Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for Roswell Springsnail, Koster's Springsnail, Noel's Amphipod, and Pecos Assiminea, 35375-35397 [2010-15067]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 75, Number 119 (Tuesday, June 22, 2010)]
[Proposed Rules]
[Pages 35375-35397]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-15067]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R2-ES-2009-0014]
[92210-1117-0000-B4]
RIN 1018-AW50


Endangered and Threatened Wildlife and Plants; Designation of 
Critical Habitat for Roswell Springsnail, Koster's Springsnail, Noel's 
Amphipod, and Pecos Assiminea

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service, propose to revise 
designated critical habitat for the Pecos assiminea (Assiminea pecos), 
and to newly designate critical habitat for the Roswell springsnail 
(Pyrgulopsis roswellensis), Koster's springsnail (Juturnia kosteri), 
and Noel's amphipod (Gammarus desperatus), under the Endangered Species 
Act of 1973, as amended. In total, we are proposing to designate as 
critical habitat approximately 515 acres (208.4 hectares) for the four 
species. The proposed critical habitat is located in Chaves County, New 
Mexico, and Pecos and Reeves Counties, Texas. We also announce the 
availability of the draft economic analysis and draft environmental 
assessment for this action.

DATES: We request that comments be received or postmarked on or before 
August 23, 2010. Please note that submissions via the Federal 
eRulemaking Portal (see ADDRESSES section, below) must be made by 11:59 
pm Eastern Standard Time on this date. We must receive requests for 
public hearings, in writing, at the address shown in the FOR FURTHER 
INFORMATION CONTACT section by August 6, 2010.

ADDRESSES: You may submit comments by one of the following methods:
     Federal eRulemaking Portal: https://www.regulations.gov. 
Search for docket number FWS-R2-ES-2009-0014 and then follow the 
instructions for submitting comments.
     U.S. mail or hand-delivery: Public Comments Processing, 
Attn: Docket No. FWS-R2-ES-2009-0014; Division of Policy and Directives 
Management; U.S. Fish and Wildlife Service; 4401 N. Fairfax Drive, 
Suite 222; Arlington, VA 22203.
    We will post all comments on https://www.regulations.gov. This 
generally means that we will post any personal information you provide 
us (see the Public Comments section below for more information).

FOR FURTHER INFORMATION CONTACT: Wally ``J'' Murphy, Field Supervisor, 
U.S. Fish and Wildlife Service, New Mexico Ecological Services Field 
Office, 2105 Osuna Rd NE, Albuquerque, NM 87113; telephone 505-761-
4781; facsimile 505-246-2542. If you use a telecommunications device 
for the deaf (TDD), call the Federal Information Relay Service (FIRS) 
at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Public Comments

    We intend that any final action resulting from this proposed rule 
will be based on the best scientific and commercial data available and 
be as accurate and as effective as possible. Therefore, we request 
comments or information from other concerned government agencies, the 
scientific community, industry, or other interested parties concerning 
the proposed revisions to critical habitat for the Pecos assiminea 
(Assiminea pecos), and the proposed critical habitat for the Roswell 
springsnail (Pyrgulopsis roswellensis), Koster's springsnail (Juturnia 
kosteri), and Noel's amphipod (Gammarus desperatus), as well as the 
draft economic analysis and draft environmental assessment of the 
proposed designation. We will consider information and recommendations 
from all interested parties. We particularly seek comments concerning:
    (1) The reasons why we should or should not designate habitat as 
``critical habitat'' under section 4 of the Endangered Species Act of 
1973, as amended (Act) (16 U.S.C. 1531 et seq.), including whether 
there are threats to the species from human activity, the degree of 
which can be expected to increase due to the designation, and whether 
that increase in threat outweighs the benefit of designation such that 
the designation of critical habitat is not prudent.
    (2) Specific information on:
     The amount and distribution of habitat for the Roswell 
springsnail,

[[Page 35376]]

Koster's springsnail, Noel's amphipod, and Pecos assiminea (four 
invertebrates);
     What areas occupied at the time of listing and that 
contain features essential to the conservation of the species we should 
include in the designation and why;
     Special management considerations or protections that the 
features essential to the conservation of the Roswell springsnail, 
Koster's springsnail, Noel's amphipod, and Pecos assiminea that have 
been identified in this proposal may require, including managing for 
the potential effects of climate change; and
     What areas not occupied at the time of listing are 
essential for the conservation of the species and why.
    (3) Land use management and current or planned activities in the 
subject areas and their possible impacts on proposed critical habitat.
    (4) Any probable economic, national security, or other relevant 
impacts of designating any area that may be included in the final 
designation. We are particularly interested in any impacts on small 
entities or families, and the benefits of including or excluding areas 
that exhibit these impacts.
    (5) Information on whether the draft economic analysis identifies 
all local costs attributable to the proposed critical habitat 
designation and information on any costs that have been inadvertently 
overlooked.
    (6) Whether the draft economic analysis correctly assesses the 
effect on regional costs associated with any land use controls that may 
derive from the designation of critical habitat.
    (7) Whether the draft economic analysis or draft environmental 
assessment makes appropriate assumptions regarding current practices 
and likely regulatory changes imposed as a result of the designation of 
critical habitat.
    (8) Whether the draft economic analysis and draft environmental 
assessment appropriately identify all costs and benefits that could 
result from the designation.
    (9) Economic data on the incremental effects that would result from 
designating any particular area as critical habitat.
    (10) Whether we could improve or modify our approach to designating 
critical habitat in any way to provide for greater public participation 
and understanding, or to better accommodate public concerns and 
comments.
    To ensure that any final action resulting from this proposed rule 
will be as accurate and as effective as possible, we request that you 
send relevant information for our consideration. The comments that will 
be most useful and likely to influence our decisions are those that you 
support by quantitative information or studies and those that include 
citations to, and analyses of, the applicable laws and regulations. 
Please make your comments as specific as possible and explain the bases 
for them. In addition, please include sufficient information with your 
comments to allow us to authenticate any scientific or commercial data 
you include.
    You must submit your comments and materials concerning this 
proposed rule, the associated draft economic analysis, and the 
associated draft environmental assessment by one of the methods listed 
above in the ADDRESSES section. We will not accept comments sent by e-
mail or fax or to an address not listed in ADDRESSES.
    If you submit a comment via https://www.regulations.gov, your entire 
comment--including any personal identifying information, such as your 
address, telephone number, or e-mail address--will be posted on the Web 
site. Please note that comments submitted to this Web site are not 
immediately viewable. When you submit a comment, the system receives it 
immediately. However, the comment will not be publicly viewable until 
we post it, which might not occur until several days after submission.
    If you mail or hand-carry a hardcopy comment directly to us that 
includes personal information, you may request at the top of your 
document that we withhold this information from public review. However, 
we cannot guarantee that we will be able to do so. To ensure that the 
electronic docket for this rulemaking is complete and all comments we 
receive are publicly available, we will post all hardcopy comments on 
https://www.regulations.gov.
    In addition, comments and materials we receive, as well as 
supporting documentation used in preparing this proposed rule, will be 
available for public inspection in two ways:
    (1) You can view them on https://www.regulations.gov. Search for 
docket number FWS-R2-ES-2009-0014.
    (2) You can make an appointment, during normal business hours, to 
view the comments and materials in person at he U.S. Fish and Wildlife 
Service, New Mexico Ecological Services Field Office (see FOR FURTHER 
INFORMATION CONTACT).
    You may obtain copies of the original proposed rule, the draft 
economic analysis, and the draft environmental assessment online at 
https://www.regulations.gov, by mail from the New Mexico Ecological 
Services Field Office (see FOR FURTHER INFORMATION CONTACT), or by 
visiting our website at https://www.fws.gov/southwest/es/NewMexico/.

