblesnail
(Fluminicola n. sp. 17). The latter three
were included under the SMP (USDA
and USDI 2007, pp. 169, 252). Although
pebblesnails in general (Fluminicola
genus) had previously been considered
part of the Hydrobiidae family (Hershler
et al. 2003, p. 275), they have since been
reassigned to the Lithoglyphidae family
(Hershler et al. 2007, p. 371).
The shell of the Shasta pebblesnail is
2.3 to 4.6 mm (0.09 to 0.18 in) tall, with
a tan, brown, or light green
periostracum and 3.25 to 4.5 whorls
(Hershler et al. 2007, pp. 417–419). The
Shasta pebblesnail has a high range of
shell variation, with shapes ranging
from subglobose to narrowly conic, and
lower whorls that are sometimes
loosened from the coiling axis and
sometimes not (Hershler et al. 2007, p.
419). This range of morphological
characteristics is the source of the
Shasta pebblesnail’s specific name
multifarius, meaning ‘‘in various
manners.’’
Distribution
Twenty occupied locations of the
Shasta pebblesnail are known, 19 of
which are in Siskiyou County,
California, and the other along the
Sacramento River in Shasta County,
California (Hershler et al. 2007, pp.
415–417). All but two sites are in
springs or spring runs, the exceptions
being two sites in the Sacramento River
itself, which may be associated with
nearby springs. Five sites are at Mount
Shasta City Park, 11 are along the
Sacramento River between Lake
Siskiyou and the southern end of
Dunsmuir, and 3 are east of the town of
McCloud in waters that drain into the
McCloud River. There is one occupied
site on Shasta-Trinity National Forest
land, within the NWFP area, and two
others in the Cantara/Ney Springs State
Wildlife Area. The rest (except for the
five mentioned above at Mount Shasta
City Park) are on private property.
Habitat and Biology
The Shasta pebblesnail occurs in cold
perennially flowing waters on substrates
ranging from sand to cobbles (Frest and
Johannes 1995b, p. 42; Frest and
Johannes 1999, pp. 40, 44, 48). It is often
associated with watercress, and it feeds
on perilithon and may eat periphyton as
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well (Frest and Johannes 1995b, pp. 42,
43; Frest and Johannes 1999, p. 40;
Furnish and Monthey 1999, Sect. 2, p.
2). We have no specific information
regarding reproduction for this species,
but members of the Fluminicola genus
typically live a single year and breed
only once (Furnish and Monthey 1999,
Sect. 2, p. 5; ORNHIC 2004, p. 2). They
generally lay eggs in the spring, which
hatch in 2 to 4 weeks. They are not
known to disperse widely, and are
highly sensitive to water pollution,
decreases in dissolved oxygen, elevated
temperatures, and sedimentation
(Furnish and Monthey 1999, Sect. 2, pp.
5, 7; Hershler et al. 2007, p. 372).
Five-Factor Evaluation of Threats for the
Shasta Pebblesnail
Factor A. The Present or Threatened
Destruction, Modification, or
Curtailment of Its Habitat or Range
Impoundments
One occupied site (identified as
USNM 1020758) is located in the main
stem of the Sacramento River, about 3
km (1.9 mi) downstream of Box Canyon
Dam, which impounds Lake Siskiyou
(Hershler et al. 2007, p. 415). Due to low
generating capacity, the dam was
exempted in 1982 from licensing
requirements under the Federal Power
Act (Siskiyou County and CDFG 1983a,
p. 2). However, the exemption requires
Siskiyou County to comply with
requirements established by CDFG for
flow releases from the lake. Those
requirements include minimum flow
volumes (40 cfs), minimum dissolved
oxygen concentrations (7.0 milligrams
per liter (mg/l)), and procedures to
minimize water temperatures during
summer months (by releasing water
from the lowest possible depth in the
lake) (Siskiyou County and CDFG
1983a, pp. 2, 3). All of these
requirements benefit Shasta
pebblesnails in downstream locations,
because the upebblesnails require cold,
well-oxygenated flowing water (see
Habitat and Biology, above). We have
obtained monitoring information from
2003, 2004, and 2006 indicating these
requirements were consistently met in
those years (Webb 2005, pp. 2–13, 18–
29; FERC 2006, p. 2). The maximum
recorded temperature during 2003 and
2004 was 59.2 °F (15.1 °C) (in October
2003), which is colder than all but one
of the average water temperatures
measured in 2009 through 2011 in the
Pit 3, 4, and 5 reaches (see Canary
duskysnail, above) (PGE 2010, p. 35;
PGE 2011, p. 24; PGE 2012, p. 24).
Minimum flow requirements were not
met for a few brief periods of 15 minutes
or less in 2002, 2005, and 2009 (Webb
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2005, p. 14; FERC 2006, pp. 3, 4; FERC
2009, p. 1), but we do not expect these
to have significantly impacted the
Shasta pebblesnails in the main stem
location. Additional water is also
supplied to that location by Ney Creek,
which joins the Sacramento River about
0.8 km (0.5 mi) upstream of the
occupied site. Two additional occupied
sites are within a mile downstream
(Hershler et al. 2007, p. 417), but these
are in springs and so less likely to be
impacted by flow releases from the dam.
Grazing and Logging
Of the 20 occupied sites, 5 are in a
small city park unlikely to be used for
grazing or logging, 2 are on property
used as a spiritual retreat by the St.
Germain Foundation, 2 are in the
Cantara/Ney Springs Wildlife Area, and
1 is in the Shasta-Trinity National
Forest within the NWFP boundary and
outside of any grazing allotments
(Hershler et al. 2007, p. 417). An
eleventh occupied site (in Shasta
County) is in a spring on a thin strip of
land between the Union Pacific railroad
tracks and Interstate 5, and thus
unlikely to be grazed or logged. This
leaves nine sites for which we lack data
regarding potential grazing impacts.
Comparisons of mapped Shasta
pebblesnail sites (Hershler et al. 2007,
pp. 404, 405; Service 2012, p. 1) with
locations of planned timber harvests
(THP Tracking Center 2012, p. 1) show
no THPs have been filed since 2009 for
lands covering any of the 20 occupied
sites.
To summarize: (1) Only a few
locations occur near impoundments,
and those impoundments are managed
to minimize potential impacts; (2) the
locations of 11 of 20 sites makes them
unlikely to be grazed or logged; (3) the
remaining 9 sites are not scheduled to
be logged in the near future, but we lack
information regarding grazing at those
sites. We conclude that, based on the
best available scientific and commercial
information, that the present or
threatened destruction, modification or
curtailment of its habitat or range does
not constitute a significant threat to the
species.
Factor B. Overutilization for
Commercial, Recreational, Scientific, or
Educational Purposes
Our review of the best available
scientific and commercial information
yielded nothing to indicate that
overutilization for commercial,
recreational, scientific, or educational
purposes is occurring at this time or is
likely to occur in the future. We
therefore conclude such overutilization
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does not constitute a threat to the Shasta
pebblesnail.
Factor C. Disease or Predation
Disease
We reviewed the best available
scientific and commercial information
regarding this species and other similar
species, and found no evidence to
indicate that disease is impacting Shasta
pebblesnail populations.
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Predation
It is likely the introduced signal
crayfish has established itself in the
upper Sacramento River, as well as the
Pit River. Predation by dense crayfish
populations can significantly impact
aquatic snails (Lorman and Magnuson
1978, p. 9). However, our only data
regarding signal crayfish densities
indicates those densities appear to be
holding stable at levels equivalent to
those of the native Shasta crayfish,
alongside which the Shasta pebblesnail
has evolved (see canary duskysnail,
above) (Ellis 1999, p. 58; PGE 2011b, pp.
iii, 10; PGE 2012b, p. 9). The known
Shasta pebblesnail sites do not overlap
the current range of the Shasta crayfish,
so only the signal crayfish poses a
potential predation impact. Hence, the
available evidence does not support the
contention that signal crayfish are
present in the range of the Shasta
pebblesnail in sufficiently high
densities to pose a predation risk to the
Shasta pebblesnail. Furthermore, the
information does not indicate any trend
in the densities of the two crayfish that
would lead us to a conclusion that the
predation risk would increase in the
future.
We therefore conclude, based on the
best available scientific and commercial
information, that neither disease nor
predation constitutes a significant threat
to the species now or in the future.
Factor D. The Inadequacy of Existing
Regulatory Mechanisms
Under this factor, we examine
whether existing regulatory mechanisms
are inadequate to address the threats to
the species discussed under the other
factors. Section 4(b)(1)(A) of the Act
requires the Service to take into account
‘‘those efforts, if any, being made by any
State or foreign nation, or any political
subdivision of a State or foreign nation,
to protect such species * * *’’. We
interpret this language to require the
Service to consider relevant Federal,
State, and Tribal laws and regulations
when developing our threat analyses.
Regulatory mechanisms, if they exist,
may preclude the need for listing if we
determine that such mechanisms
adequately address the threats to the
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species such that listing is not
warranted.
Having evaluated the significance of
the threat as mitigated by any such
conservation efforts, we analyze under
Factor D the extent to which existing
regulatory mechanisms are inadequate
to address the specific threats to the
species. We found no significant threats
to the Shasta pebblesnail under the
other factors; therefore, the analysis of
any existing regulatory mechanisms’
adequacy to address threats is not
applicable. Consequently, after
reviewing the best available commercial
and scientific information, we conclude
that the inadequacy of existing
regulatory mechanisms is not a threat to
the Shasta pebblesnail now or in the
future.
Factor E. Other Natural or Manmade
Factors Affecting Its Continued
Existence
Competition With Invasive Species
The New Zealand mudsnail (see
canary duskysnail, above) has been
reported at Castle Lake, which is about
5.6 km (3.5 mi) from Siskiyou Lake (see
Potem Creek pebblesnail, above)
(McAlexander 2012a, p. 1; McAlexander
2012b, p. 1). If the New Zealand
mudsnail were to establish itself in
Siskiyou Lake, it could potentially wash
down the Sacramento River,
establishing anywhere along the route
and thereby potentially competing
directly with the Shasta pebblesnail at
11 of its 20 known occupied sites,
including 2 sites in the river itself and
9 sites in springs that are close to the
river and hydrologically connected to it
(Hershler et al. 2007, pp. 415, 417). If
that were to happen, it could pose a
threat to the species. However, the
available information does not indicate
that such a scenario is likely. We
consider the risk of infestation to be
much lower in springs adjoining the
river since the New Zealand mudsnails
could not simply be washed to such
locations by the current. Nine of the
eleven Shasta pebblesnail sites in the
upper Sacramento River area are in
adjoining springs. Additionally, CDFG
is following a national control plan
(ANSTF 2007, entire) and has posted
information and downloadable posters
and wallet cards to its Web site (see
canary duskysnail, above) (CDFG
undated, p. 1). Accordingly, we do not
consider competition from the New
Zealand mudsnail a threat to the
species.
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Changes in Precipitation and Water
Availability Due to Climate Change
See our discussion of climate change
in general in the Changes in
Precipitation and Water Availability
Due to Climate Change section under
‘‘Factor A’’ in Five-Factor Evaluation of
Threats for the Canary Duskysnail.
Climate change is not expected to
significantly change total precipitation
in northern California, but may affect
seasonal water availability in some areas
due to changes in snowpack melting
times and in the proportion of
precipitation falling as rain rather than
snow (Dettinger et al. 2004, pp. 43, 44).
However, the water supplying many
springs in Shasta and Siskiyou Counties
is collected from wide areas and
percolates through porous volcanic
rocks to collect in large aquifers, thereby
holding extra water from seasons when
rain is plentiful and delivering it
through springs during seasons when it
is not (Service 1998, p. 18). Resulting
spring flows are generally highly stable
in volume, temperature and clarity
(Service 1998, p. 46). We lack
information regarding aquifer sizes and
collection ranges for the specific springs
supporting sites occupied by the Shasta
pebblesnail, but given the general
volcanic geology of the entire area
(USNPS 2005, p. 1), we consider it most
likely that these sites will maintain
relatively constant flow rates and water
temperatures despite climate change.
Accordingly, we do not expect changes
in precipitation or water availability due
to climate change to significantly affect
the species.
Catastrophic Events—Chemical Spills
In 1991, a Southern Pacific railroad
car carrying the herbicide metam
sodium spilled its contents into the
upper Sacramento River near Dunsmuir
(Frest and Johannes 1995b, p. 13). The
spill eliminated numerous mollusks
from the main stem, but did not
eliminate Shasta pebblesnails from their
remaining known occupied sites along
the river, presumably because most of
those sites are in springs to the side of
the main stem (Frest and Johannes
1995b, p. 73; Hershler et al. 2007, pp.
415–417). The flow from those springs
would have prevented the chemical
from traveling from the river into the
springs themselves. The one occupied
site in the main stem of the river near
Dunsmuir is about 500 m (1,640 ft)
upstream of the spill site (Frest and
Johannes 1995b, p. F4). Since the time
of the spill, the railroad company
involved (Southern Pacific) has been
acquired by the Union Pacific, which
has taken several steps to prevent a
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recurrence of the accident. These steps
include regrading the section of track,
replacing the wooden ties with concrete
ties, lowering the maximum length of
trains operating in the area, reducing the
maximum speed, upgrading
locomotives, and requiring locomotives
to be spread more evenly throughout
each train (Darling 2011, p. 4). If such
a spill were to recur, most Shasta
pebblesnail populations would again be
protected by their location in springs
and spring runs outside the main stem
flow.
Summary of Factor E
In summary, the Shasta pebblesnail is
protected from expected changes in
precipitation or water availability due to
climate change by the particular
characteristics of its habitat. Although
potential competition from the New
Zealand mudsnail is cause for concern,
no site currently occupied by the Shasta
pebblesnail has been colonized and
there is nothing to indicate the New
Zealand mudsnail will colonize any of
the locations occupied by the Shasta
pebblesnail. There is also no direct
evidence to show that any such
occupied locations would be extirpated
by such a colonization were it to occur.
The two species are not known to have
interacted in the past. If a chemical spill
were to occur, most Shasta pebblesnail
populations would be protected by their
location in springs and spring runs
outside the main stem flow. We
therefore conclude that, based on the
best available scientific and commercial
information, that other natural or
manmade factors such as competition
from the New Zealand mudsnail,
changes in precipitation or water
availability due to climate change, or
chemical spills do not constitute
significant threats to the Shasta
pebblesnail now or in the future.
mstockstill on DSK4VPTVN1PROD with PROPOSALS2
Finding for the Shasta Pebblesnail
We have carefully assessed the best
scientific and commercial information
available regarding the past, present,
and future threats faced by the Shasta
pebblesnail. We reviewed the petition,
available published and unpublished
scientific and commercial information,
VerDate Mar<15>2010
19:50 Sep 17, 2012
Jkt 226001
and information submitted to us during
our status review. This finding reflects
and incorporates that information. We
also consulted with recognized
authorities on this species and Federal
and State resource agencies. Although
only 20 occupied sites are known for the
Shasta pebblesnail, a review of the best
available information does not indicate
that populations at any site are likely to
be extirpated due to impoundments,
grazing and logging, overutilization,
disease or predation, the inadequacy of
existing regulatory mechanisms,
competition with invasive species,
changes in precipitation and water
availability due to climate change, or
catastrophic events such as chemical
spills, now or in the foreseeable future.
The best available scientific and
commercial information at this time
does not indicate that there is likely to
be a change in any of these stressors in
the future.
Based on our review of the best
available scientific and commercial
information pertaining to the five
factors, we find that the threats as
described above either alone or in
combination are not of sufficient
imminence, intensity, or magnitude to
indicate that the Shasta pebblesnail is in
danger of extinction (endangered) or
likely to become endangered within the
foreseeable future (threatened),
throughout all of its range.
Significant Portion of the Range
Having determined that the Shasta
pebblesnail is not endangered or
threatened throughout all of its range,
we must next consider whether there
are any significant portions of the range
where the Shasta pebblesnail is in
danger of extinction or is likely to
become endangered in the foreseeable
future. See Significant Portion of the
Range under Summary of Procedures for
Determining the Listing Status of
Species.
We evaluated the current range of the
Shasta pebblesnail to determine if there
is any apparent geographic
concentration of potential threats for the
species. The Shasta pebblesnail is
highly restricted in its range and the
threats occur throughout its range. We
PO 00000
Frm 00028
Fmt 4701
Sfmt 9990
considered the potential threats due to
impoundments, grazing and logging,
overutilization, disease or predation, the
inadequacy of existing regulatory
mechanisms, competition with invasive
species, changes in precipitation and
water availability due to climate change,
and catastrophic events such as
chemical spills. We found no
concentration of threats that suggests
that the Shasta pebblesnail may be in
danger of extinction in a portion of its
range. We found no portions of its range
where potential threats are significantly
concentrated or substantially greater
than in other portions of its range.
Therefore, we find that factors affecting
the species are essentially uniform
throughout its range, indicating no
portion of the range of the species
warrants further consideration of
possible endangered or threatened
status under the Act.
We find that the Shasta pebblesnail is
not in danger of extinction now, nor is
likely to become endangered within the
foreseeable future, throughout all or a
significant portion of its range.
Therefore, listing the Shasta pebblesnail
as endangered or threatened under the
Act is not warranted at this time.
References Cited
A complete list of references cited is
available on the Internet at https://
www.regulations.gov and upon a request
to the Sacramento Fish and Wildlife
Office (see ADDRESSES section).
Authors
The primary authors of this notice are
the staff members of the Sacramento
Fish and Wildlife Office.
Authority
The authority for this action is section
4 of the Endangered Species Act of
1973, as amended (16 U.S.C. 1531 et
seq.).
Dated: September 5, 2012.
Rowan W. Gould,
Acting Director, Fish and Wildlife Service.
[FR Doc. 2012–22723 Filed 9–17–12; 8:45 am]
BILLING CODE 4310–55–P
E:\FR\FM\18SEP2.SGM
18SEP2
]]>Agencies
[Federal Register Volume 77, Number 181 (Tuesday, September 18, 2012)]
[Proposed Rules]
[Pages 57921-57948]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-22723]
[[Page 57921]]
Vol. 77
Tuesday,
No. 181
September 18, 2012
Part IV
Department of the Interior
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Fish and Wildlife Service
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50 CFR Part 17
Endangered and Threatened Wildlife and Plants; 12-Month Finding on a
Petition To List 14 Aquatic Mollusks as Endangered or Threatened;
Proposed Rule
Federal Register / Vol. 77 , No. 181 / Tuesday, September 18, 2012 /
Proposed Rules
[[Page 57922]]
-----------------------------------------------------------------------
DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R8-ES-2011-0076: 4500030113]
Endangered and Threatened Wildlife and Plants; 12-Month Finding
on a Petition To List 14 Aquatic Mollusks as Endangered or Threatened
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Notice of 12-month petition finding.
-----------------------------------------------------------------------
SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a
12-month finding on a petition to list the basalt juga (Juga new
species (n. sp.) 2), canary duskysnail (Colligyrus convexus), cinnamon
juga (Juga n. sp. 3), Columbia duskysnail (Colligyrus n. sp. 1),
Fredenburg pebblesnail (Fluminicola n. sp. 11), Goose Valley
pebblesnail (Fluminicola anserinus), Hat Creek pebblesnail (Fluminicola
umbilicatus), Klamath Rim pebblesnail (Fluminicola n. sp. 3), knobby
rams-horn (Vorticifex n. sp. 1), masked duskysnail (Colligyrus n. sp.
2), nugget pebblesnail (Fluminicola seminalis), Potem Creek pebblesnail
(Fluminicola potemicus), Shasta pebblesnail (Fluminicola multifarius),
and tall pebblesnail (Fluminicola n. sp. 2) as endangered or
threatened, and to designate critical habitat, under the Endangered
Species Act of 1973, as amended (Act). The Fredenburg pebblesnail and
the Klamath Rim pebblesnail were referred to in the petition and in our
90-day finding (76 FR 61826) as the nerite pebblesnail and the
diminutive pebblesnail, respectively (see Clarification Regarding
Common Names for Two Petitioned Aquatic Mollusks, below). After review
of the best available scientific and commercial information, we find
that listing the basalt juga, cinnamon juga, Columbia duskysnail,
Fredenburg pebblesnail, Klamath Rim pebblesnail, knobby rams-horn,
masked duskysnail, and tall pebblesnail is not warranted at this time
because these snails do not constitute listable entities under the Act
(see Listable Entity Evaluation, below). We ask the public to submit to
us new information that becomes available concerning the taxonomic
status of these mollusks. We find that listing the canary duskysnail,
Goose Valley pebblesnail, Hat Creek pebblesnail, nugget pebblesnail,
Potem Creek pebblesnail, and Shasta pebblesnail is not warranted at
this time. We ask the public to submit to us new information that
becomes available concerning threats to these mollusks.
DATES: The finding announced in this document was made on September 18,
2012.
ADDRESSES: This finding is available on the Internet at https://www.regulations.gov at Docket Number FWS-R8-ES-2011-0076. Supporting
documentation we used in preparing this finding is available for public
inspection, by appointment, during normal business hours at the U.S.
Fish and Wildlife Service, Sacramento Fish and Wildlife Office, 2800
Cottage Way, Room W-2605, Sacramento, California 95825. Please submit
any new information, materials, comments, or questions concerning this
finding to the above address.
FOR FURTHER INFORMATION CONTACT: Listing Coordinator, U.S. Fish and
Wildlife Service, Sacramento Fish and Wildlife Office (see ADDRESSES);
by telephone at 916-414-6600; or by facsimile at 916-414-6712 mailto:.
If you use a telecommunications device for the deaf (TDD), please call
the Federal Information Relay Service (FIRS) at 800-877-8339.
SUPPLEMENTARY INFORMATION:
List of Acronyms
To assist the reader, the following is a partial list of acronyms
that are used in this document.
ACS = Aquatic Conservation Strategy
ANSTF = Aquatic Nuisance Species Task Force
BNSF = Burlington Northern and Santa Fe
CAL FIRE = California Department of Forestry and Fire Protection
CBD = Center for Biological Diversity
CDFG = California Department of Fish and Game
CDPR = California Department of Parks and Recreation
CNDDB = California Natural Diversity Database
DPS = distinct population segment
FERC = Federal Energy Regulatory Commission
FPA = Forest Practice Act
FRRCD = Fall River Resource Conservation District
IPCC = Intergovernmental Panel on Climate Change
NBII = National Biological Information Infrastructure
NWP = Northwest Forest Plan
OHV = off-highway vehicle
ORNHIC = Oregon Natural Heritage and Information Center
PDA = Public Domain Allotment
PGE = Pacific Gas and Electric Company
RCAs = Riparian Conservation Areas
SHU = Shasta-Trinity Unit
SMP = Survey and Manage Program
SNFPA = Sierra Nevada Forest Plan Amendment
SPR = significant portion of the range
SWRCB = State Water Resources Control Board
THP = Timber Harvest Plan
Background
Section 4(b)(3)(B) of the Act (16 U.S.C. 1531 et seq.) requires
that, for any petition to revise the Federal Lists of Threatened and
Endangered Wildlife and Plants that contains substantial scientific or
commercial information that listing a species may be warranted, we make
a finding within 12 months of the date of receipt of the petition. In
this finding, we will determine that the petitioned action is: (1) Not
warranted; (2) warranted; or (3) warranted, but the immediate proposal
of a regulation implementing the petitioned action is precluded by
other pending proposals to determine whether species are endangered or
threatened, and expeditious progress is being made to add or remove
qualified species from the Federal Lists of Endangered and Threatened
Wildlife and Plants. Section 4(b)(3)(C) of the Act requires that we
treat a petition for which the requested action is found to be
warranted but precluded as though resubmitted on the date of such
finding, that is, requiring a subsequent finding to be made within 12
months. We must publish these 12-month findings in the Federal
Register.
