Endangered and Threatened Wildlife and Plants; Removal of the Utah (Desert) Valvata Snail From the Federal List of Endangered and Threatened Wildlife, 52272-52282 [2010-20517]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 75, Number 164 (Wednesday, August 25, 2010)]
[Rules and Regulations]
[Pages 52272-52282]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-20517]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R1-ES-2008-0084; [92220-1113-0000-C6]
RIN 1018-AW16


Endangered and Threatened Wildlife and Plants; Removal of the 
Utah (Desert) Valvata Snail From the Federal List of Endangered and 
Threatened Wildlife

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: Under the authority of the Endangered Species Act of 1973, as 
amended (Act), we, the U.S. Fish and Wildlife Service (Service), are 
removing the Utah (desert) valvata snail (Valvata utahensis) from the 
Federal List of Endangered and Threatened Wildlife (List). Based on a 
thorough review of the best available scientific and commercial data, 
we determined that the Utah valvata snail is more widespread and occurs 
in a greater variety of habitats in the Snake River than known at the 
time of listing in 1992. We now know the Utah valvata snail is not 
limited to areas of cold-water springs or spring outflows; rather, it 
persists in a variety of aquatic habitats, including cold-water 
springs, spring creeks and tributaries, the mainstem Snake River and 
associated tributary stream habitats, and reservoirs influenced by dam 
operations. Given our current understanding of the species' habitat 
requirements and threats, the species does not meet the definition of 
an endangered or threatened species under the Act. Therefore, we are 
removing the Utah valvata snail from the List, thereby removing all 
protections provided by the Act.

DATES: This effective date of this rule is September 24, 2010.

ADDRESSES: This final rule is available on the Internet at https://www.regulations.gov and at https://www.fws.gov/idaho. Comments and 
materials received, including supporting documentation used in 
preparing this rule, will be available for public inspection, by 
appointment, during normal business hours at the U.S. Fish and Wildlife 
Service, Idaho Fish and Wildlife Office, 1387 S. Vinnell Way, Room 368, 
Boise, ID 83709; by telephone.

FOR FURTHER INFORMATION CONTACT: Brian Kelly, State Supervisor, at the 
above address; by telephone 208-378-5243; or by fax at 208-378-5262 e-
mail at: fw1srbocomment@fws.gov. Persons who use a telecommunications 
device for the deaf (TDD) may call the Federal Information Relay 
Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION: 

Background

    The Utah valvata snail (Valvata utahensis) was first recognized as 
a species in 1902, based on specimens collected from Utah Lake and Bear 
Lake, Utah (Walker 1902, p. 125). Its common name has since been 
changed by the American Fisheries Society to the ``desert valvata'' in 
the benchmark text for aquatic invertebrate nomenclature, Common and 
Scientific Names of Aquatic Invertebrates from the United States and 
Canada (Turgeon et al. 1998, p. 109), presumably due to the fact that 
it is no longer known to occur in Utah. However, because the species is 
currently listed in the Code of Federal Regulations as the Utah valvata 
snail, Valvata utahensis will be referred to as the Utah valvata snail 
throughout this final rule.

Range

    The Utah valvata snail, or at least its closely related ancestors, 
has been described as ranging widely across the western United States 
and Canada as far back as the Jurassic Period, 199.6  0.6 
to 145.5  4 million years ago (Taylor 1985a, p. 268). 
Fossils of the Utah valvata snail are known from Utah to California 
(Taylor 1985a, pp. 286-287). The Utah valvata snail was likely present 
in the ancestral Snake River as it flowed south from Idaho, through 
Nevada, and into northeastern California (Taylor 1985a, p. 303). The 
Snake River's course changed to join the Columbia River Basin 
approximately 2 million years ago (Hershler and Liu 2004, pp. 927-928).

[[Page 52273]]

    At the time of listing in 1992 (57 FR 59244, December 14, 1992), we 
reported the range of the Utah valvata snail as being limited to a few 
springs and mainstem Snake River sites in the Hagerman Valley, Idaho 
(River Mile (RM) 585), a few sites above and below Minidoka Dam (RM 
675), and immediately downstream of American Falls Dam (RM 709).
    New data collected since the time of listing indicate that the Utah 
valvata snail is discontinuously distributed in at least 255 miles (410 
kilometers (km)) of the Snake River and some associated tributary 
streams, an increase of nearly 122 river miles (196 km) from the known 
range at the time of listing. Their current range in the Snake River 
extends from RM 585 near the Thousand Springs Preserve (Bean in litt. 
2005), upstream to the confluence of the Henry's Fork with the Snake 
River (RM 837; Fields 2005, p. 11). Colonies of the Utah valvata snail 
have been found in the Snake River near the towns of Firth (RM 777.5), 
Shelley (RM 784.6), Payne (RM 802.6), and Roberts (RM 815), and in the 
Henry's Fork approximately 9.3 miles (15 km) upstream from its 
confluence with the Snake River (at Snake RM 832.3) (Gustafson in litt. 
2003). Based on limited mollusk surveys, the species has not been found 
upstream from the described location on the Henry's Fork or in the 
South Fork of the Snake River. Tributary streams to the Snake River 
where Utah valvata snails have been collected include Box Canyon Creek 
(RM 588) (Taylor 1985b, pp. 9-10), and one location in the Big Wood 
River (Wood River Mile (WRM) 35) (USBR 2003, p. 22).

