[Federal Register Volume 77, Number 181 (Tuesday, September 18, 2012)]
[Proposed Rules]
[Pages 57922-57948]
From the Federal Register Online via the Government Publishing 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]]


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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

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of 12-month petition finding.

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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 http://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
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           Common name                    Description                  Habitat                 Known sites
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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 
http://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