Previous Federal Actions
On March 17, 2008, we received a petition dated March 13, 2008,
from five conservation organizations: The Center for Biological
Diversity (CBD), Conservation Northwest, the Environmental Protection
Information Center, the Klamath-Siskiyou Wildlands Center, and Oregon
Wild. The petition asked us to list 32 species and subspecies of snails
and slugs (mollusks) in the Pacific Northwest as threatened or
endangered under the Act. Additionally, the petition requested that we
designate critical habitat concurrent with listing. The petition
clearly identified itself as a petition and included identification
information regarding the petitioners, as required by title 50 of the
Code of Federal Regulations (CFR) in 424.14(a). The petition included
the 14 aquatic mollusk species addressed in this finding, and provided
supporting information regarding the species' taxonomy and ecology,
range, present status, and actual and potential causes of decline.
In a June 27, 2008, letter to the petitioners, we responded that we
had reviewed the information presented in the petition and determined
that issuing an emergency regulation temporarily
[[Page 57923]]
listing the species as per section 4(b)(7) of the Act was not
warranted. We also stated that we could not address their petition at
that time due to court orders and judicially approved settlement
agreements for other listing and critical habitat determinations under
the Act that required nearly all of our listing and critical habitat
funding for fiscal years 2008 and 2009. We indicated that we
anticipated making an initial finding on their petition in fiscal year
2010.
On April 13, 2009, we received a signed email from CBD providing
updated taxonomic information regarding some of the 32 petitioned
mollusk species (Curry 2009, pp. 1-2). The email indicated that two of
the species had been formally described, two others had been combined
into a single species that had been formally described, and three
additional petitioned species had been combined into a single species
that had been formally described. The email provided a citation to the
article making the taxonomic changes, and asked us to consider the
revised species for listing as endangered or threatened under the Act.
We treated this email message as an amendment to the original petition.
Therefore, the amended petition asked us to list 29 species and
subspecies of mollusks, including the 14 aquatic species addressed
here.
We addressed the petition as funding permitted beginning in late
2009, and published a 90-day finding on October 5, 2011 (76 FR 61826).
We found that substantial scientific and commercial information had
been presented in the petition and existed in our files to indicate
listing may be warranted for 26 of the 29 petitioned mollusks. Fourteen
of those 26 mollusks are aquatic and 12 are terrestrial. We have
initiated a status review of the 14 aquatic mollusks, and present the
results here. We intend to review the status of the remaining 12
terrestrial mollusks in fiscal year 2013. This notice constitutes our
12-month finding on the June 27, 2008, petition (as amended on April
13, 2009) to list 14 aquatic mollusks as endangered or threatened.
Clarification Regarding Common Names for Two Petitioned Aquatic
Mollusks
The mollusks petitioned for listing included the ``diminutive
pebblesnail (Fluminicola n. sp. 3)'' (CBD et al. 2008, pp. 9, 44) and
the ``nerite pebblesnail (Fluminicola n. sp. 11)'' (CBD et al. 2008,
pp. 9, 46). In our 90-day finding, which was limited in scope to
information provided by the petition and available in our files, we
noted that these mollusks were sometimes referred to by cited sources
other than the petition as the Klamath Rim pebblesnail and the
Fredenburg pebblesnail, respectively (76 FR 61836, 61843). Information
that we reviewed for this status review indicates that the only
accepted common names for these mollusks are the Klamath Rim
pebblesnail and the Fredenburg pebblesnail. The only sources that refer
to these two mollusks by the common names used in the petition are the
Oregon Natural Heritage and Information Center (ORNHIC) (2004d, p. 1)
for the diminutive pebblesnail, and ORNHIC (2004j, p. 1) for the nerite
pebblesnail. However, these must be incorrect rather than simply
alternate common names because Frest and Johannes (the original
discoverers of these snails) refer to all four named mollusks as
separate species (Frest and Johannes 1993, pp. 46, 47, 49; Frest and
Johannes 2000, pp. 181, 264, 267, 273).
They note that the Klamath Rim and Fredenburg pebblesnails are
protected under the Survey and Manage Program (SMP) of the Northwest
Forest Plan (NWFP) (see Generally Applicable Federal Regulatory
Mechanisms, below), whereas the diminutive and nerite pebblesnails
``should be'' included in that program (Frest and Johannes 2000, pp.
264, 265, 268, 274). The petition only included mollusks that had been
protected under the SMP (CBD et al. 2008, p. 12). An Environmental
Impact Statement (EIS) on which we relied in our 90-day finding for
information regarding occupied locations of various mollusks,
identifies all the petitioned mollusks by their scientific names alone,
without providing common names (for example, U.S. Department of
Agriculture (USDA) and U.S. Department of the Interior (USDI) 2007, pp.
92, 251).
In the case of these two mollusks, the ``scientific names'' were
provisional and subject to change in different documents (Frest and
Johannes 1993, pp. 46, 49; Frest and Johannes 2000, pp. 264, 273) (see
Listable Entity Evaluation, below). However, we have subsequently
obtained the survey protocol for aquatic mollusk species under the SMP,
and that document identifies Fluminicola n. sp. 3 and n. sp. 11 as the
Klamath Rim and Fredenburg pebblesnails, respectively (Furnish et al.
1997, p. 29). It does not mention the diminutive or nerite
pebblesnails, presumably because they were not protected by the SMP.
Accordingly, in this document we will refer to the petitioned mollusk
Fluminicola n. sp. 3 as the Klamath Rim pebblesnail and to the
petitioned mollusk Fluminicola n. sp. 11 as the Fredenburg pebblesnail,
rather than as the diminutive and nerite pebblesnails, respectively.
Listable Entity Evaluation
Section 3(16) of the Act defines the term ``species'' to include
``any subspecies of fish or wildlife or plants, and any distinct
population segment (DPS) of any species of vertebrate fish or wildlife
which interbreeds when mature.'' Taxonomic groups or entities that meet
the Act's definition of a ``species'' can be considered for listing
under the Act and are, therefore, referred to as ``listable entities.''
Listable entities can then be listed if they are determined to meet the
definition of either an endangered or threatened species.
Of the 14 aquatic mollusks considered in this review, 8 have not
been formally described as species or subspecies in a peer-reviewed
journal, or in any other source commonly accepted by the scientific
community. This is why they have provisional scientific names,
including ``new species'' (or ``n. sp.'') and a number, rather than
accepted species names. Formal peer-reviewed description, with its
opportunities for further review and comment, is the process by which
proposed new species and subspecies become generally recognized or
rejected by the taxonomic community. We must therefore evaluate whether
the best available scientific and commercial information indicates that
these eight mollusks constitute valid species, despite their lack of
formal descriptions, for the purpose of determining whether the
mollusks in question constitute listable entities (16 U.S.C.
1533(b)(3)(A) and (B)). It is rare for us to list entities that have
not been formally described, but we have occasionally done so in the
past. Examples include two fish: The Hutton tui chub (Gila bicolor
ssp.) and Foskett speckled dace (Rhinichthys osculus ssp.) (50 FR
12302; March 28, 1985). In those instances, there was general agreement
among biologists familiar with these fish that they constituted
listable subspecies, and formal descriptions of the subspecies were in
preparation. Additionally, if our determination of the status of these
fish as valid subspecies had been incorrect, the fish would still
likely have constituted distinct vertebrate population segments, and
thus qualified as listable entities under section 3(16) of the Act.
Mollusk populations are not listable entities, unless they also
constitute valid species or subspecies, because the provision in
section 3(16) allowing DPSs to be listed only applies to vertebrates
(16 U.S.C. 1532(16)).
[[Page 57924]]
The eight aquatic mollusks reviewed here that have not been
formally described are: Basalt juga, cinnamon juga, Columbia
duskysnail, Fredenburg pebblesnail, Klamath Rim pebblesnail, knobby
rams-horn, masked duskysnail, and tall pebblesnail. Table 1 below
summarizes basic taxonomic and biological information for these
purported species.
Table 1--Basic Biology of Mollusks Lacking Formal Descriptions
----------------------------------------------------------------------------------------------------------------
Common name Description Habitat Known sites
----------------------------------------------------------------------------------------------------------------
Basalt juga...................... Shell about 22 by 10 mm Small, gravelly springs 31 sites in Hood River,
*; color bands of with unpolluted water Sherman, and Wasco
yellow, brown, pink, (Frest and Johannes Counties, OR; and
white, or tan (Frest and 1995a, p. 179). Klickitat and Skamania
Johannes 1999, p. 85). Counties, WA (BLM 2011,
entire).
Cinnamon juga.................... Shell about 15 by 8 mm; Large cold springs and 8 sites in the Shasta
cinnamon red but can spring runs, with sand- Springs complex, upper
appear black in the cobble substrate or Sacramento River,
field (Frest and exposed basalt bedrock Siskiyou County, CA
Johannes 1999, p. 89). (Frest and Johannes (Frest and Johannes
1999, p. 90). 1999, p. 90).
Columbia duskysnail.............. Shell about 1.7 by 1.4 Cold, shallow, well- 64 sites in Clackamas,
mm; translucent, off- oxygenated, slow- Wasco, Hood River, and
white, often with rust flowing springs and Multnomah Counties, OR;
to black coating (Frest outflows with soft and Skamania County, WA
and Johannes 1999, p. substrates. (Duncan (USDA and USDI 2007, p.
69). 2005b, p. 10). 93).
Fredenburg pebblesnail........... Shell about 3 by 2.5 mm; Small, shallow, cold 19 sites in Jackson
white with greenish- spring runs with County, OR. (Frest and
yellow outer layer; cobbled substrate Johannes 1999, p. 30;
white, sickle-shaped (Frest and Johannes USDA and USDI 2007, p.
penis. (Frest and 1999, p. 30). 92).
Johannes 1999, p. 29).
Klamath Rim pebblesnail.......... Shell about 2 by 2 mm; Shady areas in small, 6 sites in southern OR
white with greenish- cold, shallow spring and possibly northern
yellow outer layer; runs with gravel-cobble CA (USDA and USDI 2007,
sickle-shaped penis substrates and no large pp. 92, 251).
(Frest and Johannes water plants (Frest and
1999, p. 25). Johannes 1999, p. 26).
Knobby rams-horn................. Shell about 6 by 6 mm; Rocky substrates in 2 sites in Shasta
reddish-brown outer cold, clear water with County, CA (USDA and
layer, keeled with ribs high dissolved oxygen USDI 2007, pp. 94,
and protuberances (Frest levels (Frest and 268).
and Johannes 1995b, p. Johannes 1999, p. 99).
57; Frest and Johannes
1999, p. 98).
Masked duskysnail................ Shell described as up to Cool-water kettle lakes 3 to 4 sites at two
2 mm long (Frest and with oxygenated mud lakes: Curlew Lake,
Johannes 1995a, p. 185) substrates and aquatic Ferry County, WA, and
or as 3 to 5 mm long plant growth (Duncan Fish Lake, Chelan
(Frest and Johannes 2005e, p. 3). County, WA (Duncan
1999, p. 73); mask of 2005e, p. 3; USDA and
black pigment on neck USDI 2007, p. 94). Some
and around eyes (Frest indications of possible
and Johannes 1999, p. additional sites in ID
73). and OR (ORNHIC 2004u,
p. 1).
Tall pebblesnail................. Shell about 4.5 by 3 mm; Very cold water and 1 site at Harriman
conical, white with cobbled substrate Spring, Klamath County,
green outer layer; black (Duncan 2005b, p. 9). OR (Duncan 2005b, p. 9;
body except for white, USDA and USDI 2007, p.
flanged penis (Frest and 92).
Johannes 1999, p. 21).
----------------------------------------------------------------------------------------------------------------
* mm = millimeter.
None of these eight aquatic mollusks are included in databases of
recognized mollusk species, such as the Integrated Taxonomic
Information System (ITIS) (2010), or Turgeon et al. (1998). All eight
mollusks were first proposed as new species in an unpublished
consultation report produced in 1993 (Frest and Johannes 1993, pp. 46,
49, 50, 59, 62, 67). These eight mollusks have been addressed in
several subsequent documents (Frest and Johannes 1999, pp. 21-26, 29-
30, 69-76, 85-90, 98-101; Furnish and Monthey 1999, Sections 2, 4, 5,
entire; Frest and Johannes 2000, pp. 181, 264, 273, 274; ORNHIC 2004a,
entire; ORNHIC 2004d, entire; ORNHIC 2004j, entire; ORNHIC 2004r,
entire; ORNHIC 2004s, entire; ORNHIC 2004t, entire; ORNHIC 2004u,
entire; ORNHIC 2004v, entire; Duncan 2005b, entire; Duncan 2005e,
entire; USDA and USDI 2007, pp. 92-94, 250-252, 257-259, 268-269), but
none of those documents provide peer-reviewed evidentiary support of
the mollusks' taxonomic distinctness. Although the eight mollusks have
been treated by the U.S. Forest Service (USFS) and Bureau of Land
Management (BLM) as distinct entities under the SMP of the Northwest
Forest Plan (see Factor D, below), that program is not specifically
restricted to species or subspecies, as is the Act when applied to
invertebrates (16 U.S.C. 1532 (16)).
The unpublished descriptions of these eight mollusks are all
primarily based on shell characteristics, with occasional mention of
certain characters of the animals themselves (such as color). Snail
shell characteristics in general can vary due to environmental
influences including elevation, calcium content of the surrounding
water, and population density (Minton and Lydeard 2003, p. 76; Chak
2007, p. 3). The informal descriptions lack genetic data, data
regarding microscopic anatomical features such as the radula (tongue),
and photographs or drawings of anatomical features other than the
shell. Such data are often highly distinctive, and are of key
importance in formal descriptions (for example, Hershler et al. 2003,
pp. 278-282; Hershler et al. 2007, pp. 407-419).
At the time the petition to list these aquatic mollusks was first
submitted, only one of the petitioned mollusks (the nugget pebblesnail)
had been formally described (CBD et al. 2008, p. 9). Since then, an
additional five mollusks have been formally described and thereby
established in the scientific community as valid species. These are the
canary duskysnail, Goose Valley pebblesnail, Hat Creek pebblesnail,
Potem Creek pebblesnail, and Shasta pebblesnail (Hershler et al. 2003,
p. 278; Hershler et al. 2007, pp. 407, 409, 412, 415). For three of
these recently described species (the canary duskysnail, Goose Valley
pebblesnail, and Potem Creek pebblesnail), the formal descriptions
[[Page 57925]]
simply confirm the informal species designations under which they had
been petitioned. However, the formal description of the Hat Creek
pebblesnail combined into one species two of the petitioned mollusks
that had previously been informally described as separate species (the
umbilicate pebblesnail (Fluminicola n. sp. 19) and the Lost Creek
pebblesnail (Fluminicola n. sp. 20). Similarly, the formal description
of the Shasta pebblesnail combined four mollusks that had previously
been informally described as separate species (Hershler et al. 2007, p.
419)). Three of those had been petitioned for listing (CBD et al. 2008,
p. 9): the flat-top, Shasta Springs, and disjunct pebblesnails
(identified as Fluminicola n. sp. 3, 4, and 5 in Frest and Johannes
1995b, pp. 43, 44; but as Fluminicola n. sp. 15, 16, and 17 in Frest
and Johannes 1999, pp. 39, 43, 47 and in CBD et al. 2008, p. 9). The
fourth, the Sacramento pebblesnail (Fluminicola n. sp. 1) (Frest and
Johannes 1995b, p. 42) had not been petitioned for listing and was not
protected by the SMP (USDA and USDI 2007, pp. 92-94). In describing the
Shasta pebblesnail, the authors noted the ``[m]arked shell variation''
of the species (Hershler et al. 2007, p. 419).
The primary reason for combining multiple informally described
mollusks in the formal descriptions of the Hat Creek and Shasta
pebblesnails was that new genetic comparisons had shown those
informally described mollusks were not genetically divergent or
phylogenetically independent (Hershler et al. 2007, p. 383). Such
genetic comparisons have not yet been published for the remaining
undescribed mollusks. This suggests the remaining but undescribed
mollusks may also be determined by future taxonomic analyses to
represent populations of larger-ranging species or subspecies. New
taxonomic analyses are currently being conducted for a large number of
provisionally identified species in the Fluminicola genus (Johannes
2011, p. 1). Additionally, the establishment of the Shasta pebblesnail
as a single species, despite the marked differences in shell morphology
among its various populations, indicates that shell morphology is a
relatively poor indicator of species status for at least some of these
mollusks.
Accordingly, we conclude that the eight mollusks that have not been
formally described (as listed in Table 1, above) cannot be considered
to be listable entities under the Act at this time, and, therefore, we
will not further evaluate the status of these entities. These include
the Basalt juga, cinnamon juga, Columbia duskysnail, Fredenburg
pebblesnail, Klamath Rim pebblesnail, knobby rams-horn, masked
duskysnail, and tall pebblesnail. We, therefore, restrict the remainder
of our listing status review to the six mollusks constituting listable
entities under the Act. These are the canary duskysnail, the Goose
Valley pebblesnail, the Hat Creek pebblesnail, the nugget pebblesnail,
the Potem Creek pebblesnail, and the Shasta pebblesnail.
Generally Applicable Federal Regulatory Mechanisms
The Northwest Forest Plan
The Northwest Forest Plan (NWFP) is a set of amendments to the
resource management plans for USFS and BLM lands within the range of
the northern spotted owl (Strix occidentalis caurina) in western
Washington, Oregon, and northwestern California (referred to below as
NWFP lands) (USDA and USDI 1994a, pp. 11, 12). The NWFP was established
to protect species commonly occurring in late-successional and old-
growth forests, while also allowing for sustainable timber production
(USDA and USDI 1994a, p. 3). The NWFP established several categories of
land allocations and, with minor exceptions, restricted timber
production to those areas designated as Matrix Lands (16 percent of the
total) and to certain Adaptive Management Areas (6 percent of the
total) (USDA and USDI 1994a, pp. 6, 7). The NWFP includes two
subprograms designed to provide additional protections to specific
resources on NWFP lands. The first subprogram is the Aquatic
Conservation Strategy (ACS), which protects aquatic and riparian
habitat. The second subprogram is the SMP, which protects numerous rare
species associated with late-successional or old-growth forests that
are not adequately protected by other provisions of the NWFP (USDA and
USDI 1994a, pp. 9, 10; Olson et al. 2007, pp. 1, 2). The ACS and SMP
are particularly applicable, in varying degrees, to the six listable
aquatic mollusks considered here, and are discussed in more detail
below.
The Aquatic Conservation Strategy
The ACS was established to protect and restore aquatic ecosystems
on NWFP lands (USDA and USDI 1994b, p. B-11; Reeves et al. 2006, p.
320). The ACS includes four components: Riparian reserves, key
watersheds, watershed analysis, and watershed restoration (USDA and
USDI 1994a, pp. 9, 10). Of these, riparian reserves are the most
significant conservation tool for the aquatic mollusks considered here.
Riparian reserves include all aquatic habitat (perennial and seasonal
streams, lakes, ponds, and wetlands) on NWFP lands. Riparian reserves
are managed to maintain and restore water quality, aquatic ecosystem
physical integrity, instream flows, habitat connectivity, and other
natural features of the protected riparian and aquatic habitat (USDA
and USDI 1994b, pp. B-11, B-13). Activities with the potential to
negatively affect natural features, such as logging, road construction
and maintenance, grazing, recreation, mineral management, and fire
management are closely regulated within the reserves (USDA and USDI
1994a, p. 9; USDA and USDI 1994b, pp. C-31--C-38).
Riparian reserves incorporate buffers of 100 to 300 feet (ft) (30.5
to 91.4 meters (m)) around these aquatic features (except for wetlands
of less than 1 acre (ac) (0.4 hectares (ha)), which have buffers that
extend to the limit of the associated riparian vegetation). The six
listable aquatic mollusks considered in this review all occupy springs
(including those forming lakes or ponds) and perennial streams,
sometimes fish-bearing and sometimes not (a stream is considered fish
bearing if it supports any species of fish for any duration of time)
(USDA and USDI 1994b, p. B-14). When any of these six mollusks are on
NWFP lands in lakes, ponds, or fish-bearing streams, they are protected
by buffers extending outward 300 ft (91.4 m) from the streambanks, to
the limit of riparian vegetation or to a distance equal to the height
of two site-potential trees, whichever is greater (USDA and USDI 1994a,
p. 9). ``Site-potential tree height'' refers to the expected height
attainable by a mature conifer growing in the area (Kier Associates
2011a, p. 2). Average site-potential tree height for much of the
Pacific Northwest is about 170 ft (51.8 m). When present in non-fish-
bearing streams on NWFP lands, the six mollusks are protected by
buffers of 150 ft (45.7 m) or equal to the height of one site-potential
tree, whichever is greater. These boundaries may be modified based on
subsequent watershed analysis (USDA and USDI 1994a, p. 10; USDA and
USDI 1994b, p. B-13)).
The second component of the ACS, key watersheds, establishes
specific watersheds to be given the highest priority in watershed
restoration efforts (USDA and USDI 1994b, p. B-19). None of the key
watersheds identified under the ACS are in the known current range of,
or upstream from, any of the six aquatic mollusks that qualify as
listable entities (REO 2006, p. 5). Accordingly, the key watersheds
provision of the ACS does not affect the conservation of those
[[Page 57926]]
six mollusks, except if new locations of those species are identified
within key watersheds in the future.
The third component of the ACS, watershed analysis, is a systematic
procedure to collect information on and characterize watersheds on NWFP
lands (USDA and USDI 1994b, pp. B-20--B-31). Watershed analysis must be
conducted in key watersheds and roadless areas prior to management
activities, in riparian reserves prior to changing reserve widths, and
in any watershed prior to restoration efforts. Watershed analysis is
recommended for all watersheds, and has been conducted on an ongoing
basis since its inclusion in the NWFP (USDA 2009, p. 1). Analyses have
been conducted for portions of the upper Sacramento River and lower
McCloud River watersheds, which support occupied sites of the Shasta
pebblesnail and nugget pebblesnail, respectively.
The final component of the ACS, watershed restoration, focuses
primarily on restoring watershed aquatic habitat through the prevention
of road-related runoff, restoration of riparian vegetation, and
restoration of instream habitat complexity (USDA and USDI 1994b, p. B-
31). The Shasta-Trinity and Lassen National Forests are currently
planning or implementing several such watershed restoration projects
(USDA 2012a, pp. 4, 5; USDA 2012b, pp. 3, 5), although none of the
currently active projects involve locations near sites occupied by the
mollusks addressed in this status review at the present time.
The Survey and Manage Program
The SMP, like the ACS, was established under the NWFP and is
particularly applicable, in varying degrees, to the six listable
aquatic mollusks considered here. The six mollusks were protected under
the SMP (when on Federal lands subject to the NWFP), but the SMP
program was discontinued in 2007 (USDA and USDI 2007, pp. xii, xiii;
CBD et al. 2008, p. 5). The SMP was subsequently reinstated in
accordance with a court-approved settlement agreement in 2011
(Conservation Northwest v. Sherman 2011, C08-1067-JCC, p. 2), and is
being implemented in accordance with the 2001 Record of Decision. All
of the aquatic mollusks petitioned in 2008 (both formally described and
otherwise) are protected where they occur on NWFP lands (Conservation
Northwest v. Sherman 2011, C08-1067-JCC, Document 81-2, pp. 6, 7).