Habitat Use

    At the time of listing in 1992, the best available data indicated 
that Utah valvata snails ``characteristically require cold, fast water, 
or lotic habitats * * * in deep pools adjacent to rapids or in 
perennial flowing waters associated with large spring complexes'' (57 
FR 59244, December 14, 1992). In numerous field studies conducted since 
then, the species has been collected at a wide range of water depths, 
ranging from less than 3.2 feet (1 meter) (Stephenson and Bean 2003, 
pp. 98-99) to depths greater than 45 feet (14 meters) (USBR 2003, p. 
20), and at temperatures between 37.4 and 75.2 degrees Fahrenheit (F) 
(4 to 24 degrees Celsius (C)) (Lysne in litt. 2007; Gregg in litt. 
2006).
    Work conducted by the Idaho Department of Fish and Game (IDFG) in 
the upper Snake River demonstrated that Utah valvata snail presence was 
positively correlated with water depth (up to 18.37 feet (5.6 meters)) 
and temperature (up to 63 degrees F (17.2 degrees C)) (Fields 2005, pp. 
8-9), and Utah valvata snail density was positively correlated with 
macrophyte (a water plant large enough to be observed with the unaided 
eye) coverage, water depth, and temperature (Fields 2006, p. 6). 
Similarly, Hinson (2006, pp. 28-29) analyzed available data from 
several studies conducted by the U.S. Bureau of Reclamation (USBR) 
(2001-2004), Idaho Power Company (IPC) (1995-2002), IDFG, Idaho 
Transportation Department (2003-2004) and others, and demonstrated a 
positive relationship between Utah valvata snail presence and 
macrophytes, water depth, and fine substrates. One study reported Utah 
valvata snails in organically enriched fine sediments with a heavy 
macrophyte community, downstream of an aquaculture facility (RM 588) 
(Hinson 2006, pp. 31-32).
    Survey data and information reported since the time of listing 
demonstrate that the Utah valvata snail is able to live in reservoirs, 
which were previously thought to be unsuitable for the species (Frest 
and Johannes 1992, pp. 13-14; USBR 2002, pp. 8-9; Fields 2005, p. 16; 
Hinson 2006, pp. 23-33). We now know the Utah valvata snail persists in 
a variety of aquatic habitats, including cold-water springs, spring 
creeks and tributaries, the mainstem Snake River and associated 
tributary stream habitats, and reservoirs.
    Alterations of the Snake River, including the construction of dams 
and reservoir habitats, have changed fluvial processes resulting in the 
reduced likelihood of naturally high river flows or rapid changes in 
flows, and the retention of fine sediments (U.S. Environmental 
Protection Agency (USEPA) 2002, pp. 4.30-4.31), which may also increase 
potential habitat for the species (e.g., Lake Walcott and American 
Falls Reservoirs; however, see Summary of Factors Affecting the Species 
below for a discussion of the effects of rapidly drawing down 
reservoirs). Utah valvata snail surveys conducted downstream from 
American Falls Dam (RM 714.1) to Minidoka Dam (RM 674.5), from 1997 and 
2001-2007, consistently found Utah valvata snails on fine sediments 
within this 39-mile (62.9 km) river/reservoir reach of the Snake River 
(USBR 1997, p. 4; USBR 2003, p. 8; USBR 2004, p. 5; USBR 2005, p. 6; 
USBR 2007, pp. 9-11; USFWS 2005, p. 119). Surveys conducted downstream 
of Minidoka Dam (RM 674.5) to Lower Salmon Falls Dam (RM 573.0) have 
also documented Utah valvata snails in that reach, including one record 
from the tailrace area of Minidoka Dam (the downstream part of a dam 
where the impounded water reenters the river) in 2001 (USFWS 2005, p. 
120).
    In summary, based on available data, the Utah valvata snail is not 
as specialized in its habitat needs as we thought at the time of 
listing. In the Snake River, the species inhabits a diversity of 
aquatic habitats throughout its 255-mile (410 km) range, including 
cold-water springs, spring creeks and tributaries, mainstem and free-
flowing waters, reservoirs, and impounded reaches. The species occurs 
on a variety of substrate types including both fine sediments and more 
coarse substrates in areas both with and without macrophytes. It has 
been collected at water depths ranging from less than 3.2 feet (1 
meter) to greater than 45 feet (14 meters), and at water temperatures 
ranging from 37.4 to 75.2 degrees F (3 to 24 degrees C).

Population Density

    Like many short-lived and highly fecund invertebrates, the density 
of Utah valvata snails at occupied sites can vary greatly. For example, 
at one cold-water spring site at the Thousand Springs Preserve, Utah 
valvata snail density in 2003 ranged between 0 and 1,724 snails per 
square meter (/m\2\), with an average of 197 snails/m\2\ (Stephenson et 
al. 2004, p. 23). In the mainstem Snake River between American Falls 
Reservoir and Minidoka Dam in 2002, Utah valvata snail densities 
averaged 91 snails/m\2\ (ranging from 0 to 1,188 snails/m\2\), and in 
American Falls Reservoir densities averaged 50 snails/m\2\ (range 
unavailable) (USBR 2003, p. 20). In 2008 and 2009, monitoring efforts 
were carried out at sites first monitored by the USBR in the late 1990s 
and early 2000s below American Falls Reservoir, which is a free-flowing 
riverine environment (Gates in litt. 2009). Monitoring results indicate 
these specific colonies have decreased in density and proportional 
occurrence compared to results from the late 1990s and early 2000s, 
with the greatest densities found in 2009 ranging from 4 to 24 snails/
m\2\ and presence ranging from 5 to 9 percent (Gates in litt. 2009). 
However, 2009 monitoring sites do not represent a comprehensive survey 
of the area below American Falls Reservoir as only two of the four 
largest colonies sampled in 2008 were sampled in 2009 (Gates in litt. 
2009). Above American Falls Reservoir in the mainstem Snake River, Utah 
valvata snail densities sampled in 2004 at six sites averaged 117 
snails/m\2\ (ranging from 0 to 1,716 snails/m\2\) (Fields 2006, pp. 12-
13).

[[Page 52274]]

    Within occupied reservoirs, the proportional occurrence of snails 
is relatively high. For all field studies and surveys, lower Lake 
Walcott Reservoir had the highest proportional occurrence (USBR 2002, 
p. 5; USBR 2003, p. 6). For sample years 2001 to 2006, the relative 
proportion of samples containing Utah valvata snails ranged from 40 (in 
2004) to 62 (in 2002) percent of samples collected. Similarly, American 
Falls reservoir samples contained a high proportion of Utah valvata 
snails, with the species detected in 21 (in 2001) to 33 (in 2003) 
percent of samples. Such high proportional occurrence in reservoirs 
over multiple years is additional evidence that Utah valvata snails are 
using reservoir habitats and are not restricted to cold-water springs 
or their outflows.

Previous Federal Actions

    We listed the Utah valvata snail as endangered on December 14, 1992 
(57 FR 59244). Based on the best available data at that time we 
determined that the Utah valvata snail was threatened by proposed 
construction of new hydropower dams, the operation of existing 
hydropower dams, degraded water quality, water diversions, the 
introduced New Zealand mudsnail (Potamopyrgus antipodarum), and the 
lack of existing regulatory protections (57 FR 59244). In 1995, we 
completed the Snake River Aquatic Species Recovery Plan (Plan), which 
included the Utah valvata snail. We have not designated critical 
habitat for this species.
    On April 11, 2006, we initiated a 5-year review of the species' 
status (71 FR 18345) in accordance with section 4(c)(2) of the 
Endangered Species Act of 1973, as amended (Act; 16 U.S.C. 1531 et 
seq.). On December 26, 2006, the Service received a petition from the 
Governor of Idaho and attorneys from several irrigation districts and 
canal districts requesting that we remove the Utah valvata snail from 
the List. On June 6, 2007, the Service published a Federal Register 
notice announcing that the petition presented substantial scientific 
information indicating that removing the Utah valvata snail from the 
List may be warranted, and initiating a status review (72 FR 31264). As 
part of our best available scientific and commercial data analysis, we 
conducted a 30-day peer review on a draft status-review document, which 
was completed in September 2007 (USFWS in litt. 2007).
    On July 16, 2009, we published a warranted 12-month finding on the 
delisting petition and a proposed rule to remove the Utah valvata snail 
from the Federal List of Endangered and Threatened Wildlife (74 FR 
34539). We solicited data and comments from the public on the proposed 
rule. The comment period opened on July 16, 2009, and closed on 
September 14, 2009. A summary of the comments we received and our 
responses are provided below.

Summary of Comments and Responses

    In accordance with our policy on peer review, published on July 1, 
1994 (59 FR 34270), we solicited scientific peer review from four 
appropriate and independent experts following publication of the 
proposed rule. Reviewers were asked to review the proposed rule to help 
ensure our use of the best available scientific and commercial data, 
and to maximize the quality, objectivity, thoroughness, and utility of 
the information upon which the final rule is based. One of the peer 
reviewers submitted comments which we summarize and respond to below.

