Federal Register, Volume 77 Issue 159 (Thursday, August 16, 2012)

[Federal Register Volume 77, Number 159 (Thursday, August 16, 2012)]
[Proposed Rules]
[Pages 49602-49651]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2012-19829]

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Vol. 77

Thursday,

No. 159

August 16, 2012

Part III

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; Endangered Status for
Six West Texas Aquatic Invertebrate Species and Designation of Critical
Habitat; Proposed Rule

Federal Register / Vol. 77 , No. 159 / Thursday, August 16, 2012 /
Proposed Rules

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R2-ES-2012-0029; 4500030113]
RIN 1018-AX70

Endangered and Threatened Wildlife and Plants; Endangered Status
for Six West Texas Aquatic Invertebrate Species and Designation of
Critical Habitat

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service, propose to list as
endangered and propose critical habitat for six west Texas aquatic
invertebrate species under the Endangered Species Act. These actions
are being taken as the result of a court-approved settlement agreement.
These are proposed regulations, and if finalized the effect of these
regulations will be to conserve the species and protect their habitat
under the Endangered Species Act.

DATES: We will accept comments received or postmarked on or before
October 15, 2012. We must receive requests for public hearings, in
writing, at the address shown in FOR FURTHER INFORMATION CONTACT by
October 1, 2012.

ADDRESSES: You may submit comments by one of the following methods:
(1) Electronically: Go to the Federal eRulemaking Portal: http://www.regulations.gov and search for FWS-R2-ES-2012-0029, which is the
docket number for this rulemaking.
(2) By hard copy: Submit by U.S. mail or hand-delivery to: Public
Comments Processing, Attn: FWS-R2-ES-2012-0029; Division of Policy and
Directives Management; U.S. Fish and Wildlife Service; 4401 N. Fairfax
Drive, MS 2042-PDM; Arlington, VA 22203.
We request that you send comments only by the methods described
above. We will post all comments on http://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).
The coordinates, or plot points, or both from which the critical
habitat maps are generated are included in the administrative record
for this rulemaking and are available at (http://www.fws.gov/southwest/es/AustinTexas/), http://www.regulations.gov at Docket No. FWS-R2-ES-
2012-0029, and at the Austin Ecological Services Field Office (see FOR
FURTHER INFORMATION CONTACT). Any additional tools or supporting
information that we may develop for this rulemaking will also be
available at the Fish and Wildlife Service Web site and Field Office
set out above, and may also be included in the preamble and/or at
http://www.regulations.gov.

FOR FURTHER INFORMATION CONTACT: Adam Zerrenner, Field Supervisor, U.S.
Fish and Wildlife Service, Austin Ecological Services Field Office,
10711 Burnet Road, Suite 200, Austin, TX 78758; by telephone 512-490-
0057; or by facsimile 512-490-0974. Persons who use a
telecommunications device for the deaf (TDD) may call the Federal
Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Executive Summary

This document consists of proposed rules to list six west Texas
aquatic invertebrate species as endangered and propose critical habitat
designations for the six species. The six west Texas aquatic
invertebrate species are: Phantom Cave snail (Pyrgulopsis texana),
Phantom springsnail (Tryonia cheatumi), diminutive amphipod (Gammarus
hyalleloides), Diamond Y Spring snail (Pseudotryonia adamantina),
Gonzales springsnail (Tryonia circumstriata), and Pecos amphipod
(Gammarus pecos). The current range for the first three species is
limited to spring outflows in the San Solomon Springs system near
Balmorhea in Reeves and Jeff Davis Counties, Texas. The current range
of the latter three species is restricted to spring outflow areas
within the Diamond Y Spring system north of Fort Stockton in Pecos
County, Texas.
Why we need to publish a rule. Under the Endangered Species Act, a
species may warrant protection through listing if it is endangered or
threatened throughout all or a significant portion of its range. In
this proposal we are explaining why these six species warrant
protection under the Endangered Species Act. Five of the six species of
aquatic invertebrates are currently identified as candidates for
listing based on threats to their habitat. The table below summarizes
the status of each species:

------------------------------------------------------------------------
Species Present range Status of species
------------------------------------------------------------------------
Phantom Cave snail.......... San Solomon Spring common in a very
system (four restricted range.
springs).
Phantom Lake springsnail.... San Solomon Spring very rare in a very
system (four restricted range.
springs).
diminutive amphipod......... San Solomon Spring common in a very
system (four restricted range.
springs).
Diamond Y Spring snail...... Diamond Y Spring very rare in a very
system (two restricted range.
springs).
Gonzales springsnail........ Diamond Y Spring very rare in a very
system (two restricted range.
springs).
Pecos amphipod.............. Diamond Y Spring common in a very
system (two restricted range
springs).
------------------------------------------------------------------------

These rules propose that all six of these species should be listed
as endangered. We are proposing a listing status of endangered for
these six species of aquatic invertebrates from west Texas.
The Endangered Species Act provides the basis for our action. Under
the Endangered Species Act, we can determine that a species is
endangered or threatened based on any of five factors: (A) The present
or threatened destruction, modification, or curtailment of its habitat
or range; (B) Overutilization for commercial, recreational, scientific,
or educational purposes; (C) Disease or predation; (D) The inadequacy
of existing regulatory mechanisms; or (E) Other natural or manmade
factors affecting its continued existence. We are proposing that all
six species are endangered by the combined effects of:
Habitat loss and degradation of aquatic resources,
particularly the current and ongoing decline in spring flows that
support the habitat of all the species, and the potential for future
water contamination at the Diamond Y Spring system.
Inadequate existing regulatory mechanisms that allow
significant threats such as groundwater withdrawal.
Other natural or manmade factors, including the presence
of nonnative snails and the small, reduced ranges of the species.
These rules also propose designation of critical habitat for each
of the six species. Under the Endangered Species Act, we designate
specific areas as

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critical habitat to foster conservation of listed species. Future
actions funded, permitted, or otherwise carried out by Federal agencies
will be reviewed to ensure they do not adversely modify critical
habitat. Critical habitat does not affect private actions on private
lands. We are proposing the following areas in Texas as critical
habitat for Phantom Cave snail, Phantom springsnail, and diminutive
amphipod:

------------------------------------------------------------------------
Size of unit in
Critical habitat unit Land ownership by type hectares (acres)
------------------------------------------------------------------------
San Solomon Spring, Reeves State--Texas Parks and 1.8 (4.4)
County. Wildlife Department.
Giffin Spring, Reeves County.. Private............... 0.7 (1.7)
East Sandia Spring, Reeves Private--The Nature 1.2 (3.0)
County. Conservancy.
Phantom Lake Spring, Jeff Federal--Bureau of 0.02 (0.05)
Davis County. Reclamation.
-----------------------------------------
Total..................... ...................... 3.7 (9.2)
------------------------------------------------------------------------
Note: Area sizes may not sum due to rounding.

We are proposing the following areas as critical habitat for
Diamond Y Spring snail, Gonzales springsnail, and Pecos amphipod:

We are preparing an economic analysis. We are preparing an economic
analysis of the proposed designations of critical habitat to allow for
consideration of the economic impacts of the proposed designations of
critical habitat. We will publish an announcement and seek public
comments on the draft economic analysis when it is completed.
We will request peer review of the methods used in our proposal. We
are seeking comments from independent specialists with scientific
expertise in these species or related fields. We have invited these
peer reviewers to comment on the scientific information and methods
that we used in making this proposal. Because we will consider all
comments and information received during the comment period, our final
determinations may differ from this proposal.
We are seeking public comment on these proposed rules. Anyone is
welcome to comment on our proposal or provide additional information on
the proposal that we can use in making a final determination on the
status of these species. Please submit your comments and materials
concerning these proposed rules by one of the methods listed in the
ADDRESSES section. Within 1 year following the publication of this
proposal, we will publish in the Federal Register a final determination
to list one or more of these species as threatened or endangered, or
withdraw the proposals if new information is provided that supports
that decision.

Public Comments

We intend that any final action resulting from these proposed rules
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 the public, other concerned governmental
agencies, Native American tribes, the scientific community, industry,
or any other interested parties concerning these proposed rules. We
particularly seek comments concerning:
(1) Biological, commercial trade, or other relevant data concerning
any threats (or lack thereof) to this species and regulations that may
be addressing those threats.
(2) Additional information concerning the historical and current
status, range, distribution, and population size of this species,
including the locations of any additional populations of this species.
(3) Any information on the biological or ecological requirements of
the species, and ongoing conservation measures for the species and its
habitat.
(4) Current or planned activities in the areas occupied by the
species and possible impacts of these activities on this species.
(5) The reasons why we should or should not designate habitat as
``critical habitat'' under section 4 of the 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 may not be
prudent.
(6) Specific information on:
(a) The amount and distribution of habitat for the six west Texas
aquatic invertebrates;
(b) What areas, that were occupied at the time of listing (or are
currently occupied) and that contain features essential to the
conservation of the species, should be included in the designation and
why;
(c) Special management considerations or protection that may be
needed in critical habitat areas we are proposing, including managing
for the potential effects of climate change; and
(d) What areas not occupied at the time of listing are essential
for the conservation of the species and why.
(7) Land use designations and current or planned activities in the
subject areas and their possible impacts on proposed critical habitat.
(8) Information on the projected and reasonably likely impacts of
climate change on the six west Texas aquatic invertebrates and proposed
critical habitat.
(9) Any probable economic, national security, or other relevant
impacts of designating any area that may be included in the final
designation; in particular, any impacts on small entities or families,
and the benefits of including or excluding areas that exhibit these
impacts.
(10) Whether any specific areas we are proposing for critical
habitat designation should be considered for exclusion under section
4(b)(2) of the Act, and whether the benefits of

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potentially excluding any specific area outweigh the benefits of
including that area under section 4(b)(2) of the Act.
(11) Whether the benefits of exclusion outweigh the benefits of
including the area proposed as critical habitat around San Solomon
Spring at Balmorhea State Park based on the existing habitat
conservation plan or other relevant factors.
(12) Whether we could improve or modify our approach to designating
critical habitat in any way to provide for greater public participation
and understanding, or to better accommodate public concerns and
comments.
Please note that submissions merely stating support for or
opposition to the action under consideration without providing
supporting information, although noted, will not be considered in
making a determination, as section 4(b)(1)(A) of the Act directs that
determinations as to whether any species is a threatened or endangered
species must be made ``solely on the basis of the best scientific and
commercial data available.''
You may submit your comments and materials concerning these
proposed rules by one of the methods listed in the ADDRESSES section.
We request that you send comments only by the methods described in the
ADDRESSES section.
If you submit information via http://www.regulations.gov, your
entire submission--including any personal identifying information--will
be posted on the Web site. If your submission is made via a hardcopy
that includes personal identifying information, you may request at the
top of your document that we withhold this information from public
review. However, we cannot guarantee that we will be able to do so. We
will post all hardcopy submissions on http://www.regulations.gov.
Please include sufficient information with your comments to allow us to
verify any scientific or commercial information you include.
Comments and materials we receive, as well as supporting
documentation we used in preparing these proposed rules, will be
available for public inspection on http://www.regulations.gov, or by
appointment, during normal business hours, at the U.S. Fish and
Wildlife Service, Austin Ecological Services Field Office (see FOR
FURTHER INFORMATION CONTACT).

Previous Federal Actions

We first proposed the Phantom Cave snail and Phantom springsnail as
endangered species on April 28, 1976 (41 FR 17742). At that time, the
Phantom Cave snail (Pyrgulopsis texana) was referred to as the Reeves
County snail (Cochliopa texana), and the Phantom springsnail was
referred to as the Cheatum's snail. The proposal was withdrawn on March
6, 1979 (44 FR 12382), following 1978 amendments to the Act that made
additional requirements necessary for designating critical habitat.
Both species were added as candidates for listing in the May 22, 1984,
Notice of Review of Invertebrate Wildlife for Listing as Endangered or
Threatened Species (49 FR 21664). At that time they were categorized as
Category 2 Candidates, which meant that we had information that
proposed listing is possibly appropriate, but conclusive data on
biological vulnerability and threats was not available to support a
proposed rule at the time. They remained so designated in our
subsequent annual Candidate Notices of Review (54 FR 554, January 6,
1989; 56 FR 58804, November 21, 1991; and 59 FR 58982, November 15,
1994). In the February 28, 1996, Notice (61 FR 7596), we discontinued
the designation of Category 2 species as candidates, which removed
these two species from the candidate list.
Both species were then added back to the candidate list on October
30, 2001 (66 FR 54808). Species on the candidate list are those fish,
wildlife, and plants for which we have on file sufficient information
on biological vulnerability and threats to support preparation of a
listing proposal, but for which development of a listing regulation is
precluded by other higher priority listing activities. Since 2001, the
listing priority number for both species has been a 2, reflecting
species with threats that are both imminent and high in magnitude in
accordance with our priority guidance published on September 21, 1983
(48 FR 43098). These two snails remained candidates in subsequent
Candidate Notices of Review (67 FR 40657, June 13, 2002; 69 FR 24876,
May 4, 2004). Both species were also petitioned for listing on May 11,
2004, and were found to be warranted for listing but precluded by
higher priority activities in subsequent Candidate Notice of Reviews
(70 FR 24870, May 11, 2005; 71 FR 53756, September 12, 2006; 72 FR
69034, December 6, 2007; 73 FR 75176, December 10, 2008; 74 FR 57804,
November 9, 2009; and 75 FR 69222, November 10, 2010). The October 26,
2011, Candidate Notice of Review (76 FR 66370) stated that we were
working on proposed listing rules for these species.
We identified the Diamond Y Spring snail and Gonzales springsnail
as candidates for listing in the January 6, 1989, Endangered or
Threatened Wildlife and Plants, Annual Notice of Review (54 FR 554).
These snails were designated as Category 1 candidates, indicating we
had substantial information to support listing, but a proposed rule was
precluded by other listing activities. These two species were included
in all of our subsequent annual Candidate Notices of Review even after
discontinuing the candidate categories (56 FR 58804, November 21, 1991,
and 59 FR 58982, November 15, 1994). From 1996 to 1999 these two
species had a listing priority number of 5, reflecting species with
high magnitude but nonimminent threats (61 FR 7596, February 28, 1996;
62 FR 49398, September 19, 1997; and 64 FR 57534, October 25, 1999). In
2001 we elevated the listing priority number from 5 to 2 because of a
new, imminent threat associated with the introduction of nonnative
snails into the species' habitat. A listing priority of 2 indicates
both high magnitude and imminent threats. Both species have maintained
a listing priority of 2 since then (66 FR 54808, October 30, 2001; 67
FR 40657, June 13, 2002; and 69 FR 24876, May 4, 2004). These two
species were also petitioned for listing on May 11, 2004, and were
found to be warranted for listing but precluded by higher priority
activities in subsequent Candidate Notice of Reviews (70 FR 24870, May
11, 2005; 71 FR 53756, September 12, 2006; 72 FR 69034, December 6,
2007; 73 FR 75176, December 10, 2008; 74 FR 57804, November 9, 2009;
and 75 FR 69222, November 10, 2010). The October 26, 2011, Candidate
Notice of Review (76 FR 66370) stated that we were working on proposed
listing rules for these species.
We identified the diminutive amphipod and Pecos amphipod as
Category 2 candidate species for listing in the May 22, 1984, Notice of
Review of Invertebrate Wildlife for Listing as Endangered or Threatened
Species (49 FR 21664). They remained so designated in our subsequent
annual Candidate Notices of Review (54 FR 554, January 6, 1989; 56 FR
58804, November 21, 1991; and 59 FR 58982, November 15, 1994). In the
February 28, 1996, Notice (61 FR 7596), we discontinued the designation
of Category 2 species as candidates, which removed these two species
from the candidate list. The diminutive amphipod was added back to the
candidate list on May 11, 2005 (70 FR 24870), and has remained a
candidate with a listing priority number of 2 (reflecting both high-
magnitude and imminent threats) since that time (71 FR 53756, September
12, 2006; 72 FR

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69034, December 6, 2007; 73 FR 75176, December 10, 2008; 74 FR 57804,
November 9, 2009; and 75 FR 69222, November 10, 2010). The October 26,
2011, Candidate Notice of Review (76 FR 66370) stated that we were
working on a proposed listing rule for the diminutive amphipod.
The Pecos amphipod was not included in recent candidate notices
along with the other species in this proposal because of taxonomic
uncertainties, which have since been resolved. In the past it was
unclear whether this species range was limited to Diamond Y Spring.
Recent genetic research has confirmed that the species is endemic to
Diamond Y Spring (see full discussion below under Taxonomy,
Distribution, and Abundance of Amphipods, Pecos Amphipod). The Pecos
amphipod was included in the June 25, 2007, petition by WildEarth
Guardians to the Service seeking the listing of 475 species in the
southwestern United States. On January 6, 2009, we published a partial
90-day finding of the petition for listing 475 species which included a
finding that the petition did not present substantial scientific or
commercial information indicating that the listing of the Pecos
amphipod may be warranted (74 FR 419). During our current review of the
other species endemic to the Diamond Y Spring system, we reviewed the
status of the Pecos amphipod. Based on the results of that review, we
are proposing to list it as endangered.

Background

We intend to discuss below only those topics directly relevant to
the consideration of the listing of the six west Texas aquatic
invertebrates as endangered and proposed critical habitat designations.
We have organized this Background section into three parts. The first
part is a general description of the two primary spring systems where
the six species occur. The second part is a general description of the
life history and biology of the four snail species, followed by
specific biological information on each of the four snail species. The
third part is a general description of the life history and biology of
the two amphipod species, followed by specific biological information
on each of the two amphipod species.