Refinements to the SMP in 2001 established six species categories with
differing mitigation requirements based on the species' conservation
status and on the practicality of conducting predisturbance surveys
(surveys conducted prior to habitat-disturbing projects) (Molina et al.
2006, p. 311, 312). Rare species for which predisturbance surveys are
practical are in Category A. Thirteen of the 14 petitioned aquatic
mollusks fall into this category, including all six of the listable
mollusks (USDA and USDI 2007, pp. 92-94). The one exception among the
petitioned aquatic mollusks is the knobby rams-horn (see Table 1,
above), which is in Category E (rare, practicality of predisturbance
surveys undetermined) (Molina et al. 2006, p. 312; USDA and USDI 2007,
p. 94).
For Category A species, the SMP requires predisturbance, strategic
surveys (conducted in areas not currently under consideration for
habitat-disturbing projects), management of all known sites to support
species persistence, and annual species reviews (Molina et al. 2006, p.
312; Olson et al. 2007, abstract). Numerous such surveys and several
annual reviews have been completed (Molina et al. 2006, pp. 312-315;
USDA and USDI 2001, entire; USDA and USDI 2002, entire; USDA and USDI
2003, entire). The process of continually collecting information
through surveys, and of summarizing and updating the information in
annual reviews, produces an adaptive management approach to guide
conservation and mitigation measures for rare species associated with
late-successional or old-growth forests (Olson et al. 2007, p. 2).
Summary of Procedures for Determining the Listing Status of Species
Review of Status Based on Five Factors
Section 4 of the Act (16 U.S.C. 1533) and implementing regulations
(50 CFR part 424) set forth procedures for adding species to, removing
species from, or reclassifying species on the Federal Lists of
Endangered and Threatened Wildlife and Plants. Under section 4(a)(1) of
the Act, a species may be determined to be endangered or threatened
based on any of the following 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.
In making these findings, we discuss information below pertaining
to each species in relation to the five factors provided in section
4(a)(1) of the Act. In considering what factors might constitute
threats to a species, we must look beyond the simple exposure of the
species to a particular factor. Instead we must evaluate whether the
species may respond to the factor in a way that causes actual impacts
to the species. If there is exposure to a factor and the species
responds negatively, the factor may be a threat and, during the status
review, we attempt to determine how significant a threat it is. The
threat is significant if it drives or contributes to the risk of
extinction of the species such that the species warrants listing as
endangered or threatened as those terms are defined by the Act.
However, the identification of factors that could impact a species
negatively may not be sufficient to compel a finding that the species
warrants listing. The information must include evidence sufficient to
suggest that the potential threat has the capacity (is of sufficient
magnitude and extent) to affect the species' status such that it meets
the definition of endangered or threatened under the Act.
Distinct Population Segments
After considering the five factors, we assess whether each species
is endangered or threatened throughout all of its range. Generally, we
next consider in our findings whether a DPS or any significant portion
of the species' range meets the definition of endangered or is likely
to become endangered in the foreseeable future (threatened). The
inclusion of DPSs in the definition of species under paragraph 3(16) of
the Act only applies to vertebrate fish or wildlife. Therefore, our
Policy Regarding the Recognition of Distinct Vertebrate Population
Segments Under the Endangered Species Act (DPS Policy) (61 FR 4722;
February 7, 1996) is not applicable to mollusks and no population
segments under review could qualify as a DPS under the Act. Although
our DPS Policy is not applicable to mollusks, we do determine in our
findings whether a mollusk species is endangered or threatened in a
significant portion of its range.
Significant Portion of the Range
Under the Act and our implementing regulations, a species may
warrant listing if it is endangered or threatened throughout all or a
significant portion of its range. The Act defines ``endangered
species'' as any species which is ``in danger of extinction throughout
all or a significant portion of its range,'' and ``threatened species''
as any species which is ``likely to become an
[[Page 57927]]
endangered species within the foreseeable future throughout all or a
significant portion of its range.'' The definition of ``species'' is
also relevant to this discussion. The Act defines ``species'' as
follows: ``The term `species' includes any subspecies of fish or
wildlife or plants, and any DPS of any species of vertebrate fish or
wildlife which interbreeds when mature.'' The phrase ``significant
portion of its range'' (SPR) is not defined by the statute, and we have
never addressed in our regulations: (1) The consequences of a
determination that a species is either endangered or likely to become
so throughout a significant portion of its range, but not throughout
all of its range; or (2) what qualifies a portion of a range as
``significant.''
Two recent district court decisions have addressed whether the SPR
language allows the Service to list or protect less than all members of
a defined ``species'': Defenders of Wildlife v. Salazar, 729 F. Supp.
2d 1207 (D. Mont. 2010), concerning the Service's delisting of the
Northern Rocky Mountain gray wolf (74 FR 15123, April 2, 2009); and
WildEarth Guardians v. Salazar, 2010 U.S. Dist. LEXIS 105253 (D. Ariz.
September 30, 2010), concerning the Service's 2008 finding on a
petition to list the Gunnison's prairie dog (73 FR 6660, February 5,
2008). The Service had asserted in both of these determinations that it
had authority, in effect, to protect only some members of a
``species,'' as defined by the Act (i.e., species, subspecies, or DPS),
under the Act. Both courts ruled that the determinations were arbitrary
and capricious on the grounds that this approach violated the plain and
unambiguous language of the Act. The courts concluded that reading the
SPR language to allow protecting only a portion of a species' range is
inconsistent with the Act's definition of ``species.'' The courts
concluded that once a determination is made that a species (i.e.,
species, subspecies, or DPS) meets the definition of ``endangered
species'' or ``threatened species,'' it must be placed on the list in
its entirety and the Act's protections applied consistently to all
members of that species (subject to modification of protections through
special rules under sections 4(d) and 10(j) of the Act).
Consistent with that interpretation, and for the purposes of this
finding, we interpret the phrase ``significant portion of its range''
in the Act's definitions of ``endangered species'' and ``threatened
species'' to provide an independent basis for listing; thus there are
two situations (or factual bases) under which a species would qualify
for listing: a species may be endangered or threatened throughout all
of its range; or a species may be endangered or threatened in only a
significant portion of its range. If a species is in danger of
extinction throughout a significant portion of its range, the species
is an ``endangered species.'' The same analysis applies to ``threatened
species.'' Based on this interpretation and supported by existing case
law, the consequence of finding that a species is endangered or
threatened in only a significant portion of its range is that the
entire species shall be listed as endangered or threatened,
respectively, and the Act's protections shall be applied across the
species' entire range.
We conclude, for the purposes of this finding, that interpreting
the significant portion of its range phrase as providing an independent
basis for listing is the best interpretation of the Act because it is
consistent with the purposes and the plain meaning of the key
definitions of the Act; it does not conflict with established past
agency practice (i.e., prior to the 2007 Solicitor's Opinion), as no
consistent, long-term agency practice has been established; and it is
consistent with the judicial opinions that have most closely examined
this issue. Having concluded that the phrase ``significant portion of
its range'' provides an independent basis for listing and protecting
the entire species, we next turn to the meaning of ``significant'' to
determine the threshold for when such an independent basis for listing
exists.
Although there are potentially many ways to determine whether a
portion of a species' range is ``significant,'' we conclude, for the
purposes of this finding, that the significance of the portion of the
range should be determined based on its biological contribution to the
conservation of the species. For this reason, we describe the threshold
for ``significant'' in terms of an increase in the risk of extinction
for the species. We conclude that a biologically based definition of
``significant'' best conforms to the purposes of the Act, is consistent
with judicial interpretations, and best ensures species' conservation.
Thus, for the purposes of this finding, and as explained further below,
a portion of the range of a species is ``significant'' if its
contribution to the viability of the species is so important that
without that portion, the species would be in danger of extinction.
We evaluate biological significance based on the principles of
conservation biology using the concepts of redundancy, resiliency, and
representation. Resiliency describes the characteristics of a species
and its habitat that allow it to recover from periodic disturbance.
Redundancy (having multiple populations distributed across the
landscape) may be needed to provide a margin of safety for the species
to withstand catastrophic events. Representation (the range of
variation found in a species) ensures that the species' adaptive
capabilities are conserved. Redundancy, resiliency, and representation
are not independent of each other, and some characteristic of a species
or area may contribute to all three. For example, distribution across a
wide variety of habitat types is an indicator of representation, but it
may also indicate a broad geographic distribution contributing to
redundancy (decreasing the chance that any one event affects the entire
species), and the likelihood that some habitat types are less
susceptible to certain threats, contributing to resiliency (the ability
of the species to recover from disturbance). None of these concepts is
intended to be mutually exclusive, and a portion of a species' range
may be determined to be ``significant'' due to its contributions under
any one or more of these concepts.
For the purposes of this finding, we determine if a portion's
biological contribution is so important that the portion qualifies as
``significant'' by asking whether without that portion, the
representation, redundancy, or resiliency of the species would be so
impaired that the species would have an increased vulnerability to
threats to the point that the overall species would be in danger of
extinction (i.e., would be ``endangered''). Conversely, we would not
consider the portion of the range at issue to be ``significant'' if
there is sufficient resiliency, redundancy, and representation
elsewhere in the species' range that the species would not be in danger
of extinction throughout its range if the population in that portion of
the range in question became extirpated (extinct locally).
We recognize that this definition of ``significant'' (a portion of
the range of a species is ``significant'' if its contribution to the
viability of the species is so important that, without that portion,
the species would be in danger of extinction) establishes a threshold
that is relatively high. On the one hand, given that the consequences
of finding a species to be endangered or threatened in a significant
portion of its range would be listing the species throughout its entire
range, it is important to use a threshold for ``significant'' that is
robust. It would not be meaningful or appropriate to establish a very
low threshold whereby
[[Page 57928]]
a portion of the range can be considered ``significant'' even if only a
negligible increase in extinction risk would result from its loss.
Because nearly any portion of a species' range can be said to
contribute some increment to a species' viability, use of such a low
threshold would require us to impose restrictions and expend
conservation resources disproportionately to conservation benefit:
listing would be rangewide, even if only a portion of the range of
minor conservation importance to the species is imperiled. On the other
hand, it would be inappropriate to establish a threshold for
``significant'' that is too high. This would be the case if the
standard were, for example, that a portion of the range can be
considered ``significant'' only if threats in that portion result in
the entire species being currently endangered or threatened. Such a
high bar would not give the significant portion of its range phrase
independent meaning, as the Ninth Circuit held in Defenders of Wildlife
v. Norton, 258 F.3d 1136 (9th Cir. 2001).
The definition of ``significant'' used in this finding carefully
balances these concerns. By setting a relatively high threshold, we
minimize the degree to which restrictions will be imposed or resources
expended that do not contribute substantially to species conservation.
But we have not set the threshold so high that the phrase ``in a
significant portion of its range'' loses independent meaning.
Specifically, we have not set the threshold as high as it was under the
interpretation presented by the Service in the Defenders litigation.
Under that interpretation, the portion of the range would have to be so
important that current imperilment there would mean that the species
would be currently imperiled everywhere. Under the definition of
``significant'' used in this finding, the portion of the range need not
rise to such an exceptionally high level of biological significance.
(We recognize that if the species is imperiled in a portion that rises
to that level of biological significance, then we should conclude that
the species is in fact imperiled throughout all of its range, and that
we would not need to rely on the significant portion of its range
language for such a listing.) Rather, under this interpretation we ask
whether the species would be endangered everywhere without that
portion, i.e., if that portion were completely extirpated. In other
words, the portion of the range need not be so important that even the
species being in danger of extinction in that portion would be
sufficient to cause the species in the remainder of the range to be
endangered; rather, the complete extirpation (in a hypothetical future)
of the species in that portion would be required to cause the species
in the remainder of the range to be endangered.
The range of a species can theoretically be divided into portions
in an infinite number of ways. However, there is no purpose to
analyzing portions of the range that have no reasonable potential to be
significant or to analyzing portions of the range in which there is no
reasonable potential for the species to be endangered or threatened. To
identify only those portions that warrant further consideration, we
determine whether there is substantial information indicating that: (1)
The portions may be ``significant,'' and (2) the species may be in
danger of extinction there or likely to become so within the
foreseeable future. Depending on the biology of the species, its range,
and the threats it faces, it might be more efficient for us to address
the significance question first or the status question first. Thus, if
we determine that a portion of the range is not ``significant,'' we do
not need to determine whether the species is endangered or threatened
there; if we determine that the species is not endangered or threatened
in a portion of its range, we do not need to determine if that portion
is ``significant.'' In practice, a key part of the determination that a
species is in danger of extinction in a significant portion of its
range is whether the threats are geographically concentrated in some
way. If the threats to the species are essentially uniform throughout
its range, no portion is likely to warrant further consideration.
Moreover, if any concentration of threats to the species occurs only in
portions of the species' range that clearly would not meet the
biologically based definition of ``significant,'' such portions will
not warrant further consideration.
Evaluation of the Status of Each of the Six Mollusk Species That Are
Listable Entities
For each of the six listable aquatic mollusk species considered, we
provide a description of the species and its life history and habitat,
an evaluation of listing factors, and our finding as to whether the
petitioned action is warranted throughout its range. We then address
whether the species may be considered endangered or threatened in any
significant portion of its range.
Canary Duskysnail (Colligyrus convexus)
Species Information for the Canary Duskysnail
Taxonomy and Species Description
The canary duskysnail was formally named and described in 2003
(Hershler et al. 2003, p. 278). Prior to that it was referred to as
``Lyogyrus n. sp. 3'' (Frest and Johannes 1999, pp. 77-78; Hershler et
al. 2003, p. 278; USDA and USDI 2007, pp. 93, 169), and also as
``Lyogyrus n. sp. 1'' (Frest and Johannes 1995b, p. 50). Although the
canary duskysnail was considered to be in the Hydrobiidae family by
earlier authors (Frest and Johannes 1995b, p. 50; Frest and Johannes
1999, p. 13), and was referred to as such in the listing petition (CBD
et al. 2008, p. 9), it was placed in the family Amnicolidae when it was
formally described (Hershler et al. 2003, p. 278). It is a small (1.4
to 1.9 millimeters (mm) 0.06 to 0.07 inches (in)), aquatic snail with a
yellowish shell, sometimes with weakly striped markings on the whorls.
It is distinguishable from the other two species in its genus by its
smaller size, the highly convex whorls on the main part of its shell,
and the waviness of the shell near the opening (Hershler et al. 2003,
p. 278).
Distribution
The canary duskysnail is known from a total of 21 sites in Shasta
County, California, including 9 along the lower Pit River (California
Natural Diversity Database (CNDDB) 2012, pp. 1-5; Johannes 2012a, pp.
2-7; Pacific Gas and Electric Company (PGE) 2011, pp. 26, 37; Johannes
2012b, p. 11; PGE 2012, p. 27). Of those 21 sites, 7 are on Federal
land covered by the NWFP, 1 is on an Indian Public Domain Allotment
(PDA), 3 are in State parks, and 10 are on privately owned lands.
Repeat site monitoring at eight of those sites (see Factor A, below)
shows large shifts in population density and in presence or absence of
canary duskysnails at any given site. Site locations fall into three
broad areas: The lower Pit River and nearby Burney Creek (11 sites),
Hat Creek (2 sites), and the upper Fall and Tule River area (8 sites).
Habitat and Biology
The canary duskysnail typically occurs in shallow water on the
undersides of boulders and cobbles in pond springs and wetted areas
near streambeds (the hyporheic zone) (Hershler et al. 2003, pp. 280,
284). It is most likely a grazer on perilithon, the community of small
organisms such as
[[Page 57929]]
algae, protozoa, and bacteria growing underwater on stones (Frest and
Johannes 1995b, p. 81; Furnish and Monthey 1999, Sect. 4, p. 9). It is
most commonly found in areas lacking cover from aquatic plants, often
in association with the Shasta crayfish (Pacifastacus fortis). It is
found in, and is likely dependent on, water that is cold, clear, well-
oxygenated, and unpolluted (Frest and Johannes 1995b, p. 3). It is
often found in spring flows or in spring-influenced streams (Service
1998, p. 20; Frest and Johannes 1999, p. 78). The canary duskysnail is
a short-lived species (1 to occasionally 2 years) that only reproduces
once before dying (Frest and Johannes 1995b, p. 4; Furnish and Monthey
1999, Sect. 4, p. 7). Eggs are likely laid in the spring and hatch in 2
to 4 weeks (Furnish and Monthey 1999, Sect. 4, p. 7).
Five-Factor Evaluation of Threats for the Canary Duskysnail
Factor A. The Present or Threatened Destruction, Modification, or
Curtailment of Its Habitat or Range
Impoundments
Nine of the 21 occupied sites are in or along the lower Pit River
below Lake Britton (PGE 2011, pp. 26, 37; Johannes 2012b, p. 11; PGE
2012 p. 27). PGE maintains three dams in this area: Pit 3, 4, and 5
(PGE 2010, p. 5). Each dam sends water from its associated reservoir
through tunnels to power-generating stations located just above the
reservoirs of the next dam downstream. Flows in the natural river
channel below each dam (referred to as the Pit 3, 4, and 5 reaches)
have in the past consisted primarily of water from springs and minor
tributaries emptying below each dam. In 2007, however, the Pit 3, 4,
and 5 dams were issued a new operating license that required increased
releases of surface water from the reservoirs into their associated
reaches (PGE 2010, p. 2). These releases have the potential to
negatively impact the canary duskysnail because reservoir surface water
tends to be warmer than spring or creek water (Ellis 2012, p. 1).
Because the dams initially lacked the infrastructure to release the
required amounts of instream water, the required amounts were not
achieved until 2011 (PGE 2012, p. 1). In accordance with a facilities
modification plan, interim flow releases of approximately half the
required amounts were authorized for 2008 through 2010 while the flow
release structures of the dams were improved (PGE 2010, pp. 1, 2).
PGE was also required by the relicensing requirements to conduct
mollusk surveys in 2009, in 2011-2015, in 2018, and every 4 years
thereafter until the expiration of the license in 2043 (PGE 2012, p.
1). Following monitoring in 2009, PGE decided to monitor for mollusks
in 2010 as well (PGE 2010, p. 54; PGE 2011, p. 1). Accordingly, we now
have 3 years of survey data (2009-2011) for a total of 12 sites in the
Pit River (four sites downstream of each dam) (PGE 2011, pp. 26, 37;
PGE 2012, p. 27). The surveys found canary duskysnails at 8 of those 12
sites (as well as nugget pebblesnails at all 12 sites, as discussed
below). A ninth site in the Pit River with canary duskysnails (as
mentioned above) was not in a monitored location (Hershler et al. 2003,
p. 280; CNDDB 2012, p. 2; Johannes 2012a, p. 2).
Four of the eight monitored occupied sites are in the Pit 3 reach,
which is the farthest upstream (PGE 2011, pp. 26, 37; PGE 2012, p. 27).
During 2009, that reach also showed the lowest average water discharge
rates, lowest average water temperatures, and produced the highest
average densities of canary duskysnails, thus tending to support the
idea that canary duskysnails benefit from lower discharge rates from
the dams (PGE 2010, p. 35; PGE 2011, pp. 26, 37; PGE 2012, p. 27).
However, as average water discharge rates increased in the Pit 3 reach
from 150 cubic ft per second (cfs) in 2009 to 350 cfs in 2011, and as
average water temperatures increased as well from approximately 60 to
about 63 degrees Fahrenheit ([deg]F) (15.4 to 17.2 degrees Celsius
([deg]C)), canary duskysnail densities rose from 20 to 53 snails per
square meter (16.7 to 44.3 snails per square yard) at one location
(their highest density in the study), and dropped from 50 to 0 snails
per square meter (41.8 to 0 snails per square yard) at another
location. The populations thus showed strong fluctuations, with widely
differing responses to increasing flows. Similarly, in the Pit 5 reach,
37 snails per square meter (30.9 snails per square yard) were found in
2011 (the year of highest flows) at a location that had supported no
snails in the 2 previous years. All other occupied locations had
comparatively low population densities, and only one of those showed a
clear drop in population density over the 3-year monitoring period
(from 4 to 0 snails per square meter (3.3 to 0 snails per square
yard)). Therefore, we conclude there are no clear trends in observed
survey data attributable to changes in flow releases from dams.
The only other occupied site potentially affected by an impoundment
is at Baum Lake (CNDDB 2012, p. 4; Johannes 2012a, pp. 4, 5), a PGE-
owned reservoir on Hat Creek, just north of the town of Cassel (Service
1998, pp. 20, 43). Abundant canary duskysnails were found at the site
in 2001, under cobbles near the outflow of Crystal Lake, a spring-fed
water body that abuts and empties into Baum Lake (CNDDB 2012, p. 4;
Johannes 2012a, pp. 4, 5). Although the best available information does
not indicate the fate of that population, its presence in 2001 and the
abundant number of individual snails found at that time suggest the
impoundment of Baum Lake does not constitute a threat. Three other
occupied sites (identified in the source material as locations 102,
412, and 514) are located on the margins of spring-fed natural lakes in
water bodies draining into the Fall River (Johannes 2012a pp. 3, 6), so
the species is capable of surviving in slow-moving lake waters fed by
nearby springs.
Water Quality
The Pit River is considered a water-quality limited segment for 198
kilometers (km) (123 miles (mi)) upstream of Shasta Lake; including the
locations of all nine canary duskysnail sites known from the Pit River
(State Water Resources Control Board (SWRCB) 2010a, p. 164). Nutrients
from cattle defecation and fertilizers applied in the course of
agriculture enter the Pit River, where they promote algal growth that
decreases oxygen levels and increases water temperature. However, as
discussed above with respect to impoundments, the only population trend
data available for the canary duskysnail does not show clearly
decreasing populations, despite any temperature increases or oxygen
decreases that may be attributable to water quality.
PGE will continue to monitor mollusk populations annually as
discussed above (PGE 2012, p. 1), so if impacts from Pit water quality
or from the releases themselves do develop, they should be detected.
The operating license for the dams includes an adaptive management plan
for responding to negative impacts detected by the monitoring program
(PGE 2008, pp. 3-6). The Service serves on the Technical Review Group
which recommends specific adaptive management responses (PGE 2008, p.
2), and so will remain informed of the effectiveness of those
responses. Seven of the nine occupied locations on the Pit River are on
Federal land (either Shasta-Trinity National Forest or Lassen National
Forest) within the area covered by the NWFP. Activities on those lands
with the potential to affect water quality (or to affect the
populations directly) would have to meet the requirements of the SMP
and the ACS, as discussed
[[Page 57930]]
above. For instance, logging or road construction in the vicinity of
the Pit River or its tributaries (on Federal lands within the NWFP
area) would be subject to buffers for riparian reserves established
under the ACS as well as predisturbance surveys and mitigation as
required by the SMP.