Public Availability of Comments

    As stated above in more detail, before including your address, 
phone number, e-mail address, or other personal identifying information 
in your comment, you should be aware that your entire comment--
including your personal identifying information--may be made publicly 
available at any time. While you can ask us in your comment to withhold 
your personal identifying information from public review, we cannot 
guarantee that we will be able to do so.

Background

    It is our intent to discuss only those topics relevant to the 
designation of critical habitat in this proposed rule. For more 
information on the Roswell springsnail (Pyrgulopsis roswellensis), 
Koster's springsnail (Juturnia kosteri), Noel's amphipod (Gammarus 
desperatus), and Pecos assiminea (Assiminea pecos), refer to the final 
listing rule published in the Federal Register on August 9, 2005 (70 FR 
46304), and to the document announcing the reopening of the comment 
period on the proposed designation of lands of the Bitter Lake National 
Wildlife Refuge as critical habitat for these species that published on 
March 12, 2009 (74 FR 10701).
    All four invertebrate species are associated with aquifer-fed 
spring systems in desert grasslands of the Pecos River Basin in 
southeast New Mexico and southwest Texas. This basin has abundant 
``karst'' topography (landscape created by groundwater dissolving 
sedimentary rock), such as sinkholes, caverns, springs, and underground 
springs, which have created unique settings harboring diverse 
assemblages of plants and animals. The isolated limestone and gypsum 
springs, seeps, and wetlands located in and around Roswell, New Mexico, 
and Pecos and Reeves Counties, Texas, provide the last known habitats 
in the world for several endemic (native) species of fish, plants, 
mollusks, and crustaceans, including the Roswell springsnail and 
Koster's springsnail of the freshwater snail family Hydrobiidae, Pecos 
assiminea of the snail family Assimineidae, and Noel's amphipod (a 
crustacean of the family Gammaridae) (New Mexico Department of Game and 
Fish (NMDGF) 2005, pp. 9-12) .
    The Roswell springsnail and Koster's springsnail are aquatic 
species,

[[Page 35377]]

distributed in geographically separate populations in isolated 
limestone and gypsum springs, seeps, and wetlands. As with other snails 
in the family Hydrobiidae, the Roswell springsnail and Koster's 
springsnail are completely aquatic but can survive in seepage areas, as 
long as flows are perennial and within the species' physiological 
tolerance limits (NMDGF 2005, p. 9). The Roswell springsnail and 
Koster's springsnail are currently known only from the Middle Tract of 
Bitter Lake National Wildlife Refuge (Refuge) and a nearby complex of 
springs owned by the city of Roswell, Chaves County, New Mexico. The 
core population of Roswell springsnail is in the Sago Springs Complex 
and Bitter Creek on the Refuge. The Sago Springs Complex is 
approximately 1,000 feet (ft) (304 meters (m)) long, half of which 
flows underground with aboveground flow in the upper reaches restricted 
to sinkholes. Bitter Creek is six times longer than the Sago Springs 
Complex and has a total length of 1.1 miles (mi) (1.8 kilometers (km)). 
Roswell springsnail formerly occurred on private land at North Spring 
east of Roswell but has since been extirpated (NMDGF 2005, p. 12).
    Koster's springsnail is most abundant in the deep organic 
substrates (material on the bottom of the stream) of Bitter Creek and 
its headwaters (Lang 1999, p. B36; NMDGF 2005, p. 13) on the Refuge; it 
also occurs at the Sago Springs Complex, but in lower numbers, as well 
as in Lake St. Francis, in the southwestern corner of Impoundment 15, 
in Hunter Marsh, in the spring-ditches of Impoundments 6 and 7, and in 
several springs adjacent to the Refuge owned by the city of Roswell 
(NMDGF 2005, p. 13; Sanchez 2009, p. 1; B. Lang, NMDGF, pers. comm. 
2010) The species has not been found in recent times along the western 
boundary of the spring run originating from the saline waters of Bitter 
Lake, bordering Impoundment 3 on the Refuge (NMDGF 2005, p. 12), and it 
was recently extirpated from North Spring (NMDGF 2005, p. 11). Fossil 
records indicate that at least one or more of these snail species was 
historically found at Berrendo Spring, North Spring, and South Spring 
River,, and along the Pecos River (NMDGF 1999, pp. A1, A3, A8, A11). 
This evidence suggests an apparent historical decline in the numbers, 
range, and distribution of these species.
    The Pecos assiminea is a minute marsh snail that seldom occurs 
immersed in water but prefers a humid microhabitat created by wet mud 
or beneath vegetation mats, typically within about 1 inch (in) (2 to 3 
centimeters (cm)) of running water. Pecos assiminea is presently known 
from two sites at the Refuge, from a large population at Diamond Y 
Spring and its associated drainage in Pecos County, Texas, and at East 
Sandia Spring, in Reeves County, Texas. On the Refuge, Pecos assiminea 
occurs sporadically in Bitter Creek, in a dense population around the 
perimeter of a sinkhole within the Sago Springs Complex, on the western 
perimeter of Impoundment 7, and in the extreme southwest corner of 
Impoundment 15 (NMDGF 2005, p. 10). Critical habitat is currently 
designated for the Pecos assiminea at the Texas sites.
    Noel's amphipod is a small, freshwater shrimp in the family 
Gammaridae that inhabits shallow, cool, well-oxygenated waters of 
streams, ponds, ditches, sloughs, and springs (Holsinger 1976, p. 28; 
Pennak 1989, p. 478). Noel's amphipod is currently known from the 
following five sites at the Refuge: Sago Springs Complex, Bitter Creek 
and its headwater springs, Unit 6 spring-ditch, Unit 7 spring-ditch, 
and Hunter Marsh (NMDGF 2005, p. 9; Sanchez 2009, p. 1). It is also 
found in several springs just outside the Refuge boundary on property 
owned by the City of Roswell (G. Warrick, pers. comm., 2005). The 
species was extirpated from Lander Springbrook between 1951 and 1960, 
and the North Spring population was lost between 1978 and 1988 (NMDGF 
2005, p. 9). The extirpations were attributed to regional groundwater 
depletions and habitat alterations (spring channelization), 
respectively (Cole 1985, p. 94).