Peer Review Comments and Responses

    (1) Comment: New monitoring data collected in the Vista/Neeley 
section of the Snake River below American Falls Reservoir (RM 713; a 
free flowing riverine environment) from 2008 and 2009 indicate lower 
Utah valvata snail densities than were observed during surveys in the 
late 1990s and early 2000s. These data, along with other preliminary 
sampling results provided, suggest that Utah valvata snail populations 
can experience large fluctuations in population size within and among 
years.
    Our Response: We thank the peer reviewer for the additional 
monitoring data, which we have incorporated into this final rule.
    While the Utah valvata snail population appears to have declined 
between 2002 and 2009 in the Vista/Neeley section (RM 713) of the Snake 
River, it should be noted that different collection methods and sample 
sizes used for data collection limit our ability to precisely quantify 
site-specific Utah valvata snail population declines. Also, the data 
reported are from a small portion (within 1.92 miles (3.2 km)) (USBR 
2003, p. 4) of the 255-river-mile (410 km) range of the Utah valvata 
snail in the Snake River and tributary streams. Lastly, the 2009 
monitoring sites do not represent a comprehensive survey of the reach 
below American Falls dam because they were based on only two of the 
four largest colonies that were sampled in 2008.
    Compared to vertebrate species, most invertebrates have short 
generation times, small body size, and rapid rates of population 
increase and decline. For these reasons, invertebrate populations 
frequently undergo large fluctuations in size and may vary greatly 
between years due to environmental parameters and other factors 
affecting habitat (Ricklefs 1979, pp. 509-510; Murphy et al. 1990, p. 
41).
    In general, consistent, long-term monitoring of population 
abundance and persistence throughout the range of the Utah valvata 
snail is lacking. This limits our ability to calculate reliable 
estimates of population trends. In the case of Utah valvata snails, 
although there appears to be large interannual variation in population 
numbers at the few sites for which we have monitoring data, such as in 
the Vista/Neeley section of the Snake River, this is not necessarily an 
indication that the species' status has degraded or that the species is 
undergoing a long-term population decline.
    (2) Comment: The peer reviewer stated that the greatest threat to 
the Utah valvata snail is from annual dewatering of the Snake River 
below the mainstem dams. Annual water drawdowns expose hundreds of 
meters of littoral zone habitat in the Vista/Neeley and Coldwater 
sections of the Snake River within a period of days.
    Our Response: In making our delisting determination, we evaluated 
several threat factors, including the operation of existing hydropower 
dams. Within the Vista/Neeley section below American Falls reservoir, 
Utah valvata snails are able to re-colonize most submerged zones during 
summer high flows (USFWS 2005, p. 127). Although up to 54 percent of 
the Utah valvata population in the Neeley reach may be subject to 
desiccation from annual water withholdings upstream for storage, 
existing operations by the Bureau of Reclamation that provide minimum 
flows (350 cubic feet per second (cfs)) below American Falls Dam (USFWS 
2005, p. 25) are likely to provide for a viable population there (USFWS 
2005, pp. 127-128). While annual drawdowns are likely to negatively 
affect Utah valvata snail populations in certain years, the best 
available data indicate that these drawdowns are not likely to lead to 
significant, long-term population declines (USFWS 2005, pp. 127-128).
    A complete review and evaluation of the threats affecting the Utah 
valvata snail, including a discussion of our rationale in assessing 
those threats, is presented in the Summary of Factors Affecting the 
Species section of this rule.
    (3) Comment: The peer reviewer stated that 10 years of data 
indicate the continued coexistence of the Utah

[[Page 52275]]

valvata snail and New Zealand mudsnails in the Vista/Neeley section of 
the Snake River (RM 713), which implies that the New Zealand mudsnail 
is not considered a threat to the persistence of the Utah valvata 
snail. However, the peer reviewer recommends future population 
monitoring at these sites.
    Our Response: The Service would like to thank the peer reviewer for 
the data and comments. A complete review and evaluation of the threat 
of the New Zealand mudsnail, including a discussion of our rationale in 
assessing those threats, is presented in the Summary of Factors 
Affecting the Species section of this rule.

Public Comments and Responses

    During the 60-day comment period on the proposed rule, we received 
four public comments, in addition to the peer review comment. Public 
comments that provided new substantive information were incorporated 
into this final rule, and are addressed below.
    (4) Comment: The State of Idaho's Office of Species Conservation, 
along with three canal companies and four irrigation districts, 
supports the proposal to delist the Utah valvata snail based on new 
information regarding its distribution and habitat requirements. There 
are several management plans and measures, not identified in the 
proposed rule, which will likely benefit the Utah valvata snail by 
increasing Snake River flows including: The Nez Perce Water Rights 
Agreement, the Bell Rapids Mutual Irrigation Company Water Rights 
Purchase, and recent aquifer management planning projects within the 
range of the Utah valvata snail. In addition, information was provided 
that the 2004 Idaho Power Company Integrated Resource Plan does not 
identify new hydropower projects within the range of the Utah valvata 
snail.
    Our Response: We thank the State of Idaho and others for the 
additional information. We have incorporated the relevant information 
into the Summary of Factors Affecting the Species section below.
    (5) Comment: Several commenters provided new data and information 
regarding the ecology and threat factors affecting the Utah valvata 
snail. One commenter said that competition between the Utah valvata 
snail and the nonnative, invasive New Zealand mudsnail may be a more 
significant threat than we described, and therefore we should further 
consider the effects of the New Zealand mudsnail and other invasive 
species on the Utah valvata snail before removing it from the Federal 
List of Endangered and Threatened Wildlife. In addition, this commenter 
stated that the effects of climate change represent a new threat to the 
Utah valvata snail and its habitat and should be addressed and analyzed 
in the final rule.
    Our Response: We thank the commenters who provided new information 
and data for our consideration in making this final determination. We 
have evaluated the available scientific and commercial data regarding 
the Utah valvata contained in reports, biological assessments and 
opinions, published journal articles, and other documents.
    Our knowledge and understanding of the habitat needs of the Utah 
valvata snail has changed substantially since the species was listed in 
1992. Survey data collected since 1992 indicate that the geographic 
range of the species in the Snake River is approximately 122 river 
miles (196 km) larger than known at the time of listing, that it occurs 
in a variety of substrate types (e.g., fines to cobble size) and flows, 
and that it tolerates a range of water-quality parameters.
    Surveys have shown the New Zealand mudsnail frequently co-occurs 
with the Utah valvata snail and may compete for habitat or food. 
Although the New Zealand mudsnail has been reported at extremely high 
densities in the middle Snake River (Richards et al. 2001, p. 375), and 
at moderate-to-high densities at five sites in tributaries to the Snake 
River and the Snake River above American Falls Reservoir, there is no 
evidence that after 20 years of co-occurrence the New Zealand mudsnail 
has caused local extirpations of the Utah valvata snail.
    Regarding climate change, there is compelling evidence that we are 
living in a time of rapid, worldwide climate change. For example, 11 of 
the 12 years from 1995-2006 rank among the 12 warmest years since 1850 
(Independent Scientific Advisory Board (ISAB) 2007, p. iii). In the 
Pacific Northwest, regionally averaged temperatures have risen 1.5 
degrees F (0.8 degrees C) over the last century, and are projected to 
increase by another 3 to 10 degrees F (1.5 to 5.5 degrees C) over the 
next 100 years (Mote et al. 2003, p. 54; Karl et al. 2009, p. 135). 
While the specific effects of global climate change on the Utah valvata 
snail are unclear, aquatic species and their habitats may be 
particularly vulnerable to changes in temperatures and precipitation 
patterns. Nevertheless, our current understanding of the Utah valvata 
snail is that it occurs in a variety of substrate types (e.g., fines to 
cobble size), flows, and depths, and tolerates a range of water-quality 
parameters, including elevated water temperatures.
    Our updated evaluation of the threat factors, including climate 
change, to the Utah valvata snail is presented in the Summary of 
Factors Affecting the Species section of this final rule.
    (6) Comment: One commenter stated that populations believed to be 
Utah valvata snails may in fact be Valvata humeralis, and therefore 
recommended that we positively identify all Utah valvata snail 
populations, through genetic analysis, before removing them from the 
Federal List of Endangered and Threatened Wildlife.
    Our Response: Studies and surveys have documented the Valvata 
humeralis snail often co-occurs with the Utah valvata snail. Although 
these two species possess many similar morphological characteristics, 
they can be distinguished through variations in shell morphology. The 
Utah valvata possesses a taller shell spire and more prominent carinae 
than the Valvata humeralis (Burch 1989, pp. 82-83; Walker 1902, pp. 
121-125). Miller et al. (2006b, pp. 3-4) confirmed through genetic 
analysis that the Utah valvata snail and Valvata humeralis are distinct 
species and demonstrated that the species can be effectively 
distinguished using morphological characteristics (i.e., the 
morphological data aligned with the genetic data).
    The Service, along with other agencies and researchers, use the 
difference in shell morphology as the primary method to differentiate 
between these two species. While we acknowledge, given morphological 
similarities, there is potential to confuse individuals of these two 
species where they co-occur (Miller et al. 2006b, p. 1), genetic data 
confirm Utah valvata snail occurrence at multiple sites within the 
geographic range described at the beginning of this document (Miller et 
al. 2006b, entire). Therefore, the Service believes that additional 
genetic testing of all Utah valvata snail populations for 
identification purposes is unnecessary.