There are no locations occupied by canary duskysnails on the Pit
River upstream of the Pit 3 dam at Lake Britton. However, there are two
locations each on Burney Creek and Hat Creek, which both flow into Lake
Britton. The remaining eight canary duskysnail locations are in the
Fall River drainage, generally at the headwater springs (Service 2012a,
p. 1). Neither Burney Creek nor Hat Creek is considered water-quality
limited (SWRCB 2010a, entire; SWRCB 2010b, entire; SWRCB 2010c,
entire). However, the Fall River is affected by sedimentation extending
far enough upstream to reach the southernmost of the eight sites in the
drainage occupied by canary duskysnails (SWRCB 2010a, p. 148; SWRCB
2011, p. 2). The sedimentation was caused by historical land management
activities, and is not likely to constitute a threat to the other sites
(Fall River Resource Conservation District (FRRCD) 2005, pp. 1-3; SWRCB
2010a, p. 148).
A final area with impaired water quality is Eastman Lake, at the
headwaters of the Little Tule River, a tributary of the Fall River
(SWRCB 2010a, p. 148; SWRCB 2011, p. 1). One canary duskysnail site
(514) is located at the lake, while two others (102, 263) are just
upstream of the inlet (Johannes 2012a, pp. 3, 4, 6). At an average pH
of 8.64, the lake water is slightly more alkaline than the established
water quality objective range of 6.5 to 8.5 (SWRCB 2010d, pp. 6, 7).
The reason for the increased alkalinity is unknown, as is the optimal
pH range for the canary duskysnail. However, acidic waters (pH 5 and
below) can interfere with shell production, so freshwater snails are
generally found in waters that are at least somewhat alkaline (Wyoming
Game and Fish Department (WGFD) 2005, p. 548).
Other Habitat-Related Impacts
Grazing, spring diversions, road construction, and railroad
construction have all been mentioned as possible threats to the canary
duskysnail (Furnish and Monthey 1999, Sect. 4, p. 14; Service 2011, p.
61831). However, since the time of Furnish and Monthey's conclusions in
1999, the number of known locations has increased from 2 to 21, 10 of
which are on protected State or Federal lands (Furnish and Monthey
1999, Sect. 4, pp. 10, 11; Johannes 2012a, pp. 2-7; Johannes 2012b, p.
11; PGE 2011, pp. 26, 37; PGE 2012 p. 27). The SMP (discussed above)
has also been reinstated on Federal lands subject to the NWFP. Various
habitat improvement measures have been carried out in the upper Fall
River drainage, where the majority of occupied sites on private land
are located (FRRCD 2005, pp. 1-3). Habitat improvements include
exclusion fencing to keep cattle from streambanks, bank stabilization
projects, and the replacement and upgrade of a railroad crossing that
had collapsed twice in the past (producing extensive siltation on those
occasions) (FRRCD 2005, p. 2; Ellis and Haley 2012, p. 1). Landowners
also took steps to reduce the potential for serious wildfires and to
prevent erosion of sediment from a nearby meadow (FRRCD 2005, p. 3). In
Hat Creek, grazing has been eliminated in the general vicinity of the
PGE dams since 2001 (Stewardship Council 2007, Vol. 2, p. PM-31).
Grazing has also been eliminated from lands surrounding the two
privately owned sites occupied by canary duskysnails in the lower Pit
River. Forestry has been eliminated in areas near those sites conducted
in accordance with a conservation plan developed and implemented by a
nonprofit land-management corporation (see Grazing and Logging under
Nugget Pebblesnail, below) (Stewardship Council, Vol. 2, pp. PM 38, 40,
41, 48, 50).
The Shasta crayfish is a federally endangered species that shares
essentially the same native range and habitat requirements as the
canary duskysnail (Service 2009, pp. 4-6). The two species often co-
occur at the same locations (Hershler et al. 2003, p. 280). When we
listed the Shasta crayfish in 1988, we identified grazing, pollution,
and water use for residential development as threats to the species
(Service 1988, p. 38463). In our 2009 review of the species' status,
however, we determined those practices no longer constitute significant
impacts to the species (Service 2009, p. 9).
Summary of Factor A
In summary, no clear population trends in response to habitat
modifications are evident at any of the sites occupied by canary
duskysnails, including the eight sites monitored by PGE. The release of
additional Pit River waters from the dams under PGE's new licensing
agreements does not appear to have resulted in adverse effects on
downstream canary duskysnail populations. We also know of no occupied
sites that have been permanently lost due to habitat modifications,
although population fluctuations at some of the monitored sites
included densities of zero during some years. No cause of the
fluctuations at the monitored sites was evident. We therefore conclude,
based on the best available scientific and commercial data, that the
present or threatened destruction, modification or curtailment of its
habitat or range does not constitute a significant threat to the
species now or in the future.
Factor B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
Our review of the best available scientific and commercial
information yielded nothing to indicate that overutilization for
commercial, recreational, scientific, or educational purposes is
occurring at this time or is likely to occur in the future. We
therefore conclude such overutilization does not constitute a threat to
the canary duskysnail.
Factor C. Disease or Predation
Disease
We reviewed the best available scientific and commercial
information regarding this species and other similar species, and found
no evidence to indicate that disease is impacting canary duskysnail
populations.
Predation
There is the potential for increased predation on canary
duskysnails due to the introduction of the signal crayfish
(Pacifastacus leniusculus) into the mid-Pit River drainage in the late
1970s, and its subsequent expansion throughout the area during the
1990s and early 2000s (Ellis 1999, pp. 12, 57, 58; Service 2009, p.
10). The signal crayfish, which is native to Oregon, Washington, and
more coastal portions of northwest California, is a faster growing,
faster reproducing relative of the Shasta crayfish, with a greater
tolerance for warmer water (Ellis 1999, pp. 2, 9, 12, 13; Service 2009,
p. 9; PGE 2011c, p. 25). The signal crayfish now occurs in all the
general locations occupied by the canary duskysnail (Service 2009, pp.
5, 10; PGE 2011b, pp. 4, 10, 23) and is a generalist feeder with a diet
that very likely includes aquatic snails (Lorman and Magnuson 1978, p.
9; Ellis 1999, pp. 55, 56).
Experiments conducted with another species of crayfish in Wisconsin
indicate that dense crayfish populations can significantly impact prey
populations, including aquatic snails (Lorman and Magnuson 1978, p. 9).
However, the best available scientific and commercial information does
not
[[Page 57931]]
indicate how dense crayfish populations must generally be in order to
impact populations of aquatic snails. The best available scientific and
commercial information does not provide data on population density
trends for crayfish and aquatic snails at the same locations. Although
PGE conducted both crayfish and mollusk surveys at various locations in
the Pit 4 reach, the surveyed sites did not overlap (PGE 2010, p. 7,
PGE 2011b, p. 4). Crayfish were surveyed at foothill yellow-legged frog
breeding sites, and one such site (Canyon Creek 45.8) appears to
overlap a surveyed mollusk site referred to as Malinda Ridge by mollusk
surveyors. However, Canyon Creek 45.8 was one of the frog breeding
sites at which conditions did not allow crayfish surveys (due to risk
of injuring frog eggs) (PGE 2011b, pp. 10, 21-23).
We do know that average densities of signal crayfish remained at 3
per square meter in the Pit 4 reach from 2008 through 2011 (PGE 2011b,
p. 10, PGE 2012b, p. 9), despite increasingly large releases of warmer
surface water from reservoirs during those years (PGE 2010, p. 35; PGE
2011, p. 24; PGE 2011b, p. iii; PGE 2012, p. 24) that might be expected
to have benefitted signal crayfish (Service 2009, p. 9). Although
average densities remained steady during the monitoring period, maximum
densities of signal crayfish decreased from 14 to 7 per square meter
(PGE 2011b. p. 10; PGE 2012b, p. 9). The sampled averages of 3 per
square meter are very close to the average densities of 2.85 crayfish
per square meter estimated for the native Shasta crayfish at Lava Creek
(upper Fall River drainage) in 1990 (Ellis 1999, p. 58), and therefore
suggest that they are close to the native crayfish densities with which
the canary duskysnail evolved. The crayfish density surveys at Pit 4
reach also provide some evidence to suggest that signal crayfish
densities are remaining stable in that area, despite warmer water
temperatures from increased flows of reservoir surface water.
The evidence also does not support the possibility that, in areas
occupied by canary duskysnails, populations of signal and Shasta
crayfish might overlap to produce unusually high combined crayfish
densities. The known range of the Shasta crayfish does not extend into
Burney Creek or the lower Pit River (below Lake Britton) (Service 2009,
pp. 3-5), so the 11 canary duskysnail sites in those areas are only
subject to potential impacts from signal crayfish. Two general areas
that support canary duskysnails are known to support both species of
crayfish: The upper Fall River drainage and the area around Baum Lake
on Hat Creek (Service 2009, p. 9; Johannes 2012a, pp. 2-7). Monitoring
has shown that the occupied locations within these general areas may
support relatively high numbers of Shasta crayfish, or of signal
crayfish, but not of both (Service 2009, p. 9). As signal crayfish
numbers increase at a given location, the numbers of Shasta crayfish
drop dramatically (Ellis 1999, pp. 57, 58).
Hence, the available evidence does not support the contention that
signal crayfish are present in the range of the canary duskysnail in
sufficiently high densities to pose a predation risk to the canary
duskysnail, either by themselves or in combination with the native
Shasta crayfish. Furthermore, the information does not indicate any
trend in the densities of the two crayfish that would lead us to a
conclusion that the predation risk would increase in the future.
We therefore conclude, based on the best available scientific and
commercial information, that neither disease nor predation constitutes
a significant threat to the species now or in the future.
Factor D. The Inadequacy of Existing Regulatory Mechanisms
Under this factor, we examine whether existing regulatory
mechanisms are inadequate to address the threats to the species
discussed under the other factors. Section 4(b)(1)(A) of the Act
requires the Service to take into account ``those efforts, if any,
being made by any State or foreign nation, or any political subdivision
of a State or foreign nation, to protect such species * * *''. We
interpret this language to require the Service to consider relevant
Federal, State, and Tribal laws and regulations when developing our
threat analyses. Regulatory mechanisms, if they exist, may preclude the
need for listing if we determine that such mechanisms adequately
address the threats to the species such that listing is not warranted.
The analysis of threats to the canary duskysnail under the other
factors included consideration of the ameliorative effects of
regulatory mechanisms where applicable, such as those discussed under
Factor A and under Generally Applicable Federal Regulatory Mechanisms,
above.
Having evaluated the significance of the threat as mitigated by any
such conservation efforts, we analyze under Factor D the extent to
which existing regulatory mechanisms are inadequate to address the
specific threats to the species. We found no significant threats to the
canary duskysnail under the other factors, therefore, the analysis of
any existing regulatory mechanisms' adequacy to address threats is not
applicable. Consequently, after reviewing the best available commercial
and scientific information, we conclude that the inadequacy of existing
regulatory mechanisms is not a threat to the canary duskysnail now or
in the future.
Factor E. Other Natural or Manmade Factors Affecting Its Continued
Existence
Competition With Invasive Species
New Zealand mudsnails (Potamopyrgus antipodarum) are 4 to 6 mm
(0.12 to 0.24 in) aquatic snails that are extremely prolific and can
reach densities of hundreds of thousands per square meter in waters
outside their native New Zealand (National Biological Information
Infrastructure (NBII) 2011, pp. 1, 2). They are carried to new areas on
boots, fishing equipment, boats, or in the digestive systems of birds
and fish, and are capable of colonizing locations with a wide variety
of substrates, temperatures, and currents (NBII 2011, pp. 1-3). In the
western United States, New Zealand mudsnail populations typically
consist almost entirely of parthenogenic (asexually reproducing)
females born with embryos already developing in their reproductive
systems (NBII 2011, p. 4; Crosier and Molloy, undated, p. 1).
New Zealand mudsnails typically eat detritus (decaying organic
matter), diatoms (a type of plankton), and periphyton (essentially the
same as perilithon except on underwater surfaces of vascular plants
rather than rock surfaces) (Frest and Johannes 1995b, p. 81; NBII 2011,
p. 4). Although they reach their highest numbers in areas with numerous
vascular water plants, they can also dominate areas that lack such
plants (Hall et al. 2006, pp. 1122, 1126), indicating they eat
perilithon as necessary. As discussed above, perilithon is likely the
primary food source of the canary duskysnail (Furnish and Monthey 1999,
Sect. 4, p. 9). One study found that New Zealand mudsnails reached
higher numbers in areas with stable hydrological flows and relatively
warm water temperatures (averaging 18 [deg]C (64.4[emsp14][deg]F) as
compared to an average 6 [deg]C (42.8[emsp14][deg]F) in their native
New Zealand) (Hall et al. 2006, p. 1128). As discussed below under
Changes in Precipitation and Water Availability Due to Climate Change,
the springs with which canary duskysnails are associated tend to be
highly stable in flow (Service 1998, p. 46). Average summer water
temperatures for 2009 through 2011 measured in the lower Pit River near
sites occupied by canary
[[Page 57932]]
duskysnails ranged from 17.1 to 19.9 [deg]C (62.8 to
67.8[emsp14][deg]F) (PGE 2012, p. 24). Sites supporting canary
duskysnails are thus not ideal for New Zealand mudsnails due to the
lack of vascular plants, but they do provide favorable flow and
temperature characteristics that could facilitate the growth and
competitive ability of any New Zealand mudsnail populations that became
established at those sites.
Because of their high reproductive rate, wide habitat tolerance,
and few effective parasites or predators outside of their native
waters, New Zealand mudsnails are capable of outcompeting most native
aquatic snails for food and space (NBII 2011, pp. 1, 2). They are
extremely difficult to eradicate once established (NBII 2011, pp. 3,
4).
In 2007, New Zealand mudsnails became established at the Bridge Bay
Marina on Shasta Lake near Interstate 5 (United States Geological
Survey (USGS) 2009a, pp. 1, 2; USGS 2009b, p. 1; McAlexander 2012a, p.
1). The aerial distance between that location and the nearest known
site occupied by the canary duskysnail is about 48 km (30 mi). If the
New Zealand mudsnail were to colonize multiple areas occupied by the
canary duskysnail, it could become a serious threat to the species.
However, the likelihood that such a scenario will occur is very
uncertain. In 2011, six additional New Zealand mudsnail locations were
found in the north-central California area, but population levels were
low and all sites were on the Sacramento River (USGS 2009b, p. 1; USGS
2011, p. 40; McAlexander 2012a, p. 1). Five of those sites are
downstream of the Bridge Bay Marina, while one is upstream at Castle
Lake (USGS 2009b, p. 1; McAlexander 2012b, p. 1). No populations have
so far been found in any tributary rivers or streams, such as the Pit
River. The California Department of Fish and Game (CDFG) is following a
national management and control plan (Aquatic Nuisance Species Task
Force (ANSTF) 2007, entire) and has posted information and brochures
about the New Zealand mudsnail on its Web site, including printable
posters and wallet cards (CDFG undated, p. 1).
Although there is no recognized method for assessing the risk of
New Zealand mudsnail establishment in a given area at a given time
(ANSTF 2007, p. 17), we consider Lake Britton to be the location within
the range of the canary duskysnail currently at greatest danger of
infestation. Lake Britton supports a marina, boat launch, and fishery,
borders a state park, and is easily accessed from State Highway 89
(Stewardship Council, Vol. 2, pp. PM-37-39). In contrast, vehicle
access to the Pit 4 reservoir is more difficult, and boating is not
currently allowed (Stewardship Council, Vol. 2. pp. PM-48, PM-49).
Thus, if a boat inadvertently carrying New Zealand mudsnails were to be
towed from the Bridge Bay Marina to some body of water in the range of
the canary duskysnail, the most likely such location would be Lake
Britton. However, virtually the entire extent of the canary
duskysnail's range supports fisheries (Stewardship Council, Vol. 2. pp.
PM-21, PM-31, PM-49), so it would be possible for New Zealand mudsnails
to be carried on fishing waders from an infested fishing spot
(presumably farther downstream on the Sacramento River, rather than at
the Bridge Bay Marina itself) to almost anywhere in the range (NBII
2011, p. 3; Emery 2012, p. 1).
Once established at one location within the range of the canary
duskysnail, the likelihood of infestation at other such locations would
increase. However, to compete directly with canary duskysnails, the New
Zealand mudsnail would have to establish itself at the canary
duskysnail's occupied locations. The New Zealand mudsnail tends to have
a spotty distribution, apparently governed to a large extent by where
colonizing individuals are deposited by various vectors (USGS 2009b, p.
1; Emery 2012, p. 1). For the New Zealand mudsnail to be a threat to
the canary duskysnail, first it would have to colonize somewhere within
the range (probably Lake Britton), then it would have to establish so
many additional colonies that a large percentage of canary duskysnail
sites were overlapped. Then, it would have to outcompete the canary
duskysnails at those sites and the canary duskysnails would have to be
unable to establish themselves at different sites. All these stages are
likely to require several years, if they happen at all. Currently the
available information indicates there is no infestation at Lake Britton
or at any locations occupied by the canary duskysnail. Accordingly, we
do not consider competition from New Zealand mudsnails to be a threat
to the canary duskysnail at this time.
Fire
A large high-severity fire could potentially impact canary
duskysnails by removing ground cover (Robichaud undated, pp. 2, 4),
thereby allowing silt to wash into occupied springs and streams. Silt
can degrade water quality, cover the perilithon on which canary
duskysnails feed, and could also smother canary duskysnail eggs
(Furnish and Monthey 1999, Sect. 4, pp. 9, 14; Robichaud undated, p.
3). For the nine occupied sites in the Pit River below Lake Britton,
siltation would be expected to collect in the Pit 3, 4, and 5
reservoirs, and to wash out of the river portions below each dam fairly
quickly due to required flow releases established by the dam operating
requirements (see Impoundments, above). The remaining 12 sites are
spread out over 3 major areas, with 8 sites in the upper Fall River
watershed, and 2 each in Burney Creek (in McArthur-Burney Falls State
Park), and Hat Creek (near Cassel, CA). The closest distances between
these locations range from 12 km (7.5 mi) (Burney Creek to Hat Creek)
to 20 km (12.4 mi) (upper Fall River to Hat Creek). A fire would have
to be extremely large and precisely positioned to encompass two such
areas. Additionally, the occupied sites along the lower Pit River and
in upper Fall River watershed are likely to benefit from fire
prevention and fuel reduction activities conducted by the Shasta-
Trinity National Forest (USDA 2012a, pp. 1-15, 17-19), the Lassen
National Forest (USDA 2012b, pp. 1, 3-7, 9-12), and by landowners in
the upper Fall River watershed (FRRCD 2005, p. 3).
Changes in Precipitation and Water Availability Due to Climate Change
Our analyses under the Endangered Species Act include consideration
of ongoing and projected changes in climate. The terms ``climate'' and
``climate change'' are defined by the Intergovernmental Panel on
Climate Change (IPCC). ``Climate'' refers to the mean and variability
of different types of weather conditions over time, with 30 years being
a typical period for such measurements, although shorter or longer
periods also may be used (IPCC 2007, p. 78). The term ``climate
change'' thus refers to a change in the mean or variability of one or
more measures of climate (e.g., temperature or precipitation) that
persists for an extended period, typically decades or longer, whether
the change is due to natural variability, human activity, or both (IPCC
2007, p. 78). Various types of changes in climate can have direct or
indirect effects on species. These effects may be positive, neutral, or
negative and they may change over time, depending on the species and
other relevant considerations, such as the effects of interactions of
climate with other variables (for example, habitat fragmentation) (IPCC
2007, pp. 8-14, 18-19). In our analyses, we use our expert judgment to
weigh relevant information, including uncertainty, in our consideration
of various aspects of climate change.
[[Page 57933]]
Climate change is not expected to significantly change total
precipitation in northern California, but may affect seasonal water
availability in some areas due to changes in snowpack melting times and
the proportion of precipitation falling as rain rather than snow
(Dettinger et al. 2004, pp. 43, 44). However, the water supplying
springs occupied by the canary duskysnail in the middle Pit River
drainage (including the upper Fall River area) and in Hat Creek are
collected from wide areas in the Medicine Lake highlands and Lassen
volcanic highlands, respectively (Service 1998, p. 18). Rain and
snowmelt in those areas percolate through porous volcanic rocks to
collect in large aquifers, thereby holding extra water from seasons
when rain is plentiful and delivering it through springs during seasons
when rain is not plentiful. Resulting spring flows are highly stable in
volume, temperature, and clarity (Service 1998, p. 46). Accordingly, we
do not expect changes in precipitation or water availability due to
climate change to significantly affect the species.
Summary of Factor E
In summary, the canary duskysnail is protected from expected
changes in precipitation or water availability due to climate change by
the particular characteristics of its habitat. Although potential
competition from the New Zealand mudsnail is cause for concern, no site
currently occupied by canary duskysnail has been colonized and there is
nothing to indicate the New Zealand mudsnail will colonize any of the
multiple locations occupied by the canary duskysnail. There is also no
direct evidence to show that any such occupied locations would be
extirpated by such a colonization were it to occur. The two species are
not known to have interacted in the past. We therefore conclude that,
based on the best available scientific and commercial information, that
other natural or manmade factors such as competition from the New
Zealand mudsnail, changes in precipitation or water availability due to
climate change, or fire do not constitute significant threats to the
canary duskysnail now or in the future.
Finding for the Canary Duskysnail
We have carefully assessed the best scientific and commercial
information available regarding the past, present, and future threats
faced by the canary duskysnail. We reviewed the petition, available
published and unpublished scientific and commercial information, and
information submitted to us during our status review. This finding
reflects and incorporates that information. We also consulted with
recognized authorities on this species, and we consulted with Federal
and State resource agencies. Although only 21 occupied sites are known
for the canary duskysnail, the best available scientific and commercial
information does not clearly indicate that populations at any site are
in decline, or that any sites are likely to be lost due to
impoundments, water quality, other habitat-related impacts,
overutilization, disease or predation, the inadequacy of existing
regulatory mechanisms, competition with invasive species, or fire, now
or in the foreseeable future. The best available scientific and
commercial information at this time does not indicate that there is
likely to be a change in any of these stressors in the future. Three
years of data from an ongoing monitoring study found extreme
fluctuations in population density numbers at certain sites, but did
not indicate the fluctuations were in response to threats, or likely to
lead to permanent local extirpation. New Zealand mudsnails could be a
threat to canary duskysnails if they become established in their range,
but we have no information to indicate whether that will happen in the
foreseeable future or the extent of New Zealand mudsnail impact if they
do become established in the range of the canary duskysnail.
Based on our review of the best available scientific and commercial
information pertaining to the five factors, we find that the threats as
described above, either alone or in combination are not of sufficient
imminence, intensity, or magnitude to indicate that the canary
duskysnail is in danger of extinction (endangered) or likely to become
endangered within the foreseeable future (threatened), throughout all
of its range.
Significant Portion of the Range
Having determined that the canary duskysnail is not endangered or
threatened throughout all of its range, we must next consider whether
there are any significant portions of the range where the canary
duskysnail is in danger of extinction or is likely to become endangered
in the foreseeable future. See Significant Portion of the Range under
Summary of Procedures for Determining the Listing Status of Species.
We evaluated the current range of the canary duskysnail to
determine if there is any apparent geographic concentration of
potential threats for the species. The canary duskysnail is highly
restricted in its range and the threats occur throughout its range. We
considered the potential threats due to impoundments, water quality,
other habitat-related impacts, overutilization, disease or predation,
the inadequacy of existing regulatory mechanisms, competition with
invasive species, and fire. We found no concentration of threats that
suggests that the canary duskysnail may be in danger of extinction in a
portion of its range. We found no portions of its range where potential
threats are significantly concentrated or substantially greater than in
other portions of its range. Therefore, we find that factors affecting
the species are essentially uniform throughout its range, indicating no
portion of the range of the species warrants further consideration of
possible endangered or threatened status under the Act.