Previous Federal Actions

    On August 9, 2005, we listed Roswell springsnail (Pyrgulopsis 
roswellensis), Koster's springsnail (Juturnia kosteri), Noel's amphipod 
(Gammarus desperatus), and Pecos assiminea (Assiminea pecos) as 
endangered under the Act (70 FR 46304). In that rule, we also 
designated critical habitat for Pecos assiminea at Diamond Y Springs 
Complex in Pecos County, Texas, and at East Sandia Springs in Reeves 
County, Texas. We excluded Bitter Lake National Wildlife Refuge from 
the critical habitat designation because special management for the 
four invertebrates was already occurring on the Refuge.
    On March 12, 2009, in response to a complaint filed by Forest 
Guardians (now WildEarth Guardians) challenging the exclusion of the 
Refuge from the final critical habitat designation for the four 
species, we published a document announcing the reopening of the 
comment period on the proposed designation of lands of the Bitter Lake 
National Wildlife Refuge as critical habitat for the four invertebrates 
(74 FR 10701).

Critical Habitat

Background

    Critical habitat is defined in section 3 of the Act as:
    (i) The specific areas within the geographical area occupied by the 
species, at the time it is listed in accordance with the Act, on which 
are found those physical or biological features
    (I) essential to the conservation of the species and
    (II) which may require special management considerations or 
protection; and
    (ii) Specific areas outside the geographical area occupied by the 
species at the time it is listed, upon a determination that such areas 
are essential for the conservation of the species.
    Conservation, as defined under section 3 of the Act, means to use 
and the use of all methods and procedures that are necessary to bring 
an endangered or threatened species to the point at which the measures 
provided under the Act are no longer necessary. Such methods and 
procedures include, but are not limited to, all activities associated 
with scientific resources management such as research, census, law 
enforcement, habitat acquisition and maintenance, propagation, live 
trapping, transplantation, and, in the extraordinary case where 
population pressures within a given ecosystem cannot be otherwise 
relieved, may include regulated taking.
    Critical habitat receives protection under section 7 of the Act 
through the prohibition against Federal agencies carrying out, funding, 
or authorizing the destruction or adverse modification of critical 
habitat. Section 7(a)(2) requires consultation on Federal actions that 
may affect critical habitat. The designation of critical habitat does 
not affect land ownership or establish a refuge, wilderness, reserve, 
preserve, or other conservation area. Such designation does not allow 
the government or public to access private lands. Such designation does 
not require implementation of restoration, recovery, or enhancement 
measures by non-Federal landowners. Where a landowner seeks or requests 
Federal agency funding or authorization for an action that may affect a 
listed species or critical habitat, the consultation requirements of 
section 7(a)(2) would apply, but even in the event of a

[[Page 35378]]

destruction or adverse modification finding, the Federal action 
agency's and the applicant's obligation is not to restore or recover 
the species, but to implement reasonable and prudent alternatives to 
avoid destruction or adverse modification of critical habitat.
    For inclusion in a critical habitat designation, the habitat within 
the geographical area occupied by the species at the time it was listed 
must contain the physical and biological features essential to the 
conservation of the species and be included only if those features may 
require special management considerations or protection. Critical 
habitat designations identify, to the extent known using the best 
scientific and commercial data available, habitat areas that provide 
essential life cycle needs of the species (areas on which are found the 
physical and biological features laid out in the appropriate quantity 
and spatial arrangement for the conservation of the species). Under the 
Act and regulations at 50 CFR 424.12, we can designate critical habitat 
in areas outside the geographical area occupied by the species at the 
time it is listed only when we determine that those areas are essential 
for the conservation of the species and that designation limited to 
those areas occupied at the time of listing would be inadequate to 
ensure the conservation of the species.
    Section 4 of the Act requires that we designate critical habitat on 
the basis of the best scientific and commercial data available. 
Further, our Policy on Information Standards Under the Endangered 
Species Act (published in the Federal Register on July 1, 1994 (59 FR 
34271)), the Information Quality Act (section 515 of the Treasury and 
General Government Appropriations Act for Fiscal Year 2001 (Pub. L. 
106-554; H.R. 5658)), and our associated Information Quality 
Guidelines, provide criteria, establish procedures, and provide 
guidance to ensure that our decisions are based on the best scientific 
data available. They require our biologists, to the extent consistent 
with the Act and with the use of the best scientific data available, to 
use primary and original sources of information as the basis for 
recommendations to designate critical habitat.
    When we are determining which areas should be designated as 
critical habitat, our primary source of information is generally the 
information developed during the listing process for the species. 
Additional information sources may include the recovery plan for the 
species, articles in peer-reviewed journals, conservation plans 
developed by States and counties, scientific status surveys and 
studies, biological assessments, or other unpublished materials and 
expert opinion or personal knowledge.
    Habitat is often dynamic, and species may move from one area to 
another over time. Furthermore, we recognize that critical habitat 
designated at a particular point in time may not include all of the 
habitat areas that we may later determine are necessary for the 
recovery of the species. For these reasons, a critical habitat 
designation does not signal that habitat outside the designated area is 
unimportant or may not be required for recovery of the species.
    Areas that are important to the conservation of the species, but 
are outside the critical habitat designation, will continue to be 
subject to conservation actions we implement under section 7(a)(1) of 
the Act. Areas that support populations are also subject to the 
regulatory protections afforded by the section 7(a)(2) jeopardy 
standard, as determined on the basis of the best available scientific 
information at the time of the agency action. Federally funded or 
permitted projects affecting listed species outside their designated 
critical habitat areas may still result in jeopardy findings in some 
cases. Similarly, critical habitat designations made on the basis of 
the best available information at the time of designation will not 
control the direction and substance of future recovery plans, habitat 
conservation plans (HCPs), or other species conservation planning 
efforts if new information available at the time these planning efforts 
calls for a different outcome.

Primary Constituent Elements

    In accordance with section 3(5)(A)(i) and 4(b)(1)(A) of the Act and 
the regulations at 50 CFR 424.12, in determining which areas within the 
geographical area occupied at the time of listing to propose as 
critical habitat, we consider the physical and biological features 
essential to the conservation of the species that may require special 
management considerations or protection. These include, but are not 
limited to:
    (1) Space for individual and population growth and for normal 
behavior;
    (2) Food, water, air, light, minerals, or other nutritional or 
physiological requirements;
    (3) Cover or shelter;
    (4) Sites for breeding, reproduction, or rearing (or development) 
of offspring; and
    (5) Habitats that are protected from disturbance or are 
representative of the historic, geographical, and ecological 
distributions of a species.
    We consider the physical or biological features essential to the 
conservation of the species to be the primary constituent elements 
(PCEs) laid out in the appropriate quantity and spatial arrangement for 
the conservation of the species. We derived the specific PCEs from the 
biological needs of the Roswell springsnail, Koster's springsnail, 
Noel's amphipod, and Pecos assiminea. We determined the PCEs for the 
four invertebrates from data and studies on their general habitat and 
life history requirements including, but not limited to: Noel 1954, pp. 
120-135; Cole 1981, pp. 27-32; Taylor 1987, pp. 1-46; Pennak 1978, pp. 
451-463; Pennak 1989, pp. 474-488; NMDGF 1999, p. A1-B46; and NMDGF 
2005, pp. 1-80. A description of the essential environment as it 
relates to the specific PCEs required of the four invertebrates is 
described below.