Description of Chihuahuan Desert Springs Inhabited by Invertebrate
Species

The six west Texas aquatic invertebrate species (Phantom Cave
snail, Phantom springsnail, diminutive amphipod, Diamond Y Spring
snail, Gonzales springsnail, and Pecos amphipod) occur within a
relatively small area of the Chihuahuan Desert of the Pecos River
drainage basin of west Texas. The habitats of these species are now
isolated spring systems in expansive carbonate (limestone) deposit. The
region includes a complex of aquifers (underground water systems) where
the action of water on soluble rocks (like limestone and dolomite) has
formed abundant ``karst'' features such as sinkholes, caverns, springs,
and underground streams. These hydrogeological formations provide
unique settings where a diverse assemblage of flora and fauna has
evolved at the points where the aquifers discharge waters to the
surface through spring openings. The isolated limestone and gypsum
springs, seeps, and wetlands located in this part of west Texas provide
the only known habitats for several endemic species of fish, plants,
mollusks, and crustaceans, including the six endemic aquatic
invertebrate species addressed in these proposed rules.
In the Chihuahuan Desert, spring-adapted aquatic species are
distributed in isolated, geographically separate populations. They
likely evolved into distinct species from parent species that once
enjoyed a wider distribution during wetter, cooler climates of the
Pleistocene epoch (about 10,000 to 2.5 million years before present).
As ancient lakes and streams dried during dry periods (since the Late
Pleistocene, within about the last 100,000 years), aquatic species in
this region became patchily distributed across the landscape as
geographically isolated populations exhibiting a high degree of
endemism (species found only in a particular region, area, or spring).
Such speciation through divergence has been reported for these species
(Gervasio et al. 2004, p. 521; Brown et al. 2008, pp. 486-487; Seidel
et al. 2009, p. 2304).
San Solomon Spring System
In these proposed rules we reference the San Solomon Spring system
to include four different existing spring outflows: San Solomon Spring,
Giffin Spring, Phantom Lake Spring, and East Sandia Spring. The springs
in this area are also commonly referred to by some authors as Toyah
Basin springs or Balmorhea area springs. All of the springs
historically drained into Toyah Creek, an intermittent tributary of the
Pecos River that is now dry except following large rainfall events. All
four springs are located in proximity to one another; it is about 13
kilometers (km) (8 miles (mi)) between the farthest two (East Sandia
Spring to Phantom Lake Spring). Brune (1981, pp. 258-259, 382-386)
provides a brief overview of each of these springs and documents their
declining flows during the early and middle twentieth century.
The San Solomon Spring system is located in the Chihuahuan Desert
of west Texas at the foothills of the Davis Mountains near Balmorhea,
Texas. Phantom Lake Spring is in Jeff Davis County (on the county
boundary with Reeves County), while the other major springs in this
system are in Reeves County. In addition to being an important habitat
for rare aquatic fauna, area springs have served for centuries as an
important source of irrigation water for local farming communities.
They are all located near the small town of Balmorhea (current
population of less than 500 people) in west Texas. The area is very
rural with no nearby metropolitan centers. Land ownership in the region
is mainly private, except as described below around the spring
openings, and land use is predominantly dry-land ranching with some
irrigated farmland.
The base flows from all of these springs are thought to ultimately
originate from a regional groundwater flow system. Studies show that
groundwater moves through geologic faults from the Salt Basin northwest
of the Apache and Delaware Mountains, located 130 km (80 mi) or more to
the west of the springs (Sharp 2001, pp. 42-45; Angle 2001, p. 247;
Sharp et al. 2003, pp. 8-9; Chowdhury et al. 2004, pp. 341-342; Texas
Water Development Board 2005, p. 106). The originating groundwater and
spring outflow are moderately to highly mineralized and appear to be of
ancient origin, with the water being estimated at 10,000 to 18,000
years old (Chowdhury et al. 2004, p. 340; Texas Water Development Board
2005, p. 89). The Salt Basin Bolson aquifer is part of the larger West
Texas Bolsons and is made up of connected sub-basins underlying Wild
Horse, Michigan, Lobo, and Ryan Flats, in the middle and southern Salt
Basin Valley in Texas (Angle, 2001, p. 242). (The term bolson is of
Spanish origin and refers to a flat-floored desert valley that drains
to a playa or flat.) These aquifers, which support the base flows
(flows not influenced by seasonal rainfall events) of the San Solomon
Spring system, receive little to no modern recharge from precipitation
(Scanlon et al. 2001, p. 28; Beach et al. 2004, pp. 6-9, 8-9). Studies
of the regional flow system indicate groundwater may move from south to
north through the Salt Basin from Ryan to Lobo to Wild Horse Flats
before being discharged through the Capitan

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Formation, into the Lower Cretaceous rocks (older than Pleistocene) via
large geologic faults then exiting to the surface at the springs
(LaFave and Sharp 1987, pp. 7-12; Angle 2001, p. 247; Sharp 2001, p.
42-45; Chowdhury et al. 2004, pp. 341-342; Beach et al. 2004, Figure
4.1.13, p. 4-19, 4-53). Chemical analysis and hydrogeological studies
support this hypothesis, and the water elevations throughout these
parts of the Salt Basin Bolson aquifer are higher in elevation than the
discharge points at the springs (Chowdhury et al. 2004, p. 342).
In contrast to the base flows, the springs also respond with
periodic short-term increases in flow rates following local, seasonal
rainstorms producing runoff events through recharge areas from the
Davis Mountains located to the southwest of the springs (White et al.
1941, pp. 112-119; LaFave and Sharp 1987, pp. 11-12; Chowdhury et al.
2004, p. 341). These freshwater recharge events provide very temporary
increases in spring flows, sometimes resulting in flow spikes many
times larger than the regular base flows. The increased flows are
short-lived until the local stormwater recharge is drained away and
spring flows return to base flows supported by the distant aquifers.
Historically, many of the springs in this spring system were likely
periodically interconnected following storm events with water flowing
throughout the Toyah Creek watershed. In recent times, however, manmade
structures altered the patterns of spring outflows and stormwater
runoff, largely isolating the springs from one another except through
irrigation canals.
San Solomon Spring is by far the largest single spring in the Toyah
Basin (Brune 1981, p. 384). The artesian spring issues from the lower
Cretaceous limestone at an elevation of about 1,008 meters (m) (3,306
feet (ft)). Brune (1981, p. 385) reported spring flows in the range of
1.3 to 0.8 cubic meters per second (cms) (46 to 28 cubic feet per
second (cfs)) between 1900 and 1978 indicating an apparent declining
trend. Texas Water Development Board (2005, p. 84) studies reported an
average flow rate of about 0.85 cms (30 cfs) from data between 1965 to
2001 with a calculated slope showing a slight decline in discharge.
San Solomon Spring now provides the water for the large,
unchlorinated, flow-through swimming pool at Balmorhea State Park and
most of the irrigation water for downstream agricultural irrigation by
the Reeves County Water Improvement District No. 1 (District). The
swimming pool is concrete on the sides and natural substrates on the
bottom and was originally constructed in 1936. Balmorhea State Park is
owned and managed by Texas Parks and Wildlife Department and
encompasses about 19 hectares (ha) (46 acres (ac)) located about 6 km
(4 mi) west of Balmorhea in the historic community of Toyahvale. The
Park provides recreational opportunities of camping, wildlife viewing,
and swimming and scuba diving in the pool. The District holds the water
rights for the spring which is channeled through an extensive system of
concrete-lined irrigation channels, and much of the water is stored in
nearby Lake Balmorhea and delivered through canals for flood irrigation
on farms down gradient (Simonds 1996, p. 2).
Balmorhea State Park's primary wildlife resource focus is on
conservation of the endemic aquatic species that live in the outflow of
San Solomon Spring (Texas Parks and Wildlife Department 1999, p. 1).
Texas Parks and Wildlife Department maintains two constructed
ci[eacute]negas that are flow-through, earth-lined pools in the park to
simulate more natural aquatic habitat conditions for the conservation
of the rare species, including the Phantom Cave snail, Phantom
springsnail, and diminutive amphipods. (Ci[eacute]nega is a Spanish
term that describes a spring outflow that is a permanently wet and
marshy area.) San Solomon Spring is also inhabited by two federally
listed fishes, Comanche Springs pupfish (Cyprinodon elegans) and Pecos
gambusia (Gambusia nobilis). No nonnative fishes are known to occur in
San Solomon Spring, but two nonnative aquatic snails, red-rim melania
(Melanoides tuberculata) and quilted melania (Tarebia granifera), do
occur in the spring outflows and are a cause for concern for the native
aquatic invertebrate species.
Giffin Spring is on private property less than 1.6 km (1.0 mi) west
of Balmorhea State Park, across State Highway 17. The spring originates
from an elevation similar to San Solomon Spring. Brune (1981, p. 385)
reported flow from Giffin Spring ranging from 0.07 to 0.17 cms (2.3 to
5.9 cfs) between 1919 and 1978, with a gradually declining trend.
During calendar year 2011, Giffin Spring flow rates were recorded
between 0.10 and 0.17 cms (3.4 and 5.9 cfs) (U.S. Geological Survey
2012, p. 1). Giffin Spring water flows are captured in irrigation
earthen channels for agricultural use. Giffin Spring is also inhabited
by the federally listed Comanche springs pupfish and Pecos gambusia,
and the only nonnative aquatic species of concern there is the red-rim
melania.
Phantom Lake Spring is at the base of the Davis Mountains about 6
km (4 mi) west of Balmorhea State Park at an elevation of 1,080 m
(3,543 ft). The outflow originates from a large crevice on the side of
a limestone outcrop cliff. The 7-ha (17-ac) site around the spring and
cave opening is owned by the U.S. Bureau of Reclamation. Prior to 1940
the recorded flow of this spring was regularly exceeding 0.5 cms (18
cfs). Outflows after the 1940s were immediately captured in concrete-
lined irrigation canals and provided water for local crops before
connecting to the District's canal system in Balmorhea State Park.
Flows declined steadily over the next 70 years until ceasing completely
in about the year 2000 (Brune 1981, pp. 258-259; Allan 2000, p. 51;
Hubbs 2001, p. 306). The aquatic habitat at the spring pool has been
maintained by a pumping system since then. Phantom Lake Spring is also
inhabited by the two federally listed fishes, Comanche Springs pupfish
and Pecos gambusia, and the only nonnative aquatic species of concern
there is the red-rim melania.
East Sandia Spring is the smallest spring in the system located in
Reeves County in the community of Brogado approximately 3 km (2 mi)
northeast of the town of Balmorhea and 7.7 km (4.8 mi) northeast of
Balmorhea State Park. The spring is within a 97-ha (240-ac) preserve
owned and managed by The Nature Conservancy--a private nonprofit
conservation organization (Karges 2003, pp. 145-146). In contrast to
the other springs in the San Solomon Spring system that are derived
directly from a deep underground regional flow system, East Sandia
Spring discharges from alluvial sand and gravel from a shallow
groundwater source at an elevation of 977 m (3,224 ft) (Brune 1981, p.
385; Schuster 1997, p. 92). Water chemistry at East Sandia Spring
indicates it is not directly hydrologically connected with the other
springs in the San Solomon Spring system in the nearby area (Schuster
1997, pp. 92-93). Historically there was an additional, smaller nearby
spring outlet called West Sandia Spring. Brune (1981, pp. 385-386)
reported the combined flow of East and West Sandia Springs as
declining, with measurements ranging from 0.09 to 0.02 cms (3.2 to 0.7
cfs) between 1932 and 1976. In 1976 outflow from East Sandia was 0.01
cms (0.5 cfs) of the total 0.02 cms (0.7 cfs) of the two springs. In
1995 and 1996 Schuster (1997, p. 94) reported flows from both springs
ranging from 0.12 to 0.01 cms (4.07 cfs to 0.45 cfs),

[[Page 49607]]

with an average of 0.05 cms (1.6 cfs). The outflow waters from the
spring discharge to an irrigation canal within a few hundred meters
from its source. East Sandia Spring is also inhabited by two federally
listed fishes, Comanche Springs pupfish and Pecos gambusia, as well as
the federally endangered Pecos assiminea (Assiminea pecos) snail and
the federally threatened Pecos sunflower (Helianthus paradoxus). No
nonnative aquatic species of concern are known from East Sandia Spring.
Historically there were other area springs along Toyah Creek that
were part of the San Solomon Spring system. Saragosa and Toyah Springs
occurred in the town of Balmorhea along Toyah Creek. Brune (1981, p.
386) reported historic base flows of about 0.2 cms (6 cfs) in the 1920s
and 1940s, declining to about 0.06 cms (2 cfs) in the 1950s and 1960s,
and no flow was recorded in 1978. Brune (1981, p. 385) reported that
the flow from West Sandia Spring was about 0.01 cms (0.2 cfs) in 1976,
after combined flows from East and West Sandia Springs had exceeded
0.07 cms (2.5 cfs) between the 1930s and early 1960s. The Texas Water
Development Board (2005, p. 12) reported West Sandia and Saragosa
Springs did not discharge sufficient flow for measurement. Karges
(2003, p. 145) indicated West Sandia has only intermittent flow and
harbors no aquatic fauna. It is unconfirmed whether the six aquatic
invertebrates discussed in this document occurred in these now dry
spring sites, but given their current distribution in springs located
upstream and downstream of these historic springs, we assume that they
probably did. However, because these springs have been dry for many
decades, they no longer provide habitat for the aquatic invertebrates.
Diamond Y Spring System
The Diamond Y Spring system is within a tributary drainage flowing
northeast to the Pecos River. Diamond Y Spring (previously called
Willbank Spring) is located about 80 km (50 mi) due east of San Solomon
Spring and about 12 km (8 mi) north of the City of Fort Stockton in
Pecos County. The Diamond Y Spring system is composed of disjunct upper
and lower watercourses, separated by about 1 km (0.6 mi) of dry stream
channel.
The upper watercourse is about 1.5 km (0.9 mi) long and starts with
the Diamond Y Spring head pool, which drains into a small spring
outflow channel. The channel enters a broad valley and braids into
numerous wetland areas and is augmented by numerous small seeps. The
Diamond Y Spring outflow converges with the Leon Creek drainage and
flows through a marsh-meadow, where it is then referred to as Diamond Y
Draw. All of the small springs and seeps and their outflow comprise the
upper watercourse. These lateral water features, often not mapped, are
spread across the flat, seasonally wetted area along Diamond Y Draw.
Therefore, unlike other spring systems that have a relatively small
footprint, aquatic habitat covers a relatively large area along the
Diamond Y draw.
The lower watercourse of Diamond Y Draw has a smaller head pool
spring, referred to as Euphrasia Spring, with a small outflow stream as
well as several isolated pools and associated seeps and wetland areas.
The total length of the lower watercourse is about 1 km (0.6 mi) and
has extended below the bridge at State Highway 18 during wetter seasons
in the past. The upper watercourse is only hydrologically connected to
the lower watercourse by surface flows during rare large rainstorm
runoff events. The lower watercourse also contains small springs and
seeps laterally separated from the main spring outflow channels.
Virtually all of the Diamond Y Spring area (both upper and lower
watercourses and the area in between) occurs on the Diamond Y Spring
Preserve, which is owned and managed by The Nature Conservancy. The
Diamond Y Spring Preserve is 1,603 ha (3,962 ac) of contiguous land
around Diamond Y Draw. The surrounding watershed and the land area over
the contributing aquifers are all privately owned and managed as ranch
land and have been developed for oil and gas extraction. In addition, a
natural gas processing plant is located within 0.8 km (0.5 mi) upslope
of the headpool in the upper watercourse of Diamond Y Spring. Diamond Y
Spring is also inhabited by two federally listed fishes, Leon Springs
pupfish (Cyprinodon bovinus) and Pecos gambusia, as well as the
federally endangered Pecos assiminea snail and the federally threatened
Pecos sunflower. The only nonnative species of concern at Diamond Y
Spring is the red-rim melania, which is only known to occur in the
upper watercourse.
Studies by Boghici (1997, p. v) indicate that the spring flow at
Diamond Y Spring originates chiefly from the Rustler aquifer waters
underlying the Delaware Basin to the northwest of the spring outlets
(Boghici and Van Broekhoven 2001, p. 219). The Rustler aquifer
underlies an area of approximately 1,200 sq km (480 sq mi) encompassing
most of Reeves County and parts of Culberson, Pecos, Loving, and Ward
Counties (Boghici and Van Broekhoven 2001, p. 219). Much of the water
contains high total dissolved solids (Boghici and Van Broekhoven 2001,
p. 219) making it difficult for agricultural or municipal use;
therefore, the aquifer has experienced only limited pumping in the past
(Mace 2001, pp. 7-9).
Other springs in the area may have once provided habitat for the
aquatic species but limited information is generally available on
historic distribution of the invertebrates. Leon Springs, a large
spring that historically occurred about 14 km (9 miles) upstream along
Leon Creek, historically discharged about 0.7 cms (25 cfs) in 1920, 0.5
cms (18 cfs) in the 1930s, 0.4 cms (14 cfs) in the 1940s, and no
discharge from 1958 to 1971 (Brune 1981, p. 359). Nearby groundwater
pumping to irrigate farm lands began in 1946, which lowered the
contributing aquifer by 40 m (130 feet) by the 1970s and resulted in
the loss of the spring. The only circumstantial evidence that any of
the three invertebrates that occur in nearby Diamond Y Spring may have
occurred in Leon Springs is that the spring is within the same drainage
and an endemic fish, Leon Springs pupfish, once occurred in both
Diamond Y and Leon Springs.
Comanche Springs is another large historic spring located in the
City of Fort Stockton. Prior to the 1950s, this spring discharged more
than 1.2 cms (42 cfs) (Brune 1981, p. 358) and provided habitat for
rare species of fishes and invertebrates. As a result of groundwater
pumping for agriculture, the spring ceased flowing by 1962 (Brune 1981,
p. 358), eliminating all aquatic-dependent plants and animals (Scudday
1977, pp. 515-518; Scudday 2003, pp. 135-136). Although we do not have
data confirming that Comanche Springs was inhabited by all of the
Diamond Y Spring species, there is evidence that at least the two
snails (Diamond Y Spring snail and Gonzales springsnail) occurred there
at some time in the past (see Taxonomy, Distribution, Abundance, and
Habitat of Snails, below).