We find that the canary duskysnail is not in danger of extinction
now, nor is likely to become endangered within the foreseeable future,
throughout all or a significant portion of its range. Therefore,
listing the canary duskysnail as endangered or threatened under the Act
is not warranted at this time.
Goose Valley Pebblesnail (Fluminicola anserinus)
Species Information for the Goose Valley Pebblesnail
Taxonomy and Species Description
The Goose Valley pebblesnail was formally named and described in
2007 (Hershler et al. 2007, p. 409). Prior to 2007, it was referred to
as the globular pebblesnail, ``Fluminicola n. sp. 18'' (Frest and
Johannes 1993, p. 52; Frest and Johannes 1999, pp. 51-52; Furnish and
Monthey 1999, Sect. 2, p. 6; CBD et al. 2008, p. 49). It was assigned a
different provisional scientific name (``Fluminicola n. sp. 6'') by
Frest and Johannes (1995b, p. 44), although it remained the ``globular
pebblesnail'' as referred to in that source. Although pebblesnails in
general (Fluminicola genus) had previously been considered part of the
Hydrobiidae family (Hershler et al. 2003, p. 275), they have since been
reassigned to the Lithoglyphidae family (Hershler et al. 2007, p. 371).
The Goose Valley pebblesnail is a small aquatic snail, roughly 2 to
3.5 mm (0.08 to 0.14 in) tall, with about 3.25 to 3.75 major whorls
(Hershler et al. 2007, pp. 372, 410-412). Its head is dark brown, while
the periostracum (outer layer) is tan or light green. It is similar in
appearance to the Potem Creek pebblesnail (described below), but has a
larger shell aperture with a more reinforced periphery (among other
[[Page 57934]]
differences) (Furnish et al. 1997, p. 48; Hershler et al. 2007, pp.
409, 410).
Distribution
The Goose Valley pebblesnail is known from a total of 13 locations,
2 in the upper Sacramento River drainage in Siskiyou County, California
(Frest and Johannes 1995b, pp. T12, A6, B24), and 11 (after accounting
for overlap from different sources) in the lower Pit River drainage,
Shasta County, California (Frest and Johannes 1995b, pp. T13, A7;
Hershler et al. 2007, pp. 376, 409, 410; Haley 2012a, p. 3). Further
review has indicated that the Siskiyou County sites must be considered
unconfirmed (Johannes 2012c, pp. 1-4).
The type locality for the Goose Valley pebblesnail is a spring on
the west side of Goose Valley, about 10 km (6.3 mi) east of the
crossing of Highways 89 and 299, and about 6.5 km (4 mi) from the Pit
River (Hershler et al. 2007, p. 409). All other occupied sites in the
drainage are in the valley formed by the Pit River itself. Nine sites
are in springs along the Pit 4 reach (below Pit 4 dam) on Shasta-
Trinity National Forest land in the NWFP area (Hershler et al. 2007,
pp. 376, 409, 410; Haley 2012a, p. 3). The 11th site is upstream, in a
spring on private land near Lake Britton (Hershler et al. 2007, pp.
376, 409, 410). The unconfirmed sites in the upper Sacramento River
drainage are located in springs somewhat east of the river and north of
Mossbrae Falls Frest and Johannes 1995b, pp. T12, A6, B24). Those sites
also support Shasta pebblesnails (discussed below).
Habitat and Biology
The Goose Valley pebblesnail occurs in springs and spring-fed
habitats, generally on the sides and undersides of stones in shaded
areas with few water plants (Frest and Johannes 1999, p. 52; Spring
Rivers 2001, p. 22). It is likely to be a perilithon grazer (Furnish et
al. 1997, p. 31; Frest and Johannes 1999, p. 52). We have no specific
information regarding the reproduction of this species, but members of
the Fluminicola genus typically live a single year and breed only once
(Furnish and Monthey 1999, Sect. 2, p. 5; ORNHIC 2004, p. 2). They
generally lay eggs in the spring, which hatch in 2 to 4 weeks. They are
not known to disperse widely, and are highly sensitive to water
pollution, decreases in dissolved oxygen, elevated temperatures, and
sedimentation (Furnish and Monthey 1999, Sect. 2, pp. 5, 7; Hershler et
al. 2007, p. 372).
Five-Factor Evaluation of Threats to the Goose Valley Pebblesnail
Factor A. The Present or Threatened Destruction, Modification, or
Curtailment of Its Habitat or Range
Impoundments
Although 9 of the 11 known occupied sites are downstream of the Pit
4 dam, the sites consist of springs or spring-fed creeks near the Pit
River and thus physically removed from any warmer high-water flows
released by the dams (Hershler et al. 2007, pp. 376, 409, 410; Haley
2012a, p. 3). A tenth occupied site is near Lake Britton, at 878 m
(2,880 ft) elevation (Hershler et al. 2007, p. 409). The lake surface
is lower than 841 m (2,759 ft) when full, and we are not aware of any
plans to raise the level of the lake. The final occupied location, at
Goose Valley, is not influenced by dams. Therefore, we conclude the
habitat of the Goose Valley pebblesnail is not currently at risk of
modification due to impoundments nor do we expect it to be so in the
future.
Agriculture
The type locality is a spring on the edge of Goose Valley, the
floor of which is completely converted to agriculture. The site is
within 50 m (164 ft) of converted land, but it is separated by Goose
Valley Road, and is on sloped and forested terrain. The limits of the
converted land have not changed since at least 2001, and the occupied
site is on land zoned as unclassified, whereas the valley floor is
zoned as exclusive agriculture and agricultural preserve (Shasta County
2003, p. 1; Shasta County 2012, p. 1). The best available scientific
and commercial information does not indicate that the quality of the
site has been damaged by its proximity to converted agricultural lands
over the past decade, nor is there any indication that the location of
the spring itself is likely to be converted to agriculture. None of the
other occupied locations are near agricultural lands.
Diversions and Grazing
In our 90-day finding, we indicated that diversions of spring water
for agricultural and other uses, and grazing in and around occupied
locations, were potential threats. However, these conclusions were
largely based on generalized information for the mid and lower Pit
River area (Hershler et al. 2003, p. 277) and the upper Sacramento
River (ORNHIC 2004e, p. 2), where we now know no occupied locations
exist (see Distribution, above). Nine of the 11 known sites in the Pit
River drainage are within the NWFP area on the Shasta-Trinity National
Forest and, as such, are protected by the SMP and ACS (see Generally
Applicable Federal Regulatory Mechanisms, above). Proposed diversions
or grazing practices at those locations would have to take into account
the buffer requirements established by the ACS riparian reserves, as
well as the survey and mitigation requirements of the SMP. We are not
aware of evidence suggesting any such practices are occurring on
Shasta-Trinity National Forest land.
In summary, although the type locality is close to agricultural
land, most occupied locations are near flows influenced by dams, and
diversions and grazing occur within the larger geographic area occupied
by the species, a review of the best available scientific and
commercial information does not indicate that any of these factors are
negatively impacting any populations of Goose Valley pebblesnails. We
therefore conclude that the present or threatened destruction,
modification or curtailment of its habitat or range does not constitute
a significant threat to the species now or in the future.
Factor B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
Our review of the best available scientific and commercial
information yielded nothing to indicate that overutilization for
commercial, recreational, scientific, or educational purposes is
occurring at this time or is likely to occur in the future. We
therefore conclude such overutilization does not constitute a threat to
the Goose Valley pebblesnail.
Factor C. Disease or Predation
Disease
We reviewed the best available scientific and commercial
information regarding this species and other similar species, and found
no evidence to indicate that disease is impacting Goose Valley
pebblesnail populations.
Predation
There is a potential for increased predation on Goose Valley
pebblesnails due to the establishment of the signal crayfish in the mid
and lower Pit River drainage (Ellis 1999, pp. 12, 57, 58; Service 2009,
p. 10). As discussed above with regard to the canary duskysnail, signal
crayfish predation can significantly impact mollusk populations when
the crayfish are at high densities (Lorman and Magnuson 1978, p. 9).
The known Goose Valley pebblesnail sites do not overlap the current
range of the Shasta crayfish, so only the signal crayfish poses a
potential predation impact. The only
[[Page 57935]]
information we have regarding crayfish densities applies to the Pit 4
reach and does not indicate that crayfish densities at that location
are either particularly high (as compared to populations of native
crayfish at other locations) or increasing (Ellis 1999, p. 58; PGE
2011b, pp. iii, 10; PGE 2012b, p. 9). Hence, the available evidence
does not support the contention that signal crayfish are present in the
range of the Goose Valley pebblesnail in sufficiently high densities to
pose a predation risk to the Goose Valley pebblesnail. Furthermore, the
information does not indicate any trend in the densities of the signal
crayfish that would lead us to a conclusion that the predation risk
would increase in the future.
We therefore conclude, based on the best available scientific and
commercial information, that neither disease nor predation constitutes
a significant threat to the species now or in the future.
Factor D. The Inadequacy of Existing Regulatory Mechanisms
Under this factor, we examine whether existing regulatory
mechanisms are inadequate to address the threats to the species
discussed under the other factors. Section 4(b)(1)(A) of the Act
requires the Service to take into account ``those efforts, if any,
being made by any State or foreign nation, or any political subdivision
of a State or foreign nation, to protect such species * * *''. We
interpret this language to require the Service to consider relevant
Federal, State, and Tribal laws and regulations when developing our
threat analyses. Regulatory mechanisms, if they exist, may preclude the
need for listing if we determine that such mechanisms adequately
address the threats to the species such that listing is not warranted.
The analysis of threats to the Goose Valley pebblesnail under the other
factors included consideration of the ameliorative effects of
regulatory mechanisms where applicable, such as those discussed under
Factor A and under Generally Applicable Federal Regulatory Mechanisms,
above.
Having evaluated the significance of the threat as mitigated by any
such conservation efforts, we analyze under Factor D the extent to
which existing regulatory mechanisms are inadequate to address the
specific threats to the species. We found no significant threats to the
Goose Valley pebblesnail under the other factors, therefore, the
analysis of any existing regulatory mechanisms' adequacy to address
threats is not applicable. Consequently, after reviewing the best
available commercial and scientific information, we conclude that the
inadequacy of existing regulatory mechanisms is not a threat to the
Goose Valley pebblesnail now or in the future.
Factor E. Other Natural or Manmade Factors Affecting Its Continued
Existence
Competition With Invasive Species
An invasion by the New Zealand mudsnail into the lower Pit River
drainage could constitute a serious threat to the Goose Valley
pebblesnail due to competition for food and space (see canary
duskysnail, above). However, we found no information to indicate New
Zealand mudsnails are currently in the lower Pit River, nor did we find
specific information to indicate the likelihood of an invasion by New
Zealand mudsnails in the near future. Additionally, the occupied spring
at Goose Valley would be less likely to be colonized by the New Zealand
mudsnail because it drains into Goose Valley, where it is used for
agriculture, rather than into the Pit River, which is visited by
boaters and fishermen who may inadvertently transport the mudsnail from
previously visited sites.
Changes in Precipitation and Water Availability Due to Climate Change
See our discussion of climate change in general in the Changes in
Precipitation and Water Availability Due to Climate Change section
under ``Factor A'' in Five-Factor Evaluation of Threats for the Canary
Duskysnail. Climate change is not expected to significantly change
total precipitation in northern California, but may affect seasonal
water availability in some areas due to changes in snowpack melting
times and the proportion of precipitation falling as rain rather than
snow (Dettinger et al. 2004, pp. 43, 44). However, the water supplying
springs occupied by the Goose Valley pebblesnail in the middle Pit
River drainage is collected from wide areas in the Medicine Lake
highlands (Service 1998, p. 18). Rain and snowmelt in those areas
percolate through porous volcanic rocks to collect in large aquifers,
thereby holding extra water from seasons when rain is plentiful and
delivering it through springs during seasons when it is not. Resulting
spring flows are highly stable in volume, temperature, and clarity
(Service 1998, p. 46). Similarly, the size of the aquifer that supplies
the water for the Goose Valley spring is estimated at approximately 18
square km (7 square mi) (CDWR 2003, p. 1). All occupied locations of
the Goose Valley pebblesnail are in springs or small spring-fed
streams, rather than in the main current of the Pit River, and so are
likely to be protected from temperature and flow variations by the
springs' stable flows. Accordingly, we do not expect changes in
precipitation or water availability due to climate change to
significantly affect the species.
Fire
Fire could potentially affect Goose Valley pebblesnails by
increased siltation due to the accumulation of ash or subsequent
erosional deposition of soil in their springs or streams. However, most
siltation should clear relatively quickly from the four occupied
locations in the lower Pit River drainage, because the flow rates for
those locations are high (Haley 2012b, p. 1). Biologists working on
mollusk surveys in the lower Pit River both before and after the
Shasta-Trinity Unit (SHU) Lightning Complex Fire of early August 2009
(PGE 2010, p. 13) did not consider the impacts to nearby springs and
streams to be serious or lasting (Ellis and Haley 2012, p. 1). A search
of fire data archived by the California Department of Forestry and Fire
Protection (CAL FIRE) and extending back to 2003, indicates that the
SHU Lightning Complex Fire, at 17,623 ac (7,132 ha) (CAL FIRE 2009, p.
1) was the largest in Shasta County on record (Service 2012, p. 1).
Future Shasta County fires are therefore likely to be smaller than the
SHU Lightning Complex Fire, and to have smaller impacts (such as less
siltation from the accumulation of ash). Since the SHU Lightning
Complex fire did not produce serious impacts to Goose Valley
pebblesnail habitats, smaller fires would not be expected to either.
Summary of Factor E
In summary, the Goose Valley pebblesnail is protected from likely
impacts of climate change and fire by the particular characteristics of
its habitat. Although potential competition from the New Zealand
mudsnail is cause for concern, no site currently occupied by Goose
Valley pebblesnail has been colonized, and there is nothing to indicate
the New Zealand mudsnail will colonize multiple locations occupied by
the Goose Valley pebblesnail. There is also no direct evidence to show
that any such occupied locations would be extirpated by such a
colonization, were it to occur. The two species are not known to have
interacted in the past. We therefore conclude, based on the best
available scientific and commercial information, that other natural or
manmade factors such as competition from the New Zealand mudsnail,
changes in
[[Page 57936]]
precipitation or water availability due to climate change, or fire do
not constitute significant threats to the Goose Valley pebblesnail now
or in the future.
Finding for the Goose Valley Pebblesnail
We have carefully assessed the best scientific and commercial
information available regarding the past, present, and future threats
faced by the Goose Valley pebblesnail. We reviewed the petition,
available published and unpublished scientific and commercial
information, and information submitted to us during our status review.
This finding reflects and incorporates that information. We also
consulted with recognized authorities on this species and Federal and
State resource agencies. Although only 11 occupied sites are known for
the Goose Valley pebblesnail, a review of the best available
information does not indicate that populations at any site are in
decline, or that any sites are likely to be lost due to impoundments,
agriculture, diversions and grazing, overutilization, disease or
predation, the inadequacy of existing regulatory mechanisms,
competition with invasive species, changes in precipitation and water
availability due to climate change, or fire, now or in the foreseeable
future. The best available scientific and commercial information at
this time does not indicate that there is likely to be a change in any
of these stressors in the future.
Based on our review of the best available scientific and commercial
information pertaining to the five factors, we find that the threats as
described above, either alone or in combination, are not of sufficient
imminence, intensity, or magnitude to indicate that the Goose Valley
pebblesnail is in danger of extinction (endangered) or likely to become
endangered within the foreseeable future (threatened), throughout all
of its range.
Significant Portion of the Range
Having determined that the Goose Valley pebblesnail is not
endangered or threatened throughout all of its range, we must next
consider whether there are any significant portions of the range where
the Goose Valley pebblesnail is in danger of extinction or is likely to
become endangered in the foreseeable future. See Significant Portion of
the Range under Summary of Procedures for Determining the Listing
Status of Species.
We evaluated the current range of the Goose Valley pebblesnail to
determine if there is any apparent geographic concentration of
potential threats for the species. The Goose Valley pebblesnail is
highly restricted in its range and the threats occur throughout its
range. We considered the potential threats due to impoundments,
agriculture, diversions and grazing, overutilization, disease or
predation, the inadequacy of existing regulatory mechanisms,
competition with invasive species, changes in precipitation and water
availability due to climate change, and fire. We found no concentration
of threats that suggests that the Goose Valley pebblesnail may be in
danger of extinction in a portion of its range. We found no portions of
its range where potential threats are significantly concentrated or
substantially greater than in other portions of its range. Therefore,
we find that factors affecting the species are essentially uniform
throughout its range, indicating no portion of the range of the species
warrants further consideration of possible endangered or threatened
status under the Act.
We find that the Goose Valley pebblesnail is not in danger of
extinction now, nor is likely to become endangered within the
foreseeable future, throughout all or a significant portion of its
range. Therefore, listing the Goose Valley pebblesnail as endangered or
threatened under the Act is not warranted at this time.
Hat Creek Pebblesnail (Fluminicola umbilicatus)
Species Information for the Hat Creek Pebblesnail
Taxonomy and Species Description
The Hat Creek pebblesnail is an aquatic snail that was formally
named and described in 2007 (Hershler et al. 2007, p. 407). This
species combines two taxa previously considered likely species but
never formally described, the umbilicate pebblesnail (Fluminicola n.
sp. 19) (Frest and Johannes 1999, p. 55) and the Lost Creek pebblesnail
(Fluminicola n. sp. 20) (Frest and Johannes 1999, pp. 55, 59). The
shell of the Hat Creek pebblesnail is subglobose (rounded top) to ovate
conic (egg shaped top), and ranges from 2.1 to 5.4 mm (0.08 to 0.2 in)
tall, with 3.25 to 4.5 major whorls (Hershler et al. 2007, p. 409). The
periostracum can be tan, brown, or light green. The head is dark brown
to almost black. Adult Hat Creek pebblesnails are somewhat unusual
among Fluminicola species in having a visible open space near the
opening of the shell, called an umbilicus, around which the whorls wrap
(Frest and Johannes 1999, pp. 55, 58).
Distribution
The Hat Creek pebblesnail is known from five locations in the upper
Hat Creek watershed, Shasta County, close to the intersection of State
Highways 44 and 89. The locations fall into two groups, one of which
centers on Hat Creek itself and the other on nearby Lost Creek. Lost
Creek disappears into a lava tube, and is presumed to connect to Hat
Creek (ORNHIC 2004f, p. 1). The groups are roughly 13 km (8 mi) apart,
and the furthest distance of occupied locations within each group is
roughly 1 km (0.6 mi). One occupied location in each group is on Lassen
National Forest land, while the others are on private inholdings within
the general boundaries of the National Forest.
Habitat and Biology
The Hat Creek pebblesnail appears limited to cold water springs and
spring runs (Frest and Johannes 1999, pp. 56, 60). It occurs on sand-
gravel substrates, and on water plants such as watercress (genus
Nasturtium, formerly Rorippa) and brooklime (Veronica sp.). It grazes
on perilithon and periphyton. We have no specific information regarding
the reproduction of this species, but members of the Fluminicola genus
typically live a single year and breed only once (Furnish and Monthey
1999, Sect. 4, p. 7 and Sect. 6, p. 4; ORNHIC 2004f, p. 2). They
generally lay eggs in the spring, which hatch in 2 to 4 weeks. They are
not known to disperse widely, and are highly sensitive to water
pollution, decreases in dissolved oxygen, elevated temperatures, and
sedimentation (Furnish and Monthey 1999, Sect. 4, pp. 7, 8).
Five-Factor Evaluation of Threats to the Hat Creek Pebblesnail
Factor A. The Present or Threatened Destruction, Modification, or
Curtailment of Its Habitat or Range
Timber Production
Lassen National Forest plans to reduce fuel loads by removing small
conifers upstream of the two southernmost sites occupied by Hat Creek
pebblesnails (Burton 2012, p. 1). Such operations, if not carefully
conducted, could potentially remove shading foliage and collapse
riverbanks, thereby causing siltation and increased water temperatures
that could impact Hat Creek pebblesnails downstream. However, the
operations will take place in Riparian Conservation Areas (RCAs,
discussed below), and are subject to protective regulations likely to
prevent serious habitat impacts. In keeping with these regulations, the
fuel reduction projects will proceed with a minimum
[[Page 57937]]
of disturbance, and conifers will be cut by hand to avoid unnecessary
use of heavy machinery near the stream (Burton 2012, p. 1).
Timber Production--Protective Regulatory Mechanisms
The Sierra Nevada Forest Plan Amendment (SNFPA)--The SNFPA is a set
of amendments to the resource management plans of national forests in
the Sierra Nevada and Modoc Plateau areas of California (USDA 2004, p.
15). The SNFPA applies to those portions of the Lassen National Forest
not covered by the NWFP, including the two areas within the National
Forest occupied by Hat Creek pebblesnails. The SNFPA includes a sub-
program called the Aquatic Management Strategy (AMS), which establishes
RCAs around perennial streams and other hydrological or topographic
depressions, such as ponds and springs (USDA 2004, pp. 32, 42).
Activities within the RCAs require site-specific analyses to ensure the
activity conforms to several riparian conservation objectives (USDA
2004, p. 33). Those objectives include maintaining or restoring
geomorphic and biological characteristics of special aquatic features
and ensuring that activities enhance or maintain physical and
biological characteristics associated with aquatic and riparian-
dependent species. Although they also include provisions for improving
habitat, such improvements are subject to funding and may take time to
address situations in which habitat has already been impacted, such as
recreational vehicle impacts upstream of the occupied sites on Hat
Creek.
Grazing
The two occupied sites on Hat Creek are not near grazed areas, but
two of the three occupied sites on Lost Creek are on private land in a
location that is subject to grazing (Burton 2012, p. 1). The third Lost
Creek site is on ungrazed land in the Lassen National Forest, about
0.64 km (0.4 mi) downstream from the grazed area. Cattle grazing in and
around streams can trample banks and riparian vegetation, resulting in
wider, shallower, muddier, and less shaded waters (Meehan and Platts
1978, pp. 275-276; Stephenson and Street 1978, p. 152; Kauffman and
Krueger 1984, p. 432). If such impacts were to occur in the vicinity of
the sites occupied by Hat Creek pebblesnails, they could threaten the
snail populations, which (as discussed under Habitat and Biology,
above) are highly sensitive to water pollution, decreases in dissolved
oxygen, elevated temperatures, and sedimentation. However, the stream
in the area of the occupied sites is protected from cattle by a
combination of fencing, brush, and rocks (Suarez 2012, p. 1). Cattle
are typically driven across the stream twice per year, but the
substrate at the crossing site is primarily rock, so the stream bed
suffers little trampling damage.
Impoundments
The two occupied sites on Hat Creek are not near impoundments, but
the three occupied sites on Lost Creek are downstream of one small
impoundment and upstream from another, with approximately 2.5 km (1.5
mi) of perennial stream between the two reservoirs (Burton 2012, p. 1).