Space for Individual and Population Growth and for Normal Behavior

Roswell springsnail, Koster's springsnail, Noel's amphipod
    The aquatic environment provides foraging and sheltering habitat 
for Roswell springsnail, Koster's springsnail, and Noel's amphipod, as 
well as habitat structure necessary for reproduction and survival of 
offspring. These invertebrates are completely aquatic and require 
perennial, flowing water for all of their life stages. The springsnails 
can survive in seepage areas, as long as flows are perennial and within 
the species' physiological tolerance limit; pool-like habitat is less 
suitable for these species, which prefer flowing water. They inhabit 
springs and spring-fed wetland systems with variable water temperatures 
(10-20 degrees Celsius (\o\C) (50-68 degrees Fahrenheit (\o\F)). In 
general, the springsnails inhabit slow to moderate water velocities 
over compact substrate ranging from deep organic silts to gypsum sands 
and gravel (NMDGF 2005, pp. 13, 16). Habitat of Koster's springsnail 
consists of soft substrates of springs and seeps (Taylor 1987, p. 43). 
Roswell springsnail, on the other hand, was found to be most abundant 
on hard, gypsum substrate (NMDGF 2005, p. 16), which may make the 
species more susceptible to sedimentation. Noel's amphipod is found 
beneath stones and in aquatic vegetation (Cole 1988, p. 5; Smith 2001, 
pp. 572-574). The addition of stones, which increased current velocity, 
appeared to improve habitat for Noel's amphipod along Unit 6 spring-
ditch on the Refuge (Lang 2002, p. 2).

[[Page 35379]]

    The two springsnails and Noel's amphipod are sensitive to water 
contamination. Amphipods generally do not tolerate habitat desiccation 
(drying), standing water, sedimentation, or other adverse environmental 
conditions; they are very sensitive to habitat degradation (NMDGF 2000, 
p. B3; Smith 2001, p. 575; NMDGF 2005, p. 15). Further, Taylor (1985, 
p. 15) concluded that an unidentified groundwater pollutant was 
responsible for reduction in abundance of springsnail species in the 
headspring and outflow of Diamond Y Spring, in Pecos County, Texas.
Pecos assiminea
    The Pecos assiminea requires saturated, moist soil at stream or 
spring-run margins and is found in wet mud or beneath mats of 
vegetation, usually within 1 in (2 to 3 cm) of flowing water. Spring 
complexes that contain flowing water create saturated soils that 
provide the specific habitat needed for population growth, sheltering, 
and normal behavior of the species. Although this snail seldom occurs 
immersed in water, the species cannot withstand permanent drying of 
springs or spring complexes. Consequently, wetland plant species are 
required to provide leaf litter (dead leaf material), shade, and 
appropriate microhabitat. Plant species such as American three-square 
(Scirpus americanus), spike rush (Eleocharis spp.), inland saltgrass 
(Distichlis spicata), and rushes (Juncus spp.) provide the appropriate 
cover and shelter required by Pecos assiminea (NMDGF 2005, p. 13).

Food

    Invertebrates in small spring ecosystems depend on food from two 
sources: that which grows in or on the substrate (aquatic and attached 
plants and algae) and that which falls or is blown into the system 
(primarily leaves). Leaves from nonnative plants that fall into the 
water are often less suitable food sources for invertebrates because of 
either their resins or their physical structure (Bailey et al. 2001, p. 
445). Water is also the medium necessary to provide the algae, detritus 
(dead or partially decayed plant materials or animals), bacteria, and 
submergent vegetation on which all four species depend as a food 
resource.
Roswell springsnail and Koster's springsnail
    The springsnails feed on algae, bacteria, and decaying organic 
material (NMDGF 2005, p. 14). They will also incidentally ingest small 
invertebrates while grazing on algae and detritus. Submergent 
vegetation contributes the necessary nutrients, detritus, and bacteria 
on which these species forage. Resource abundance and productivity 
appears to be an important factor in regulating population size (NMDGF 
2005, p. 16).
Noel's amphipod
    Amphipods are omnivorous, feeding on algae, submergent vegetation, 
and decaying organic matter (Holsinger 1976, p. 28; Pennak 1989, p. 
476). Noel's amphipod is often found in beds of submerged aquatic 
plants, indicating that they probably feed on a surface film of algae, 
diatoms, bacteria, and fungi (Smith 2001, p. 575; NMDGF 2005, p. 14). 
Young amphipods depend on microbial foods, such as algae and bacteria, 
associated with aquatic plants (Covich and Thorp 1991, p. 677). 
Cannibalism may occur at high densities when food becomes limiting 
(Smith 2001, p. 575; NMDGF 2005, p. 15).
Pecos assiminea
    The Pecos assiminea has a file-like radula (a ribbon of teeth) 
situated behind the mouth that it uses to graze or scrape food from the 
foraging surface. Saturated soils and wetland vegetation adjacent to 
spring complexes contribute to the necessary components to support the 
algae, detritus, and bacteria on which this species forages.

Summary of Primary Constituent Elements

Roswell springsnail and Koster's springsnail
    Based on the above needs and our current knowledge of the life 
history, biology, and ecology of the species and the habitat 
requirements for sustaining the essential life history functions of the 
species, we have determined that the primary constituent element 
essential to the conservation of Roswell springsnail and Koster's 
springsnail is springs and spring-fed wetland systems that:
    (1) Have permanent, flowing, unpolluted water;
    (2) Have slow to moderate water velocities;
    (3) Have substrates ranging from deep organic silts to limestone 
cobble and gypsum;
    (4) Have stable water levels with natural diurnal (daily) and 
seasonal variations;
    (5) Consist of fresh to moderately saline water;
    (6) Vary in temperature between 10-20 \o\C (50-68 \o\F) with 
natural seasonal and diurnal variations slightly above and below that 
range; and
    (7) Provide abundant food, consisting of:
    (a) Algae, bacteria, and decaying organic material; and
    (b) Submergent vegetation that contributes the necessary nutrients, 
detritus, and bacteria on which these species forage.
Noel's amphipod
    Based on the above needs and our current knowledge of the life 
history, biology, and ecology of the species and the habitat 
requirements for sustaining the essential life history functions of the 
species, we have determined that the primary constituent element 
essential to the conservation of Noel's amphipod is springs and spring-
fed wetland systems that:
    (1) Have permanent, flowing, unpolluted water;
    (2) Have slow to moderate water velocities;
    (3) Have substrates including limestone cobble and aquatic 
vegetation;
    (4) Have stable water levels with natural diurnal (daily) and 
seasonal variations;
    (5) Consist of fresh to moderately saline water;
    (6) Have minimal sedimentation;
    (7) Vary in temperature between 10-20 \o\C (50-68 \o\F) with 
natural seasonal and diurnal variations slightly above and below that 
range; and
    (8) Provide abundant food, consisting of:
    (a) Submergent vegetation and decaying organic matter;
    (b) A surface film of algae, diatoms, bacteria, and fungi; and
    (c) Microbial foods, such as algae and bacteria, associated with 
aquatic plants algae, bacteria, and decaying organic material.
Pecos assiminea
    Based on the above needs and our current knowledge of the life 
history, biology, and ecology of the species and the habitat 
requirements for sustaining the essential life history functions of the 
species, we have determined that the primary constituent element 
essential to the conservation of Pecos assiminea is moist or saturated 
soil at stream or spring run margins:
    (1) With native vegetation growing in or adapted to aquatic or very 
wet environment, such as salt grass or sedges;
    (2) That consists of wet mud or occurs beneath mats of vegetation;
    (3) That is within 1 inch (2 to 3 centimeters) of flowing water;
    (4) That has native wetland plant species that provide leaf litter, 
shade, cover, and appropriate microhabitat;
    (5) That contains wetland vegetation adjacent to spring complexes 
that

[[Page 35380]]

supports the algae, detritus, and bacteria needed for foraging;
    (6) That has adjacent spring complexes with:
    (a) Permanent, flowing, unpolluted, fresh to moderately saline 
water; and
    (b) Stable water levels with natural diurnal and seasonal 
variations.