Summary of Factors Affecting the Species

    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 List of 
Endangered and Threatened Wildlife (List).
    Under section 4 of the Act, a species may be determined to be 
endangered or threatened on the basis of any of the following five 
factors: (A) Present or threatened destruction, modification, or 
curtailment of habitat or range; (B)

[[Page 52276]]

overutilization for commercial, recreational, scientific, or 
educational purposes; (C) disease or predation; (D) inadequacy of 
existing regulatory mechanisms; or (E) other natural or manmade factors 
affecting its continued existence. We must consider these same five 
factors in delisting a species. We may delist a species according to 50 
CFR 424.11(d) if the best available scientific and commercial data 
indicate that the species is neither endangered nor threatened for the 
following reasons: (1) The species is extinct; (2) the species has 
recovered and is no longer endangered or threatened; or (3) the 
original scientific data used at the time the species was classified 
were in error.
    A species is ``endangered'' for purposes of the Act if it is in 
danger of extinction throughout all or a significant portion of its 
range and is ``threatened'' if it is likely to become endangered within 
the foreseeable future throughout all or a significant portion of its 
range.

Factor A. The Present or Threatened Destruction, Modification, or 
Curtailment of the Species' Habitat or Range

Construction of New Hydropower Dams
    In our 1992 final rule listing the Utah valvata snail as an 
endangered species, we stated: ``Six proposed hydroelectric projects, 
including two high dam facilities, would alter free flowing river 
reaches within the existing range of [the Utah valvata snail]. Dam 
construction threatens the [Utah valvata snail] through direct habitat 
modification and moderates the Snake River's ability to assimilate 
point and non-point pollution. Further hydroelectric development along 
the Snake River would inundate existing mollusc habitats through 
impoundment, reduce critical shallow, littoral shoreline habitats in 
tailwater areas due to operating water fluctuations, elevate water 
temperatures, reduce dissolved oxygen levels in impounded sediments, 
and further fragment remaining mainstem populations or colonies of 
these snails'' (57 FR 59251).
    Since the time of listing, proposed hydroelectric projects 
discussed in the 1992 final rule are no longer moving forward. The A.J. 
Wiley project and Dike Hydro Partners preliminary permits have lapsed; 
the Kanaka Rapids, Empire Rapids, and Boulder Rapids permits were 
denied by the Federal Energy Regulatory Commission (FERC) in 1995; 
there was a notice of surrender of the preliminary permit for the River 
Side Project in 2002; and two other proposed projects, the Eagle Rock 
and Star Falls Hydroelectric Projects, were denied preliminary permits 
by the FERC. In 2003, a notice was provided of surrender of preliminary 
permit for the Auger Falls Project. Information provided by the State 
of Idaho indicates that all proposals and preliminary permits for the 
construction of new dams along the mid-Snake River have either lapsed 
or been denied by the FERC (Caswell in litt. 2006). In addition, the 
2006 IPC Integrated Resource Plan does not identify any new, large 
hydropower projects within the Snake River (IPC 2006, p. 57). Lastly, 
recent studies have shown that the Utah valvata snail is not as limited 
in its geographic range or habitat needs as we had thought at the time 
of listing (see Background section above).
Operation of Existing Hydropower Dams
    In the 1992 final rule, we discussed peak-loading, the practice of 
artificially raising and lowering river levels to meet short-term 
electrical needs by local run-of-the-river hydroelectric projects, as a 
threat to the Utah valvata snail. We also stated, as was our 
understanding at the time, that the Utah valvata snail ``cannot 
tolerate true impoundment or reservoir conditions'' (57 FR 59248). 
Studies conducted since the time of listing have shown the Utah valvata 
snail is able to persist in reservoirs and in areas downstream of peak-
loading dams, contrary to our understanding of the species at the time 
of listing (USFWS 2005, pp. 105, 127-128; 57 FR 59244, 59245). For 
example, Lake Walcott (RM 702.5 to 673.5; upstream of Minidoka Dam) 
appears to contain the largest population of Utah valvata snails in the 
Snake River system (USFWS 2005, pp. 111-112). This is likely due to 
relatively good water quality in the reservoir compared to downstream 
sections of the Snake River near Hagerman where water quality is 
influenced by agricultural, municipal, and aquaculture flows into the 
river. In lower Lake Walcott, there is a large area of suitable Utah 
valvata snail habitat that remains submerged despite annual drawdowns 
during the irrigation season (the reservoir fluctuates up to 5 feet 
(1.5 meters) annually, thereby limiting the number of snails affected 
by dewatering and desiccation). Further, surveys conducted in the 
mainstem Snake River in 1997, 1998, and 2001 from American Falls Dam 
(RM 714.1) to Lake Walcott (RM 702.5) indicate a fairly large and 
viable population of Utah valvata snails even though shoreline habitats 
in this stretch undergo annual dewatering (USFWS 2005, p. 119). In 
American Falls reservoir, dam operations and fluctuating flows have 
been estimated to kill between 5 and 40 percent of the Utah valvata 
snails through dewatering and desiccation of their habitat in most 
years. Nevertheless, Utah valvata snails continue to persist in both 
American Falls and Lake Walcott reservoirs with relatively high 
proportional occurrence (USFWS 2005, p. 119).
Degraded Water Quality
    In the 1992 final listing rule, we stated: ``The quality of water 
in [snail] habitats has a direct effect on the species [sic] survival. 
The [Utah valvata snail] require[s] cold, well-oxygenated unpolluted 
water for survival. Any factor that leads to deterioration in water 
quality would likely extirpate [the Utah valvata snail]'' (57 FR 
59252). As described above in the Species Information section, our 
understanding of the species' habitat requirements has changed 
substantially since 1992. Furthermore, new information has become 
available indicating (a) improvements to Snake River water quality 
where the species lives, and (b) that Utah valvata snails inhabit and 
persist in reaches of the Snake River rich in nutrients (e.g., nitrogen 
and phosphorus).
    Factors that are known to degrade water quality in the Snake River 
include reduced water flow, warming due to impoundments, and increases 
in the concentration of nutrients, sediment, and pollutants reaching 
the river from agricultural and aquaculture inputs (USFWS 2005, p. 
106). In the 1990s and early 2000s, several water-quality assessments 
were completed for the Snake River by the USEPA, USBR, U.S. Geological 
Survey (USGS), and IPC. All of these assessments generally demonstrate 
that water quality in the Snake River of southern Idaho meets Idaho's 
water-quality criteria for the protection of aquatic life for some 
months of the year, but may be poor in reservoirs or during summer when 
temperatures are high and flows are low (Clark et al. 1998, pp. 20-21, 
24-27; Clark et al. 2004, pp. 38-40; Clark and Ott 1996, p. 553; Clark 
1997, pp. 1-2, 19; Meitl 2002, p. 33).
    Several reaches of the Snake River are classified as water-quality-
impaired due to the presence of one or more pollutants (e.g., Total 
Phosphorus (TP), sediments, total coliforms) in excess of State or 
Federal guidelines. Nutrient-enriched waters primarily enter the Snake 
River via springs, tributaries, fish-farm effluents, municipal waste-
treatment facilities, and irrigation returns (USEPA 2002, pp. 4-18 to 
4-24). Irrigation water returned to rivers is generally warmer, 
contains pesticides or pesticide byproducts, has been enriched with 
nutrients from agriculture (e.g.,