There is some potential for increases in water temperatures in the Lost
Creek occupied sites due to releases from the upper reservoir. However,
the small upstream reservoir exposes relatively little still surface
water to the sun as compared to the much larger Pit 3, 4, and 5
reservoirs, and so is less likely to produce significantly higher
downstream temperatures (see Impoundments, under Canary Duskysnail,
above). Both the upstream reservoir and the water below it in Lost
Creek support coldwater fish such as rainbow trout (Burton 2012, p. 1).
The downstream reservoir is over 200 m (650 ft) from the nearest
occupied location. The downstream dam includes an overflow outlet, so
the reservoir is unlikely to back up during high flows and inundate
sites occupied by Hat Creek pebblesnails.
Recreation
An area about 4.8 km (3 mi) long along Hat Creek, upstream of the
occupied sites, has been heavily impacted by off-highway vehicle (OHV)
use in and around the creek (Burton 2012, p. 1). Impacts at the OHV
site include crushed riparian vegetation and collapsed stream banks,
resulting in increased siltation and potentially higher temperatures.
However, the nearest site occupied by the Hat Creek pebblesnail is a
spring off the side of Hat Creek (Hershler et al. 2007, p. 407), while
the other occupied site in the area is farther downstream in Hat Creek,
approximately 2 km (1.2 mi) from the edge of the recreational area and
2.6 km (1.6 mi) from the area of primary impact. Because of distance to
the second site, and spring flows from the first, sediment and
increased temperatures produced by upstream recreational use would be
unlikely to significantly affect either occupied site. There is no
evidence of OHV impacts at the spring.
Accordingly, although timber management, grazing, impoundments, and
OHV use all occur in the general vicinity of occupied sites, the best
available evidence indicates they are not impacting occupied habitat.
We therefore conclude, based on the best available scientific and
commercial information, that the present or threatened destruction,
modification or curtailment of its habitat or range does not constitute
a significant threat to the species now or in the future.
Factor B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
Our review of the best available scientific and commercial
information yielded nothing to indicate that overutilization for
commercial, recreational, scientific, or educational purposes is
occurring at this time, or is likely to occur in the future. We
therefore conclude such overutilization does not constitute a threat to
the Hat Creek pebblesnail.
Factor C. Disease or Predation
Disease
We reviewed the best available scientific and commercial
information regarding this species and other similar species, and found
no evidence to indicate that disease is impacting Hat Creek pebblesnail
populations.
Predation
Predation by the introduced signal crayfish could threaten Hat
Creek pebblesnail populations if the signal crayfish were present in
sufficiently high densities (see canary duskysnail, above). However, we
have no direct evidence that either signal or Shasta crayfish are
present in the upper portions of Hat Creek or Lost Creek. The closest
area for which we have signal crayfish density information is the
middle Pit River, where densities were roughly equal to native crayfish
densities as measured in the upper Fall River (Ellis 1999, p. 58; PGE
2011b, pp. iii, 10; PGE 2012b, p. 9). Hence, the available evidence
does not support the contention that signal crayfish are present in Hat
or Lost Creeks in sufficiently high densities to pose a predation risk
to the Hat Creek pebblesnail. Furthermore, the information does not
indicate any trend in the densities of either crayfish that would lead
us to a conclusion that the predation risk would increase in the
future.
We therefore conclude, based on the best available scientific and
commercial
[[Page 57938]]
information, that neither disease nor predation constitutes a
significant threat to the species now or in the future.
Factor D. The Inadequacy of Existing Regulatory Mechanisms
Under this factor, we examine whether existing regulatory
mechanisms are inadequate to address the threats to the species
discussed under the other factors. Section 4(b)(1)(A) of the Act
requires the Service to take into account ``those efforts, if any,
being made by any State or foreign nation, or any political subdivision
of a State or foreign nation, to protect such species...''. We
interpret this language to require the Service to consider relevant
Federal, State, and Tribal laws and regulations when developing our
threat analyses. Regulatory mechanisms, if they exist, may preclude the
need for listing if we determine that such mechanisms adequately
address the threats to the species such that listing is not warranted.
The analysis of threats to the Hat Creek pebblesnail under the other
factors included consideration of the ameliorative effects of
regulatory mechanisms where applicable, such as those discussed under
Factor A and under Generally Applicable Federal Regulatory Mechanisms,
above.
Having evaluated the significance of the threat as mitigated by any
such conservation efforts, we analyze under Factor D the extent to
which existing regulatory mechanisms are inadequate to address the
specific threats to the species. We found no significant threats to the
Hat Creek pebblesnail under the other factors, therefore, the analysis
of any existing regulatory mechanisms' adequacy to address threats is
not applicable. Consequently, after reviewing the best available
commercial and scientific information, we conclude that the inadequacy
of existing regulatory mechanisms is not a threat to the Hat Creek
pebblesnail now or in the future.
Factor E. Other Natural or Manmade Factors Affecting Its Continued
Existence
Competition With Invasive Species
New Zealand mudsnails are not currently known to occur within the
range of the Hat Creek pebblesnail (Lost Creek and upper Hat Creek). If
New Zealand mudsnails were to become established in those areas, they
would likely compete with Hat Creek pebblesnails for food and space
(see canary duskysnail, above). Typically, New Zealand mudsnails
establish themselves in new areas after being transported on boating or
angling equipment (ANTSF 2005, p. 1). Upper Hat Creek and Lost Creek
are popular fishing destinations, but lack boating facilities, so the
likelihood of New Zealand mudsnail infestation in these areas may be
somewhat lower than for areas in the canary duskysnail's range that
support both fishing and boating, such as Lake Britton.
Changes in Precipitation and Water Availability Due to Climate Change
See our discussion of climate change in general in the Changes in
Precipitation and Water Availability Due to Climate Change section
under ``Factor A'' in Five-Factor Evaluation of Threats for the Canary
Duskysnail. Climate change is not expected to significantly change
total precipitation in northern California, but may affect seasonal
water availability in some areas due to changes in snowpack melting
times and the proportion of precipitation falling as rain rather than
snow (Dettinger et al. 2004, pp. 43, 44). However, the water supplying
springs emptying into Lost Creek and upper Hat Creek are collected from
wide areas in the Lassen volcanic highlands (Service 1998, p. 18). Rain
and snowmelt in those areas percolate through porous volcanic rocks to
collect in large aquifers, thereby holding extra water from seasons
when rain is plentiful and delivering it through springs during seasons
when it is not. Resulting spring flows are highly stable in volume,
temperature and clarity (Service 1998, p. 46). Accordingly, we do not
expect changes in precipitation or water availability due to climate
change to significantly affect the species.
Catastrophic Events--Highway Spill
Spills from tank trucks carrying chemicals, such as pesticides or
gasoline, on State Highway 44 near the two occupied sites on Hat Creek
could potentially impact the Hat Creek pebblesnails at those sites.
Chemical spills can eliminate pebblesnail populations (see discussion
of Chemical Spills under Nugget Pebblesnail (Fluminicola seminalis),
below). However, the more upstream of the two occupied sites is in a
spring near the creek (Hershler et al. 2007, p. 407), and the highway
pulls away from the creek upstream of that location, so a tanker spill
would have to occur directly above that site in order to significantly
impact the pebblesnail population there. The highway runs close to the
creek from that point to the second occupied site, a distance of about
1.2 km (0.75 mi), so a spill somewhere along that stretch might impact
the second site. We are not aware of any previous spills within that
region, however, and we consider the likelihood of a major chemical
spill within that relatively small area to be low.
Summary of Factor E
We find that neither highway spills, competition with the New
Zealand mudsnail, nor changes in precipitation or water availability
due to climate change are a threat to the Hat Creek pebblesnail.
Although a chemical spill off the highway could potentially impact up
to two locations, the likelihood of such an event is extremely low. No
site occupied by the Hat Creek pebblesnail has been colonized by the
New Zealand mudsnail and the lack of boating opportunities makes
invasion by the mudsnail less likely. The springs supplying Hat and
Lost Creeks are resistant to the fluctuations in temperature and water
availability associated with predicted climate changes. We therefore
conclude that, based on the best available scientific and commercial
information, that other natural or manmade factors as described above,
do not constitute significant threats to the Hat Creek pebblesnail now
or in the future.
Finding for the Hat Creek Pebblesnail
We have carefully assessed the best scientific and commercial
information available regarding the past, present, and future threats
faced by the Hat Creek pebblesnail. We reviewed the petition, available
published and unpublished scientific and commercial information, and
information submitted to us during our status review. This finding
reflects and incorporates that information. We also consulted with
recognized authorities on this species and Federal and State resource
agencies. Although only five occupied sites are known for the Hat Creek
pebblesnail, a review of the best available data does not indicate that
populations at any site are in decline, or that any sites are likely to
be lost due to timber production and management, grazing, impoundments,
recreation, overutilization, disease or predation, the inadequacy of
existing regulatory mechanisms, competition with invasive species,
changes in precipitation and water availability due to climate change,
or catastrophic events such as highways spills, now or in the
foreseeable future. The best available scientific and commercial
information at this time does not indicate that there is likely to be a
change in any of these stressors in the future.
Based on our review of the best available scientific and commercial
information pertaining to the five factors, we find that the threats as
[[Page 57939]]
described above, either alone or in combination are not of sufficient
imminence, intensity, or magnitude to indicate that the Hat Creek
pebblesnail is in danger of extinction (endangered) or likely to become
endangered within the foreseeable future (threatened), throughout all
of its range.
Significant Portion of the Range
Having determined that the Hat Creek pebblesnail is not endangered
or threatened throughout all of its range, we must next consider
whether there are any significant portions of the range where the Hat
Creek pebblesnail is in danger of extinction or is likely to become
endangered in the foreseeable future. See Significant Portion of the
Range under Summary of Procedures for Determining the Listing Status of
Species.
We evaluated the current range of the Hat Creek pebblesnail to
determine if there is any apparent geographic concentration of
potential threats for the species. The Hat Creek pebblesnail is highly
restricted in its range and the threats occur throughout its range. We
considered the potential threats due to timber production and
management, grazing, impoundments, recreation, overutilization, disease
or predation, the inadequacy of existing regulatory mechanisms,
competition with invasive species, changes in precipitation and water
availability due to climate change, and catastrophic events such as
highways spills. We found no concentration of threats that suggests
that the Hat Creek pebblesnail may be in danger of extinction in a
portion of its range. We found no portions of its range where potential
threats are significantly concentrated or substantially greater than in
other portions of its range. Therefore, we find that factors affecting
the species are essentially uniform throughout its range, indicating no
portion of the range of the species warrants further consideration of
possible endangered or threatened status under the Act.
We find that the Hat Creek pebblesnail is not in danger of
extinction now, nor is likely to become endangered within the
foreseeable future, throughout all or a significant portion of its
range. Therefore, listing the Hat Creek pebblesnail as endangered or
threatened under the Act is not warranted at this time.
Nugget Pebblesnail (Fluminicola seminalis)
Species Information for the Nugget Pebblesnail
Taxonomy and Species Description
The nugget pebblesnail was first described as Palludina seminalis
in 1842 (Hershler and Frest 1996, p. 15). After undergoing several name
changes, it was redescribed as Fluminicola seminalis in 1996 (Hershler
and Frest 1996, p. 15). It has a globose to broadly conical shell with
4 to 4.5 whorls (Frest and Johannes 1995b, p. 49; Hershler and Frest
1996, p. 16). The shell can be tan, brown, or light green, and has a
large opening. Its distinguishing features, as compared to other
pebblesnails, include (among other features) its relatively large size
(about 6 to 8 mm (0.24 to 0.31 in), thick periostracum, and thin
parietal lip (on the side of the opening toward the inside of the
whorls) (Hershler et al. 2007, p. 405). The snail itself is black with
a pale gray head (Hershler and Frest 1996, p. 16). Although
pebblesnails in general (Fluminicola genus) had previously been
considered part of the Hydrobiidae family (Hershler et al. 2003, p.
275), they have since been reassigned to the Lithoglyphidae family
(Hershler et al. 2007, p. 371).
Distribution
The nugget pebblesnail is known from approximately 44 occupied
sites in Shasta, Lassen, and Tehama Counties. The sites can be grouped
into five general areas: The mid and lower Pit River and nearby
tributaries including Hat Creek; the upper Fall River drainage; Ash
Creek (a tributary of the upper Pit River in Lassen County); the
McCloud River near Lake Shasta; and Battle Creek, along the Shasta-
Tehama County boundary. The majority of known sites (37 of 44) are in
the mid and lower Pit River and upper Fall River areas. The local
abundance of this snail at occupied sites can be high (Frest and
Johannes 1995b, p. 50).
The nugget pebblesnail was formerly widespread in the upper
Sacramento River above Lake Shasta, but was apparently extirpated from
the entire region in 1991 due to the Cantara Spill, in which a railcar
containing the herbicide metam sodium derailed and spilled its contents
into the river (Frest and Johannes 1995b, pp. 13, 50; Hershler and
Frest 1996, p. 16; ORNHIC 2004k, p. 1).
Habitat and Biology
The nugget pebblesnail prefers gravel-boulder substrate and clear,
cold, flowing water, but has been found on soft substrate in a few very
large spring pools (Frest and Johannes 1995b, p. 50). It is a riparian
associate, apparently grazes on perilithon and periphyton, and possibly
on fine particles of detritus as well (Frest and Johannes 1993, p. 54;
Furnish et al. 1997, p. 31). We have no specific information regarding
the reproduction of this species, but members of the Fluminicola genus
typically live a single year and breed only once (Furnish and Monthey
1999, Sect. 3, p. 4; ORNHIC 2004f, p. 2). They generally lay eggs in
the spring, which hatch in 2 to 4 weeks. They are not known to disperse
widely, and are sensitive to water pollution, decreases in dissolved
oxygen, elevated temperatures, and sedimentation (Furnish and Monthey
1999, Sect. 3, pp. 5, 8).
Five-Factor Evaluation of Threats to the Nugget Pebblesnail
Factor A. The Present or Threatened Destruction, Modification, or
Curtailment of Its Habitat or Range
Impoundments
Thirteen of the 44 occupied sites are in or along the lower Pit
River below Lake Britton (Hershler et al. 2007, p. 405; Haley 2012a, p.
3; PGE 2011, pp. 26, 37; PGE 2012 p. 27). Twelve of those 13 sites were
monitored by PGE from 2009 through 2011, in accordance with the 2007
relicensing requirements for the Pit 3, 4, and 5 dams (see canary
duskysnail, above). Flow releases from the dams for 2009 and 2010 were
at interim levels (higher than in previous years but lower than the
final levels required by the relicensing agreements (PGE 2010, pp. 1,
2). Flow releases had reached their final required levels in 2011 and
are expected to remain at those levels thereafter.
Increased flows from dams may negatively impact nugget pebblesnails
by raising water temperatures (see canary duskysnail, above) (Ellis
2012, p. 1). As average flows increased from 2009 to 2011, average
temperatures did in fact go up, and average density of nugget
pebblesnails decreased at the four locations monitored in the Pit 3
reach (PGE 2010, p. 35; PGE 2011, pp. 24, 26, 37; PGE 2012, pp. 24,
27). Average densities of nugget pebblesnails likewise decreased each
year over the 3-year period at each of four sites in the Pit 5 reach.
However, average water temperatures in the Pit 5 reach were highest in
2009 at one of those locations, highest in 2010 at another location,
and remained essentially unchanged at a third location. This may be due
to variations in air temperature
[[Page 57940]]
across the 3 years (PGE 2010, p. 35; PGE 2011, p. 24; PGE 2012, p. 24).
In the Pit 4 reach, there was a varied response, with July surveys
showing an overall average increase in nugget pebblesnail density from
2009 to 2011, and August surveys showing a (smaller) overall decrease.
Thus, increased water temperatures and increased flows were closely
correlated with decreased population densities in the Pit 3 reach, but
not in the Pit 4 or 5 reaches.
Despite any decreases, nugget pebblesnails remained common
throughout the three survey years, and no sites were extirpated (PGE
2011, pp. 26 37; PGE 2012, p. 27). Average densities in 2009 ranged
from 240 to 4,970 snails per square meter, while in 2011 they ranged
from 10 to 5,058 snails per square meter. The nugget pebblesnail was
also the most common aquatic snail in each of the three areas surveyed
in 2009 (PGE 2010, p. 41), whereas, in the following 2 years it was the
most common in the Pit 3 and Pit 4 reaches, but the second-most common
in the Pit 5 reach (PGE 2011, p. 29; PGE 2012, p. 28). Accordingly,
while the current data from PGE surveys indicate that increased flow
releases may have impacted the nugget pebblesnail in at least some of
their lower Pit River sites, high densities of nugget pebblesnails
persist in all three reaches despite these impacts. We therefore do not
consider the existing data to indicate that increased flows are likely
to threaten the continued existence of the nugget pebblesnail in the
area. PGE will continue to monitor mollusk populations, so any
significant declines in nugget pebblesnail populations should be
detected promptly (PGE 2012, p. 1).
Four sites in the lower Hat Creek watershed also are potentially
affected by dams. Two of these are in Baum Lake near the outflow of
Crystal Lake, and close to the Baum Lake location of canary duskysnails
(discussed above) (Hershler et al. 2007, p. 405). Another occupied site
is at Crystal Lake, a spring-fed lake that flows into Baum Lake at its
eastern end (PGE 2006, fig 1, p. 46; Hershler et al. 2007, p. 405). A
fourth site is upstream of Baum Lake, just below the PGE dam (Hat Creek
1) that forms Cassel Pond. Licensing requirements, established by the
Federal Energy Regulatory Commission (FERC) when the two dams were
relicensed in 2002 establish minimum flows of 8 cfs in Hat Creek below
the Hat Creek 1 dam (White 2008, pp. 1, 2) and also require PGE to
maintain the surface of Baum Lake at a constant height (FERC 2011, p.
1). Accordingly, the occupied sites in Baum Lake are likely to be kept
at a constant depth, and the occupied site below the Hat Creek 1 dam is
unlikely to be left without water. The nugget pebblesnails at those
locations are therefore unlikely to lose the cold, well-oxygenated
flows they require.
Two occupied sites are in the McCloud River near Lake Shasta
(Hershler et al. 2007, p. 405; Haley 2012a, p. 3). One could
potentially be inundated by the lake if a proposal to raise the height
of Shasta dam up to 18.5 ft (5.6 m) is carried out (U.S. Bureau of
Reclamation (USBR) 2007, p. ES 6; USBR 2011, pp. 1-6). Inundation
resulting from the higher reservoir level made possible by raising the
dam height would likely remove necessary flows and would extirpate the
site. The best available scientific and commercial information does not
indicate the likelihood of the proposal being implemented (USBR 2011,
pp. 182-184), nor the likelihood of relocating the nugget pebblesnails
or otherwise mitigating the project's impact.
Water Quality
The Pit River is considered a water-quality limited segment for 198
km (123 mi) upstream of Shasta Lake, due to added nutrients from
agriculture and grazing that encourage algal growth (see canary
duskysnail above) (SWRCB 2010a, p. 164). Sixteen sites occupied by the
nugget pebblesnail are within that area, including the 12 sites
considered above with regard to impoundments, and an additional 4 sites
upstream of the Pit 3, 4 and 5 reaches. Although we lack information
regarding the impacts (if any) of the impaired water quality on the
snails, snail populations at 12 of the 16 occupied sites are subject to
annual monitoring (see Impoundments). At this point, after only 3 years
of monitoring and 1 year at the full flow releases established by the
operating license, the data do not indicate that water quality is a
threat to nugget pebblesnail populations in the lower Pit River.
Sediment levels in the upper Fall River and high pH in Eastman Lake
(see canary duskysnail, above) may affect nugget pebblesnails at three
occupied sites in those locations. Three additional occupied sites in
upper Ash Creek (Lassen County) may also be subject to alkalinity
levels slightly above the established water quality limit of 8.5 pH
(SWRCB 2010a, p. 137; SWRCB 2010b, p. 1). Three water quality samples
from the area showed pH levels of 8.62, 8.53, and 8.58 (SWRCB 2010b, p.
8).
The three occupied sites in upper Ash Creek discussed above may
also be subject to levels of Escherichia coli (E. coli) bacteria (an
indicator of sewage contamination) exceeding water quality standards
(SWRCB 2010 (Ash Cr), pp. 5, 6). A single sample taken from upper Ash
Creek in 2005 showed an E. coli density greater than three times the
water quality standard for non-contact recreation, and greater than 5.5
times the standard for water contact recreation (SWRCB 2010 (Ash Cr),
pp. 6, 7). The source of contamination was not established (SWRCB
2010(Ash Cr), p. 5), although feces from grazing cattle is a
possibility (see below). Although nugget pebblesnails are considered
sensitive to water pollution (Furnish and Monthey 1999, Sect. 3, pp. 5,
8), their response to E. coli contamination is not known. No population
trend data are available for nugget pebblesnails in Ash Creek,
therefore, it is difficult to infer any direct response to E. coli
levels at this location.
Grazing and Logging
In the middle and lower Pit River area (including lower Hat Creek),
7 occupied sites are on National Forest lands in the NWFP area, 14 are
on PGE lands, and 1 is in MacArthur-Burney State Park (Stewardship
Council 2007, Vol. 2, pp. PM-20, PM-30, PM-38, PM-58). The sites on
NWFP lands benefit from the SMP and ACS, (see Generally Applicable
Federal Regulatory Mechanisms, above) and so are unlikely to be
threatened by grazing or logging taking place on those lands. Such
activities would be subject under the SMP to predisturbance surveys and
management of known sites to support species persistence (Molina et al.
2006, p. 312; Olson et al. 2007, abstract). Under the ACS they would
also be subject to close regulation within riparian reserve buffer
areas so as to maintain water quality and aquatic ecosystem integrity
(USDA and USDI 1994a, p. 9; USDA and USDI 1994b, pp. C-31-C-38). The
site at the State Park is also unlikely to be threatened by grazing or
logging, as the Park is committed to maintaining its scenic features in
a natural condition (California Department of Parks and Recreation
(CDPR) 1997, p. 46), and to take measures to monitor and maintain
natural water quality, channel flow, and sediment transport rates (CDPR
1997, p. 47). Although the State is considering closing several State
Parks in order to save money, neither MacArthur-Burney State Park, nor
Ahjumawi Lava Springs State Park (discussed below) are among those
being considered for closure (CDPR 2012, p. 2).
Lands owned by PGE are also subject to conservation management. Due
to bankruptcy proceedings in 2004 (Stewardship Council 2007, Vol. 1,
pp. ES-1, ES-2), PGE accepted a settlement
[[Page 57941]]
agreement with the California Public Utilities Commission (PUC) that
requires PGE to protect the lands associated with its dams, either by
establishing conservation easements or by donating the land to
qualified conservation managers. A nonprofit corporation was
established that published a land conservation plan in 2007
(Stewardship Council 2007, Vol. 1, p. ES-1). As the plan indicates,
grazing has been eliminated to protect water quality in the areas of
the Pit 3, 4, and 5 dams and associated reaches since the late 1980s
(Stewardship Council, Vol. 2, p. PM-47). Grazing was eliminated in the
general vicinity of the PGE dams on Hat Creek in 2001 (Stewardship
Council 2007, Vol. 2, p. PM-31). Current timber management activities
on the PGE Hat Creek and Fall River lands are restricted to mitigating
for watershed and forest health issues (Stewardship Council 2007, Vol.