Life History and Biology of Snails

The background information presented in this section applies to all
four species of snails in these proposed rules: Phantom Cave snail,
Phantom springsnail, Diamond Y Spring snail, and Gonzales springsnail.
All four of these snails are in the family Hydrobiidae and are strictly
aquatic with respiration occurring through an internal gill. These
hydrobiid snails (snails in the family Hydrobiidae)

[[Page 49608]]

typically reproduce several times during the spring to fall breeding
season (Brown 1991, p. 292) and are sexually dimorphic (males and
females are shaped differently), with females being characteristically
larger and longer-lived than males. Snails in the Pyrgulopsis genus
(Phantom Cave snail) reproduce through laying a single small egg
capsule deposited on a hard surface (Hershler 1998, p. 14). The other
three snail species are ovoviviparous, meaning the larval stage is
completed in the egg capsule, and upon hatching, the snails emerge into
their adult form (Brusca and Brusca 1990, p. 759; Hershler and Sada
2002, p. 256). The lifespan of most aquatic snails is thought to be 9
to 15 months (Taylor 1985, p. 16; Pennak 1989, p. 552).
All of these snails are presumably fine-particle feeders on
detritus (organic material from decomposing organisms) and periphyton
(mixture of algae and other microbes attached to submerged surfaces)
associated with the substrates (mud, rocks, and vegetation) (Allan
1995, p. 83; Hershler and Sada 2002, p. 256; Lysne et al. 2007, p.
649). Dundee and Dundee (1969, p. 207) found diatoms (a group of
single-celled algae) to be the primary component in the digestive
tract, indicating they are a primary food source.
These hydrobiid snails from west Texas occur in mainly flowing
water habitats such as small springs, seeps, marshes, spring pools, and
their outflows. Proximity to spring vents, where water emerges from the
ground, plays a key role in the life history of springsnails. Many
springsnail species exhibit decreased abundance farther away from
spring vents, presumably due to their need for stable water chemistry
(Hershler 1994, p. 68; Hershler 1998, p. 11; Hershler and Sada 2002, p.
256; Martinez and Thome 2006, p. 14). Several habitat parameters of
springs, such as temperature, substrate type, dissolved carbon dioxide,
dissolved oxygen, conductivity, and water depth have been shown to
influence the distribution and abundance of other related species of
springsnails (O'Brien and Blinn 1999, pp. 231-232; Mladenka and
Minshall 2001, pp. 209-211; Malcom et al. 2005, p. 75; Martinez and
Thome 2006, pp. 12-15; Lysne et al. 2007, p. 650). Dissolved salts such
as calcium carbonate may also be important factors because they are
essential for shell formation (Pennak 1989, p. 552). Hydrobiid snails
as a group are considered sensitive to water quality changes, and each
species is usually found within relatively narrow habitat parameters
(Sada 2008, p. 59).
Native fishes have been shown to prey upon these snails (Winemiller
and Anderson 1997, pp. 209-210; Brown et al. 2008, p. 489), but it is
unknown to what degree predatory pressure may play a role in
controlling population abundances or influencing habitat use. There are
currently no nonnative fishes in the springs where the species occur,
so there is no unnatural predation pressure from fish suspected.
Because of their small size and dependence on water, significant
dispersal (in other words, movement between spring systems) does not
likely occur, although on rare occasions aquatic snails have been
transported by becoming attached to the feathers and feet of migratory
birds (Roscoe 1955, p. 66; Dundee et al. 1967, pp. 89-90). In general,
the species have little capacity to move beyond their isolated aquatic
environments.

Taxonomy, Distribution, Abundance, and Habitat of Snails

Phantom Cave Snail (Pyrgulopsis texana Pilsbry 1935)
The Phantom Cave snail was first described by Pilsbry (1935, pp.
91-92). It is a very small snail, measuring only 0.98 to 1.27
millimeters (mm) (0.04 to 0.05 inches (in)) long (Dundee and Dundee
1969, p. 207). Until 2010, the species was placed in the genus
Cochliopa (Dundee and Dundee 1969, p. 209; Taylor 1987, p. 40).
Hershler et al. (2010, pp. 247-250) reviewed the systematics of the
species and transferred Phantom Cave snail to the genus Pyrgulopsis
after morphological and mitochondrial DNA analysis. Hershler et al.
(2010, p. 251) also noted some minimal differences in shell size
(individuals were smaller at East Sandia Spring) and mitochondrial DNA
sequence variation among populations of Phantom Cave snails in
different springs. The low level of variation (small differences) among
the populations did not support recognizing different conservation
units for the species. Hershler et al. (2010, p. 251) expected this
small difference among the populations because of their proximity
(separated by 6 to 13 km (4 to 8 mi)) and the past connectedness of the
aquatic habitats by Toyah Creek that would have allowed mixing of the
populations before human alterations and declining flows. Based on
these published studies we conclude that Phantom Cave snail is a
listable entity under the Act.
The Phantom Cave snail only occurs in the four remaining desert
spring outflow channels associated with the San Solomon Spring system
(San Solomon, Phantom, Giffin, and East Sandia springs). Hershler et
al. (2010, p. 250) did not include Giffin Spring in this species
distribution, but unpublished data from Lang (2011, p. 5) confirms that
the species is also found in Giffin Spring outflows as well as the
other three springs in the San Solomon Spring system. The geographic
extent of the historic range for the Phantom Cave snail was likely not
larger than the present range, but the species may have occurred in
additional small springs contained within the current range of the San
Solomon Spring system, such as Saragosa and Toyah Springs. It likely
also had a larger distribution within Phantom Lake Spring and San
Solomon Spring before the habitat there was modified and reduced in
conversion of spring outflow channels into irrigation ditches.
Within its current, limited range, Phantom Cave snails can exist in
very high densities. Dundee and Dundee (1969, pp. 207) described the
abundance of the Phantom Cave snails at Phantom Lake Spring in 1968 as
persisting ``in such tremendous numbers that the bottom and sides of
the canal appear black from the cover of snails.'' Today the snails are
limited to the small pool at the mouth of Phantom Cave and cannot be
found in the irrigation canal downstream. At San Solomon Spring, Taylor
(1987, p. 41) reported the Phantom Cave snail was abundant and
generally distributed in the canals from 1965 to 1981. Density data and
simple population size estimates based on underwater observations
indicate there may be over 3.8 million individuals of this species at
San Solomon Spring (Bradstreet 2011, p. 55). Lang (2011) also reported
very high densities (not total population estimates) of Phantom Cave
snails (with standard deviations): San Solomon Spring from
2009 sampling in the main canal, 71,740 per sq m (6,672 per sq ft;
47,229 per sq m, 4,393 per sq ft); Giffin
Spring at road crossing in 2001, 4,518 per sq m (420 per sq ft; 4,157 per sq m, 387 per sq ft); East Sandia Spring in
2009, 41,215 per sq m (3,832 per sq ft; 30,587 per sq m,
2,845 per sq ft); and Phantom Lake Spring in 2009, 1,378
per sq m (128 per sq ft; 626 per sq m, 58 per
sq ft). From these data, it is evident that when conditions are
favorable Phantom Cave snails can reach tremendous population sizes in
very small areas.
Phantom Cave snails are found concentrated near the spring source
(Hershler et al. 2010, p. 250) and can occur as far as a few hundred
meters downstream of a large spring outlet like San Solomon Spring.
Despite its common name, it has not been found

[[Page 49609]]

within Phantom Cave proper, but only within the outflow of Phantom Lake
Spring. Bradstreet (2011, p. 55) found the highest abundances of
Phantom Cave snails at San Solomon Spring outflows in the high-velocity
areas in the irrigation canals and the lowest abundances in the San
Solomon Ci[eacute]nega. The species was not collected from the newest
constructed ci[eacute]nega in 2010. Habitat of the species is found on
both soft and firm substrates on the margins of spring outflows (Taylor
1987, p. 41). They are also commonly found attached to plants,
particularly in dense stands of submerged vegetation (Chara sp.). Field
and laboratory experiments have suggested Phantom Cave snails prefer
substrates harder and larger in size (Bradstreet 2011, p. 91).
Phantom Springsnail (Tryonia cheatumi Pilsbry 1935)
The Phantom springsnail was first described by Pilsbry (1935, p.
91) as Potamopyrgus cheatumi. The species was later included in the
genus Lyrodes and eventually placed in the genus Tryonia (Taylor 1987,
pp. 38-39). It is a small snail measuring only 2.9 to 3.6 mm (0.11 to
0.14 in) long (Taylor 1987, p. 39). Systematic studies of Tryonia
snails in the Family Hydrobiidae using mitochondrial DNA sequences and
morphological characters confirms the species is a ``true Tryonia,'' in
other words, it is appropriately classified in the genus Tryonia
(Hershler et al. 1999, p. 383; Hershler 2001, p. 6; Hershler et al.
2011, pp. 5-6). Based on these published studies, we conclude that
Phantom springsnail is a listable entity under the Act.
The Phantom springsnail only occurs in the four remaining desert
spring outflow channels associated with the San Solomon Spring system
(San Solomon, Phantom, Giffin, and East Sandia springs) (Taylor 1987,
p. 40; Allan 2011, p. 1; Lang 2011, entire). The historic range for the
Phantom springsnail was likely not larger than present, but the species
may have occurred in other springs within the San Solomon Spring
system, such as Saragosa and Toyah Springs. It likely also had a wider
distribution within Phantom Lake Spring and San Solomon Spring before
the habitat there was modified and reduced.
Within its current, limited range, Phantom springsnails can have
moderate densities of abundance, but have never been recorded as high
as the Phantom Cave snail. In the 1980s, Taylor (1987, p. 40) described
Phantom springsnails as abundant in the outflow ditch several hundred
meters downstream of Phantom Lake Spring. The snails are now limited to
low densities in the small pool at the mouth of Phantom Cave and cannot
be found in the irrigation canal downstream as it does not have water
(Allan 2009, p. 1). Density data and simple population size estimates
based on underwater observations indicate there may be over 460,000
individuals of this species at San Solomon Spring (Bradstreet 2011, p.
55). Lang (2011) reports the following densities (not population
estimates) of Phantom springsnails (with standard
deviations): San Solomon Spring from 2009 sampling in the main canal,
11,681 per sq m (1,086 per sq ft; 11,925 per sq m, 1,109 per sq ft); Giffin Spring at road crossing in 2001, 3,857
per sq m (358 per sq ft; 6,110 per sq m, 568
per sq ft); East Sandia Spring in 2009, 65,845 per sq m (6,123 per sq
ft; 60,962 per sq m, 5,669 per sq ft); and
Phantom Lake Spring in 2009, 31,462 per sq m (2,926 per sq ft; 20,251 per sq m, 1,883 per sq ft). Phantom
springsnails can reach high population sizes in very small areas with
favorable conditions.
Phantom springsnails are usually found concentrated near the spring
source but once occurred as far as a few hundred meters downstream when
Phantom Lake Spring was a large flowing spring (Dundee and Dundee 1969,
p. 207; Taylor 1987, p. 40). The species is most abundant in the
swimming pool at Balmorhea State Park, but has not been found in either
of the constructed ci[eacute]negas at the Park in 2010 and 2011 (Allan
2011, p. 3; Bradstreet 2011, pp. 55). The species is found on both soft
and firm substrates on the margins of spring outflows (Taylor 1987, p.
41), and they are also commonly found attached to plants, particularly
in dense stands of submerged vegetation (Chara sp.).
Diamond Y Spring Snail (Pseudotryonia adamantina Taylor 1987)
The Diamond Y Spring snail was first described by Taylor (1987, p.
41) as Tryonia adamantina. It is a small snail measuring only 2.9 to
3.6 mm (0.11 to 0.14 in) long (Taylor 1987, p. 41). Systematic studies
(Hershler et al.1999, p. 377; Hershler 2001, pp. 7, 16) of these snails
have been conducted using mitochondrial DNA sequences and morphological
characters. These analyses resulted in the Diamond Y Spring snail being
reclassified into the new genus Pseudotryonia (Hershler 2001, p. 16).
Based on these published studies, we conclude that Diamond Y Spring
snail is a listable entity under the Act.
Taylor (1985, p. 1; 1987, p. 38) was the earliest to document the
distribution and abundance of aquatic snails in the Diamond Y Spring
system, referencing surveys from 1968 to 1984. In 1968, the Diamond Y
Spring snail was considered abundant in the outflow of Diamond Y Spring
in the upper watercourse for about 1.6 km (1 mi) downstream of the
spring head pool, but by 1984 the species was present in only areas
along stream margins (near the banks) (Taylor 1985, p. 1). Average
density estimates in 1984 at 12 of 14 sampled sites in the upper
watercourse ranged from 500 to 93,700 individuals per sq m (50 to 8,700
per sq ft), with very low densities in the upstream areas near the
headspring (Taylor 1985, p. 25). However, the Diamond Y Spring snail
was largely absent from the headspring and main spring flow channel
where it had been abundant in 1968 surveys (Taylor 1985, p. 13).
Instead it was most common in small numbers along the outflow stream
margins and lateral springs (Taylor 1985, pp. 13-15). Over time, the
distribution of the Diamond Y Spring snail in the upper watercourse has
continued to recede so that it is no longer found in the outflow
channel at all but may be restricted to small lateral spring seeps
disconnected from the main spring flow channel (Landye 2000, p. 1;
Echelle et al. 2001, pp. 24-25). Surveys by Lang (2011, pp. 7-8) in
2001 and 2003 found only 2 and 7 individuals, respectively, in the
outflow channel of Diamond Y Spring. Additional surveys in 2009 and
2010 (Ladd 2010, p. 18; Lang 2011, p. 12) did not find Diamond Y Spring
snails in the upper watercourse. However, neither researcher surveyed
extensively in the lateral spring seeps downstream from the main spring
outflow.
The Diamond Y Spring snail was not previously reported from the
lower watercourse until first detected there in 2001 at the outflow of
Euphrasia Spring (Lang 2011, p. 6). It was confirmed there again in
2009 (Lang 2011, p. 13) and currently occurs within at least the first
50 m (160 feet) in the outflow channel of Euphrasia Spring (Ladd 2010,
p. 18). Ladd (2010, p. 37) roughly estimated the total number of
Diamond Y Spring snails in the lower watercourse to be about 35,000
individuals with the highest density reported as 2,500 individuals per
sq m (230 per sq ft). Lang (2011, p. 13) estimated densities of Diamond
Y Spring snails in 2009 at 16,695 per sq m (1,552 per sq ft; 18,212 per sq m, 1,694 per sq ft) in Euphrasia Spring
outflow, which suggests a much larger population than that estimated by
Ladd (2010, p. 37).
In summary, the Diamond Y Spring snail was historically common in
the upper watercourse and absent from the lower watercourse. Currently
it is very

[[Page 49610]]

rare in the upper watercourse and limited to small side seeps (and may
be extirpated), and it occurs in the lower watercourse in the outflow
of Euphrasia Spring. The historic distribution of this species may have
been larger than the present distribution. Other area springs nearby
such as Leon and Comanche Springs may have harbored the species. There
is one collection of very old, dead shells of the species that was made
from Comanche Springs in 1998 (Worthington 1998, unpublished data)
whose identification was recently confirmed as Diamond Y Spring snail
(Hershler 2011, pers. comm.). However, because these springs have been
dry for more than four decades and shells can remain intact for
thousands of years, it is impossible to know how old the shells might
be. Therefore, we are unable to confirm if the recent historic
distribution included Comanche Springs.
Habitat of the species is primarily soft substrates on the margins
of small springs, seeps, and marshes in shallow flowing water
associated with emergent bulrush (Scirpus americanus) and saltgrass
(Distichlis spicata) (Taylor 1987, p. 38; Echelle et al. 2001, p. 5).
Gonzales Springsnail (Tryonia circumstriata Leonard and Ho 1960)
The Gonzales springsnail was first described as a late Pleistocene
fossil record, Calipyrgula circumstriata, from the Pecos River near
Independence Creek in Terrell County, Texas (Leonard and Ho 1960, p.
126). The snail from Diamond Y Spring area was first described as
Tryonia stocktonensis by Taylor (1987, p. 37). It is a small snail,
measuring only 3.0 to 3.7 mm (0.11 to 0.14 in) long. Systematic studies
later changed the name to Tryonia circumstriata, integrating it with
the fossilized snails from the Pecos River (Hershler 2001, p. 7), and
confirming the species as a ``true Tryonia,'' in other words, it is
appropriately classified in the genus Tryonia (Hershler et al. 2011,
pp. 5-6). Based on these published studies, we conclude that Gonzales
springsnail is a listable entity under the Act.
Taylor (1985, pp. 18-19; 1987, p. 38) found Gonzales springsnail
only in the first 27 m (90 ft) of the outflow from Euphrasia Spring.
The species has been consistently found in this short stretch of spring
outflow channel since then (Echelle et al. 2001, p. 20; Lang 2011, pp.
6, 13). Ladd (2010, pp. 23-24) reported that Gonzales springsnails no
longer occurred in the lower watercourse and had been replaced by
Diamond Y Spring snails. However, reevaluation of voucher specimens
collected by Lang (2011, p. 13) concurrently in 2009 with those by Ladd
(2010, p. 14) confirmed the species is still present in the Euphrasia
Spring outflow channel of the lower watercourse.
Gonzales springsnail was first reported in the upper watercourse in
1991 during collections from one site in the Diamond Y Spring outflow
and one small side seep near the spring head (Fullington and Goodloe
1991, p. 3). The species has since been collected from this area (Lang
2011, pp. 7-9), and Echelle et al. (2001, p. 20) found it to be the
most abundant snail for the first 430-m (1,400-ft) downstream from the
spring head. Ladd (2010, p. 18) also found Gonzales springsnail in the
outflow of Diamond Y Spring, but only from 125 to 422 m (410 to 1,384
ft) downstream of the spring head (Ladd 2011, pers. comm.). The
Gonzales springsnail appears to have replaced the Diamond Y Spring
snail in some of the habitat in the upper watercourse (Brown 2008, p.
489) since 1991.
Taylor (1985, p. 19) calculated densities for Gonzales springsnails
in the outflow of Euphrasia Spring in the range of 50,480 to 85,360
individuals per sq m (4,690 to 7,930 individuals per sq ft) and
estimated the population size in that 27-m (90-ft) stretch to be at
least 162,000 individuals and estimated the total population of over
one million individuals as a reasonable estimate. Lang (2011, p. 13)
estimated the density of Gonzales springsnails in the Euphrasia Spring
outflow to be 3,086 individuals per sq m (287 per sq ft; 5,061 per sq m, 471per sq ft). Ladd (2010, p. 37)
estimated the population of Gonzales springsnails in the upper
watercourse to be only about 11,000 individuals.
As with the Diamond Y Spring snail, the historic distribution of
the Gonzales springsnail may have been larger than the present
distribution. Other area springs nearby such as Leon and Comanche
Springs may have harbored the species. There is one collection of dead
shells of the species that was made from Comanche Springs in 1998
(Worthington 1998, unpublished data) whose identification was recently
confirmed as Gonzales springsnail (Hershler 2011, pers. comm.).
However, because these springs have been dry for more than four decades
and shells can remain intact for thousands of years, it is impossible
to know how old the shells might be. Therefore, we are unable to
confirm if the recent historic distribution included Comanche Springs.
Habitat of the species is primarily soft substrates on the margins
of small springs, seeps, and marshes in shallow flowing water
associated with emergent bulrush and saltgrass (Taylor 1987, p. 38;
Echelle et al. 2001, p. 5).