[[Page 52277]]

nitrogen and phosphorous), and frequently contains elevated sediment 
loads. Pollutants in fish-farm effluent include nutrients derived from 
metabolic wastes of the fish and unconsumed fish food, disinfectants, 
bacteria, and residual quantities of drugs used to control disease 
outbreaks. Elevated levels of fine sediments, nitrogen, and trace 
elements (including cadmium, chromium, copper, lead, and zinc) have 
been measured immediately downstream of several aquaculture discharges 
(Hinson 2003, pp. 42-45). Additionally, concentrations of lead, 
cadmium, and arsenic have been detected in snails collected from the 
Snake River (Richards in litt. 2003).
    The effects of pollutants detected in the Snake River (e.g., 
metals, pesticides, excess nutrients) on the growth, reproduction, and 
survival of the Utah valvata snail have not been evaluated. The Utah 
valvata snail has been documented to occur in low-oxygen, organically-
enriched sediments with heavy macrophyte communities downstream of an 
aquaculture facility (RM 588) (Hinson 2003, p. 17), indicating that the 
species may not be as sensitive to these pollutants as we once 
believed. Based on the best available data, we are not aware that water 
quality in the Snake River limits growth, reproduction, or survival of 
the Utah valvata snail in any portion of its range.
    Although several reaches of the Snake River are classified as water 
quality impaired (see further discussion below in Factor D), there have 
been improvements in Total Suspended Solids (TSS) in certain reaches of 
the River, primarily as a result of changing irrigation practices 
between 1990 and 2005. There have also been substantial declines in TP 
from changing agricultural practices and changing aquaculture feeds in 
the middle Snake River downstream of Lake Walcott. Data collected by 
the Idaho Department of Environmental Quality (IDEQ) show decreases of 
TSS near 64 percent compared to 1990 levels, and decreases of TP near 
33 percent compared to 1990 levels (Buhidar in litt. 2006). The 
specific water-quality parameters required for the survival and 
persistence of the Utah valvata snails are not known. However, the Utah 
valvata snail occurs over a relatively large documented range of over 
255 river miles (410 km) (USFWS 2005, pp. 110-113) and has the ability 
to tolerate and persist in a variety of aquatic habitats with some 
degree of water-quality degradation (Lysne and Koetsier 2006, pp. 234-
237). For example, studies conducted by the USBR in 2003 in Lake 
Walcott Reservoir indicated the highest Utah valvata snail densities 
occurred in the lower reservoir, where the sediments had the greatest 
percentage of organic content (an indicator that oxygen levels are 
likely low) (Hinson 2006, p. 19).
    Summary of Factor A: Our understanding of the habitat needs of the 
Utah valvata snail has changed substantially since the species was 
listed in 1992. Compared to our knowledge at the time of listing, 
survey data collected since 1992 indicate that the geographic range of 
the species in the Snake River is approximately 122 river miles (196 
km) longer and that the species occurs on a variety of substrate types 
(e.g., fines to cobble size) and in varying water flows and depths. The 
Utah valvata snail also tolerates a wider range of water-quality 
parameters (e.g., dissolved oxygen and temperature) than was originally 
believed. Threats pertaining to the construction of new hydropower dams 
as cited in the 1992 final rule no longer exist as the plans for dam 
construction have expired or been withdrawn. The operation of existing 
hydropower dams and reservoirs upstream of Minidoka Dam primarily 
affect the distribution of the Utah valvata snail along shoreline areas 
due to fluctuating flows and seasonal dewatering; however, the species 
persists throughout these reservoirs with relatively high proportional 
occurrence. The available information does not suggest that degraded 
water quality in the Snake River is affecting the species' population 
numbers or distribution. Evidence indicates that improvements have been 
made in Snake River water-quality parameters, including TSS and TP in 
some Snake River reaches, since listing. Therefore, based on the best 
available scientific and commercial data, threats of present or future 
destruction, modification, or curtailment of the Utah valvata snail's 
habitat or range do not rise to the level such that the species meets 
the definition of either endangered or threatened under the Act.

Factor B. Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    There is no known commercial or recreational use of the species and 
collections for scientific or educational purposes are limited in scope 
and extent. While collection could result in mortality of individuals 
within a small area, they are unlikely to have population-level effects 
because only a few individuals and institutions are interested in 
collecting the species and the life-history strategy of the species 
makes populations relatively resilient to limited mortality (i.e., 
invests little in reproduction, relatively high reproductive output 
(many eggs laid at a time), early age of reproduction, and short 
lifespan). Therefore, based on the best available scientific and 
commercial data, threats from overutilization for commercial, 
recreational, scientific, or educational purposes to the Utah valvata 
snail do not rise to the level such that the species meets the 
definition of either endangered or threatened under the Act.