Special Management Considerations or Protection

    When designating critical habitat, we assess whether the specific 
areas within the geographical area occupied by the species at the time 
of listing contain features that are essential to the conservation of 
the species and that may require special management considerations or 
protection. As stated in the final listing rule (70 FR 46304, August 9, 
2005), threats to the four invertebrates include reducing or 
eliminating water in suitable or occupied habitat through drought or 
pumping; introducing pollutants to levels unsuitable for the species 
from urban areas, agriculture, release of chemicals, and oil and gas 
operations; fires that reduce or eliminate available habitat; and 
introducing nonnative species into the invertebrates' inhabited spring 
systems such that suitable habitat is reduced or eliminated. Each of 
these threats is discussed below.
Water Quantity
    These four species depend on water for survival. Therefore, the 
loss or alteration of spring habitat continues to be the main threat to 
the four invertebrates. The scattered distribution of springs makes 
them aquatic islands of unique habitat in an arid-land matrix (Myers 
and Resh 1999, p. 815). Members of the snail family Hydrobiidae 
(including Roswell and Koster's springsnails) are susceptible to 
extirpation or extinction because they often occur in isolated desert 
springs (Hershler 1989, p. 294; Hershler and Pratt 1990, p. 291; 
Hershler 1994, p. 1; Lydeard et al. 2004, p. 326). There is evidence 
these habitats have been historically reduced or eliminated by aquifer 
depletion (Jones and Balleau 1996, p. 4). The lowering of water tables 
through aquifer withdrawals for irrigation and municipal use has 
degraded desert spring habitats. At least two historic sites for the 
invertebrates (South Spring, Lander Spring) are currently dry due to 
aquifer depletion (Cole 1981, p. 27; Jones and Balleau 1996, p. 5), and 
Berrendo Spring, historical habitat for the Roswell springsnail, is 
currently at 12 percent of the original 1880s flow. However, during the 
mid-1970s, the areas proposed in this document as critical habitat 
continued to flow, even though groundwater pumping was at its highest 
rate and the area was experiencing extreme drought (McCord et al. 2007, 
p. 15). This suggests these springs and seeps may be somewhat resilient 
to reduced water levels, although climate change may test that 
resiliency. Models suggest climate change may cause the southwestern 
United States to experience the greatest temperature increase of any 
area in the lower 48 States (IPCC 2007, p. 15). There is also high 
confidence that many semi-arid areas like the western United States 
will suffer a decrease in water resources due to climate change (IPCC 
2007, p. 16), as a result of less annual mean precipitation and reduced 
length of snow season and snow depth (Christensen et al. 2007, p. 850). 
These predictions underscore the importance of maintaining aquifer 
levels to ensure survival of the four invertebrates.
    The primary threat to Pecos assiminea in Texas is the potential 
failure of spring flow due to excessive groundwater pumping or drought 
or both, which would result in total habitat loss for the species. 
Diamond Y Spring is the last major spring still flowing in Pecos 
County, Texas (Veni 1991, p. 2). Pumping of the regional aquifer system 
for agricultural production of crops has resulted in the drying of most 
other springs in this region (Brune 1981, p. 356). Other springs that 
have already failed include Comanche Springs, which was once a large 
spring in Fort Stockton, Texas, about 8 mi (12.9 km) from Diamond Y 
Spring. Comanche Springs flowed at more than 142 cubic feet per second 
(cfs) (4.0 cubic meters per second (cms)) (Scudday 1977, p. 515; Brune 
1981, p. 358) and undoubtedly provided habitat for rare species of fish 
and invertebrates, including springsnails. The spring ceased flowing by 
1962 (Brune 1981, p. 358) except for brief periods (Small and Ozuna 
1993, p. 26). Leon Springs, located upstream of Diamond Y Spring in the 
Leon Creek watershed, was measured at 18 cfs (0.5 cms) in the 1930s and 
was also known to contain rare fish, but ceased flowing in the 1950s 
following significant irrigation pumping (Brune 1981, p. 359). There 
have been no continuous records of spring flow discharge at Diamond Y 
Spring by which to determine trends in spring flow.
    East Sandia Spring discharges at an elevation of 3,205 ft (977 m) 
from alluvial sand and gravel (Schuster 1997, pp. 92-93). Brune (1981, 
pp. 385-386) noted that flows from East Sandia Springs were declining. 
East Sandia Spring may be very susceptible to over-pumping in the area 
of the local aquifer that supports the spring. Measured discharges in 
1995 and 1996 ranged from 0.45 to 4.07 cfs (0.013 to 0.11 cms) 
(Schuster 1997, p. 94). The small outflow channel from East Sandia 
Spring has not been significantly modified, and water flows into an 
irrigation system approximately 328 to 656 ft (100 to 200 m) after 
surfacing.
Water Contamination
    Water contamination, particularly from oil and gas operations, is a 
significant threat for these four invertebrates. In order to assess the 
potential for contamination, a study was completed in September 1999 to 
delineate the area that serves as sources of water for the springs on 
the Refuge (Balleau et al. 1999, pp. 1-42). This study reported that 
the sources of water that will reach the Refuge's springs include a 
broad area beginning west of Roswell near Eightmile Draw, extending to 
the northeast to Salt Creek, and southeast to the Refuge. This area 
represents possible pathways that contaminants may enter the 
groundwater that feeds the springs on the Refuge. This broad area sits 
within a portion of the Roswell Basin and contains a mosaic of Federal, 
State, and private lands with multiple land uses including expanding 
urban development.
    There are 378 natural gas and oil wells in the 12-township area 
encompassing the source-water capture zone for the Middle Tract of the 
Refuge (the only tract on which these species are found) that are 
potential sources of contamination (Go-Tech 2010). Of these, 17 oil and 
gas leases are currently within the habitat protection zone designated 
by the Bureau of Land Management (BLM) to reduce risk from drilling 
operations to the four invertebrates. This habitat protection zone 
encompasses 12,585 ac (5,093 ha) of the Federal mineral estate within 
the water resource area for the Refuge (U.S. Fish and Wildlife Service 
(Service) 2005a, pp. 3-8). Twenty natural gas wells currently exist on 
these leases. The BLM has estimated a maximum potential development of 
66 additional wells within the habitat protection zone, according to 
well spacing requirements established by the New Mexico Oil 
Conservation Division (Service 2005a, p. 4-6). From 2002 to 2004, there 
were 200 notices of ``intentions to drill'' (59 on State, 33 on 
private, and 108 on Federal lands) filed for oil or natural gas in 
Chaves County (Go-Tech 2005).
    There are numerous examples in which oil and gas operations have 
met regulatory standards within karst lands