Life History, Biology, and Habitat of Amphipods

The background information presented here applies to both species
of amphipods in these proposed rules: diminutive amphipod and Pecos
amphipod. These amphipods, in the family Gammaridae, are small
freshwater inland crustaceans sometimes referred to as freshwater
shrimp. Gammarids commonly inhabit shallow, cool, well-oxygenated
waters of streams, ponds, ditches, sloughs, and springs (Smith 2001, p.
574). These bottom-dwelling amphipods feed on algae, submergent
vegetation, and decaying organic matter (Smith 2001, p. 572). Amphipod
eggs are held within a marsupium (brood pouch) within the female's
exoskeleton (Smith 2001, p. 573). Most amphipods complete their life
cycle in 1 year and breed from February to October, depending on water
temperature (Smith 2001, p. 572). Amphipods form breeding pairs that
remain attached for 1 to 7 days at or near the substrate while
continuing to feed and swim (Bousfield 1989, p. 1721). They can produce
from 15 to 50 offspring, forming a ``brood.'' Most amphipods produce
one brood, but some species produce a series of broods during the
breeding season (Smith 2001, p. 573).
These two species, diminutive amphipod and Pecos amphipod, are part
of a related group of amphipods, referred to as the Gammarus pecos
species complex, that are restricted to desert spring systems from the
Pecos River Basin in southeast New Mexico and west Texas (Cole 1985, p.
93; Lang et al. 2003, p. 47; Gervasio et al. 2004, p. 521). Similar to
the snails, it is thought that these freshwater amphipods are derived
from a widespread ancestral marine amphipod that was isolated inland
during the recession of the Late Cretaceous sea, about 66 million years
ago (Holsinger 1967, pp. 125-133; Lang et al. 2003, p. 47). They likely
evolved into distinct species during recent dry periods (since the Late
Pleistocene, about 100,000 years ago) through allopatric speciation
(that is, speciation by geographic separation) following separation and
isolation in the remnant aquatic habitats associated with springs
(Gervasio et al. 2004, p. 528).
Amphipods in the Gammarus pecos species complex only occur in
desert spring outflow channels on substrates, often within interstitial
spaces on and

[[Page 49611]]

underneath rocks and within gravels (Lang et al. 2003, p. 49) and are
most commonly found in microhabitats with flowing water. They are also
commonly found in dense stands of submerged vegetation (Cole 1976, p.
80). Because of their affinity for constant water temperatures, they
are most common in the immediate spring outflow channels, usually only
a few hundred meters downstream of spring outlets.
Amphipods play important roles in the processing of nutrients in
aquatic ecosystems and are also considered sensitive to changes in
aquatic habitat conditions (for example, stream velocities, light
intensity, zooplankton availability, and the presence of heavy metals)
and are often considered ecological indicators of ecosystem health and
integrity (Covich and Thorpe 1991, pp. 672-673, 679; Lang et al. 2003,
p. 48). Water chemistry parameters, such as salinity, pH, and
temperature, are also key components to amphipod habitats (Covich and
Thorpe 1991, pp. 672-673).

Taxonomy, Distribution, and Abundance of Amphipods

Diminutive Amphipod (Gammarus hyalleloides Cole 1976)
W.L. Minckley first collected the diminutive amphipod from Phantom
Lake Spring in the San Solomon Spring system in 1967, and the species
was first formally described by Cole (1976, pp. 80-85). The name comes
from the species being considered the smallest of the known North
American freshwater Gammarus amphipods. Adults generally range in
length from 5 to 8 mm (0.20 to 0.24 in).
There has been some disparity in the literature regarding the
taxonomic boundaries for the amphipods from the San Solomon Spring
system. In Cole's (1985, pp. 101-102) description of the Gammarus pecos
species complex of amphipods based solely on morphological
measurements, he considered the diminutive amphipod to be endemic only
to Phantom Lake Spring, and amphipods from San Solomon and Diamond Y
Springs were both considered to be the Pecos amphipod (G. pecos). This
study did not include samples of amphipods from East Sandia or Giffin
Springs. However, allozyme electrophoresis data on genetic variation
strongly support that the populations from the San Solomon Spring
system form a distinct group from the Pecos amphipod at Diamond Y
Spring (Gervasio et al. 2004, pp. 523-530). Based on these data, we
consider the Pecos amphipod to be limited to the Diamond Y Spring
system.
The results of these genetic studies also suggested that the three
Gammarus amphipod populations from San Solomon, Giffin, and East Sandia
Springs are a taxonomically unresolved group differentiated from the
diminutive amphipod at Phantom Lake Spring (Gervasio et al. 2004, pp.
523-530). Further genetic analysis using mitochondrial DNA (mtDNA) by
Seidel et al. (2009, p. 2309) also indicates that the diminutive
amphipod may be limited to Phantom Lake Spring and the Gammarus species
at the other three springs should be considered a new and undescribed
species. However, the extent of genetic divergence measured between
these populations is not definitive. For example, the 19-base pair
divergence between the population at Phantom Lake Spring and the other
San Solomon Spring system populations (Seidel et al. 2009, Figure 3, p.
2307) represents about 1.7 percent mtDNA sequence divergence (of the
1,100 base pairs of the mitochondrial DNA sequenced (using the
cytochrome c oxidase I (COI) gene). This is a relatively low level of
divergence to support species separation, as a recent review of a
multitude of different animals (20,731 vertebrates and invertebrates)
suggested that the mean mtDNA distances (using the COI gene) between
subspecies is 3.78 percent (0.16) divergence and between
species is 11.06 percent (0.53) divergence (Kartavtsev
2011, pp. 57-58).
Recent evaluations of species boundaries of amphipods from China
suggest mtDNA genetic distances of at least 4 percent were appropriate
to support species differentiation, and the species they described all
exceeded 15 percent divergence (Hou and Li 2010, p. 220). In addition,
no species descriptions using morphological or ecological analysis have
been completed for these populations, which would be important
information in any taxonomic revision (Hou and Li 2010, p. 216).
Therefore, the data available does not currently support taxonomically
separating the amphipod population at Phantom Lake Spring from the
populations at San Solomon, Giffin, and East Sandia Springs into
different listable entities under the Act. So, for the purposes of
these proposed rules, based on the best available scientific
information, we are including all four populations of Gammarus
amphipods from the San Solomon Spring system as part of the Gammarus
hyalleloides species (diminutive amphipod), and we consider diminutive
amphipod a listable entity under the Act. We recognize that the
taxonomy of these populations could change as additional information is
collected and further analyses are published.
The diminutive amphipod only occurs in the four springs from the
San Solomon Spring system (Gervasio et al. 2004, pp. 520-522). There is
no available information that the species' historic distribution was
larger than the present distribution, but other area springs (such as
Saragosa, Toyah, and West Sandia Springs) may have contained the
species. However, because these springs have been dry for many decades,
if the species historically occurred there, they are now extirpated.
There is no opportunity to determine the full extent of the historic
distribution of these amphipods because of the lack of historic surveys
and collections.
Within its limited range, diminutive amphipod can be very abundant.
For example, in May 2001, Lang et al. (2003, p. 51) estimated mean
densities at San Solomon, Giffin, and East Sandia Springs of 6,833
amphipods per sq m (635 per sq ft; standard deviation 5,416
per sq m, 504 per sq ft); 1,167 amphipods per sq m (108 per
sq ft; 730 per sq m, 68 per sq ft), and 4,625
amphipods per sq m (430 per sq ft; 804 per sq m, 75 per sq ft), respectively. In 2009 Lang (2011, p. 11) reported
the density at Phantom Lake Spring as 165 amphipods per sq m (15 per sq
ft; 165 per sq m, 15 per sq ft).
Pecos Amphipod (Gammarus pecos Cole and Bousfield 1970)
The Pecos amphipod was first collected in 1964 from Diamond Y
Spring and was described by Cole and Bousfield (1970, p. 89). Cole
(1985, p. 101) analyzed morphological characteristics of the Gammarus
pecos species complex and suggested the Gammarus amphipod from San
Solomon Spring should also be included as Pecos amphipod. However,
updated genetic analyses based on allozymes (Gervasio et al. 2004, p.
526) and mitochondrial DNA (Seidel et al. 2009, p. 2309) have shown
that Pecos amphipods are limited in distribution to the Diamond Y
Spring system. In addition, Gervasio et al. (2004, pp. 523, 526)
evaluated amphipods from three different locations within the Diamond Y
Spring system and found no significant differences in genetic
variation, indicating they all represented a single species. Based on
these published studies, we conclude that Pecos amphipod is a listable
entity under the Act.
The Pecos amphipod is generally found in all the flowing water
habitats associated with the outflows of springs and seeps in the
Diamond Y Spring

[[Page 49612]]

system (Echelle et al. 2001, p. 20; Lang et al. 2003, p. 51; Allan
2011, p. 2; Lang 2011, entire). There is no available information to
determine if the species' historic distribution was larger than the
present distribution. Other area springs, such as Comanche and Leon
Springs, may have contained the same or similar species of amphipod,
but because these springs have been dry for many decades (Brune 1981,
pp. 256-263, 382-386), there is no opportunity to determine the
potential historic occurrence of amphipods. Pecos amphipods are often
locally abundant, with reported mean densities ranging from 2,208
individuals per sq m (205 per sq ft; 1,585 per sq m, 147 per sq ft) to 8,042 individuals per sq m (748 per sq ft;
7,229 per sq m, 672 per sq ft) (Lang et al.
2003, p. 51).

Summary of Factors Affecting the Species

Section 4 of the Act (16 U.S.C. 1533), and its implementing
regulations at 50 CFR part 424, set forth the procedures for adding
species to the Federal Lists of Endangered and Threatened Wildlife and
Plants. Under section 4(a)(1) of the Act, the Service determines
whether a species is endangered or threatened because of 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; and (E) other natural or manmade
factors affecting its continued existence. Listing actions may be
warranted based on any of the above threat factors, singly or in
combination. Each of these factors is discussed below.
Based on the similarity in geographic ranges and threats to
habitats, we have divided this analysis into two sections, one covering
the three species from the San Solomon Spring system and then a second
analysis covering the three species from the Diamond Y Spring system.
After each analysis we provide proposed determinations for each
species.

San Solomon Spring Species--Phantom Cave Snail, Phantom Springsnail,
and Diminutive Amphipod

The following analysis applies to the three species that occur in
the San Solomon Spring system in Reeves and Jeff Davis Counties, Texas:
Phantom Cave snail, Phantom Lake springsnail, and diminutive amphipod.
A. The Present or Threatened Destruction, Modification, or Curtailment
of Their Habitat or Range (San Solomon Spring Species)
The three species in the San Solomon Spring system are threatened
by the past and future destruction of their habitat and reduction in
their range. The discussion below evaluates the stressors of: (1)
Spring flow declines; (2) water quality changes and contamination; and
(3) modification of spring channels.
Spring Flow Declines
The primary threat to the continued existence of the San Solomon
Spring species is the degradation and potential future loss of aquatic
habitat (flowing water from the spring outlets) due to the decline of
groundwater levels in the aquifers that support spring surface flows.
Habitat for these species is exclusively aquatic and completely
dependent on spring flows emerging to the surface from underground
aquifer sources. Spring flows throughout the San Solomon Spring system
have and continue to decline in flow rate, and as spring flows decline,
available aquatic habitat is reduced and altered. If one spring ceases
to flow continually, all habitats for the Phantom Cave snail, Phantom
Lake springsnail, and diminutive amphipod are lost, and the populations
will be extirpated. If all of the springs lose consistent surface
flows, all natural habitats for these aquatic invertebrates will be
gone, and the species will become extinct.
The springs do not have to cease flowing completely to have an
adverse effect on invertebrate populations. The small size of the
spring outflows at Phantom, Giffin, and East Sandia Springs makes them
particularly susceptible to changes in water chemistry, increased water
temperatures during the summer and freezing in the winter. Because
these springs are small, any reductions in the flow rates from the
springs can reduce the quantity and quality of available habitat for
the species, which decreases the number of individuals available and
increases the risk of extinction. Water temperatures and chemical
factors in springs, such as dissolved oxygen and pH, do not typically
fluctuate to a large degree (Hubbs 2001, p. 324), and invertebrates are
narrowly adapted to spring conditions and are sensitive to changes in
water quality (Hershler 1998, p. 11; Sada 2008, p. 69). Spring flow
declines can lead to the degradation and loss of aquatic invertebrate
habitat and present a substantial threat to these species.
The precise reason for the declining spring flows remains
uncertain, but it is presumed to be related to a combination of
groundwater pumping, mainly for agricultural irrigation, and a lack of
natural recharge to the supporting aquifers due to limited rainfall and
geologic circumstances that prevent recharge. In addition, future
changes in the regional climate are expected to exacerbate declining
flows. The San Solomon Spring system historically may have had a
combined discharged of about 2.8 cms (100 cfs) or 89 million cubic
meters per year (cmy) (72,000 acre-feet per year (afy)) (Beach et al.
2004, p. 4-53), while today the total discharge is roughly one-third
that amount. Some smaller springs, such as Saragosa, Toyah, and West
Sandia Springs have already ceased flowing and likely resulted in the
extirpation of local populations of these species (assuming they were
present there historically). The most dramatic recent decline in flow
rates have been observed at Phantom Lake Spring, which is the highest
elevation spring in the system and, not unexpectedly, was the first
large spring to cease flowing.
Phantom Lake Spring was a historically large desert ci[eacute]nega
with a pond of water more than several acres in size (Hubbs 2001, p.
307). The spring outflow is at about 1,080 m (3,543 ft) in elevation
and previously provided habitat for the endemic native aquatic fauna.
The outflow from Phantom Lake Spring was originally isolated from the
other surface springs in the system, as the spring discharge quickly
recharged back underground (Brune 1981, p. 258). Human modifications to
the spring outflow captured and channeled the spring water into a canal
system for use by local landowners and irrigation by the local water
users (Simonds 1996, p. 3). The outflow canal joins the main San
Solomon canal within Balmorhea State Park. Despite the significant
habitat alterations, the native aquatic fauna (including these three
invertebrates) have persisted, though in much reduced numbers of total
individuals, in the small pool of water at the mouth of the spring.
Flows from Phantom Lake Spring have been steadily declining since
measurements were first taken in the 1930s (Brune 1981, p. 259).
Discharge data have been recorded from the spring at least six to eight
times per year since the 1940s by the U.S. Geological Survey, and the
record shows a steady decline of base flows from greater than 0.3 cms
(10 cfs) in the 1940s to 0 cms (0 cfs) in 1999 (Service 2009b, p. 23).
The data also show that the spring can have short-term flow peaks
resulting from local rainfall events in the Davis Mountains (Sharp et
al. 1999, p. 4;

[[Page 49613]]

Chowdhury et al. 2004, p. 341). These flow peaks are from fast recharge
of the local aquifer system and discharge through the springs. The flow
peaks do not come from direct surface water runoff because the outflow
spring is within an extremely small surface drainage basin that is not
connected to surface drainage basins from the Davis Mountains upslope.
However, after each flow increase, the base flow has returned to the
same declining trend within a few months.
Exploration of Phantom Cave by cave divers has led to additional
information about the nature of the spring and its supporting aquifer.
Over 2,440 m (8,000 ft) of the underwater cave have been mapped. Beyond
the entrance, the cave is a substantial conduit that transports a large
volume of water, in the 0.6 to 0.7 cms (20 to 25 cfs) range, generally
from the northwest to the southeast (Tucker 2009, p. 8), consistent
with regional flow pattern hypothesis (Chowdhury et al. 2004, p. 319).
The amount of water measured is in the range of the rate of flow at San
Solomon Spring and, along with water chemistry data (Chowdhury et al.
2004, p. 340), confirms that the groundwater flowing by Phantom Lake
Spring likely discharges at San Solomon Spring. Tucker (2009, p. 8)
recorded a 1-m (3-ft) decline in the water surface elevation within the
cave between 1996 and 2009 indicating a decline in the amount of
groundwater flowing through Phantom Cave.
Phantom Lake Spring ceased flowing in about 1999 (Allan 2000, p.
51; Service 2009b, p. 23). All that remained of the spring outflow
habitat was a small pool of water with about 37 sq m (400 sq ft) of
wetted surface area. Hubbs (2001, pp. 323-324) documented changes in
water quality (increased temperature, decreased dissolved oxygen, and
decreased coefficient of variation for pH, turbidity, ammonia, and
salinity) and fish community structure at Phantom Lake Spring following
cessation of natural flows. In May 2001, the U.S. Bureau of
Reclamation, in cooperation with the Service, installed an emergency
pump system to bring water from within the cave to the springhead in
order to prevent complete drying of the pool and loss of the federally
listed endangered fishes and candidate invertebrates that occur there.
Habitat for the San Solomon Spring system invertebrates continues to be
maintained at Phantom Lake Spring, and in 2011 the small pool was
enlarged, nearly doubling the amount of aquatic habitat available for
the species (Service 2012, entire).
The three San Solomon Spring species have maintained minimal
populations at Phantom Lake Spring despite the habitat being
drastically modified from its original state and being maintained by a
pump system since 2000. However, because the habitat is sustained with
a pump system, the risk of extirpation of these populations continues
to be extremely high from the potential for a pump failure or some
unforeseen event. For example, the pump system failed several times
during 2008, resulting in stagnant pools and near drying conditions,
placing severe stress on the invertebrate populations (Allan 2008, pp.
1-2). Substantial efforts were implemented in 2011 to improve the
reliability of the pump system and the quality of the habitat (Service
2012, pp. 5-9). However, because the habitat is completely maintained
by artificial means, the potential loss of the invertebrate population
will continue to be an imminent threat of high magnitude to the
populations at Phantom Lake Spring.
Although long-term data for San Solomon Spring flows are limited,
they appear to have declined somewhat over the history of record,
though not as severely as Phantom Lake Spring (Schuster 1997, pp. 86-
90; Sharp et al. 1999, p. 4). Some recent declines in overall flow have
likely occurred due to drought conditions and declining aquifer levels
(Sharp et al. 2003, p. 7). San Solomon Spring discharges are usually in
the 0.6 to 0.8 cms (25 to 30 cfs) range (Ashworth et al. 1997, p. 3;
Schuster 1997, p. 86) and are consistent with the theory that the water
bypassing Phantom Lake Spring discharges at San Solomon Spring.
In Giffin Spring, Brune (1981, pp. 384-385) documented a gradual
decline in flow between the 1930s and 1970s, but the discharge has
remained relatively constant since that time, with outflow of about
0.08 to 0.1 cms (3 to 4 cfs) (Ashworth et al. 1997, p. 3; U.S.
Geological Survey 2012, p. 2). Although the flow rates from Giffin
Spring appear to be steady in recent years, its small size makes the
threat of spring flow loss imminent and of high magnitude because even
a small decline in flow rate may have substantial impacts on the
habitat provided by the spring flow. Also, it would only take a small
decline in spring flow rates to result in desiccation of the spring.
Brune (1981, p. 385) noted that flows from Sandia Springs
(combining East and West Sandia Springs) were declining up until 1976.
East Sandia may be very susceptible to over pumping of the local
aquifer in the nearby area that supports the small spring. Measured
discharges in 1995 and 1996 ranged from 0.013 to 0.12 cms (0.45 to 4.07
cfs) (Schuster 1997, p. 94). Like the former springs of West Sandia and
Saragosa, which also originated in shallow aquifers and previously
ceased flowing (Ashworth et al. 1997, p. 3), East Sandia Spring's very
small volume of water makes it particularly at risk of failure from any
local changes in groundwater conditions.
The exact causes for the decline in flow from the San Solomon
Spring system are unknown. Some of the possible reasons, which are
likely acting together, include groundwater pumping of the Salt Basin
Bolson aquifer areas west of the springs, long-term climatic changes,
or changes in the geologic structure that permits regional interbasin
flow of groundwater (Sharp et al. 1999, p. 4; Sharp et al. 2003, p. 7).
Studies indicate that the base flows originate from ancient waters to
the west (Chadhury et al. 2004, p. 340) and that many of the aquifers
in west Texas receive little to no recharge from precipitation (Scanlon
et al. 2001, p. 28) and are influenced by regional groundwater flow
patterns (Sharp 2001, p. 41).
Ashworth et al. (1997, entire) provided a brief study to examine
the cause of declining spring flows in the San Solomon Spring system.
They concluded that declines in spring flows in the 1990s were more
likely the result of diminished recharge due to the extended dry period
rather than from groundwater pumpage (Ashworth et al. 1997, p. 5).
Although possibly a factor, drought is unlikely the only reason for the
declines because the drought of record in the 1950s had no measurable
effect on the overall flow trend at Phantom Lake Spring (Allan 2000, p.
51; Sharp 2001, p. 49) and because the contributing aquifer receives
virtually no recharge from most precipitation events (Beach et al.
2004, pp. 6-9, 8-9). Also, Ashworth et al. (1997, entire) did not
consider the effects of the regional flow system in relation to the
declining spring flows. Further, an assessment of the springs near
Balmorhea by Sharp (2001, p. 49) concluded that irrigation pumpage
since 1945 has caused many springs in the area to cease flowing,
lowering water-table elevations and creating a cone of depression in
the area (that is, a lowering of the groundwater elevation around
pumping areas).
The Texas Water Development Board (2005, entire) completed a
comprehensive study to ascertain the potential causes of spring flow
declines in the San Solomon Spring system, including a detailed
analysis of historic regional groundwater pumping trends. The study was
unable to quantify direct