2, pp. PM-3, PM-31). A single timber management unit of 2,499 ac (1,011
ha) exists in the vicinity of Lake Britton and the Pit 3 reach and is
managed for multiple uses (Stewardship Council, Vol. 2, p. PM-40). In
the Pit 4 reach, six timber management units totaling 2,123 ac (859 ha)
are currently managed for sustainable production, with the most recent
harvest in 2005 and 2006 (Stewardship Council, Vol. 2, p. PM-50).
Timber harvest on private lands is governed by the state Nejedly-
Z'berg Forest Practice Act (FPA). The FPA requires timber harvesters to
submit a publicly reviewable Timber Harvest Plan (THP) to the
California Department of Forest and Fire Protection (CAL FIRE) (Kier
Associates 2011b, p. 2) and to maintain buffers around fish-bearing
streams of at least 75 ft (23 m) within which at least 50 percent of
overstory and understory vegetation and 75 percent of total original
vegetation must remain uncut (CAL FIRE 2012, pp. 68-72).
In the upper Fall River drainage, eight occupied sites are on
private land, one is on an Indian PDA, and three are in the Ahjumawi
Lava Springs State Park. Various habitat improvement measures have been
carried out by private landowners in the area, including the erection
of exclusion fencing, bank stabilization projects, and the replacement
and upgrade of a railroad crossing that had collapsed twice in the past
(see canary duskysnail, above) (FRRCD 2005, pp. 1-3; Ellis and Haley
2012, p. 1). Landowners also took steps to reduce the potential for
serious wildfires and to prevent erosion of sediment from a nearby
meadow (FRRCD 2005, p. 3).
A general plan is not yet completed for Ahjumawi Lava Springs State
Park, but the California State Park System maintains a resource
management program with the general goal of protecting, restoring, and
maintaining the natural resources within the Parks (CDPR 2012, p. 2).
There are three occupied sites in upper Ash Creek in Lassen County;
two occupied sites are in the Modoc National Forest and the other is on
private land. The sites in the National Forest are in the Ash Creek
management unit of the Round Valley grazing allotment, where grazing is
not currently permitted (Raymond 2012, p. 1). Grazing does occur on
private lands farther upstream from the National Forest, however
(Raymond 2012, p. 1), so it may occur in the vicinity of the occupied
site on private land. Grazing in and around streams on private land is
not closely regulated, and can lead to trampled vegetation, fecal
matter in the water, and a muddier and warmer stream (Meehan and Platts
1978, p. 276; Stephenson and Street 1978, p. 152; Kauffman and Krueger
1984, p. 432), all of which would negatively impact the nugget
pebblesnail. We do not have information regarding the extent of grazing
on private lands in the area, nor of the extent to which protective
management actions may have been taken.
The Modoc National Forest also expects to offer a timber sale this
year in the vicinity of Ash Creek, possibly leading to timber removal
in the spring of 2013 (Raymond and Bryan 2012, p. 1). Timber removal
would be subject to restrictions established by the SNFPA (see Hat
Creek pebblesnail, above).
Summary of Factor A
In summary, flow rates from the Pit 3, 4, and 5 dams, as well as
impaired water quality, may be affecting occupied locations in the
lower Pit River, but the nugget pebblesnail remains extremely common in
the area, and ongoing monitoring will alert us if species persistence
in the area becomes threatened. Potential water quality issues may also
apply to three sites in the upper Fall River drainage and to three
sites at Ash Creek, but the available data do not show that resident
nugget pebblesnail populations are, or are likely to be, impacted by
these issues. Available data also do not suggest that any occupied
sites are threatened by grazing or logging, and most occupied locations
along the Pit River also receive high levels of regulatory protection
from grazing and logging. Seven of those sites are protected by the SMP
and ACS, fourteen are protected by conservation provisions established
for PGE lands under a settlement agreement, and one is protected by
State Park regulations. In the upper Fall River drainage several
habitat improvement projects have been completed by landowners, while
in the Ash Creek drainage two occupied sites are on un-grazed Federal
land protected by the SNFPA, and one is on grazed private land. We
conclude, based on the best available scientific and commercial
information, that the present or threatened destruction, modification
or curtailment of its habitat or range does not constitute a
significant threat to the species now or in the future.
Factor B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
Our review of the best available scientific and commercial
information yielded nothing to indicate that overutilization for
commercial, recreational, scientific, or educational purposes is
occurring at this time or is likely to occur in the future. We
therefore conclude such overutilization does not constitute a threat to
the nugget pebblesnail.
Factor C. Disease or Predation
Disease
We reviewed the best available scientific and commercial
information regarding this species and other similar species, and found
no evidence to indicate that disease is impacting nugget pebblesnail
populations.
Predation
The nugget pebblesnail occurs in the same general areas as the
canary duskysnail, and may also be subject to predation by the
introduced signal crayfish. Predation by dense crayfish populations can
significantly impact aquatic snails (Lorman and Magnuson 1978, p. 9).
However, our only data regarding signal crayfish densities indicate
those densities appear to be holding stable at levels equivalent to
those of the native Shasta crayfish, alongside which the nugget
pebblesnail has evolved (see Canary Duskysnail, above) (Ellis 1999, p.
58; PGE 2011b, pp. iii, 10; PGE 2012b, p. 9). We do not expect occupied
areas within the current range of both crayfish species to be subject
to high combined crayfish densities, because past monitoring has shown
a strong tendency for one or the other crayfish species to be common in
an area, but not both (Ellis 1999, pp. 57, 58; Service 2009, p. 9) (see
Canary Duskysnail, above). Hence, the available evidence does not
support the contention that signal crayfish are
[[Page 57942]]
present in the range of the nugget pebblesnail in sufficiently high
densities to pose a predation risk to the nugget pebblesnail.
Furthermore, the information does not indicate any trend in the
densities of the signal crayfish that would lead us to a conclusion
that the predation risk would increase in the future.
We therefore conclude, based on the best available scientific and
commercial information, that neither disease nor predation constitutes
a significant threat to the species now or in the future.
Factor D. The Inadequacy of Existing Regulatory Mechanisms
Under this factor, we examine whether existing regulatory
mechanisms are inadequate to address the threats to the species
discussed under the other factors. Section 4(b)(1)(A) of the Act
requires the Service to take into account ``those efforts, if any,
being made by any State or foreign nation, or any political subdivision
of a State or foreign nation, to protect such species * * *''. We
interpret this language to require the Service to consider relevant
Federal, State, and Tribal laws and regulations when developing our
threat analyses. Regulatory mechanisms, if they exist, may preclude the
need for listing if we determine that such mechanisms adequately
address the threats to the species such that listing is not warranted.
The analysis of threats to the nugget pebblesnail under the other
Factors included consideration of the ameliorative effects of
regulatory mechanisms where applicable, such as those discussed under
Factor A and under Generally Applicable Federal Regulatory Mechanisms,
above.
Having evaluated the significance of the threat as mitigated by any
such conservation efforts, we analyze under Factor D the extent to
which existing regulatory mechanisms are inadequate to address the
specific threats to the species. We found no significant threats to the
nugget pebblesnail under the other factors, therefore, the analysis of
any existing regulatory mechanisms' adequacy to address threats is not
applicable. Consequently, after reviewing the best available commercial
and scientific information, we conclude that the inadequacy of existing
regulatory mechanisms is not a threat to the nugget pebblesnail now or
in the future.
Factor E. Other Natural or Manmade Factors Affecting Its Continued
Existence
Competition With Invasive Species
The New Zealand mudsnail has the potential to outcompete and
thereby threaten the nugget pebblesnail if it can establish itself at a
significant number of locations that the nugget pebblesnail currently
occupies (see canary duskysnail, above). However, the level of threat
is somewhat reduced by the nugget pebblesnail's greater range as
compared to the canary duskysnail. We consider Lake Britton to be at
greatest danger of infestation within that range, due to its ease of
access, marina, boat launch, fishery, and nearby state park
(Stewardship Council, Vol. 2, pp. PM-37-39). As discussed above in
relation to the canary duskysnail, once the first infestation point is
established, new infestation points could be expected to establish
themselves from that base. At that point, if it occurs, we could
ascertain whether the New Zealand mudsnail was spreading in a manner
likely to threaten the nugget pebblesnail in a significant portion of
its range. At the current time, no infestations of New Zealand mudsnail
are known within the nugget pebblesnail's range. Accordingly, we do not
consider competition from New Zealand mudsnails to be a threat to the
canary duskysnail at this time.
Changes in Precipitation and Water Availability Due to Climate Change
See our discussion of climate change in general in the Changes in
Precipitation and Water Availability Due to Climate Change section
under ``Factor A'' in Five-Factor Evaluation of Threats for the Canary
Duskysnail. Climate change is not expected to significantly change
total precipitation in northern California, but may affect seasonal
water availability in some areas due to changes in snowpack melting
times and in the proportion of precipitation falling as rain rather
than snow (Dettinger et al. 2004, pp. 43, 44). However, the springs
that support sites occupied by the nugget pebblesnail in the middle and
lower Pit River and upper Fall River drainages are supplied by large
aquifers of porous lava that collect and store water from wide areas,
thereby holding extra water from seasons when rain is plentiful and
delivering it through springs during seasons when it is not (see canary
duskysnail, above). Resulting spring flows are highly stable in volume,
temperature, and clarity (Service 1998, p. 46) We lack information
regarding aquifer sizes and collection ranges for the six occupied
sites that are not in the middle and lower Pit River or upper Fall
River drainages, but given the general volcanic geology of the entire
area (U.S. National Park Service (USNPS) 2005, p. 1), we consider it
most likely that these sites also will maintain relatively constant
flow rates and water temperatures despite climate change.
Catastrophic Events--Chemical Spills
The nugget pebblesnail was apparently extirpated from the upper
Sacramento River due to a catastrophic spill of herbicide (the Cantara
Spill) from a derailed rail car in 1991 (see Distribution, above)
(Frest and Johannes 1995b, pp. 13, 50; Hershler and Frest 1996, p. 16;
ORNHIC 2004k, p. 1). A rail line owned by the McCloud River Railroad
crosses the Pit River just upstream of Lake Britton, but freight
service on the line was discontinued in 2006 (Trainweb undated, p. 1).
A rail line owned by the Burlington Northern and Santa Fe (BNSF)
railroad crosses the Pit River much farther upstream in Lassen County,
south of the town of Nubieber, and runs close to the Pit River for
almost 4 km (2.5 mi) after the crossing. However, the point where the
rail line leaves the vicinity of the Pit River is approximately 50 km
(31 mi) upstream of the closest known occupied site on the Pit River.
Although the Cantara spill's effects may have reached such a distance
(Frest and Johannes 1995b, p. 73), in this case a spill from the BNSF
line would have to travel 50 km (31 mi) to affect one occupied nugget
pebblesnail site, then approximately 6.7 km (4.2 mi) to affect two
more, then approximately 23 km (14 mi) farther (including approximately
11 km (6.8 mi) through Lake Britton) to the next occupied site. If a
very large spill were to occur, the most sites it could affect would be
the three Pit River sites upstream of Lake Britton. That would still
leave 41 known occupied sites, and so would not pose a threat to the
species.
Summary of Factor E
In summary, the nugget pebblesnail is protected from likely impacts
of changes in precipitation or water availability due to climate change
by the particular characteristics of its habitat. Although potential
competition from the New Zealand mudsnail is cause for concern, no site
currently occupied by nugget pebblesnail has been colonized and the
best available information does not indicate it will colonize areas
occupied by the nugget pebblesnail, or that it will threaten the nugget
pebblesnail with extinction if it does so. We conclude that, based on
the best available
[[Page 57943]]
scientific and commercial information, that other natural or manmade
factors such as competition from the New Zealand mudsnail, changes in
precipitation or water availability due to climate change, and chemical
spills are not a threat to the nugget pebblesnail now or in the future.
Finding for the Nugget Pebblesnail
We have carefully assessed the best scientific and commercial
information available regarding the past, present, and future threats
faced by the nugget pebblesnail. We reviewed the petition, available
published and unpublished scientific and commercial information, and
information submitted to us during the public comment period following
our 90-day petition finding. This finding reflects and incorporates
information we received during the public comment period. We also
consulted with recognized authorities on this species and Federal and
State resource agencies. The nugget pebblesnail occupies 44 sites, and
a review of the best available information does not indicate that
populations at any site are likely to be extirpated due to
impoundments, water quality, grazing and logging, overutilization,
disease or predation, the inadequacy of existing regulatory mechanisms,
competition with invasive species, changes in precipitation and water
availability due to climate change, or catastrophic events such as
chemical spills, now or in the foreseeable future. The best available
scientific and commercial information at this time does not indicate
that there is likely to be a change in any of these stressors in the
future.
Based on our review of the best available scientific and commercial
information pertaining to the five factors, we find that the threats as
described above either alone or in combination, are not of sufficient
imminence, intensity, or magnitude to indicate that the nugget
pebblesnail is in danger of extinction (endangered) or likely to become
endangered within the foreseeable future (threatened), throughout all
of its range.
Significant Portion of the Range
Having determined that the nugget pebblesnail is not endangered or
threatened throughout all of its range, we must next consider whether
there are any significant portions of the range where the nugget
pebblesnail is in danger of extinction or is likely to become
endangered in the foreseeable future. See Significant Portion of the
Range under Summary of Procedures for Determining the Listing Status of
Species.
We evaluated the current range of the nugget pebblesnail to
determine if there is any apparent geographic concentration of
potential threats for the species. The nugget pebblesnail is highly
restricted in its range and the threats occur throughout its range. We
considered the potential threats due to impoundments, water quality,
grazing and logging, overutilization, disease or predation, the
inadequacy of existing regulatory mechanisms, competition with invasive
species, changes in precipitation and water availability due to climate
change, and catastrophic events such as chemical spills. We found no
concentration of threats that suggests that the nugget pebblesnail may
be in danger of extinction in a portion of its range. We found no
portions of its range where potential threats are significantly
concentrated or substantially greater than in other portions of its
range. Therefore, we find that factors affecting the species are
essentially uniform throughout its range, indicating no portion of the
range of the species warrants further consideration of possible
endangered or threatened status under the Act.
We find that the nugget pebblesnail is not in danger of extinction
now, nor is likely to become endangered within the foreseeable future,
throughout all or a significant portion of its range. Therefore,
listing the nugget pebblesnail as endangered or threatened under the
Act is not warranted at this time.
Potem Creek Pebblesnail (Fluminicola Potemicus)
Species Information for the Potem Creek Pebblesnail
Taxonomy and Species Description
The Potem Creek pebblesnail was formally named and described in
2007 (Hershler et al. 2007, pp. 412-415). Prior to 2007, it was
referred to as the ``Potem pebblesnail (Fluminicola n. sp. 14)'' (Frest
and Johannes 1999, pp. 35-38). It was also referred to as the ``Potem
pebblesnail (Fluminicola n. sp. 2)'' by Frest and Johannes (1995b, pp.
42, 43) (Hershler et al. 2007, p. 414). Although pebblesnails in
general (Fluminicola genus) had previously been considered part of the
Hydrobiidae family (Hershler et al. 2003, p. 275), they have since been
reassigned to the Lithoglyphidae family (Hershler et al. 2007, p. 371).
The shell of the Potem Creek pebblesnail is about 2.5 to 3.3 mm
(0.1 to 0.13 in) tall, with 3 to 3.75 whorls. Its periostracum is tan
or light green, and the head of the snail itself is pale brown or gray
(Hershler et al. 2007, p. 412).
Distribution
Only one occupied site (the type location) for the Potem Creek
pebblesnail is mentioned in the formal description of the species
(Hershler et al. 2007, p. 412). However, that description indicates the
species was previously referred to as Fluminicola n. sp. 2 (Hershler et
al. 2007, p. 412). Fluminicola n. sp. 2 (common name Potem pebblesnail)
has been identified at 11 locations (Frest and Johannes 1995b, pp. T10-
T13, T17, T22, T23), including the 1 site mentioned by Hershler et al.
(2007, p. 412) and 7 sites in the upper Sacramento River drainage.
Subsequent communications indicate that the snails from the upper
Sacramento River sites were likely Shasta pebblesnails (Fluminicola
multifarius) rather than Potem pebblesnails (Hershler 2012, pp. 2-5;
Johannes 2012c, pp. 2, 3). However, this has not been confirmed by
reexamination of all the specimens involved (Hershler 2012, p. 2;
Johannes 2012c, p. 1). As discussed below, Shasta pebblesnails are
unusually variable in form (Hershler et al. 2007, p. 419). Prior to
genetic tests establishing the species identity of the Shasta and Potem
Creek pebblesnails (Hershler et al. 2007, pp. 380-382), the particular
morphological characteristics separating one from the other may not
have been clear. The seven Potem pebblesnail sites in the upper
Sacramento River, and the three Potem pebblesnail sites in the Pit
River drainage (other than the Potem Creek pebblesnail type location)
identified by Frest and Johannes in 1995 (Frest and Johannes 1995b, pp.
T13, T17), are, therefore, considered unconfirmed.
We have also received information regarding three additional sites
in the lower Pit River drainage with snails tentatively identified
(based on shell alone) as Potem Creek pebblesnails (Haley 2012, pp. 1,
3). Therefore, we are aware of 1 confirmed site (the type location) and
13 unconfirmed sites. Seven of the unconfirmed sites are in the upper
Sacramento River drainage, while all of the other sites are in the
lower Pit River drainage. One of the unconfirmed sites in the Pit River
drainage is on Shasta-Trinity National Forest land within the NWFP
area. All other sites are on private land. The type location is on a
small private inholding within the perimeter of the Shasta-Trinity
National Forest.
Habitat and Biology
The Potem Creek pebblesnail occurs on muddy or silty substrates in
small, cold springs and spring runs (Frest and Johannes 1995b, p. A7
(site 36); Frest
[[Page 57944]]
and Johannes 1999, p. 36). It appears to graze on partly decayed
deciduous leaves (Frest and Johannes 1999, p. 36). We have no specific
information regarding reproduction for this species, but members of the
Fluminicola genus typically live a single year and breed only once
(Furnish and Monthey 1999, Sect. 2, p. 5; ORNHIC 2004, p. 2). They
generally lay eggs in the spring, which hatch in 2 to 4 weeks. They are
not known to disperse widely, and are highly sensitive to water
pollution, decreases in dissolved oxygen, elevated temperatures, and
sedimentation (Furnish and Monthey 1999, Sect. 2, pp. 5, 7; Hershler et
al. 2007, p. 372).
Factor A. The Present or Threatened Destruction, Modification, or
Curtailment of Its Habitat or Range
Impoundments
All of the Potem Creek pebblesnail occupied sites (confirmed and
unconfirmed) are in small spring ponds or creeks (Frest and Johannes
1995b, pp. 42, A3, A4, A6-A8, A14, A22, T10-T13, T17, T22, T23;
Hershler et al. 2007, p. 412; Haley 2012, p. 3) and are thus relatively
unlikely to be affected by flow releases from major dams. The three
unconfirmed locations found by Haley (2012, p. 3) are very close to the
edges of the Pit 6 and Pit 7 reservoirs, but we are not aware of any
plans to raise the surface levels of those lakes (which could impede
flows and raise temperatures). The surface level of Shasta Lake may be
raised up to 18.5 ft (5.6 m) if a proposal by USBR to enlarge Shasta
Dam is implemented (see nugget pebblesnail, above), but the closest
occupied location of the Potem Creek pebblesnail (the type location) is
over 350 ft (107 m) above the current elevation of the lake surface,
and would therefore remain unaffected. We conclude that, based on the
best available scientific and commercial information, that the present
or threatened destruction, modification or curtailment of its habitat
or range does not constitute a significant threat to the species.
Factor B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
Our review of the best available scientific and commercial
information yielded nothing to indicate that overutilization for
commercial, recreational, scientific, or educational purposes is
occurring at this time or is likely to occur in the future. We
therefore conclude such overutilization does not constitute a threat to
the Potem Creek pebblesnail.
Factor C. Disease or Predation
Disease
We reviewed the best available scientific and commercial
information regarding this species and other similar species, and found
no evidence to indicate that disease is impacting Potem Creek
pebblesnail populations.
Predation
The Potem Creek pebblesnail occurs in the same general areas as the
canary duskysnail, and may also be subject to predation by the
introduced signal crayfish. Predation by dense crayfish populations can
significantly impact aquatic snails (Lorman and Magnuson 1978, p. 9).
However, our only data regarding signal crayfish density indicates
those densities appear to be holding stable at levels equivalent to
those of the native Shasta crayfish, alongside which the Potem Creek
pebblesnail has evolved (see canary duskysnail, above) (Ellis 1999, p.
58; PGE 2011b, pp. iii, 10; PGE 2012b, p. 9). None of the confirmed or
unconfirmed Potem Creek pebblesnail sites overlap the current range of
the Shasta crayfish, so only the signal crayfish poses a potential
predation impact. Hence, the available evidence does not support the
contention that signal crayfish are present in the range of the Potem
Creek pebblesnail in sufficiently high densities to pose a predation
risk to the Potem Creek pebblesnail. Furthermore, the information does
not indicate any trend in the densities of the signal crayfish that
would lead us to a conclusion that the predation risk would increase in
the future.
We therefore conclude, based on the best available scientific and
commercial information, that neither disease nor predation constitutes
a significant threat to the species now or in the future.
Factor D. The Inadequacy of Existing Regulatory Mechanisms
Under this factor, we examine whether existing regulatory
mechanisms are inadequate to address the threats to the species
discussed under the other factors. Section 4(b)(1)(A) of the Act
requires the Service to take into account ``those efforts, if any,
being made by any State or foreign nation, or any political subdivision
of a State or foreign nation, to protect such species * * * ''. We
interpret this language to require the Service to consider relevant
Federal, State, and Tribal laws and regulations when developing our
threat analyses. Regulatory mechanisms, if they exist, may preclude the
need for listing if we determine that such mechanisms adequately
address the threats to the species such that listing is not warranted.
Having evaluated the significance of the threat as mitigated by any
such conservation efforts, we analyze under Factor D the extent to
which existing regulatory mechanisms are inadequate to address the
specific threats to the species. We found no significant threats to the
Potem Creek pebblesnail under the other factors, therefore, the
analysis of any existing regulatory mechanisms' adequacy to address
threats is not applicable. Consequently, after reviewing the best
available commercial and scientific information, we conclude that the
inadequacy of existing regulatory mechanisms is not a threat to the
Potem Creek pebblesnail now or in the future.
Factor E. Other Natural or Manmade Factors Affecting Its Continued
Existence
Competition with Invasive Species
The New Zealand mudsnail is a potential threat to the Potem Creek
pebblesnail (see canary duskysnail, above). The level of threat is
significantly reduced in the three occupied locations (including the
type location) that are far from the Pit River. Because New Zealand
mudsnails are transported on boats and fishing equipment (NBII 2011,
pp. 1-3), they are less likely to become established in smaller creeks
where boating is not possible and fishing by non-locals is less common.
The seven unconfirmed sites in the upper Sacramento River are at
greater potential risk because New Zealand mudsnails have been reported
at Castle Lake, which is about 5.6 km (3.5 mi) from Siskiyou Lake
(McAlexander 2012a, p. 1; McAlexander 2012b, p. 1). If the New Zealand
mudsnail established itself in Siskiyou Lake, it might then easily wash
down the Sacramento River, potentially establishing anywhere along the
route, which might include any of the seven unconfirmed occupied sites.