[[Page 35381]]

in New Mexico and other States, but these measures failed to protect 
groundwater resources and prevent aquifer drawdown (McCord et al. 2007, 
p. 8). To clean the aquifer would be extremely difficult should it 
become contaminated by oil, chemicals, or organics, such as nitrates. 
In most cases, contamination of an underground aquifer by agricultural, 
industrial, or domestic sources is treated only at the source. When a 
contamination site is discovered, the source of the contamination is 
treated, and rarely do remediation efforts pump water from the aquifer 
and treat it before sending it back. This is largely because these 
techniques are very costly and difficult to apply (S. McGrath, pers. 
comm. 2001). Because these invertebrate species are sensitive to 
contaminants, efforts to clean up pollution after the aquifer has been 
contaminated may not be sufficient to protect these species and the 
aquatic habitat on which they depend.
    Currently there are two active gas wells on the Middle Tract of the 
Refuge that are upstream (within the underground watershed) of occupied 
habitat for the four invertebrates. In 2006, Yates Petroleum applied 
for two additional gas wells, one of which would have been just 
upstream of occupied habitat for the four invertebrates. The 
applications have since been withdrawn, although the potential for oil 
and gas development remains.
    The Diamond Y Springs Complex is within an active oil and gas 
extraction field. At this time there are still many active wells and 
pipelines located within a hundred meters of the surface waters at the 
springs. In addition, a natural gas refinery is located within 0.5 mi 
(0.8 km) upstream of Diamond Y Spring. There are also old brine pits, 
which can contribute salt and other mineral pollutants to the 
groundwater, associated with previous drilling within feet of surface 
waters. In addition, oil and gas pipelines cross the spring outflow 
channels and marshes where the species occurs, creating a constant 
potential for contamination from pollutants from leaks or spills. These 
activities pose a threat to the habitat of the Pecos assiminea by 
creating the potential for pollutants to enter underground aquifers 
that contribute to spring flow or by point sources from spills and 
leaks of petroleum products on the surface.
    As an example of the likelihood of a spill occurring, in 1992 
approximately 10,600 barrels of crude oil were released from a 6-in 
(15.2 cm) pipeline that traverses Leon Creek above its confluence with 
Diamond Y Draw. The oil was from a ruptured pipeline at a point several 
hundred feet away from the Leon Creek channel. The site itself is about 
1 mi (1.6 km) overland from Diamond Y Spring. The distance that surface 
runoff of oil residues must travel is about 2 mi (3.2 km) down Leon 
Creek to reach Diamond Y Draw. The pipeline was operated at the time of 
the spill by the Texas-New Mexico Pipeline Company, but ownership has 
since been transferred to several other companies. The Texas Railroad 
Commission has been responsible for overseeing cleanup of the spill 
site. Remediation of the site initially involved aboveground land 
farming of contaminated soil and rock strata to allow microbial 
degradation. In recent years, remediation efforts have focused on 
vacuuming oil residues from the surface of groundwater exposed by 
trenches dug at the spill site. No impacts on the rare fauna of Diamond 
Y Springs Complex have been observed, but no specific monitoring of the 
effects of the spill was undertaken (Service 2005a, pp. 4-12).
Fire
    Fire suppression efforts on the Refuge are largely restricted to 
established roads due to the safety hazards of transporting equipment 
over karst terrain. This severely limits the ability to quickly 
suppress fires that threaten fragile aquatic habitats on the Refuge. On 
March 5, 2000, the Sandhill wildfire burned 1,000 ac (405 ha) of the 
western portion of the Refuge, including portions of Bitter Creek. The 
fire burned through Dragonfly Spring, a spring in the headwaters of 
Bitter Creek, which is occupied habitat for Noel's amphipod and 
Koster's springsnail. The fire eliminated vegetation shading the 
spring, and generated a substantial amount of ash in the spring system 
(Lang 2002, p. 3; NMDGF 2005, p. 15). This resulted in the formation of 
dense algal mats, increased water temperature fluctuations, increased 
maximum water temperatures, and decreased dissolved oxygen levels (Lang 
2002, pp. 5-6). The pre-fire dominant vegetation of submerged aquatic 
plants and mixed native grasses within the burned area has also been 
replaced by the invasive common reed (Phragmites australis) (NMDGF 
2005, p. 15; 2008, p. 8). Following the fire at Dragonfly Spring, a 
dramatic reduction in Noel's amphipod was observed, and Koster's 
springsnail presently occurs at lower densities than were observed 
prior to the fire (Lang 2002, p. 7; NMDGF 2006a, p. 9). Strategically 
timed prescribed burns throughout the range of the species would 
significantly reduce fuel loads, limiting the risk of detrimental 
wildfires.
    Removal of vegetative cover by burning in habitats occupied by 
Pecos assiminea may be an important factor in decline or loss of 
populations (Taylor 1987, p. 5, NMDGF 2005, p. 16). It is likely that 
Pecos assiminea may survive fire or other vegetation reduction if 
sufficient litter and ground cover remain to sustain appropriate soil 
moisture and humidity at a microhabitat scale (NMDGF 2005, p. 16; 
Service 2004, pp. 4-5). Complete combustion of vegetation and litter, 
high soil temperatures during fire, or extensive vegetation removal 
resulting in soil and litter drying may create unsuitable habitat 
conditions and loss of populations (NMDGF 2005, p. 16). Pecos assiminea 
was discovered at Dragonfly Spring following the burning of habitat 
there during the Sandhill Fire (NMDGF 2005, p. 16). Season of burning, 
intensity of the fire, and frequency of fire likely determine the 
magnitude of the fire's effects on Pecos assiminea population 
persistence and abundance (NMDGF 2005, p. 16), as the species has been 
found to persist in areas following fires (Lang 2002, p. B8). Pecos 
assiminea is relatively vulnerable to fires because the assiminea 
resides at or near the surface of the water.
Introduced Species
    Introduced species are one of the most serious threats to native 
aquatic species (Williams et al. 1989, p. 18; Lodge et al. 2000, p. 7). 
Because the distribution of the four invertebrates is so limited, and 
their habitat so restricted, introduction of certain nonnative species 
into their habitat could be devastating. Several invasive terrestrial 
plant species that may affect the invertebrates are present on the 
Refuge, including saltcedar (Tamarix ramossisima), common reed, and 
Russian thistle (Salsola spp.). Control and removal of nonnative 
vegetation has been identified as a factor responsible for localized 
extirpations of populations of Pecos assiminea in Mexico and New Mexico 
(Taylor 1987, p. 5). Saltcedar, found on the Refuge and at Diamond Y 
Spring Complex and East Sandia Spring, threatens spring habitats 
primarily through the amount of water it consumes and from the chemical 
composition of the leaves that drop to the ground and into the springs. 
Saltcedar leaves that fall to the ground and into the water add salt to 
the system, as their leaves contain salt glands (DiTomaso 1998, p. 
333). Additionally, dense stands of common reed choke the stream 
channel, slowing water velocity and creating more pool-like habitat; 
this habitat is less suitable for Roswell and Koster's springsnails,