[[Page 49614]]

correlations between changes in groundwater pumping in the surrounding
counties and spring flow decline over time at Phantom Lake Spring
(Texas Water Development Board 2005, p. 93). However, they suggested
that because of the large distance between the source groundwater and
the springs and the long travel time for the water to reach the spring
outlets, any impacts of pumping are likely to be reflected much later
in time (Texas Water Development Board 2005, p. 92). The authors did
conclude that groundwater pumping will impact groundwater levels and
spring flow rates if it is occurring anywhere along the flow path
system (Texas Water Development Board 2005, p. 92).
Groundwater pumping for irrigated agriculture has had a measurable
effect on groundwater levels in the areas that likely support the
spring flows at the San Solomon Spring system. For example, between the
1950s and 2000 the Salt Basin Bolson aquifer in Lobo Flat fell in
surface elevation in the range of 15 to 30 m (50 to near 100 ft), and
in Wild Horse Flat from 6 to 30 m (20 to 50 ft) (Angle 2001, p. 248;
Beach et al. 2004, p. 4-9). Beach et al. (2004, p. 4-10) found
significant pumping, especially in the Wild Horse Flat area, locally
influences flow patterns in the aquifer system. The relationship of
regional flow exists because Wild Horse Flat is located in the lowest
part of the hydraulically connected Salt Basin Bolson aquifer, and next
highest is Lobo, followed by Ryan Flat, which is at the highest
elevations (Beach et al. 2004, p. 9-32). This means that water
withdrawn from any southern part of the basin (Ryan and Lobo Flats) may
affect the volume of water discharging out of Wild Horse Flat toward
the springs. Because these bolson aquifers have little to no direct
recharge from precipitation (Beach et al. 2004, pp. 6-9, 8-9), these
groundwater declines can be expected to permanently reduce the amount
of water available for discharge in the springs in the San Solomon
Spring system. This is evidenced by the marked decline of groundwater
flow out of the Wild Horse Flat toward the southeast (the direction of
the springs) (Beach et al. 2004, p. 9-27). Based on this information,
it appears reasonable that past and future groundwater withdrawals in
the Salt Basin Bolson aquifers are likely one of the causes of
decreased spring flows in the San Solomon Spring system.
Groundwater pumping withdrawals in Culberson, Jeff Davis, and
Presidio Counties in the Salt Basin Bolson aquifer are expected to
continue in the future mainly to support irrigated agriculture (Region
F Water Planning Group 2010, pp. 2-16-2-19) and will result in
continued lowering of the groundwater levels in the Salt Basin Bolson
aquifer. The latest plans from Groundwater Management Area 4 (the
planning group covering the relevant portion of the Salt Basin Bolson
aquifer) expect over 69 million cubic m (56,000 af) of groundwater
pumping per year for the next 50 years, resulting in an average
drawdown of 22 to 24 m (72 to 78 feet) in the West Texas Bolsons (Salt
Basin) aquifer by 2060 (Adams 2010, p. 2; Oliver 2010, p. 7). There
have been no studies evaluating the effects of this level of
anticipated drawdown on spring flows. The aquifer in the Wild Horse
Flat area (the likely spring source) can range from 60 to 300 m (200 to
1,000 ft) thick. So although it is impossible to determine precisely,
we anticipate the planned level of groundwater drawdown will likely
result in continued future declines in spring flow rates in the San
Solomon Spring system.
Another reason that spring flows may be declining is from an
increase in the frequency and duration of local and regional drought
associated with climatic changes. The term ``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 2007a, 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 2007a, p. 78).
Although the bulk of spring flows appear to originate from ancient
water sources with limited recent recharge, any decreases in regional
precipitation patterns due to prolonged drought will further stress
groundwater availability and increase the risk of diminishment or
drying of the springs. Drought affects both surface and groundwater
resources and can lead to diminished water quality (Woodhouse and
Overpeck 1998, p. 2693) in addition to reducing groundwater quantities.
Lack of rainfall may also indirectly affect aquifer levels by resulting
in an increase in groundwater pumping to offset water shortages from
low precipitation (Mace and Wade 2008, p. 665).
Recent drought conditions may be indicative of more common future
conditions. The current, multiyear drought in the western United
States, including the Southwest, is the most severe drought recorded
since 1900 (Overpeck and Udall 2010, p. 1642). In 2011, Texas
experienced the worst annual drought since recordkeeping began in 1895
(NOAA 2012, p. 4), and only one other year since 1550 (the year 1789)
was as dry as 2011 based on tree-ring climate reconstruction (NOAA
2011, pp. 20-22). In addition, numerous climate change models predict
an overall decrease in annual precipitation in the southwestern United
States and northern Mexico.
Future global climate change may result in increased magnitude of
droughts and further contribute to impacts on the aquatic habitat from
reduction of spring flows. There is high confidence that many semi-arid
areas like the western United States will suffer a decrease in water
resources due to ongoing climate change (IPCC 2007b, p. 7; Karl et al.
2009, pp. 129-131), as a result of less annual mean precipitation.
Milly et al. (2005, p. 347) also project a 10 to 30 percent decrease in
precipitation in mid-latitude western North America by the year 2050
based on an ensemble of 12 climate models. Even under lower greenhouse
gas emission scenarios, recent projections forecast a 10 percent
decline in precipitation in western Texas by 2080 to 2099 (Karl et al.
2009, pp. 129-130). Assessments of climate change in west Texas suggest
that the area is likely to become warmer and at least slightly drier
(Texas Water Development Board 2008, pp. 22-25).
The potential effects of future climate change could reduce overall
water availability in this region of western Texas and compound the
stressors associated with declining flows from the San Solomon Spring
system. As a result of the effects of increased drought, spring flows
could decline indirectly as a result of increased pumping of
groundwater to accommodate human needs for additional water supplies
(Mace and Wade 2008, p. 664; Texas Water Development Board 2012c, p.
231).
In conclusion, the Phantom Cave snail, Phantom springsnail, and
diminutive amphipod all face significant threats from the current and
future loss of habitat associated with declining spring flows. Some
springs in the San Solomon Spring system have already gone dry, and
aquatic habitat at Phantom Lake Spring has not yet been lost only
because of the maintenance of a pumping system. While the sources of
the stress of declining spring flows are not known for certain, the
best available scientific information indicates that it is the result
of a combination of factors including past and current groundwater

[[Page 49615]]

pumping, the complex hydrogeologic conditions that produce these
springs (ancient waters from a regional flow system), and climatic
changes (decreased precipitation and recharge). The threat of habitat
loss from declining spring flows affects all four of the remaining
populations, as all are at risk of future loss from declining spring
flows. All indications are that the source of this threat will persist
into the future and will result in continued degradation of the
species' habitats, putting the Phantom Cave snail, Phantom springsnail,
and diminutive amphipod at a high risk of extinction.
Water Quality Changes and Contamination
Another potential factor that could impact habitat of the San
Solomon Spring species is the potential degradation of water quality
from point and nonpoint pollutant sources. This can occur either
directly into surface water or indirectly through contamination of
groundwater that discharges into spring run habitats used by the
species. The primary threat for contamination in these springs comes
from herbicide and pesticide use in nearby agricultural areas. There
are no oil and gas operations in the area around the San Solomon Spring
system.
These aquatic invertebrates are sensitive to water contamination.
Hydrobiid snails as a group are considered sensitive to water quality
changes, and each species is usually found within relatively narrow
habitat parameters (Sada 2008, p. 59). Amphipods generally do not
tolerate habitat desiccation (drying), standing water, sedimentation,
or other adverse environmental conditions; they are considered very
sensitive to habitat degradation (Covich and Thorpe 1991, pp. 676-677).
The exposure of the spring habitats to pollutants is limited
because most of the nearby agricultural activity mainly occurs in
downstream areas where herbicide or pesticide use would not likely come
into contact with the species or their habitat in upstream spring
outlets. To ensure these pollutants do not affect these spring outflow
habitats, their use has been limited in an informal protected area in
the outflows of San Solomon and Giffin Springs (Service 2004, pp. 20-
21). This area was developed in cooperation with the U.S. Environmental
Protection Agency and the Texas Department of Agriculture. While there
are more agriculture activities far upstream in the aquifer source
area, there is no information indicating concerns about contaminants
from those sources.
In addition, Texas Parks and Wildlife Department completed a
Habitat Conservation Plan and received an incidental take permit
(Service 2009a, entire) in 2009 under section 10(a)(1)(B) (U.S.C.
1539(a)(1)(B)) of the Act for management activities at Balmorhea State
Park (Texas Parks and Wildlife Department 1999, entire). The three
aquatic invertebrate candidate species from the San Solomon Spring
system were all included as covered species in the permit (Service
2009a, pp. 20-22). This permit authorizes ``take'' of the invertebrates
(which were candidates at the time of issuance) in the State Park for
ongoing management activities while minimizing impacts to the aquatic
species. The activities included in the Habitat Conservation Plan are a
part of Texas Parks and Wildlife Department's operation and maintenance
of the State Park, including the drawdowns associated with cleaning the
swimming pool and vegetation management within the refuge canal and
ci[eacute]nega. The Habitat Conservation Plan also calls for
restrictions and guidelines for chemical use in and near aquatic
habitats to avoid and minimize impacts to the three aquatic
invertebrate species (Service 2009a, pp. 9, 29-32).
Because the use of potential pollutants is very limited within the
range of the San Solomon Spring species, at this time we do not find
that the Phantom Cave snail, Phantom springsnail, and diminutive
amphipod are at a heightened risk of extinction from water quality
changes or contamination.
Modification of Spring Channels
The natural ci[eacute]nega habitats of the San Solomon Spring
system have been heavily altered over time primarily to accommodate
agricultural irrigation. Most significant was the draining of wetland
areas and the modification of spring outlets to develop the water
resources for human use. San Solomon and Phantom Lake Springs have been
altered the most severely through capture and diversion of the spring
outlets into concrete irrigation canals. Giffin Spring appears to have
been dredged in the past, and the outflow is now immediately captured
in high-banked, earthen-lined canals. The outflow of East Sandia Spring
does not appear to have been altered in an appreciable way, but it may
have been minimally channelized to connect the spring flow to the
irrigation canals.
The Reeves County Water Improvement District No. 1 maintains an
extensive system of about 100 km (60 mi) of irrigation canals that now
provide only minimal aquatic habitat for the invertebrate species near
the spring sources. Most of the canals are concrete-lined with high
water velocities and little natural substrate available. Many of the
canals are also regularly dewatered as part of the normal water
management operations. Before the canals were constructed, the suitable
habitat areas around the spring openings, particularly at San Solomon
Spring, were much larger in size. The conversion of the natural aquatic
mosaic of habitats into linear irrigation canals represents a past
impact resulting in significant habitat loss and an increase in the
overall risk of extinction by lowering the amount of habitat available
to the species and, therefore, lowering the overall number of
individuals in the populations affected. These reductions in population
size result in an increase in the risk of extirpation of local
populations and, ultimately, the extinction of the species as a whole.
Because the physical conditions of the spring channels have changed
dramatically in the past, the species are now at a greater risk of
extinction because of the alterations to the ecosystem and the overall
lower number of individuals likely making up the populations.
A number of efforts have been undertaken at Balmorhea State Park to
conserve and maintain aquatic habitats at some of the spring sites to
conserve habitat for the native aquatic species. First, a refuge canal
encircling the historic motel was built in 1974 to create habitat for
the endangered fishes, Comanche Springs pupfish and Pecos gambusia
(Garrett 2003, p. 153). Although the canal was concrete-lined, it had
slower moderate water velocities, and natural substrates covered the
wide concrete bottom and provided usable habitat for the aquatic
invertebrates. Second, the 1-ha (2.5-ac) San Solomon Ci[eacute]nega was
built in 1996 to create an additional flow-through pond of water for
habitat of the native aquatic species (Garrett 2003, pp. 153-154).
Finally, during 2009 and 2010, a portion of the deteriorating 1974
refuge canal was removed and relocated away from the motel. The wetted
area was expanded to create a new, larger ci[eacute]nega habitat. This
was intended to provide additional natural habitat for the federally
listed endangered fishes and candidate invertebrates (Service 2009c, p.
3; Lockwood 2010, p. 3). All of these efforts have been generally
successful in providing additional habitat areas for the aquatic
invertebrates, although neither the snails nor amphipods have been
shown to use the newest ci[eacute]nega pond to date (Allan 2011, p. 3).

[[Page 49616]]