Factor C. Disease or Predation

    Parasitic trematodes similar to those of the genus Microphallus 
have been identified in some freshwater snails (e.g., Pyrgulopsis 
robusta) that share similar habitats in the Snake River in Idaho 
(Dybdahl et al. 2005, p. 8). However, the occurrence of trematode 
parasites on the Utah valvata snail has not been studied.
    Predators of the Utah valvata snail have not been documented; 
however, we assume that some predation by native and nonnative species 
occurs. Aquatic snails in general are prey for numerous invertebrates 
and vertebrates (Dillon 2000, pp. 274-304), and predation on other 
aquatic snails by crayfish and fish is well documented (Lodge et al. 
1994, p. 1265; Martin et al. 1992, p. 476; Merrick et al. 1992, p. 225; 
Lodge et al. 1998, p. 53; McCarthy and Fisher 2000, p. 387).
    While disease or predation likely results in some Utah valvata 
snail mortality, the life-history strategy of the species makes 
populations relatively resilient to limited mortality (i.e., invests 
little in reproduction, relatively high reproductive output (many eggs 
laid at a time), early age of reproduction, and short lifespan). 
Therefore, based on the best available scientific and commercial data, 
threats from disease or predation to the Utah valvata snail do not rise 
to the level such that the species meets the definition of either 
endangered or threatened under the Act.

Factor D. Inadequacy of Existing Regulatory Mechanisms

    In the 1992 final listing rule, we found inadequate regulatory 
mechanisms to be a threat because: (1) Regulations were inadequate to 
curb further water withdrawal from groundwater spring outflows or 
tributary spring streams; (2) it was unlikely that pollution-control 
regulations would reverse the trend in nutrient loading any time soon; 
(3) there was a lack of State-mandated protections for invertebrate 
species in Idaho; and (4) regulations did not

[[Page 52278]]

require FERC or the U.S. Army Corps of Engineers to address Service 
concerns regarding licensing hydroelectric projects or permitting 
projects under the Clean Water Act (33 U.S.C. 1251 et seq.) for 
unlisted snails. Below, we address each of these four concerns.
Groundwater Withdrawal Regulations
    Since 1992, new information has become available clarifying the 
habitat requirements of the Utah valvata snail. The species is not 
limited to cool, fast-water, or lotic habitats, or perennial flowing 
waters associated with large spring complexes, as previously believed. 
The species is able to live in a variety of aquatic habitats, and is 
locally abundant throughout a 255-mile (410 km) stretch of the Snake 
River in tributary streams, in the mainstem Snake River, and in 
reservoirs that are managed for annual drawdowns.
    The Idaho Department of Water Resources (IDWR) manages water in the 
State of Idaho. Among the IDWR's responsibilities is the development of 
the State Water Plan (IDWR in litt. 1996). The State Water Plan was 
updated in 1996, and included a table of federally endangered and 
threatened species in Idaho, including five Snake River aquatic snails 
listed as endangered or threatened in 1992: The Utah valvata snail, 
Idaho springsnail (Pyrgulopsis (=Fontelicella) idahoensis) (delisted in 
2007), Snake River Physa (Physa natricina), Bliss Rapids snail 
(Taylorconcha serpenticola), and Banbury Springs Lanx (Lanx n sp. 
(undescribed)) (see 57 FR 59244). The State Water Plan outlines 
objectives for the conservation, development, management, and optimum 
use of all unappropriated waters in the State. One of these objectives 
is to ``maintain, and where possible enhance water quality and water-
related habitats'' (IDWR in litt. 1996). It is the intent of the State 
Water Plan that any water savings realized by conservation or improved 
efficiencies is appropriated to other beneficial uses (e.g., fish and 
wildlife, hydropower, or agriculture). Another IDWR regulatory 
mechanism is the ability of the Idaho Water Resource Board to 
appropriate water for minimum stream flows when in the public interest 
(IDWR in litt. 2010).
    Since 1992, the IDWR and other State agencies have also created 
additional regulatory mechanisms that limit future surface and 
groundwater development, including the continuation of various 
moratoria on new consumptive water rights and the designation of Water 
Management Districts (Caswell in litt. 2007). The State is working with 
numerous interested parties to stabilize aquifer levels and enhance 
cold-water-spring outflows that feed into the Snake River within the 
range of the Utah valvata snail. In 2008, the Idaho Legislature 
approved House Bill 428 establishing the Statewide Comprehensive 
Aquifer Planning and Management Program (SCAPMP) (I.C. section 42-1779) 
and House Bill 644 which created the Aquifer Planning and Management 
Fund (I.C. section 42-1780) (State of Idaho in litt. 2008a, 2008b). 
Under the SCAPMP, the Eastern Snake River Plane Aquifer (ESPA) was 
identified for management planning (IDWR 2009, entire). In 2009, the 
ESPA Comprehensive Aquifer Management Plan (CAMP) was made final. The 
goal of the ESPA CAMP is to ``sustain the economic viability and social 
and environmental health of the Eastern Snake Plain by adaptively 
managing a balance between water use and supplies'' (IDWR 2009, p. 4). 
The ESPA CAMP ``establishes a long-term program for managing water 
supply and demand in the ESPA through a phased approach to 
implementation, together with an adaptive management process to allow 
for adjustments or changes in management techniques as implementation 
proceeds'' (IDWR 2009, p. 4). The long-term objective of the ESPA CAMP 
is a net increase of 600,000 acre-feet of water annually by the year 
2030 (IDWR 2009, p. 4). However, this is a discretionary document and 
does not have regulatory authority.
    In 2005, Congress and the Idaho Legislature approved the Snake 
River Water Rights Agreement (SRWRA) in the Snake River Basin 
Adjudication (SRBA) (State of Idaho in litt. 2005a; USA in litt. 2004). 
The Snake River Component of the SRWRA allows the USBR to lease up to 
427,000 acre-feet of water for flow augmentation, and acquire up to 
60,000 acre-feet of water rights from the Snake River between Milner 
(RM 639) and Swan Falls (RM 458), increasing total flow augmentation up 
to 487,000 acre-feet within the range of the Utah valvata snail (IDWR 
in litt. 2004). In 2005, the USBR acquired water rights through a 30-
year lease with the State of Idaho for 98,000 acre-feet of water from 
the Bell Rapids Mutual Irrigation Company (State of Idaho in litt. 
2005b). This will potentially benefit the Utah valvata snail by 
increasing available wetted areas and connectivity of available 
habitats within the range of the species.
    The State of Idaho established moratoria in 1993 (the year after 
the Utah valvata's listing) that restricted further surface-water and 
groundwater withdrawals for consumptive uses from the Snake River Plain 
aquifer between American Falls Reservoir (RM 714.1) and C.J. Strike 
Reservoir (RM 494). The 1993 moratoria, extended by Executive Order in 
2004 (Caswell in litt. 2006, attachment 1), have not yet resulted in 
stabilization of the Snake River Plain aquifer levels. Depletion of 
spring flows and declining groundwater levels are a collective effect 
of drought conditions, changes in irrigation practices (the use of 
central-pivot sprinklers contribute little to groundwater recharge), 
and groundwater pumping (University of Idaho in litt. 2010).
    Although we anticipate groundwater levels in the Snake River Plain 
aquifer will likely continue to decline in the near future, even as 
water-conservation measures are developed and implemented, this is 
unlikely to endanger or threaten the Utah valvata snail given the 
species' distribution over a 255-mile (410-km) range and its ability to 
survive and persist in a wide variety of aquatic habitats not dependent 
upon Snake River Plain groundwater outflows.
Pollution Control Regulations
    Since 1992, reductions in sediment (TSS) and phosphorus (TP) 
loading have improved water quality in localized reaches of the Snake 
River (Buhidar in litt. 2005) (see Factor A above). Various State-
managed water-quality programs are being implemented within the range 
of the Utah valvata snail. These programs tier off the Clean Water Act 
(CWA), which requires States to establish water-quality standards that 
provide for (1) the protection and propagation of fish, shellfish, and 
wildlife, and (2) recreation in and on the water. As required by the 
CWA, Idaho has established water-quality standards (e.g., for water 
temperature and dissolved oxygen) for the protection of cold-water 
biota (e.g., invertebrate species) in many reaches of the Snake River. 
The CWA also specifies that States must include an anti-degradation 
policy in their water quality regulations that protects water-body uses 
and high-quality waters. Idaho's anti-degradation policy, updated in 
the State's 1993 triennial review, is detailed in their Water Quality 
Standards (IDEQ in litt. 2009).
    The IDEQ works closely with the USEPA to manage point and non-point 
sources of pollution to water bodies of the State through the National 
Pollutant Discharge Elimination System (NPDES) program under the CWA. 
IDEQ has not been granted authority by the USEPA to issue NPDES permits 
directly; all NPDES permits are issued by the USEPA Region 10 (USEPA in 
litt. 2010). These NPDES permits are written to