[[Page 35382]]

which prefer flowing water. Finally, Russian thistle (tumbleweed) can 
create problems in spring systems by being blown into the channel, 
slowing flow and overloading the system with organic material (Service 
2005b, p. 2).
    Nonnative mollusks have affected the distribution and abundance of 
native mollusks in the United States. Of particular concern for three 
of the invertebrates (Noel's amphipod, Roswell springsnail, and 
Koster's springsnail) is the red-rim melania (Melanoides tuberculata), 
a snail that can reach tremendous population sizes and has been found 
in isolated springs in the west. The red-rim melania has caused the 
decline and local extirpation of native snail species, and it is 
considered a threat to endemic aquatic snails that occupy springs and 
streams in the Bonneville Basin of Utah (Rader et al. 2003, p. 655). It 
is easily transported on fishing boats and gear or aquatic plants, and 
because it reproduces asexually (individuals can develop from 
unfertilized eggs), a single individual is capable of founding a new 
population. It has become established in isolated desert spring 
ecosystems such as Ash Meadows, Nevada, and Cuatro Cienegas, Mexico, 
and within the last 15 years, the red-rim melania has become 
established in Diamond Y Springs Complex (Echelle 2001, p. 18). It has 
become the most abundant snail in the upper watercourse of the Diamond 
Y Springs Complex (Echelle 2001, p. 14). In many locations, this exotic 
snail is so numerous that it essentially is the substrate in the small 
stream channel. The effect the species is having on native snails is 
not known; however, because it is aquatic it probably has less effect 
on Pecos assiminea than on the other endemic aquatic snails present in 
the spring.

Criteria Used To Identify Critical Habitat

    As required by section 4(b) of the Act, we used the best scientific 
and commercial data available in determining areas within the 
geographical area occupied at the time of listing that contain the 
features essential to the conservation of Roswell springsnail, Koster's 
springsnail, Noel's amphipod, and Pecos assiminea, as well as in 
determining if areas outside of the geographical area occupied at the 
time of listing are essential for the conservation of the four 
invertebrates. We relied on information from knowledgeable biologists 
and recommendations contained in State wildlife resource reports (Cole 
1985; Jones and Balleau 1996, pp. 1-16; Boghici 1997, pp. 1-120; 
Balleau et al. 1999, pp. 1-42; NMDGF 1999, pp. A1-B46; NMDGF 2006b, pp. 
1-16; NMDGF 2007, pp. 1-20; and NMDGF 2008, pp. 1-28) and the State 
recovery plan (NMDGF 2005, pp. 1-80) in making this determination. We 
also reviewed the available literature pertaining to habitat 
requirements, historic localities, and current localities for these 
species. This includes data submitted during section 7 consultations 
and regional geographic information system (GIS) coverages.
    In proposing designation of revised critical habitat for the Pecos 
assiminea, and critical habitat for Roswell springsnail, Koster's 
springsnail, and Noel's amphipod,, we selected areas based on the best 
scientific data available that possess those PCEs essential to the 
conservation of the species that may require special management 
considerations or protection. We identified critical habitat units that 
have the highest likelihood to contain populations of the four 
invertebrates based on the presence of the defined PCEs and the kind, 
amount, and quality of habitat associated with those occurrences. The 
units contain the appropriate quantity and distribution of PCEs to 
support the life cycle stages we have determined are essential to the 
conservation of the species.
    The four invertebrates currently exist throughout their ranges in a 
spatial arrangement that would provide for their long-term 
conservation. For this reason, we are not currently proposing any areas 
outside the geographical area presently occupied by the species, 
because the occupied areas are sufficient for the conservation of the 
species.
    When determining revised critical habitat boundaries within this 
proposed rule, we made every effort to avoid including structures such 
as culverts and roads, because areas with such structures lack PCEs for 
Roswell springsnail, Koster's springsnail, Noel's amphipod, and Pecos 
assiminea. The scale of the maps we prepared under the parameters for 
publication within the Code of Federal Regulations may not reflect the 
exclusion of such areas. Any such structures inadvertently left inside 
critical habitat boundaries shown on the maps of this proposed rule 
have been excluded by text in the proposed rule and are not proposed 
for designation as critical habitat. Therefore, if the critical habitat 
were finalized as proposed, a Federal action involving these areas 
would not trigger section 7 consultation with respect to critical 
habitat and the requirement of no adverse modification unless the 
specific action would affect the PCEs in the adjacent critical habitat.
Essential Areas
    For areas not occupied by the species at the time of listing, the 
Service must demonstrate that these areas are essential to the 
conservation of the species in order to include them in a critical 
habitat designation. The four invertebrates are not migratory, nor is 
there frequent gene exchange between populations or critical habitat 
units. Further, the proposed critical habitat units in New Mexico and 
west Texas are sufficiently distant (40 to 100 mi (64 to 161 km)) from 
one another to rule out Pecos assiminea gene exchange. Therefore, due 
to the lack of frequent gene exchange, we have determined that each of 
these populations is essential to the conservation of the species 
because they provide for the maintenance of the genetic diversity of 
the four invertebrates. The areas we have determined meet the 
definition of critical habitat for the four invertebrates include 
populations containing all of the known remaining genetic diversity 
within each species.
    Locations from within the historical range of the four 
invertebrates, including North Spring, Berrendo Spring, South Spring 
River, and Lander Springbrook, are no longer suitable habitat for the 
four invertebrates, and the species have been extirpated from these 
sites. South Spring and Lander Spring are both dry due to aquifer 
depletion (Cole 1981, p. 27; Jones and Balleau 1996, p. 5), and reaches 
of Berrendo Creek (the springbrook from Berrendo Spring) remain dry and 
unable to support the invertebrates (NMDGF 2005, p. 18). North Spring, 
located on the grounds of the Roswell Country Club, was enclosed by a 
brick wall, native vegetation was removed from the margins of the 
springhead and springbrook, and the banks were sodded (Cole, 1988, p. 
2; NMDGF 2005, p. 18). The brick wall at North Spring has since been 
removed and the spring outflow has been widened, allowing a nearby pond 
to back into the spring, introducing carp to the system (B. Lang, 
NMDGF, pers. comm., 2010). Springsnails have not been found at North 
Spring since 1995, and suitable habitat is not present there. Because 
these formerly occupied sites have been so severely impacted in the 
past, it is not likely that they could be rehabilitated in the future 
and once again contain suitable habitat for the four invertebrates; 
therefore, they are unlikely to contribute to the recovery of the 
species and not considered essential to the conservation of the 
species.