At Phantom Lake Spring, a pupfish refuge canal was built in 1993
(Young et al. 1993, pp. 1-3) to increase the available aquatic habitat
that had been destroyed by the irrigation canal. Winemiller and
Anderson (1997, pp. 204-213) showed that the refuge canal was used by
endangered fish species when water was available. Stomach analysis of
the endangered pupfish from Phantom Lake Spring showed that the Phantom
Cave snail and diminutive amphipod were a part of the fish's diet
(Winemiller and Anderson 1997, pp. 209-210), indicating that the
invertebrates also used the refuge canal. The refuge canal was
constructed for a design flow down to about 0.01 cms (0.5 cfs), which
at the time of construction was the lowest flow ever recorded out of
Phantom Lake Spring. The subsequent loss of spring flow eliminated the
usefulness of the refuge canal because the canal went dry beginning in
about 2000.
All the water for the remaining spring head pool at Phantom Lake
Spring is being provided by a pump system to bring water from about 23
m (75 ft) within the cave out to the surface. The small outflow pool
was enlarged in 2011 (U.S. Bureau of Reclamation 2011, p. 1; Service
2012, entire) to encompass about 75 sq m (800 sq ft) of wetted area. In
2011, the pool was relatively stable and all three of the San Solomon
Spring invertebrates were present (Allan 2011, p. 3; Service 2012, p.
9).
In summary, the modifications to the natural spring channels at San
Solomon, Phantom Lake, and Giffin Springs represent activities that
occurred in the past and resulted in a deterioration of the available
habitat for the Phantom Cave snail, Phantom springsnail, and diminutive
amphipod. Actions by conservation agencies over the past few decades
have mitigated the impacts of those actions by restoring some natural
functions to the outflow channels. While additional impacts from
modifications are not likely to occur in the future because of land
ownership by conservation entities at three of the four spring sites,
the past modifications have contributed to the endangerment of these
species by reducing the overall quantity of available habitat and,
therefore, reducing the number of individuals of each species that can
inhabit the spring outflows. The lower the overall number of
individuals of each species and the lower the amount of available
habitat, the greater the risk of extinction. Therefore, the
modification of spring channels contributes to increased risk of
extinction in the future as a consequence of the negative impacts of
the past actions.
Other Conservation Efforts
All four of these springs in the San Solomon Spring system are
inhabited by two fishes federally listed as endangered--Comanche
Springs pupfish (Service 1981, pp. 1-2) and Pecos gambusia (Service
1983, p. 4). Critical habitat has not been designated for either
species. In addition, East Sandia Spring is also inhabited by the
federally threatened Pecos sunflower (Service 2005, p. 4) and the
federally endangered Pecos assiminea snail (Service 2010, p. 5). Both
the Pecos sunflower and the Pecos assiminea snail also have critical
habitat designated at East Sandia Spring (73 FR 17762, April 1, 2008;
76 FR 33036, June 7, 2011, respectively).
The Phantom Cave snail, Phantom springsnail, and diminutive
amphipod have been afforded some protection indirectly in the past due
to the presence of these other listed species in the same locations.
Management and protection of the spring habitats by Texas Parks and
Wildlife Department at San Solomon Spring, U.S. Bureau of Reclamation
at Phantom Lake Spring, and The Nature Conservancy at East Sandia
Spring have benefited the aquatic invertebrates. However, the primary
threat from the loss of habitat due to declining spring flows related
to groundwater changes have not been abated by the Federal listing of
the fish or other species. Therefore, the conservation efforts provided
by the concomitant occurrence of species already listed under the Act
have not prevented the past and ongoing habitat loss, nor is it
expected to prevent future habitat loss.
Summary of Factor A
Based on our evaluation of the best available information, we
conclude that the present and future destruction and modification of
the habitat of the Phantom Cave snail, Phantom springsnail, and
diminutive amphipod is a significant threat. Some of these impacts
occurred in the past from the loss of natural spring flows at several
springs likely within the historic range. The impacts are occurring now
and are likely to continue in the future throughout the current range
as groundwater levels decline and increase the possibility of the loss
of additional springs. As additional springs are lost, the number of
populations will decline and further increase the risk of extinction of
these species. The sources of this threat are not confirmed but are
presumed to include a combination of factors associated with
groundwater pumping, hydrogeologic structure of the supporting
groundwater, and climatic changes. The risk of extinction is also
heightened by the past alteration of spring channels reducing the
available habitat and the number of individuals in each population.
B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes (San Solomon Spring Species)
There are very few people who are interested in or study
springsnails and amphipods, and those who do are sensitive to their
rarity and endemism. Consequently, collection for scientific or
educational purposes is very limited. There are no known commercial or
recreational uses of these invertebrates. For these reasons we conclude
that overutilization for commercial, recreational, scientific, or
educational purposes is currently not a threat to the Phantom Lake
snail, Phantom springsnail, and diminutive amphipod, and we have no
indication that these factors will affect these species in the future.
C. Disease or Predation (San Solomon Spring Species)
The San Solomon Spring species are not known to be affected by any
disease. These invertebrates are likely natural prey species for fishes
and crayfishes that occur in their habitats. Native snails and
amphipods have been found as small proportions of the diets of native
fishes at San Solomon and Phantom Lake Springs (Winemiller and Anderson
1997, p. 201; Hargrave 2010, p. 10), and crayfish are a known predator
of snails (Hershler 1998, p. 14). Bradstreet (2011, p. 98) assumed that
snails at San Solomon Spring were prey for both fishes and crayfishes
and suspected that the native snails may be more susceptible than the
nonnative snails because of their small body size and thinner shells.
In addition, Ladd and Rogowski (2012, p. 289) suggested that the
nonnative red-rim melania (Melanoides tuberculata) may prey upon native
snail eggs of a different species. However, our knowledge of such
predation is very limited, and the extent to which the predation might
affect native springsnails is unknown. For more discussion about red-
rim melania see ``Factor E. Other Natural or Manmade Factors Affecting
Its Continued Existence.'' We are not aware of any other information
indicating that the San Solomon Spring species are affected by disease
or predation factors. For these reasons we conclude that disease or
predation are not significant threats to the Phantom Lake snail,

[[Page 49617]]

Phantom springsnail, and diminutive amphipod, and we have no indication
that these factors will affect these species more severely in the
future.
D. The Inadequacy of Existing Regulatory Mechanisms (San Solomon Spring
Species)
Under this factor, we examine whether existing regulatory
mechanisms are inadequate to address the threats to the species
discussed under Factors A and E. Section 4(b)(1)(A) of the Endangered
Species 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 or regulations that may
minimize any of the threats we describe in threat analyses under the
other four factors, or otherwise enhance conservation of the species.
An example would be the terms and conditions attached to a grazing
permit that describe how a permittee will manage livestock on a BLM
allotment. They are nondiscretionary and enforceable, and are
considered a regulatory mechanism under this analysis. Other examples
include State governmental actions enforced under a State statute or
constitution, or Federal action under statute.
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. Regulatory mechanisms, if they exist,
may reduce or eliminate the impacts from one or more identified
threats. In this section, we review existing State and Federal
regulatory mechanisms to determine whether they effectively reduce or
remove threats to the three San Solomon Spring species.
Texas laws provide no specific protection for these invertebrate
species, as they are not listed as threatened or endangered by the
Texas Parks and Wildlife Department. However, even if they were listed
by the State, those regulations (Title 31 Part 2 of Texas
Administrative Code) would only prohibit the taking, possession,
transportation, or sale of any animal species without the issuance of a
permit. The State makes no provision for the protection of the habitat
of listed species, which is the main threat to these aquatic
invertebrates.
Some protection for the habitat of this species is provided with
the land ownership of the springs by Federal (Phantom Lake Spring owned
by the U.S. Bureau of Reclamation) and State (San Solomon Spring owned
by Texas Parks and Wildlife Department) agencies, and by The Nature
Conservancy (East Sandia Spring). However, this land ownership only
protects the spring outflow channels and provides no protection for
maintaining groundwater levels to ensure continuous spring flows.
In the following discussion, we evaluate the existing local
regulations related to groundwater management within areas that might
provide indirect benefits to the species' habitats through management
of groundwater levels.
Local Groundwater Regulations
One regulatory mechanism that could provide some protection to the
spring flows for these species comes from local groundwater
conservation districts. Groundwater in Texas is generally governed by
the rule of capture unless there is a groundwater district in place.
The rule of capture allows a landowner to produce as much groundwater
as he or she chooses, as long as the water is not wasted (Mace 2001, p.
11). However, local groundwater conservation districts have been
established throughout much of Texas and are now the preferred method
for groundwater management in the State (Texas Water Development Board
2012, pp. 23-258). Groundwater districts ``may regulate the location
and production of wells, with certain voluntary and mandatory
exemptions'' (Texas Water Development Board 2012, p. 27).
There are currently four local groundwater districts in the area
west of the springs (Texas Water Development Board 2011, p. 1) that
could possibly manage groundwater to protect spring flows in the San
Solomon Spring system. The Culberson County Groundwater Conservation
District covers the southwestern portion of Culberson County and was
confirmed (established by the Texas legislature and approved by local
voters) in 1998. The Jeff Davis County Underground Water Conservation
District covers all of Jeff Davis County and was confirmed in 1993. The
Presidio County Underground Water Conservation District covers all of
Presidio County and was confirmed in 1999. The Hudspeth County
Underground Water District No. 1 covers the northwest portion of
Hudspeth County and was confirmed in 1957. This area of Hudspeth County
manages the Bone Spring-Victoria Peak aquifer (Hudspeth County
Underground Water District No. 1 2007, p. 1), which is not known to
contribute water to the regional flow that supplies the San Solomon
Spring system (Ashworth 2001, pp. 143-144). Therefore, we will not
further consider that groundwater district.
In 2010 the Groundwater Management Area 4 established ``desired
future conditions'' for the aquifers occurring within the five-county
area of west Texas (Adams 2010, entire; Texas Water Development Board
2012a, entire). These projected conditions are important because they
guide the plans for water use of groundwater within groundwater
conservation districts in order to attain the desired future condition
of each aquifer they manage (Texas Water Development Board 2012c, p.
23). In the following discussion we review the plans and desired future
conditions for the groundwater conservation districts in Culberson,
Jeff Davis, and Presidio Counties relative to the potential regulation
of groundwater for maintaining spring flows and abating future declines
in the San Solomon Spring system.
The Culberson County Groundwater Conservation District seeks to
implement water management strategies to ``prevent the extreme decline
of water levels for the benefit of all water right owners, the economy,
our citizens, and the environment of the territory inside the
district'' (Culberson County Groundwater Conservation District 2007, p.
1). The missions of Jeff Davis County Underground Water District and
Presidio County Underground Water Conservation District are to ``strive
to develop, promote, and implement water conservation and management
strategies to protect water resources for the benefit of the citizens,
economy, and environment of the District'' (Jeff Davis County
Underground Water Conservation District 2008, p. 1; Presidio County
Underground Water Conservation District 2009, p. 1). However, all three
management plans specifically exclude addressing natural resources
issues as a goal because, ``The District has no documented occurrences
of endangered or threatened species dependent upon groundwater
resources'' (Culberson County Groundwater Conservation District 2007,
p. 10; Jeff Davis County Underground Water Conservation District 2008,
p. 19; Presidio County Underground Water Conservation District 2009, p.
14). This lack of acknowledgement of the relationship of the
groundwater resources under the Districts' management to the
conservation of the spring flow habitat at the San Solomon Spring
system prevents any direct benefits of their management plans for the
three aquatic invertebrates.

[[Page 49618]]

We also considered the desired future condition of the relevant
aquifer that supports San Solomon Spring system flows. The Culberson
County Groundwater Conservation District manages the groundwater where
the bulk of groundwater pumping occurs in the Salt Basin Bolson aquifer
(part of the West Texas Bolson, the source of the water for the San
Solomon Spring system) (Oliver 2010, p. 7). The desired future
condition for aquifers within the Culberson County Groundwater
Conservation District area includes a 24-m (78-ft) drawdown for the
West Texas Bolsons (Salt Basin Bolson aquifer in Wild Horse Flat) to
accommodate an average annual groundwater pumping of 46 million cm
(38,000 af) (Adams 2010, p. 2; Oliver 2010, p. 7). The desired future
condition for the West Texas Bolsons for Jeff Davis County Underground
Water Conservation District includes a 72-ft (22-m) drawdown over the
next 50 years to accommodate an average annual groundwater pumping of
10 million cm (8,075 af) (Adams 2010, p. 2; Oliver 2010, p. 7). The
desired future condition for the West Texas Bolsons for Presidio County
Underground Water District also includes a 72-ft (22-m) drawdown over
the next 50 years to accommodate an average annual groundwater pumping
of 12 million cm (9,793 af) (Adams 2010, p. 2; Oliver 2010, p. 7).
These drawdowns are based on analysis using groundwater availability
models developed for the Texas Water Development Board (Beach et al.
2004, p. 10-6-10-8; Oliver 2010, entire). We expect that these
groundwater districts will use their district rules to regulate water
withdrawals in such a way as to implement these desired future
conditions.
The Salt Basin Bolson aquifer in the Wild Horse Flat area (the
likely spring source) can range from 60 to 300 m (200 to 1,000 ft)
thick. So although it is impossible to determine precisely, we
anticipate the planned level of groundwater drawdown will likely result
in continued future declines in spring flow rates in the San Solomon
Spring system. Therefore, we expect that continued drawdown of the
aquifers as identified in the desired future conditions will contribute
to ongoing and future spring flow declines. Based on these desired
future conditions from the groundwater conservation districts, we
conclude that the regulatory mechanisms available to the groundwater
districts directing future groundwater withdrawal rates from the
aquifers that support spring flows in the San Solomon Spring system are
inadequate to protect against ongoing and future modification of
habitat for the Phantom Cave snail, Phantom springsnail, and diminutive
amphipod.
Summary of Factor D
Although there are some regulatory mechanisms in place, such as the
existence of groundwater conservation districts, we find that the
mechanisms are not serving to alleviate or limit the salient threats to
the Phantom Cave snail, Phantom springsnail, or diminutive amphipod.
We, therefore, conclude that these existing regulatory mechanisms are
inadequate to sufficiently reduce the identified threats to the Phantom
Cave snail, Phantom springsnail, and diminutive amphipod now and in the
future.
E. Other Natural or Manmade Factors Affecting Their Continued Existence
(San Solomon Spring Species)
We considered three other factors that may be affecting the
continued existence of the San Solomon Spring species: nonnative
snails, other nonnative species, and the small, reduced ranges of the
three San Solomon Spring species.
Nonnative Snails
Another factor that may be impacting the San Solomon Spring species
is the presence of two nonnative snails that occur in a portion of
their range. The red-rim melania and quilted melania both occur at San
Solomon Spring, and the red-rim melania also occurs at Phantom Lake and
Giffin Springs (Allan 2011, p. 1; Bradstreet 2011, pp. 4-5; Lang 2011,
pp. 4-5, 11). Both species are native to Africa and Asia and have been
imported into the United States as aquarium species. They are now
established in various locations across the southern and western
portions of the United States (Bradstreet 2011, pp. 4-5; U.S.
Geological Survey 2009, p. 2; Benson 2012, p. 2).
The red-rim melania was first reported from Phantom Lake Spring
during the 1990s (Fullington 1993, p. 2; McDermott 2000, pp. 14-15) and
was first reported from Giffin Spring in 2001 (Lang 2011, pp. 4-5). The
species has been at San Solomon Spring for some time longer (Texas
Parks and Wildlife Department 1999, p. 14), but it is not found in East
Sandia Spring (Lang 2011, p. 10; Allan 2011, p. 1). Bradstreet reported
the red-rim melania in all of the habitats throughout San Solomon
Spring at moderate densities compared to other snails, with a total
population estimate of about 390,000 snails ( 350,000)
(Bradstreet 2011, pp. 45-55). Lang (2011, pp. 4-5) also found moderate
densities of red-rim melania at Giffin Spring in both the headspring
area and downstream spring run area.
The quilted melania was first reported as being at San Solomon
Spring in 1999 (Texas Parks and Wildlife Department 1999, p. 14) from
observations in 1995 (Bowles 2012, pers. comm.). It was later collected
in 2001 (Lang 2011, p. 4), but not identified until Bradstreet (2011,
p. 4) confirmed its presence there. The species is not found in any
other springs in the San Solomon Spring system, but occurs in all
habitats throughout San Solomon Spring at moderate densities compared
to other snails, with a total population estimate of about 840,000
snails (1,070,000) (Bradstreet 2011, pp. 45-55).
The mechanism and extent of potential effects of the two nonnative
snails on the native invertebrates have not been studied directly.
However, because both nonnative snails occur in relatively high
abundances, it is reasonable to presume that they are likely competing
for space and food resources in the limited habitats in which they
occur. Rader et al. (2003, pp. 651-655) reviewed the biology and
possible impacts of red-rim melania and suggested that the species had
already displaced some native springsnails in spring systems of the
Bonneville Basin of Utah. Appleton et al. (2009, entire) reviewed the
biology and possible impacts of the quilted melania and found
potentially significant impacts likely to occur to the native benthic
invertebrate community in aquatic systems in South Africa. Currently,
East Sandia Spring has remained free of nonnative snails, but their
invasion there is a continuing concern (Bradstreet 2011, p. 95). We
conclude that these two snails may be having some negative effects on
the Phantom Cave snail, Phantom springsnail, and diminutive amphipod
based on a potential for competition for spaces and food resources.
Other Nonnative Species
A potential future threat to these species comes from the possible
introduction of additional nonnative species into their habitat. In
general, introduced species are a serious threat to native aquatic
species (Williams et al. 1989, p. 18; Lodge et al. 2000, p. 7). The
threat is particularly elevated at San Solomon Spring where the public
access to the habitat is prolific by the thousands of visitors to the
Balmorhea State Park who swim in the spring outflow pool.
Unfortunately, people will sometimes release nonnative species into
natural waters, intentionally or

[[Page 49619]]

unintentionally, without understanding the potential impacts to native
species. In spite of regulations that do not permit it, visitors to the
Park may release nonnative species into the outflow waters of San
Solomon Spring. This is presumably how the two nonnative snails became
established there. Nonnative fishes are sometimes seen and removed from
the water by Park personnel (Texas Parks and Wildlife Department 1999,
pp. 46-47). The Park makes some effort to minimize the risk of
nonnative species introductions by prohibiting fishing (so no live bait
is released) and by taking measures to educate visitors about the
prohibition of releasing species into the water (Texas Parks and
Wildlife Department 1999, pp. 48). In spite of these efforts, there is
an ongoing risk, which cannot be fully determined, that novel and
destructive nonnative species could be introduced in the future. This
risk is much lower at the other three springs in the San Solomon Spring
system because of the lack of public access to these sites.
We conclude that the future introduction of any nonnative species
represents an ongoing concern to the aquatic invertebrates, however,
the immediacy of this happening is relatively low because it is only a
future possibility. In addition, the severity of the impact is also
relatively low because it is most likely to occur only at San Solomon
Spring and the actual effects of any nonnative species on the Phantom
Cave snail, Phantom springsnail, and diminutive amphipod are unknown at
this time.
Small, Reduced Range
One important factor that contributes to the high risk of
extinction for these species is their naturally small range that has
been reduced from past destruction of their habitat. While the overall
extent of geographic range of the species has not changed, the number
and distribution of local populations within their range has likely
been reduced when other small springs within the San Solomon Spring
system (such as Saragosa, Toyah, and West Sandia Springs) ceased to
flow (Brune 1981, p. 386; Karges 2003, p. 145). These species are now
currently limited to four small spring outflow areas, with the
populations at Phantom Lake Spring in imminent threat of loss.
The geographically small range with only four populations of these
invertebrate species increases the risk of extinction from any effects
associated with other threats or stochastic events. When species are
limited to small, isolated habitats, they are more likely to become
extinct due to a local event that negatively affects the populations
(Shepard 1993, pp. 354-357; McKinney 1997, p. 497; Minckley and Unmack
2000, pp. 52-53). In addition, the species are restricted to aquatic
habitats in small spring systems and have minimal mobility and no other
habitats available for colonization, so it is unlikely their range will
ever expand beyond the current extent. This situation makes the
magnitude of impact of any possible threat very high. In other words,
the resulting effects of any of the threat factors under consideration
here, even if they are relatively small on a temporal or geographic
scale, could result in complete extinction of the species. While the
small, reduced range does not represent an independent threat to these
species, it does substantially increase the risk of extinction from the
effects of other threats, including those addressed in this analysis
and those that could occur in the future from unknown sources.
Summary of Factor E
The potential impacts of these nonnative snails and any future
introductions of other nonnative species on the Phantom Cave snail,
Phantom springsnail, and diminutive amphipod are largely unknown with
the current available information. But the nonnative snails are
presumed to have some negative consequences to the native snails
through competition for space and resources. The effects on the
diminutive amphipod are even less clear, but competition could still be
occurring. These nonnative snails have likely been co-occurring for at
least 20 years at three of the four known locations for these species,
and there is currently nothing preventing the invasion of the species
into East Sandia Spring. Considering the best available information, we
conclude that the presence of these two nonnative snails and the
potential future introductions of nonnative species currently represent
a low-intensity threat to the Phantom Cave snail, Phantom Lake
springsnail, and diminutive amphipod. In addition, the small, reduced
ranges of these species limit the number of available populations and
increase the risk of extinction from other threats. In combination with
the past and future threats from habitat modification and loss, these
factors contribute to the increased risk of extinction to the three
native species.