[[Page 52279]]

meet all applicable water-quality standards established for a water 
body to protect human health and aquatic life. Waters that do not meet 
water-quality standards due to point and non-point sources of pollution 
are listed on USEPA's 303(d) list of impaired water bodies. States must 
submit to USEPA a 303(d) list (water-quality-limited waters) and a 
305(b) report (status of the State's waters) every 2 years. IDEQ, under 
authority of the State Nutrient Management Act, is coordinating efforts 
to identify and quantify contributing sources of pollutants (including 
nutrient and sediment loading) to the Snake River basin via the Total 
Maximum Daily Load (TMDL) approach. In water bodies that are currently 
not meeting water-quality standards, the TMDL approach applies 
pollution-control strategies through several of the following programs: 
State Agricultural Water Quality Program, Clean Water Act section 401 
Certification, Bureau of Land Management (BLM) Resource Management 
Plans, the State Water Plan, and local ordinances. Since the time of 
listing in 1992, the following TMDLs have been approved by the USEPA 
(approval year(s) in parentheses) within the Utah valvata range: The 
Big Wood River (2002), Billinglsey Creek (2005), Blackfoot River (2002, 
2007), Idaho Falls (2004), Lake Walcott (2000, 2007), Little Wood River 
(2005), Palisades (2002), Portneuf River (2001), Raft River (2004), 
Snake River--King Hill to C.J. Strike (2006), Middle Snake River--
aquaculture wasteload allocation (2005), and the Teton River (a 
tributary of Henry's Fork of the Snake River) and Teton River 
Supplement (2003). Implementation plans that specify pollution-control 
strategies and monitoring needed to meet TMDL recommendations and goals 
are either in place or under development for 9 of these 12 areas 
(IDEQ--2010a; 2010b).
State Invertebrate Species Regulations
    There are no specific State regulatory protections for the Utah 
valvata snail in Idaho. The primary threats to the species, as 
identified in our 1992 listing rule, were related to the loss or 
alteration of its aquatic habitats. The lack of specific regulations 
protecting individual Utah valvata snails does not, by itself, imply 
that the species is endangered or threatened.
    While there are no State regulatory protections for the Utah 
valvata snail, it is considered a Species of Greatest Conservation Need 
(SGCN) as identified in the State of Idaho Comprehensive Wildlife 
Conservation Strategy (CWCS) (IDFG 2005 p. 4-75). The aim of the CWCS 
is to provide a common framework that will enable conservation partners 
to jointly implement a long-term approach for the benefit of SGCN 
through proactive conservation to promote cost-effective solutions 
instead of reactive measures enacted in the face of imminent losses 
(IDFG 2005, p. V).
Federal Consultation Regulations
    The threat of insufficient regulatory mechanisms to address Utah 
valvata conservation needs in the 1992 listing rule was primarily 
related to the proposed construction of six hydroelectric dams within 
the suspected, limited geographic range of the species, coupled with 
our belief at the time of listing that the species required cold, fast-
water, or lotic habitats, and was negatively impacted by dams that 
inundated free-flowing river environments. As previously described, 
hydroelectric dams are no longer being proposed for construction in the 
middle Snake River, and our understanding of Utah valvata snail 
geographic range, ecology, and habitat requirements has changed. Thus, 
the importance of a regulatory mechanism to address these threats is no 
longer a significant issue with regard to the conservation of the Utah 
valvata snail.
    Summary of Factor D: Although there are no specific State 
regulations protecting the Utah valvata snail, it is considered a SGCN 
as identified in the Idaho CWCS. The primary threats identified in the 
final listing rule were related to the loss or alteration of the 
species' habitat. Furthermore, as our understanding of the species' 
habitat requirements has changed, so has our understanding of the 
species' conservation and regulatory needs. Regulatory mechanisms such 
as Idaho's water-quality standards and TMDLs will continue to apply to 
habitats occupied by Utah valvata snails. Therefore, based on the best 
available scientific and commercial data, threats from inadequate 
regulatory mechanisms to the Utah valvata snail do not rise to the 
level such that the species meets the definition of either endangered 
or threatened under the Act.

Factor E. Other Natural or Manmade Factors Affecting the Species' 
Continued Existence

Invasive Species
    The final listing rule stated that nonnative New Zealand mudsnails 
were not yet abundant in cold-water spring flows with colonies of the 
Utah valvata snail, but that they likely did compete with the species 
in the mainstem Snake River habitats (57 FR 59254). Surveys have found 
that Utah valvata snails and New Zealand mudsnails frequently co-occur 
in cold-water spring, mainstem Snake River, and reservoir habitats (37 
percent co-occurrence in combined habitat types), which may indicate 
that these two species are able to co-exist or that they actually have 
slightly different resource preferences (e.g., periphytic vs. 
perilithic algae) (Hinson 2006, p. 42). However, Hinson (2006, p. 41) 
also notes that the overlap in habitat utilization between the Utah 
valvata snail and the New Zealand mudsnail could lead to direct 
competition for resources between these two species.
    In 2002 and 2004, the USBR reported that New Zealand mudsnails were 
increasing in Lake Walcott, yet the densities observed were 
substantially lower than those observed in mainstem Snake River 
habitats (USBR 2003, p. 19; USBR 2005, p. 6). Further upstream, surveys 
conducted throughout American Falls Reservoir indicate that the 
distribution of New Zealand mudsnails appears to be limited to the 
upper end of American Falls Reservoir near the input of the Snake and 
Portneuf rivers (USBR 2003, p. 21), where the habitat is not dewatered 
due to water withdrawals for irrigation. Surveys conducted even further 
upstream in the Snake River and tributaries (Fields 2005, pp. 8-12) 
found moderate-to-high densities of the New Zealand mudsnail at five 
sites. However, Fields (2005, p. 10) stated that the current 
distribution of New Zealand mudsnails in the Snake River above American 
Falls Reservoir could more strongly reflect patterns of introductions 
rather than habitat preferences. Populations of the New Zealand 
mudsnail are not known to occur in the Wood River, where a small native 
or introduced population of the Utah valvata snail is thought to occur. 
The overall impact on the Utah valvata snail from the nonnative New 
Zealand mudsnail is not fully understood (Lysne 2003, pp. 85-86; Hinson 
2006, p. 41). However, after approximately 20 years of co-occurrence, 
there is no evidence suggesting that the New Zealand mudsnail has 
supplanted or poses an extinction risk to the Utah valvata snail (Gates 
in litt. 2009).
Climate Change
    There is compelling evidence that we are living in a time of rapid, 
worldwide climate change. Although the extent of warming likely to 
occur is not known with certainty at this time, the Intergovernmental 
Panel on Climate Change (IPCC) has concluded that warming of the 
climate is unequivocal, and that continued greenhouse gas emissions at 
or above current rates will cause further warming (IPCC 2007, p.