[[Page 35383]]

Occupancy
    We consider an area to be currently occupied if Roswell 
springsnail, Koster's springsnail, Pecos assiminea, or Noel's amphipod 
were found to be present by species experts within the last 5 years and 
no major habitat modification has occurred which would preclude their 
presence. Five years is an appropriate time period because surveys may 
not occur in all areas in all years. The species would be likely to 
persist in an area over multiple years unless major habitat 
modification occurred. We are proposing to designate as critical 
habitat all sites on or near the Refuge currently occupied by at least 
one of the four invertebrates.
    In summary, this proposed critical habitat designation includes 
populations of the four invertebrates and habitats that possess the 
physical and biological features essential to the conservation of the 
species. We believe the populations included in this designation, if 
secured, would provide for the conservation of the Roswell springsnail, 
Koster's springsnail, Pecos assiminea, and Noel's amphipod by:
    (1) Maintaining the physical and biological features essential to 
the conservation of the species in areas where populations of the four 
invertebrates are known to occur, and
    (2) Maintaining the current distribution, thus preserving genetic 
variation throughout the ranges of the four invertebrates and 
minimizing the potential effects of local extinction.

Summary of Changes from Previously Proposed and Designated Critical 
Habitat

    The areas identified in this proposed rule constitute a proposed 
revision of the areas we designated as critical habitat for the Pecos 
assiminea on August 9, 2005 (70 FR 46304). The significant differences 
between the 2005 rule and this proposal include the following:
    (1) Currently, two units in Texas (Diamond Y Spring complex and 
East Sandia Springs) totaling 396.5 ac (160.5 ha) are designated as 
critical habitat for the Pecos assiminea (70 FR 46304, August 9, 2005). 
We did not designate any areas as critical habitat for the Roswell 
springsnail, Koster's springsnail, and Noel's amphipod in 2005, nor did 
we designate any lands of the Bitter Lake National Wildlife Refuge 
(Refuge) as critical habitat for these species. This proposed rule, 
which is based partly on new occupancy information since we originally 
proposed critical habitat, includes two units on the Refuge totaling 
67.8 ac (27.4 ha). If adopted, this proposed rule would result in an 
increase of 70.6 ac (28.6 ha) from currently designated critical 
habitat for the Pecos assiminea and would include new critical habitat 
for the Roswell springsnail, Koster's springsnail, and Noel's amphipod.
    (2) As stated above, our 2005 critical habitat designation (70 FR 
46304; August 9, 2005) did not include any Refuge lands. In that rule, 
we determined that Refuge lands did not meet the definition of critical 
habitat in section 3(5)(A) of the Act because the special management 
for the four invertebrates was already occurring on the Refuge. In 
order to more fully consider special management of threats that may be 
occurring outside the Refuge boundaries, we are now proposing certain 
Refuge lands for critical habitat designation.
    (3) In our February 12, 2002, proposal to designate critical 
habitat for the four invertebrates (67 FR 6459) we proposed 1,127 ac 
(456 ha) of critical habitat on the Refuge. This proposed designation 
of critical habitat includes only 67.8 ac (27.4 ha) on the Refuge; 
updated GIS techniques have allowed us to more closely map the 
wetlands, springs, and seeps on the Refuge in which the four 
invertebrates occur.
    (4) This proposed designation of critical habitat includes 2.8 ac 
(1.1 ha) in one unit in the city of Roswell, New Mexico, adjacent to 
the Refuge that are not currently designated as critical habitat. We 
did not include this site in the August 9, 2005, designation (70 FR 
46304) because occupancy by Noel's amphipod and Koster's springsnail 
was first documented following publication of the proposed rule to 
designate critical habitat (67 FR 6459; February 12, 2002).
    (5) This proposed designation of critical habitat includes the two 
units in Texas (Diamond Y Spring complex and East Sandia Springs) 
currently designated for Pecos assiminea, but we have used updated GIS 
information to offer more refined boundaries within those two units. 
While the critical habitat boundary at Diamond Y Spring complex did not 
change, the acreage calculation increased from 380 ac (153.8 ha) in the 
2005 final rule (70 FR 46304, August 9, 2005) to 441.5 ac (178.7 ha) in 
this proposed rule. At East Sandia Spring, updated GIS techniques have 
allowed us to more closely map the wetlands, springs, and seeps in this 
area, resulting in fewer acres proposed for critical habitat; we 
designated 16.5 ac (6.7 ha) in 2005 (70 FR 46304, August 9, 2005), and 
we are proposing 3.0 ac (1.2 ha) for designation in this rule.
    (6) This proposed designation of critical habitat includes more 
detailed PCEs than we proposed for Roswell and Koster's springnails and 
Noel's amphipod in our 2002 proposal (67 FR 6459, February 12, 2002) or 
we adopted for Pecos assiminea in our 2005 designation (70 FR 46304, 
August 9, 2005); this detail adds clarity to the designation.
    (7) We are proposing as critical habitat all occupied sites for the 
four invertebrates, as all of these sites are essential to the 
conservation of the species.

Proposed Critical Habitat Designation

    We are proposing four units as critical habitat for the Roswell 
springsnail, Koster's springsnail, Noel's amphipod, and Pecos assiminea 
in New Mexico and Texas. The critical habitat areas we describe below 
constitute our current best assessment of areas that meet the 
definition of critical habitat for the four invertebrates. Roswell 
springsnail, Koster's springsnail, and Noel's amphipod occur in two of 
the four units; the two units we propose as critical habitat for these 
invertebrates, and their approximate areas, are displayed in Table 1. 
Pecos assiminea occurs in all four units; the four units we propose as 
revised critical habitat for this species, and their approximate areas, 
are displayed in Table 2. All locations were occupied at the time of 
listing and are currently occupied by the invertebrates.

    TABLE 1. Proposed critical habitat units for Roswell springsnail,
  Koster's springsnail, and Noel's amphipod [Area estimates reflect all
             land within critical habitat unit boundaries.]
------------------------------------------------------------------------
                                   Land Ownership by    Size of Unit in
      Critical Habitat Unit              Type          Acres (Hectares)
------------------------------------------------------------------------
1. Sago/Bitter Creek Complex      Service             31.9 (12.9)
=================================
2. Impoundment Complex            Service             35.9 (14.5)
                                  City of Roswell...  2.8 (1.1)
=================================

[[Page 35384]]

 
Total                                                 70.6 (28.6)
------------------------------------------------------------------------
Note: Area sizes may not sum due to rounding.


  TABLE 2. Proposed revised critical habitat units for Pecos assiminea.
      [Area estimates reflect all land within critical habitat unit
                              boundaries.]
------------------------------------------------------------------------
                                   Land Ownership by    Size of Unit in
      Critical Habitat Unit              Type          Acres (Hectares)
------------------------------------------------------------------------
1. Sago/Bitter Creek Complex      Service             31.9 (12.9)
=================================
2. Impoundment Complex            Service             35.9 (14.5)
                                  City of Roswell...  2.8 (1.1)
=================================
3. Diamond Y Springs Complex      The Nature          441.4 (178.6)
                                   Conservancy
=================================
4. East Sandia Spring             The Nature          3.0 (1.2)
                                   Conservancy
=================================
Total                                                 515.0 (208.4)
------------------------------------------------------------------------
Note: Area sizes may not sum due to rounding.

    We present brief descriptions of the units and reasons why the 
proposed cri