Proposed Determination--San Solomon Spring Species

We have carefully assessed the best scientific and commercial
information available regarding the past, present, and future threats
to the Phantom Cave snail, Phantom springsnail, and diminutive
amphipod. We find the species are in danger of extinction due to the
current and ongoing modification and destruction of their habitat and
range (Factor A) from the ongoing and future decline in spring flows,
and historic modification of spring channels. The most significant
factor threatening these species is a result of historic and future
declines in regional groundwater levels that have caused some springs
to cease flowing and threatens the remaining springs with the same
fate. We did not find any significant threats to the species under
Factors B or C. We found that existing regulatory mechanisms are
inadequate to provide protection to the species through groundwater
management by groundwater conservation districts (Factor D) from
existing and future threats. Finally, two nonnative snails occur in
portions of the species' range that could be another factor negatively
affecting the species (Factor E). The severity of the impact from these
nonnative snails or other future introductions of nonnative species is
not known, but such introductions may contribute to the risk of
extinction from the threats to habitat through reducing the abundance
of the three aquatic invertebrates through competition for space and
resources. The small, reduced ranges (Factor E) of these species, when
coupled with the presence of additional threats, also put them at a
heightened risk of extinction.
The elevated risk of extinction of the Phantom Cave snail, Phantom
springsnail, and diminutive amphipod is a result of the cumulative
nature of the stressors on the species and their habitats. For example,
the past reduction in available habitat through modification of spring
channels resulted in a lower number of individuals contributing to the
sizes of the populations. In addition, the loss of other small springs
that may have been inhabited by the species reduced the number of
populations that would contribute to the species' overall viability. In
this diminished state, the species are also facing future risks from
the impacts of continuing declining spring flows, exacerbated by
potential extended future droughts resulting from global climate
change, and potential effects from nonnative species. All of these
factors contribute together to heighten the risk of extinction and lead
to our finding that the Phantom Cave snail, Phantom springsnail, and
diminutive amphipod are in danger of

[[Page 49620]]

extinction throughout all of their ranges and warrant listing as
endangered species.
The Act defines an endangered species as any species that is ``in
danger of extinction throughout all or a significant portion of its
range'' and a threatened species as any species ``that is likely to
become endangered throughout all or a significant portion of its range
within the foreseeable future.'' We have carefully assessed the best
scientific and commercial information available regarding the past,
present, and future threats to the species, and have determined that
the Phantom Cave snail, Phantom springsnail, and diminutive amphipod
all meet the definition of endangered species under the Act.
Significant threats are occurring now and in the foreseeable future, at
a high intensity, and across the species' entire range, placing them on
the brink of extinction at the present time. Because the threats are
placing the species in danger of extinction now and not only in the
foreseeable future, we have determined that they meet the definition of
endangered species rather than threatened species. Therefore, on the
basis of the best available scientific and commercial information, we
propose listing the Phantom Cave snail, Phantom springsnail, and
diminutive amphipod as endangered species in accordance with sections
3(6) and 4(a)(1) of the Act.
Under the Act and our implementing regulations, a species may
warrant listing if it is threatened or endangered throughout all or a
significant portion of its range. The species proposed for listing in
this rule are highly restricted within their range, and the threats
occur throughout their range. Therefore, we assessed the status of the
species throughout their entire range. The threats to the survival of
the species occur throughout the species' range and are not restricted
to any particular significant portion of that range. Accordingly, our
assessment and proposed determination applies to the species throughout
their entire range.

Diamond Y Spring Species--Diamond Y Spring Snail, Gonzales Springsnail,
and Pecos Amphipod

The following five-factor analysis applies to the three species
that occur in the Diamond Y Spring system in Pecos County, Texas:
Diamond Y Spring snail, Gonzales springsnail, and Pecos amphipod.
A. The Present or Threatened Destruction, Modification, or Curtailment
of Their Habitat or Range (Diamond Y Spring Species)
Spring Flow Decline
The primary threat to the continued existence of the Diamond Y
Spring species is the degradation and potential future loss of aquatic
habitat (flowing water from the spring outlets) due to the decline of
groundwater levels in the aquifers that support spring surface flows.
Habitat for these species is exclusively aquatic and completely
dependent upon spring outflows. Spring flows in the Diamond Y Spring
system appear to have declined in flow rate over time, and as spring
flows decline available aquatic habitat is reduced and altered. When a
spring ceases to flow continually, all habitats for these species are
lost, and the populations will be extirpated. When all of the springs
lose consistent surface flows, all natural habitats for these aquatic
invertebrates will be gone, and the species will become extinct. We
know springs in this area can fail due to groundwater pumping, because
larger nearby springs, such as Comanche and Leon Springs have already
ceased flowing and likely resulted in the extirpation of local
populations of these species (assuming they were present historically).
The springs do not have to cease flowing completely to have an
adverse effect on invertebrate populations. The small size of the
spring outflows in the Diamond Y Spring system makes them particularly
susceptible to changes in water chemistry, increased water
temperatures, and freezing. Because these springs are small, any
reductions in the flow rates from the springs can reduce the available
habitat for the species, decreasing the number of individuals and
increasing the risk of extinction. Water temperatures and chemical
factors such as dissolved oxygen in springs do not typically fluctuate
(Hubbs 2001, p. 324); invertebrates are narrowly adapted to spring
conditions and are sensitive to changes in water quality (Hershler
1998, p. 11). Spring flow declines can lead to the degradation and loss
of aquatic invertebrate habitat and present a substantial threat to the
species.
There have been no regular recordings of spring flow discharge at
Diamond Y Spring to quantify any trends in spring flow. The total flow
rates are very low, as Veni (1991, p. 86) estimated total discharge
from the upper watercourse at 0.05 to .08 cms (2 to 3 cfs) and from the
lower watercourse at 0.04 to 0.05 cms (1 to 2 cfs). The nature of the
system with many diffuse and unconfined small springs and seeps makes
the estimates of water quantity discharging from the spring system
difficult to obtain. However, many authors (Veni 1991, p. 86; Echelle
et al. 2001, p. 28; Karges 2003, pp. 144-145) have described the
reductions in available surface waters observed compared to older
descriptions of the area (Kennedy 1977, p. 93; Hubbs et al. 1978, p.
489; Taylor 1985, pp. 4, 15, 21). The amount of aquatic habitat may
vary to some degree based on annual and seasonal conditions, but the
overall trend in the reduction in the amount of surface water over the
last several decades is apparent.
A clear example of the loss in aquatic habitat comes from Kennedy's
(1977, p. 93) description of one of his study sites in 1974. Station 2
was called a ``very large pool'' near Leon Creek of about 1,500 to
2,500 sq m (16,000 to 27,000 sq ft) with shallow depths of 0.5 to 0.6 m
(1.6 to 2.0 ft), with a small 2-m (6.6-ft) deep depression in the
center. Today very little open water is found in this area, only marshy
soils with occasional trickles of surface flow. This slow loss of
aquatic habitat has occurred throughout the system over time and
represents a substantial threat to the continued existence of the
Diamond Y Spring snail, Gonzales springsnail, and the Pecos amphipod.
The precise reason for the declining spring flows remains
uncertain, but it is presumed to be related to a combination of
groundwater pumping, mainly for agricultural irrigation, and a lack of
natural recharge to the supporting aquifers. In addition, future
changes in the regional climate are expected to exacerbate declining
flows.
Initial studies of the Diamond Y Spring system suggested that the
Edwards-Trinity aquifer was the primary source of flows (Veni 1991, p.
86). However, later studies seem to confirm that the Rustler aquifer is
instead more likely the chief source of water (Boghici 1997, p. 107).
The Rustler aquifer is one of the less-studied aquifers in Texas and
encompasses most of Reeves County and parts of Culberson, Pecos,
Loving, and Ward Counties in the Delaware Basin of west Texas (Boghici
and Van Broekhoven 2001, pp. 209-210). The Rustler strata are thought
to be between 75 to 200 m (250 to 670 ft) thick (Boghici and Van
Broekhoven 2001, p. 207). Very little recharge to the aquifer likely
comes from precipitation in the Rustler Hills in Culberson County, but
most of it may be contributed by cross-formational flows from old water
from deeper aquifer formations (Boghici and Van

[[Page 49621]]

Broekhoven 2001, pp. 218-219). Groundwater planning for the Rustler
aquifer anticipates no annual recharge (Middle Pecos Groundwater
Conservation District 2010b, p. 18).
Historic pumping from the Rustler aquifer in Pecos County may have
contributed to declining spring flows, as withdrawals of up to 9
million cm (7,500 af) in 1958 were recorded, with estimates from 1970
to 1997 suggesting groundwater use averaged between 430,000 cm (350 af)
to 2 million cm (1,550 af) per year (Boghici and Van Broekhoven 2001,
p. 218). As a result, declines in water levels in Pecos County wells in
the Rustler aquifer from the mid-1960s through the late 1970s of up to
30 m (100 ft) have been recorded (Boghici and Van Broekhoven 2001, p.
213). We assume that groundwater pumping has had some impacts on spring
flows of the Diamond Y Spring system in the past; however, they have
not yet been substantial enough to cause the main springs to cease
flowing.
Future groundwater withdrawals may further impact spring flow rates
if they occur in areas of the Rustler Aquifer that affect the spring
source areas. Groundwater pumping withdrawals in Pecos County are
expected to continue in the future mainly to support irrigated
agriculture (Region F Water Planning Group 2011, pp. 2-16-2-19) and
will result in continued lowering of the groundwater levels in the
Rustler aquifer. The latest plans from Groundwater Management Area 3
(the planning group covering the relevant portion of the Rustler
Aquifer) allows for a groundwater withdrawal in the Rustler Aquifer not
to exceed 90 m (300 ft) in the year 2060 (Middle Pecos Groundwater
Conservation District 2010a, p. 2). This level of drawdown will
accommodate 12.9 million cm (10,508 af) of annual withdrawals by
pumping (Middle Pecos Groundwater Conservation District 2010b, p. 15).
This level of pumping would be 30 times more than the long-term average
and could result in an extensive reduction in the available groundwater
in the aquifer based on the total thickness of the Rustler strata.
Therefore, we anticipate this level of groundwater drawdown may
contribute to continued declines in spring flow rates in the Diamond Y
Spring system.
Another factor possibly contributing to declining spring flows is
climatic changes that may increase the frequency and duration of local
and regional drought. The term ``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 2007a, 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
2007a, p. 78).
Although the bulk of spring flows probably originates from water
sources with limited recent recharge, any decreases in regional
precipitation patterns due to prolonged drought will further stress
groundwater availability and increase the risk of diminishment or
drying of the springs. Drought affects both surface and groundwater
resources and can lead to diminished water quality (Woodhouse and
Overpeck 1998, p. 2693; MacRae et al. 2001, pp. 4, 10) in addition to
reducing groundwater quantities. Lack of rainfall may also indirectly
affect aquifer levels by resulting in an increase in groundwater
pumping to offset water shortages from low precipitation (Mace and Wade
2008, p. 665).
Recent drought conditions may be indicative of more common future
conditions. The current, multiyear drought in the western United
States, including the Southwest, is the most severe drought recorded
since 1900 (Overpeck and Udall 2010, p. 1642). In 2011, Texas
experienced the worst annual drought since recordkeeping began in 1895
(NOAA 2012, p. 4), and only 1 other year since 1550 (the year 1789) was
as dry as 2011 based on tree-ring climate reconstruction (NOAA 2011,
pp. 20-22). In addition, numerous climate change models predict an
overall decrease in annual precipitation in the southwestern United
States and northern Mexico.
Future global climate change may result in increased severity of
droughts and further contribute to impacts on the aquatic habitat from
reduction of spring flows. There is high confidence that many semiarid
areas like the western United States will suffer a decrease in water
resources due to ongoing climate change (IPCC 2007b, p. 7; Karl et al.
2009, pp. 129-131), as a result of less annual mean precipitation.
Milly et al. (2005, p. 347) also project a 10 to 30 percent decrease in
precipitation in mid-latitude western North America by the year 2050
based on an ensemble of 12 climate models. Even under lower greenhouse
gas emission scenarios, recent projections forecast a 10 percent
decline in precipitation in western Texas by 2080 to 2099 (Karl et al.
2009, pp. 129-130). Assessments of climate change in west Texas suggest
that the area is likely to become warmer and at least slightly drier
(Texas Water Development Board 2008, pp. 22-25).
The potential effects of future climate change could reduce overall
water availability in this region of western Texas and compound the
stressors associated with declining flows from the Diamond Y Spring
system. As a result of the effects of increased drought, spring flows
could decline indirectly as a result of increased pumping of
groundwater to accommodate human needs for additional water supplies
(Mace and Wade 2008, p. 664; Texas Water Development Board 2012c, p.
231).
In conclusion, the Diamond Y Spring snail, Gonzales springsnail,
and Pecos amphipod are in danger of extinction because of the past and
expected future loss of habitat associated with declining spring flows.
Some nearby springs have already gone dry. While the sources of the
stress of declining spring flows are not known for certain, the best
available scientific information would indicate that it is the result
of a combination of factors including past and current groundwater
pumping and climatic changes (decreased precipitation and recharge).
The threat of habitat loss from declining spring flows affects all the
entire range of all three species, as all are at risk of future loss
due to declining spring flows. All indications are that the source of
this threat will persist into the future and will result in continued
degradation of the species' habitats, placing them at a high risk of
extinction.
Water Quality Changes and Contamination
Another potential factor that could impact habitat of the Diamond Y
Spring species is the potential degradation of water quality from point
pollutant sources. This can occur either directly into surface water or
indirectly through contamination of groundwater that discharges into
spring run habitats used by the species. The primary threat for
contamination in these springs comes from activities related to oil and
gas exploration, extraction, transportation, and processing.
Oil and gas activities are a source of significant threat to the
Diamond Y Spring species because of the potential groundwater or
surface water contamination from pollutants (Veni 1991, p. 83;
Fullington 1991, p. 6). The Diamond Y Spring system is within an active
oil and gas extraction field that has been operational for many
decades. In 1990, there were 45 active and plugged wells within the
Diamond Y Preserve and an estimated 800 to 1,000 wells perforated the
aquifers within the

[[Page 49622]]

springs' drainage basins (Veni 1991, p. 83). At this time there are
still many active wells located within about 100 m (about 300 ft) of
surface waters. In addition, a natural gas processing plant, known as
the Gomez Plant, is located within 0.8 km (0.5 mi) upslope of Diamond Y
Spring. Oil and gas pipelines cross the habitat, and many oil
extraction wells are located near the occupied habitat. Oil and gas
drilling also occurs throughout the area of supporting groundwater
providing another potential source of contamination through the
groundwater supply. The Gomez Plant, which collects and processes
natural gas is located about 350 m (1,100 feet) up gradient from the
head pool of Diamond Y Spring (Hoover 2011, p. 1). Taylor (1985, p. 15)
suggested that an unidentified groundwater pollutant may have been
responsible for reductions in abundance of Diamond Y Spring snail in
the headspring and outflow of Diamond Y Spring, although there never
were any follow-up studies done to investigate the presumption. The
potential for an event catastrophic to the Diamond Y Spring species
from a contaminant spill or leak is possible at any time (Veni 1991, p.
83).
As an example of the possibility for spills, in 1992 approximately
10,600 barrels of crude oil were released from a 15-cm (6-in) pipeline
that traverses Leon Creek above its confluence with Diamond Y Draw. The
oil was from a pipeline, which ruptured at a point several hundred feet
away from the Leon Creek channel. The spill site itself is about 1.6 km
(1 mi) overland from Diamond Y Spring. 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 later years, remediation efforts 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 have been observed, but no specific monitoring of the effects
of the spill was undertaken (Industrial Economics, Inc. 2005, p. 4-12).
If a contaminant were to leak into the habitat of the species from
any of the various sources, the effects of the contamination could
result in death to exposed individuals, reductions in food
availability, or other ecological impacts (such as long-term alteration
to water or soil chemistry and the microorganisms that serve as the
base of food web in the aquatic ecosystem). The effects of a surface
spill or leak might be contained to a local area and only affect a
portion of the populations; however, an event that contaminated the
groundwater could impact both the upper and lower watercourses and
eliminate the entire range of all three species. There is currently no
regular monitoring of the water quality occurring for these species or
their habitats, so it is unlikely that the effects would be detected
quickly to allow for a timely response.
These invertebrates are sensitive to water contamination. Hydrobiid
snails as a group are considered sensitive to water quality changes,
and each species is usually found within relatively narrow habitat
parameters (Sada 2008, p. 59). Taylor (1985, p. 15) suggested that an
unidentified groundwater pollutant may have been responsible for
reductions in abundance of Diamond Y Spring snails in the headspring
and outflow of Diamond Y Spring, although no follow-up studies were
ever conducted to investigate the presumption. Additionally, amphipods
generally do not tolerate habitat desiccation (drying), standing water,
sedimentation, or other adverse environmental conditions; they are
considered very sensitive to habitat degradation (Covich and Thorpe
1991, pp. 676-677).
Several conservation measures have been implemented in the past to
reduce the potential for a contamination event. In the 1970s the U.S.
Department of Agriculture, Natural Resources Conservation Service (then
the Soil Conservation Service) built a small berm encompassing the
south side of Diamond Y Spring to prevent a surface spill from the
Gomez Plant from reaching the spring head. After The Nature Conservancy
purchased the Diamond Y Springs Preserve in 1990, oil and gas companies
undertook a number of conservation measures to minimize the potential
for contamination of the aquatic habitats. These measures included
decommissioning buried corrodible metal pipelines and replacing them
with synthetic surface lines, installing emergency shut-off valves,
building berms around oil pad sites, and removing abandoned oil pad
sites and their access roads that had been impeding surface water flow
(Karges 2003, p. 144).
Presently, there is no evidence of habitat destruction or
modification due to groundwater or surface water contamination from
leaks or spills, and no major spills affecting the habitat have been
reported in the past (Veni 1991, p. 83). However, the potential for
future adverse effects from a catastrophic event is an ongoing threat
of high severity of potential impact but not immediate.
Modification of Spring Channels
The spring outflow channels in the Diamond Y Spring system have
remained mostly intact. The main subtle changes in the past were a
result of some cattle grazing before The Nature Conservancy
discontinued livestock use in 2000, and roads and well pads that were
constructed in the spring outflow areas. Most of these structures were
removed by the oil and gas industry following The Nature Conservancy's
ownership in 1990. Several caliche (hard calcium carbonate material)
roads still cross the spring outflows with small culverts used to pass
the restricted flows.
A recent concern has been raised regarding the encroachment of
bulrush into the spring channels. Bulrush is an emergent plant that
grows in dense stands along the margins of spring channels. (An
emergent plant is one rooted in shallow water and having most of its
vegetative growth above the water.) When flow levels decline, reducing
water depths and velocities, bulrush can become very dense and dominate
the wetted channel. In 1998, bulrush made up 39 percent (
33 percent) of the plant species in the wetted marsh areas of the
Diamond Y Draw (Van Auken et al. 2007, p. 54). Observations by
Itzkowitz (2008, p. 5; 2010, pp. 13-14) found that bulrush were
increasing in density at several locations within the upper and lower
watercourses in Diamond Y Draw resulting in the loss of open water
habitats. Itzkowitz (2010, pp. 13-14) also noted a positive response by
bulrush following a controlled fire for grassland management.
In addition to water level declines, the bulrush encroachment may
have been aided by a small flume that was installed in 2000 about 100 m
(300 ft) downstream of the springhead pool at Diamond Y Spring (Service
1999, p. 2). The purpose of the flume was to facilitate spring flow
monitoring, but the instrumentation was not maintained. The flume
remains in place and is now being used for flow measurements by the
U.S. Geological Survey. The installation of the flume may have slightly
impounded the water upstream creating shallow, slow overflow areas
along the bank promoting bulrush growth. This potential effect of the
action was not foreseen (Service 1999, p. 3). Whether or not the flume
was the cause, the area upstream of it is now overgrown with bulrush,
and the two