Since the Sacramento River occupied sites are unconfirmed, however, and
since the available data does not indicate New Zealand mudsnails will
establish themselves at Lake Siskiyou or points downstream, we do not
consider the New Zealand mudsnail a threat to the continued existence
of the Potem Creek pebblesnail.
Changes in Precipitation and Water Availability Due to Climate Change
See our discussion of climate change in general in the Changes in
Precipitation and Water Availability Due to Climate Change section
under
[[Page 57945]]
``Factor A'' in Five-Factor Evaluation of Threats for the Canary
Duskysnail. Climate change is not expected to significantly change
total precipitation in northern California, but may affect seasonal
water availability in some areas due to changes in snowpack melting
times and in the proportion of precipitation falling as rain rather
than snow (Dettinger et al. 2004, pp. 43, 44). However, the springs
supporting sites occupied by the Potem Creek pebblesnail in the middle
and lower Pit River are supplied by large aquifers of porous lava that
collect and store water from wide areas (see canary duskysnail, above).
The aquifers are therefore able to provide water to the springs at
highly constant flow rates and temperatures, despite fluctuations in
precipitation. We lack information regarding aquifer sizes and
collection ranges for the seven unconfirmed sites in the upper
Sacramento River drainage, but based on the best available scientific
and commercial information and given the general volcanic geology of
the entire area (USNPS 2005, p. 1), we consider it most likely that
these sites also will maintain relatively constant flow rates and water
temperatures despite climate change.
Catastrophic Events--Fire
Siltation caused by fires would be likely to be cleared relatively
quickly by springs in the lower Pit River area (see Goose Valley
pebblesnail, above). We do not know the flow rate of the spring at the
type location of the Potem Creek pebblesnail, however, so fire remains
a concern at that site. However, for a fire at the location to threaten
the species, it would have to be serious enough to produce extensive
siltation; the flow of the spring would have to be insufficient to
flush that siltation; the seven unconfirmed occupied sites in the upper
Sacramento River drainage would have to be unoccupied; and the six
unconfirmed occupied locations in the Pit River drainage, (located at
distances of 6 to 20 km (3.7 to 12.4 mi) from the type location) would
have to be unoccupied or similarly affected by the fire. We consider
such a combination of circumstances unlikely. Additionally, the Potem
Creek pebblesnail occurs on muddy or silty substrates (see Habitat and
Biology, above), and so is likely to be less strongly affected by
siltation than other pebblesnail species.
Summary of Factor E
In summary, the Potem Creek pebblesnail is protected from expected
changes in precipitation or water availability due to climate change by
the particular characteristics of its habitat. Although potential
competition from the New Zealand mudsnail is cause for concern, no site
currently occupied by the Potem Creek pebblesnail has been colonized
and there is nothing to indicate the New Zealand mudsnail will colonize
any of the locations occupied by the Potem Creek pebblesnail. There is
also no direct evidence to show that any such occupied locations would
be extirpated by such a colonization were it to occur. The two species
are not known to have interacted in the past. We consider catastrophic
events such as fire to be unlikely, and the Potem Creek pebblesnail is
likely to be less strongly affected by siltation than other pebblesnail
species. We therefore conclude that, based on the best available
scientific and commercial information, that other natural or manmade
factors such as competition from the New Zealand mudsnail, changes in
precipitation or water availability due to climate change, or fire do
not constitute significant threats to the Potem Creek pebblesnail now
or in the future.
Finding for the Potem Creek Pebblesnail
We have carefully assessed the best scientific and commercial
information available regarding the past, present, and future threats
faced by the Potem Creek pebblesnail. We reviewed the petition,
available published and unpublished scientific and commercial
information, and information submitted to us during our status review.
This finding reflects and incorporates that information. We also
consulted with recognized authorities on this species, and we consulted
with Federal and State resource agencies. Although only 1 confirmed and
13 unconfirmed occupied sites are known for the Potem Creek
pebblesnail, review of the best available information did not indicate
that populations at any site are likely to be extirpated due to
impoundments, overutilization, disease or predation, the inadequacy of
existing regulatory mechanisms, competition with invasive species,
changes in precipitation and water availability due to climate change,
or catastrophic events such as fire, now or in the foreseeable future.
The best available scientific and commercial information at this time
does not indicate that there is likely to be a change in any of these
stressors in the future.
Based on our review of the best available scientific and commercial
information pertaining to the five factors, we find that the threats as
described above either alone or in combination are not of sufficient
imminence, intensity, or magnitude to indicate that the Potem Creek
pebblesnail is in danger of extinction (endangered) or likely to become
endangered within the foreseeable future (threatened), throughout all
of its range.
Significant Portion of the Range
Having determined that the Potem Creek pebblesnail is not
endangered or threatened throughout all of its range, we must next
consider whether there are any significant portions of the range where
the Potem Creek pebblesnail is in danger of extinction or is likely to
become endangered in the foreseeable future. See Significant Portion of
the Range under Summary of Procedures for Determining the Listing
Status of Species.
We evaluated the current range of the Potem Creek pebblesnail to
determine if there is any apparent geographic concentration of
potential threats for the species. The Potem Creek pebblesnail is
highly restricted in its range and the threats occur throughout its
range. We considered the potential threats due to impoundments,
overutilization, disease or predation, the inadequacy of existing
regulatory mechanisms, competition with invasive species, changes in
precipitation and water availability due to climate change, and
catastrophic events such as fire. We found no concentration of threats
that suggests that the Potem Creek pebblesnail may be in danger of
extinction in a portion of its range. We found no portions of its range
where potential threats are significantly concentrated or substantially
greater than in other portions of its range. Therefore, we find that
factors affecting the species are essentially uniform throughout its
range, indicating no portion of the range of the species warrants
further consideration of possible endangered or threatened status under
the Act.
We find that the Potem Creek pebblesnail is not in danger of
extinction now, nor is likely to become endangered within the
foreseeable future, throughout all or a significant portion of its
range. Therefore, listing the Potem Creek pebblesnail as endangered or
threatened under the Act is not warranted at this time.
Shasta Pebblesnail (Fluminicola multifarius)
Species Information for the Shasta Pebblesnail
Taxonomy and Species Description
The Shasta pebblesnail is an aquatic snail that was formally named
and described in 2007 (Hershler et al. 2007, pp. 415-419). This species
combines
[[Page 57946]]
four taxa previously considered likely species, but never formally
described: The Sacramento pebblesnail (Fluminicola n. sp. 1) (Frest and
Johannes 1995b, pp. 42, D14) and three species discussed in Frest and
Johannes 1999 (pp. 39-50), the flat top pebblesnail (Fluminicola n. sp.
15), the Shasta Springs pebblesnail (Fluminicola n. sp. 16), and the
disjunct pebblesnail (Fluminicola n. sp. 17). The latter three were
included under the SMP (USDA and USDI 2007, pp. 169, 252). Although
pebblesnails in general (Fluminicola genus) had previously been
considered part of the Hydrobiidae family (Hershler et al. 2003, p.
275), they have since been reassigned to the Lithoglyphidae family
(Hershler et al. 2007, p. 371).
The shell of the Shasta pebblesnail is 2.3 to 4.6 mm (0.09 to 0.18
in) tall, with a tan, brown, or light green periostracum and 3.25 to
4.5 whorls (Hershler et al. 2007, pp. 417-419). The Shasta pebblesnail
has a high range of shell variation, with shapes ranging from
subglobose to narrowly conic, and lower whorls that are sometimes
loosened from the coiling axis and sometimes not (Hershler et al. 2007,
p. 419). This range of morphological characteristics is the source of
the Shasta pebblesnail's specific name multifarius, meaning ``in
various manners.''
Distribution
Twenty occupied locations of the Shasta pebblesnail are known, 19
of which are in Siskiyou County, California, and the other along the
Sacramento River in Shasta County, California (Hershler et al. 2007,
pp. 415-417). All but two sites are in springs or spring runs, the
exceptions being two sites in the Sacramento River itself, which may be
associated with nearby springs. Five sites are at Mount Shasta City
Park, 11 are along the Sacramento River between Lake Siskiyou and the
southern end of Dunsmuir, and 3 are east of the town of McCloud in
waters that drain into the McCloud River. There is one occupied site on
Shasta-Trinity National Forest land, within the NWFP area, and two
others in the Cantara/Ney Springs State Wildlife Area. The rest (except
for the five mentioned above at Mount Shasta City Park) are on private
property.
Habitat and Biology
The Shasta pebblesnail occurs in cold perennially flowing waters on
substrates ranging from sand to cobbles (Frest and Johannes 1995b, p.
42; Frest and Johannes 1999, pp. 40, 44, 48). It is often associated
with watercress, and it feeds on perilithon and may eat periphyton as
well (Frest and Johannes 1995b, pp. 42, 43; Frest and Johannes 1999, p.
40; Furnish and Monthey 1999, Sect. 2, p. 2). We have no specific
information regarding reproduction for this species, but members of the
Fluminicola genus typically live a single year and breed only once
(Furnish and Monthey 1999, Sect. 2, p. 5; ORNHIC 2004, p. 2). They
generally lay eggs in the spring, which hatch in 2 to 4 weeks. They are
not known to disperse widely, and are highly sensitive to water
pollution, decreases in dissolved oxygen, elevated temperatures, and
sedimentation (Furnish and Monthey 1999, Sect. 2, pp. 5, 7; Hershler et
al. 2007, p. 372).
Five-Factor Evaluation of Threats for the Shasta Pebblesnail
Factor A. The Present or Threatened Destruction, Modification, or
Curtailment of Its Habitat or Range
Impoundments
One occupied site (identified as USNM 1020758) is located in the
main stem of the Sacramento River, about 3 km (1.9 mi) downstream of
Box Canyon Dam, which impounds Lake Siskiyou (Hershler et al. 2007, p.
415). Due to low generating capacity, the dam was exempted in 1982 from
licensing requirements under the Federal Power Act (Siskiyou County and
CDFG 1983a, p. 2). However, the exemption requires Siskiyou County to
comply with requirements established by CDFG for flow releases from the
lake. Those requirements include minimum flow volumes (40 cfs), minimum
dissolved oxygen concentrations (7.0 milligrams per liter (mg/l)), and
procedures to minimize water temperatures during summer months (by
releasing water from the lowest possible depth in the lake) (Siskiyou
County and CDFG 1983a, pp. 2, 3). All of these requirements benefit
Shasta pebblesnails in downstream locations, because the upebblesnails
require cold, well-oxygenated flowing water (see Habitat and Biology,
above). We have obtained monitoring information from 2003, 2004, and
2006 indicating these requirements were consistently met in those years
(Webb 2005, pp. 2-13, 18-29; FERC 2006, p. 2). The maximum recorded
temperature during 2003 and 2004 was 59.2 [deg]F (15.1 [deg]C) (in
October 2003), which is colder than all but one of the average water
temperatures measured in 2009 through 2011 in the Pit 3, 4, and 5
reaches (see Canary duskysnail, above) (PGE 2010, p. 35; PGE 2011, p.
24; PGE 2012, p. 24). Minimum flow requirements were not met for a few
brief periods of 15 minutes or less in 2002, 2005, and 2009 (Webb 2005,
p. 14; FERC 2006, pp. 3, 4; FERC 2009, p. 1), but we do not expect
these to have significantly impacted the Shasta pebblesnails in the
main stem location. Additional water is also supplied to that location
by Ney Creek, which joins the Sacramento River about 0.8 km (0.5 mi)
upstream of the occupied site. Two additional occupied sites are within
a mile downstream (Hershler et al. 2007, p. 417), but these are in
springs and so less likely to be impacted by flow releases from the
dam.
Grazing and Logging
Of the 20 occupied sites, 5 are in a small city park unlikely to be
used for grazing or logging, 2 are on property used as a spiritual
retreat by the St. Germain Foundation, 2 are in the Cantara/Ney Springs
Wildlife Area, and 1 is in the Shasta-Trinity National Forest within
the NWFP boundary and outside of any grazing allotments (Hershler et
al. 2007, p. 417). An eleventh occupied site (in Shasta County) is in a
spring on a thin strip of land between the Union Pacific railroad
tracks and Interstate 5, and thus unlikely to be grazed or logged. This
leaves nine sites for which we lack data regarding potential grazing
impacts. Comparisons of mapped Shasta pebblesnail sites (Hershler et
al. 2007, pp. 404, 405; Service 2012, p. 1) with locations of planned
timber harvests (THP Tracking Center 2012, p. 1) show no THPs have been
filed since 2009 for lands covering any of the 20 occupied sites.
To summarize: (1) Only a few locations occur near impoundments, and
those impoundments are managed to minimize potential impacts; (2) the
locations of 11 of 20 sites makes them unlikely to be grazed or logged;
(3) the remaining 9 sites are not scheduled to be logged in the near
future, but we lack information regarding grazing at those sites. We
conclude that, based on the best available scientific and commercial
information, that the present or threatened destruction, modification
or curtailment of its habitat or range does not constitute a
significant threat to the species.
Factor B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
Our review of the best available scientific and commercial
information yielded nothing to indicate that overutilization for
commercial, recreational, scientific, or educational purposes is
occurring at this time or is likely to occur in the future. We
therefore conclude such overutilization
[[Page 57947]]
does not constitute a threat to the Shasta pebblesnail.
Factor C. Disease or Predation
Disease
We reviewed the best available scientific and commercial
information regarding this species and other similar species, and found
no evidence to indicate that disease is impacting Shasta pebblesnail
populations.
Predation
It is likely the introduced signal crayfish has established itself
in the upper Sacramento River, as well as the Pit River. Predation by
dense crayfish populations can significantly impact aquatic snails
(Lorman and Magnuson 1978, p. 9). However, our only data regarding
signal crayfish densities indicates those densities appear to be
holding stable at levels equivalent to those of the native Shasta
crayfish, alongside which the Shasta pebblesnail has evolved (see
canary duskysnail, above) (Ellis 1999, p. 58; PGE 2011b, pp. iii, 10;
PGE 2012b, p. 9). The known Shasta pebblesnail sites do not overlap the
current range of the Shasta crayfish, so only the signal crayfish poses
a potential predation impact. Hence, the available evidence does not
support the contention that signal crayfish are present in the range of
the Shasta pebblesnail in sufficiently high densities to pose a
predation risk to the Shasta pebblesnail. Furthermore, the information
does not indicate any trend in the densities of the two crayfish that
would lead us to a conclusion that the predation risk would increase in
the future.
We therefore conclude, based on the best available scientific and
commercial information, that neither disease nor predation constitutes
a significant threat to the species now or in the future.
Factor D. The Inadequacy of Existing Regulatory Mechanisms
Under this factor, we examine whether existing regulatory
mechanisms are inadequate to address the threats to the species
discussed under the other factors. Section 4(b)(1)(A) of the Act
requires the Service to take into account ``those efforts, if any,
being made by any State or foreign nation, or any political subdivision
of a State or foreign nation, to protect such species * * *''. We
interpret this language to require the Service to consider relevant
Federal, State, and Tribal laws and regulations when developing our
threat analyses. Regulatory mechanisms, if they exist, may preclude the
need for listing if we determine that such mechanisms adequately
address the threats to the species such that listing is not warranted.
Having evaluated the significance of the threat as mitigated by any
such conservation efforts, we analyze under Factor D the extent to
which existing regulatory mechanisms are inadequate to address the
specific threats to the species. We found no significant threats to the
Shasta pebblesnail under the other factors; therefore, the analysis of
any existing regulatory mechanisms' adequacy to address threats is not
applicable. Consequently, after reviewing the best available commercial
and scientific information, we conclude that the inadequacy of existing
regulatory mechanisms is not a threat to the Shasta pebblesnail now or
in the future.
Factor E. Other Natural or Manmade Factors Affecting Its Continued
Existence
Competition With Invasive Species
The New Zealand mudsnail (see canary duskysnail, above) has been
reported at Castle Lake, which is about 5.6 km (3.5 mi) from Siskiyou
Lake (see Potem Creek pebblesnail, above) (McAlexander 2012a, p. 1;
McAlexander 2012b, p. 1). If the New Zealand mudsnail were to establish
itself in Siskiyou Lake, it could potentially wash down the Sacramento
River, establishing anywhere along the route and thereby potentially
competing directly with the Shasta pebblesnail at 11 of its 20 known
occupied sites, including 2 sites in the river itself and 9 sites in
springs that are close to the river and hydrologically connected to it
(Hershler et al. 2007, pp. 415, 417). If that were to happen, it could
pose a threat to the species. However, the available information does
not indicate that such a scenario is likely. We consider the risk of
infestation to be much lower in springs adjoining the river since the
New Zealand mudsnails could not simply be washed to such locations by
the current. Nine of the eleven Shasta pebblesnail sites in the upper
Sacramento River area are in adjoining springs. Additionally, CDFG is
following a national control plan (ANSTF 2007, entire) and has posted
information and downloadable posters and wallet cards to its Web site
(see canary duskysnail, above) (CDFG undated, p. 1). Accordingly, we do
not consider competition from the New Zealand mudsnail a threat to the
species.
Changes in Precipitation and Water Availability Due to Climate Change
See our discussion of climate change in general in the Changes in
Precipitation and Water Availability Due to Climate Change section
under ``Factor A'' in Five-Factor Evaluation of Threats for the Canary
Duskysnail. Climate change is not expected to significantly change
total precipitation in northern California, but may affect seasonal
water availability in some areas due to changes in snowpack melting
times and in the proportion of precipitation falling as rain rather
than snow (Dettinger et al. 2004, pp. 43, 44). However, the water
supplying many springs in Shasta and Siskiyou Counties is collected
from wide areas and percolates through porous volcanic rocks to collect
in large aquifers, thereby holding extra water from seasons when rain
is plentiful and delivering it through springs during seasons when it
is not (Service 1998, p. 18). Resulting spring flows are generally
highly stable in volume, temperature and clarity (Service 1998, p. 46).
We lack information regarding aquifer sizes and collection ranges for
the specific springs supporting sites occupied by the Shasta
pebblesnail, but given the general volcanic geology of the entire area
(USNPS 2005, p. 1), we consider it most likely that these sites will
maintain relatively constant flow rates and water temperatures despite
climate change. Accordingly, we do not expect changes in precipitation
or water availability due to climate change to significantly affect the
species.
Catastrophic Events--Chemical Spills
In 1991, a Southern Pacific railroad car carrying the herbicide
metam sodium spilled its contents into the upper Sacramento River near
Dunsmuir (Frest and Johannes 1995b, p. 13). The spill eliminated
numerous mollusks from the main stem, but did not eliminate Shasta
pebblesnails from their remaining known occupied sites along the river,
presumably because most of those sites are in springs to the side of
the main stem (Frest and Johannes 1995b, p. 73; Hershler et al. 2007,
pp. 415-417). The flow from those springs would have prevented the
chemical from traveling from the river into the springs themselves. The
one occupied site in the main stem of the river near Dunsmuir is about
500 m (1,640 ft) upstream of the spill site (Frest and Johannes 1995b,
p. F4). Since the time of the spill, the railroad company involved
(Southern Pacific) has been acquired by the Union Pacific, which has
taken several steps to prevent a
[[Page 57948]]
recurrence of the accident. These steps include regrading the section
of track, replacing the wooden ties with concrete ties, lowering the
maximum length of trains operating in the area, reducing the maximum
speed, upgrading locomotives, and requiring locomotives to be spread
more evenly throughout each train (Darling 2011, p. 4). If such a spill
were to recur, most Shasta pebblesnail populations would again be
protected by their location in springs and spring runs outside the main
stem flow.
Summary of Factor E
In summary, the Shasta pebblesnail is protected from expected
changes in precipitation or water availability due to climate change by
the particular characteristics of its habitat. Although potential
competition from the New Zealand mudsnail is cause for concern, no site
currently occupied by the Shasta pebblesnail has been colonized and
there is nothing to indicate the New Zealand mudsnail will colonize any
of the locations occupied by the Shasta pebblesnail. There is also no
direct evidence to show that any such occupied locations would be
extirpated by such a colonization were it to occur. The two species are
not known to have interacted in the past. If a chemical spill were to
occur, most Shasta pebblesnail populations would be protected by their
location in springs and spring runs outside the main stem flow. We
therefore conclude that, based on the best available scientific and
commercial information, that other natural or manmade factors such as
competition from the New Zealand mudsnail, changes in precipitation or
water availability due to climate change, or chemical spills do not
constitute significant threats to the Shasta pebblesnail now or in the
future.
Finding for the Shasta Pebblesnail
We have carefully assessed the best scientific and commercial
information available regarding the past, present, and future threats
faced by the Shasta pebblesnail. We reviewed the petition, available
published and unpublished scientific and commercial information, and
information submitted to us during our status review. This finding
reflects and incorporates that information. We also consulted with
recognized authorities on this species and Federal and State resource
agencies. Although only 20 occupied sites are known for the Shasta
pebblesnail, a review of the best available information does not
indicate that populations at any site are likely to be extirpated due
to impoundments, grazing and logging, overutilization, disease or
predation, the inadequacy of existing regulatory mechanisms,
competition with invasive species, changes in precipitation and water
availability due to climate change, or catastrophic events such as
chemical spills, now or in the foreseeable future. The best available
scientific and commercial information at this time does not indicate
that there is likely to be a change in any of these stressors in the
future.
Based on our review of the best available scientific and commercial
information pertaining to the five factors, we find that the threats as
described above either alone or in combination are not of sufficient
imminence, intensity, or magnitude to indicate that the Shasta
pebblesnail is in danger of extinction (endangered) or likely to become
endangered within the foreseeable future (threatened), throughout all
of its range.
Significant Portion of the Range
Having determined that the Shasta pebblesnail is not endangered or
threatened throughout all of its range, we must next consider whether
there are any significant portions of the range where the Shasta
pebblesnail is in danger of extinction or is likely to become
endangered in the foreseeable future. See Significant Portion of the
Range under Summary of Procedures for Determining the Listing Status of
Species.
We evaluated the current range of the Shasta pebblesnail to
determine if there is any apparent geographic concentration of
potential threats for the species. The Shasta pebblesnail is highly
restricted in its range and the threats occur throughout its range. We
considered the potential threats due to impoundments, grazing and
logging, overutilization, disease or predation, the inadequacy of
existing regulatory mechanisms, competition with invasive species,
changes in precipitation and water availability due to climate change,
and catastrophic events such as chemical spills. We found no
concentration of threats that suggests that the Shasta pebblesnail may
be in danger of extinction in a portion of its range. We found no
portions of its range where potential threats are significantly
concentrated or substantially greater than in other portions of its
range. Therefore, we find that factors affecting the species are
essentially uniform throughout its range, indicating no portion of the
range of the species warrants further consideration of possible
endangered or threatened status under the Act.
We find that the Shasta pebblesnail is not in danger of extinction
now, nor is likely to become endangered within the foreseeable future,
throughout all or a significant portion of its range. Therefore,
listing the Shasta pebblesnail as endangered or threatened under the
Act is not warranted at this time.
References Cited
A complete list of references cited is available on the Internet at
https://www.regulations.gov and upon a request to the Sacramento Fish
and Wildlife Office (see ADDRESSES section).
Authors
The primary authors of this notice are the staff members of the
Sacramento Fish and Wildlife Office.
Authority
The authority for this action is section 4 of the Endangered
Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).
Dated: September 5, 2012.
Rowan W. Gould,
Acting Director, Fish and Wildlife Service.
[FR Doc. 2012-22723 Filed 9-17-12; 8:45 am]
BILLING CODE 4310-55-P