[[Page 52280]]

30). For example, 11 of the last 12 years evaluated (1995-2006) rank 
among the 12 warmest years since 1850 (ISAB 2007, p. iii). In the 
Pacific Northwest, regionally averaged temperatures have risen 1.5 
degrees F (0.8 degrees C) over the last century, and are projected to 
increase by another 3 to 10 degrees F (1.5 to 5.5 degrees C) over the 
next 100 years (Mote et al. 2003, p. 54; Karl et al. 2009, p. 135). 
While the specific effects of global climate change on the Utah valvata 
snail are unclear, aquatic species and their habitats may be 
particularly vulnerable to changes in temperatures and precipitation 
patterns.
    Rising temperatures due to climate change can affect aquatic 
species, such as the Utah valvata snail, by altering the timing and 
precipitation events in the Pacific Northwest (Karl et al. 2009, p. 
135). Increased cool season temperatures cause precipitation to fall in 
the form of rain as opposed to snow, contributing to earlier snowmelt, 
earlier timing of spring runoff, and lower water levels during the warm 
season (Karl et al. 2009, p. 135). Many fish and wildlife species in 
the Pacific Northwest, especially aquatic species, are dependent on the 
timing of spring snowmelt runoff (Karl et al. 2009, p. 135). Areas 
along the warmer western slopes of the Cascade Mountains are projected 
to see a 30 percent or more reduction in warm season runoff by mid-
century, while the interior, colder areas along the Rocky Mountains are 
projected to experience a smaller, 10 percent reduction in spring 
runoff (Karl et al. 2009, p. 135). Summer flows will also likely 
decrease while water temperature will increase, thereby stressing many 
aquatic organisms, especially those that have narrow temperature and 
depth requirements.
    Despite projected changes in climate in the Pacific Northwest, we 
now know the Utah valvata snail is not as specialized in its habitat 
needs as we thought at the time of listing and can persist in a broad 
range of water flows, depths, and temperatures. In the Snake River, the 
species inhabits a diversity of aquatic habitats throughout its 255-
mile (410 km) range, including cold-water springs, spring creeks and 
tributaries, mainstem and free-flowing waters, reservoirs, and 
impounded Snake River reaches. The species occurs on a variety of 
substrate types including both fine sediments and more coarse 
substrates in areas both with and without macrophytes. It has been 
collected at a wide range of water depths, ranging from less than 3.2 
feet (1 meter) to greater than 45 feet (14 meters), and at water 
temperatures ranging from 37.4 to 75.2 degrees F (3 to 24 degrees C).
    Summary of Factor E: The New Zealand mudsnail frequently co-occurs 
with the Utah valvata snail and may be competing for habitat or food. 
The New Zealand mudsnail can reach extremely high densities in the 
middle Snake River (Richards et al. 2001, p. 375), and has been 
recorded at moderate-to-high densities at five sites in tributaries to 
the Snake River and the Snake River above American Falls Reservoir. 
Populations of the New Zealand mudsnail are not known to occur in the 
Wood River. The precise impact on the Utah valvata snail from the 
invasion of the New Zealand mudsnail is unknown (Lysne 2003, pp. 85-86; 
Hinson 2006, p. 41). However, after approximately 20 years of co-
occurrence, there is no evidence suggesting that the New Zealand 
mudsnail has supplanted or caused local extirpations of the Utah 
valvata snail.
    Further, while numerous scientific studies indicate that the world 
is warming due to anthropogenic causes, and that increasing 
temperatures will impact precipitation patterns in the Pacific 
Northwest, it is difficult at this time to determine the precise 
effects this change will have on the Utah valvata snail. Nevertheless, 
given the wide variety of habitat conditions, water depths, and 
temperature ranges the Utah valvata snail has been found to occupy, the 
species is likely to be resilient to moderate changes in temperature 
and precipitation patterns. Therefore, threats from other natural or 
manmade factors do not rise to the level such that the species meets 
the definition of either endangered or threatened under the Act.
Conclusion
    As required by the Act, we considered potential threat factors to 
assess whether the Utah valvata snail is endangered or threatened 
throughout its range. Information collected since the species' listing 
in 1992 indicates that the Utah valvata snail is widely distributed and 
occurs in a variety of ecological settings over a 255-mile range of the 
Snake River. Much of the Snake River within the range of the Utah 
valvata is influenced by seasonal dam operations for hydroelectric or 
agricultural purposes, yet the species persists in these varied 
mainstem Snake River systems, including impounded reservoir habitats 
(e.g., Lake Walcott and American Falls reservoirs). None of the threats 
that we identified in the 1992 listing determination appear to be 
significant to the species (individually or in combination) in light of 
our current understanding of its distribution and life history; nor 
have we identified any significant new threats to the species. 
Therefore, we find that the Utah valvata snail is not in danger of 
extinction throughout its range, nor is it likely to become so in the 
foreseeable future.
    The Service has determined that the original data for 
classification of the Utah valvata snail used in 1992 were in error. 
However, it is important to note that the original data for 
classification constituted the best scientific and commercial data 
available at the time and were in error only in the sense that they 
were incomplete when viewed in context of the data now available. The 
primary considerations to delist the Utah valvata snail are described 
in the five-factor analysis above.
    Having determined that the Utah valvata snail does not meet the 
definition of endangered or threatened throughout its range, we must 
next consider whether there are any significant portions of its range 
that are in danger of extinction or are likely to become endangered in 
the foreseeable future. A portion of a species' range is significant if 
it is part of the current range of the species and is important to the 
conservation of the species because it contributes meaningfully to the 
representation, resiliency, or redundancy of the species. The 
contribution must be at a level such that its loss would result in a 
decrease in the ability to conserve the species.
    Applying the definition described above, we first address whether 
any portions of Utah valvata's range warranted further consideration. 
Based on a genetic study of the Utah valvata snail (Miller et al. 
2006a) and the ecological settings in which the species occurs 
throughout its range, three potential population units could be 
analyzed as to whether they constituted a significant portion of its 
range: The Wood River population unit (WRM 35), the Snake River 
population unit (RM 585 through RM 837), and the Hagerman population 
unit (isolated springs adjacent to the Snake River at RM 585). We then 
evaluated whether each unit constitutes a significant portion of the 
range of the species, and if so, whether that portion was endangered or 
threatened.
Wood River Population Unit
    There is a high degree of uncertainty concerning the distribution 
and abundance of the species in the Wood River since there has been 
only one documented colony and systematic surveys have not been 
conducted. Based on the limited information we have on the Utah valvata 
snail in the Wood River, this colony does not appear to exist in an 
unusual or unique ecological

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setting or contain a large portion of