[[Page 49623]]

snails have not been found in this section for some time.
There are several ways in which dense bulrush stands may alter
habitat for the invertebrates. Bulrush grows to a height of about 0.7 m
(2 ft) tall in very dense stands. Dense bulrush thickets will result in
increased shading of the water surface, which is likely to reduce the
algae and other food sources for the invertebrates. In addition, the
stems will slow the water velocity, and the root masses will collect
sediments and alter the substrates in the stream. These small changes
in habitat conditions may result in proportionally large areas of the
spring outflow channels being unsuitable for use by the invertebrates,
particularly the springsnails. Supporting this idea is the reported
distributions of the snails that found them in highest abundance in
areas with more open flowing water not dominated by bulrush (Allan
2011, p. 2). The impacts of dense bulrush stands as a result of
declining spring flow rates may be negatively affecting the
distribution and abundance of the invertebrates within the Diamond Y
Spring system.
Another recent impact to spring channels comes from disturbance by
feral hogs (Sus scrofa). These species have been released or escaped
from domestic livestock and have become free-ranging over time (Mapston
2005, p. 6). They have been in Texas for about 300 years and occur
throughout the State. The area around Diamond Y Spring has not
previously been reported as within their distribution (Mapston 2005, p.
5), but they have now been confirmed there (Allan 2011, p. 2). The
feral hogs prefer wet and marshy areas and damage spring channels by
creating wallows, muddy depressions used to keep cool and coat
themselves with mud (Mapston 2005, p. 15). In 2011, wallows were
observed in spring channels formerly inhabited by the invertebrates in
both the upper and lower watercourses at the Diamond Y Preserve (Allan
2011, p. 2). The alterations in the spring channels caused by the
wallows make the affected area uninhabitable by the invertebrates. The
effects of feral hog wallows are limited to small areas but act as
another stressor on the very limited habitat of these three Diamond Y
Spring species.
Some protection for the spring channel habitats for the Diamond Y
Spring species is provided with the ownership and management of the
Diamond Y Spring Preserve by The Nature Conservancy (Karges 2003, pp.
143-144). Their land stewardship efforts ensure that intentional or
direct impacts to the spring channel habitats will not occur. However,
land ownership by The Nature Conservancy provides limited ability to
prevent changes such as increases in bulrush or to control feral hogs.
Moreover, the Nature Conservancy can provide little protection from the
main threats to this species--the loss of necessary groundwater levels
to ensure adequate spring flows or contamination of groundwater from
oil and gas activities (Taylor 1985, p. 21; Karges 2003, pp. 144-145).
In summary, the modifications to the natural spring channels at the
Diamond Y Spring system represent activities that are occurring now and
will likely continue in the future through the continued encroachment
of bulrush as spring flows continue to decline and through the effects
of feral hog wallows. Conservation actions over the past two decades
have removed and minimized some past impacts to spring channels by
removing livestock and rehabilitating former oil pads and access roads.
While additional direct modifications are not likely to occur in the
future because of land ownership by The Nature Conservancy, future
modifications from bulrush encroachment and feral hog wallows
contribute to the suite of threats to the species' habitat by reducing
the overall quantity of available habitat and, therefore, reducing the
number of individuals of each species that can inhabit the springs. The
lower the overall number of individuals of each species and the less
available habitat, the greater the risk of extinction. Therefore, the
modification of spring channels contributes to increased risk of
extinction in the future as a consequence of ongoing and future
impacts.
Other Conservation Efforts
The Diamond Y Spring system is inhabited by two fishes federally
listed as endangered--Leon Springs pupfish (Service 1985, pp. 3) and
Pecos gambusia (Service 1983, p. 4). In addition, the area is also
inhabited by the federally threatened Pecos sunflower (Service 2005, p.
4) and the federally endangered Pecos assiminea snail (Service 2010, p.
5). Critical habitat has not been designated for Pecos gambusia. The
Diamond Y Spring has been designated as critical habitat for Leon
Springs pupfish, Pecos sunflower, and Pecos assiminea snail (45 FR
54678, August 15, 1980; 73 FR 17762, April 1, 2008; 76 FR 33036, June
7, 2011, respectively).
The three Diamond Y Spring species have been afforded some
protection indirectly in the past due to the presence of these other
listed species in the same locations. Management and protection of the
spring habitats by Texas Parks and Wildlife Department, The Nature
Conservancy, and the Service has benefited the aquatic invertebrates
(Karges 2007, pp. 19-20). However, the primary threat from the loss of
habitat due to declining spring flows related to groundwater changes
have not been abated by the Federal listing of the fish or other
species. Therefore, the conservation efforts provided by the
concomitant occurrence of species already listed under the Act have not
prevented past and current habitat loss, nor are they expected to do so
in the future.
Summary of Factor A
Based on our evaluation of the best available information, we
conclude that the present and future destruction and modification of
the habitat of the Diamond Y Spring snail, Gonzales springsnail, and
Pecos amphipod is a significant threat. These impacts in the past have
come from the loss of natural spring flows at several springs likely
within the historic range, and the future threat of the loss of
additional springs as groundwater levels are likely to decline in the
future. As springs decline throughout the small range of these species,
the number of individuals and populations will decline and continue to
increase the risk of extinction of these species. The sources of this
threat are not confirmed but are presumed to include a combination of
factors associated with groundwater pumping and climatic changes. The
potential for a spill of contaminants from oil and gas operations
presents a constant future threat to the quality of the aquatic
habitat. Finally, the risk of extinction is heightened by the ongoing
and future modification of spring channels, which reduces the number of
individuals in each population, from the encroachment of bulrush and
the presence of feral hogs.
B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes (Diamond Y Spring Species)
There are very few people who are interested in or study
springsnails and amphipods, and those who do are sensitive to their
rarity and endemism. Consequently, collection for scientific or
educational purposes is very limited. There are no known commercial or
recreational uses of these invertebrates. For these reasons we conclude
that overutilization for commercial, recreational, scientific, or
educational purposes are not a threat to the Diamond Y Spring snail,
Gonzales springsnail, and Pecos amphipod, and

[[Page 49624]]

we have no indication that these factors will affect these species in
the future.
C. Disease or Predation (Diamond Y Spring Species)
The Diamond Y Spring species are not known to be affected by any
disease. These invertebrates are likely natural prey species for fishes
that occur in their habitats. There are no known nonnative predatory
fishes within their spring habitats, but there are crayfish, which are
known to prey on snails (Hershler 1998, p. 14). Ladd and Rogowski
(2012, p. 289) suggested that the nonnative red-rim melania may prey
upon different species of native snail eggs. However, the evidence of
such predation is very limited, and the extent to which the predation
might affect native snails is unknown. For more discussion about red-
rim melania, see ``Factor E. Other Natural or Manmade Factors Affecting
Its Continued Existence (Diamond Y Spring Species).'' We are not aware
of any other information indicating that the Diamond Y Spring species
are affected by disease or predation. For these reasons we conclude
that neither disease nor predation are threats to the Diamond Y Spring
snail, Gonzales springsnail, and Pecos amphipod, and we have no
indication that these factors will affect these species in the future.
D. The Inadequacy of Existing Regulatory Mechanisms (Diamond Y Spring
Species)
Under this factor, we examine whether existing regulatory
mechanisms are inadequate to address the threats to the species
discussed under the other four factors. Section 4(b)(1)(A) of the
Endangered Species 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 that
may minimize any of the threats we describe in threat analyses under
the other four factors, or otherwise enhance conservation of the
species. An example would be the terms and conditions attached to a
grazing permit that describe how a permittee will manage livestock on a
BLM allotment. They are nondiscretionary and enforceable, and are
considered a regulatory mechanism under this analysis. Other examples
include State governmental actions enforced under a State statute or
constitution, or Federal action under statute.
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. Regulatory mechanisms, if they exist,
may reduce or eliminate the impacts from one or more identified
threats. In this section, we review existing State and Federal
regulatory mechanisms to determine whether they effectively reduce or
remove threats to the three San Solomon Spring species.
Texas laws provide no specific protection for these invertebrate
species, as they are not listed as threatened or endangered by the
Texas Parks and Wildlife Department. However, even if they were listed
by the State, those regulations (Title 31 Part 2 of Texas
Administrative Code) would only prohibit the taking, possession,
transportation, or sale of any animal species without the issuance of a
permit. The State makes no provision for the protection of the habitat
of listed species, which is the main threat to these aquatic
invertebrates.
Some protection for the habitat of this species is provided with
the land ownership of the springs by The Nature Conservancy. However,
this land ownership only protects the spring outflow channels and
provides no protection for maintaining groundwater levels to ensure
continuous spring flows.
In the following discussion we evaluate the local regulations
related to groundwater management within areas that might provide
indirect benefits to the species' habitats through management of
groundwater withdrawals, and Texas regulations for oil and gas
activities.
Local Groundwater Regulations
One regulatory mechanism that could provide some protection to the
spring flows for these species comes from local groundwater
conservation districts. Groundwater in Texas is generally governed by
the rule of capture unless there is a groundwater district in place.
The rule of capture allows a landowner to produce as much groundwater
as he or she chooses, as long as the water is not wasted (Mace 2001, p.
11). However, local groundwater conservation districts have been
established throughout much of Texas and are now the preferred method
for groundwater management in the State (Texas Water Development Board
2012, pp. 23-258). Groundwater districts ``may regulate the location
and production of wells, with certain voluntary and mandatory
exemptions'' (Texas Water Development Board 2012, p. 27).
There is currently one local groundwater district in the area
(Texas Water Development Board 2011, p. 1) that could possibly manage
groundwater to protect spring flows in the Diamond Y Spring system. The
Middle Pecos Groundwater Conservation District covers all of Pecos
County and was confirmed in 2002. The Middle Pecos County Groundwater
Conservation District seeks to implement water management strategies to
``help maintain a sustainable, adequate, reliable, cost effective and
high quality source of groundwater to promote the vitality, economy and
environment of the District'' (Middle Pecos Groundwater Conservation
District 2010b, p. 1). However, the management plan provides no
objectives to maintain spring flow at Diamond Y Spring or to otherwise
conserve the three aquatic invertebrates. This lack of acknowledgement
of the relationship between the groundwater resources under the
Districts' management to the conservation of the spring flow habitat at
the Diamond Y Spring system limits any direct benefits of the
management plan for the three aquatic invertebrates.
In 2010 the Groundwater Management Area 3 established ``desired
future conditions'' for the aquifers occurring within a six-county area
of west Texas (Texas Water Development Board 2012b, entire). These
projected conditions are important because they guide the plans for
water use of groundwater within groundwater conservation districts in
order to attain the desired future condition of each aquifer they
manage (Texas Water Development Board 2012c, p. 23). The latest plans
from Groundwater Management Area 3 (the planning group covering the
relevant portion of the Rustler aquifer) allows for a groundwater
withdrawal in the Rustler aquifer not to exceed a 90 m (300 ft)
drawdown in the year 2060 (Middle Pecos Groundwater Conservation
District 2010a, p. 2). The Rustler strata are thought to be between
only about 75 and 200 m (250 and 670 ft) thick. This level of drawdown
will accommodate 12.9 million cm (10,508 af) of annual withdrawals by
pumping (Middle Pecos Groundwater Conservation District 2010b, p. 15;
Williams 2010, pp. 3-5). We expect that the groundwater district will
use their district rules to regulate water withdrawals in such a way as
to implement these desired future conditions.
We expect that continued drawdown of the Rustler aquifer as
identified in the desired future conditions will

[[Page 49625]]

contribute to ongoing and future spring flow declines. Based on these
desired future conditions from the groundwater conservation district,
we find that the regulatory mechanisms directing future groundwater
withdrawal rates from the aquifer that supports spring flows in the
Diamond Y Spring system are inadequate to protect against ongoing and
future modification of habitat for the Diamond Y Spring snail, Gonzales
springsnail, and Pecos amphipod.
Texas Regulations for Oil and Gas Activities
The Railroad Commission of Texas has regulations that govern many
activities by the oil and gas industries to minimize the opportunity
for the release of contaminants into the surface water or groundwater
in Texas (Texas Administrative Code, Title 16. Economic Regulation,
Part 1). While the many regulations in place may be effective at
reducing the risk of contaminant releases, they cannot remove the
threat of a catastrophic event that could lead to the extinction of the
aquatic invertebrates. Therefore, because of the inherent risk
associated with oil and gas activities in proximity to the habitats of
the three Diamond Y Spring species, and the severe consequences to the
species of any contamination, Texas regulations for oil and gas
activities cannot remove or alleviate the threats associated with water
contamination from an oil or gas spill.
Summary of Factor D
Although there are regulatory mechanisms in place, such as the
existence of a local groundwater conservation district and State
regulations of oil and gas operations, we find that the mechanisms are
not serving to alleviate or limit the threats to the Diamond Y Spring
snail, Gonzales springsnail, or Pecos amphipod. We, therefore, conclude
that these mechanisms are inadequate to sufficiently reduce the
identified threats to these species.
E. Other Natural or Manmade Factors Affecting Their Continued Existence
(Diamond Y Spring Species)
We considered four other factors that may be affecting the
continued existence of the Diamond Y Spring species: nonnative fish
management, nonnative snail, other nonnative species, and the small,
reduced ranges of the three Diamond Y Spring species.
Nonnative Fish Management
Another source of potential impacts to these species comes from the
indirect effect of management to control nonnative fishes in Diamond Y
Spring. One of the major threats to the endangered Leon Springs
pupfish, which is also endemic to the Diamond Y Spring system, is
hybridization with the introduced, nonnative sheepshead minnow
(Cyprinodon variegatus). On two separate occasions efforts to eradicate
the sheepshead minnow have incorporated the use of fish toxicants in
the upper watercourse to kill and remove all the fish and restock with
pure Leon Springs pupfish. The first time was in the 1970s when the
chemical rotenone was used (Hubbs et al. 1978, pp. 489-490) with no
documented conservation efforts or monitoring for the invertebrate
community.
A second restoration effort was made in 1998 when the fish toxicant
Antimycin A was used (Echelle et al. 2001, pp. 9-10) in the upper
watercourse. In that effort, actions were taken to preserve some
invertebrates (holding them in tanks) during the treatment, and an
intense monitoring effort was conducted to measure the distribution and
abundance of the invertebrates immediately before and for 1 year after
the chemical treatment (Echelle et al. 2001, p. 14). The results
suggested that the Antimycin A had an immediate and dramatic negative
effect on Pecos amphipods; however, their abundance returned to
pretreatment levels within 7 months (Echelle et al. 2001, p. 23).
Gonzales springsnail also showed a decline in abundance that persisted
during the 1 year of monitoring following the treatment at both treated
and untreated sites (Echelle et al. 2001, pp. 23, 51).
There is no information available on the impacts of the initial
rotenone treatment, but we suspect that, like the later Antimycin A
treatment, there were at least short-term effects on the individuals of
the Diamond Y Spring species. Both of these chemicals kill fish and
other gill-breathing animals (like the three invertebrates) by
inhibiting their use of oxygen at the cellular level (U.S. Army Corps
of Engineers 2009, p. 2). Both chemicals are active for only a short
time, degrade quickly in the environment, and are not toxic beyond the
initial application. The long-term effects of these impacts are
uncertain, but the available information indicates that the Gonzales
springsnail may have responded negatively over at least 1 year. This
action was limited to the upper watercourse populations, and the
effects were likely short-term in nature.
The use of fish toxicants represents past stressors that are no
longer directly affecting the species but may have some lasting
consequences to the distribution and abundance of the snails. Currently
the Gonzales springsnail occurs in this area of the upper watercourse
in a very narrow stretch of the outflow channel from Diamond Y Spring,
and the Diamond Y Spring snail may no longer occur in this stretch.
Whether or not the application of the fish toxicants influenced these
changes in distribution and the current status of the Gonzales
springsnail is unknown. However, there is some possibility that these
actions could have contributed to the current absence of the Diamond Y
Spring snail from this reach and the restricted distribution of the
Gonzales springsnail that now occurs in this reach. These actions only
occurred in the past, and we do not anticipate them occurring again in
the future. If the sheepshead minnow were to invade this habitat again,
we do not expect that chemical treatment would be used due to a
heightened concern about conservation of the invertebrates. Therefore,
we consider this threat relatively insignificant because it was not
severe in its impact on the species, and it is not likely to occur
again in the future.
Nonnative Snail
Another factor that may be impacting the Diamond Y Spring species
is the presence of the nonnative red-rim melania, an invertebrate
species native to Africa and Asia that has been imported as an aquarium
species and is now established in various locations across the southern
and western portions of the United States (Benson 2012, p. 2).
The red-rim melania became established in Diamond Y Spring in the
mid 1990s (Echelle et al. 2001, p. 15; McDermott 2000, p. 15). The
exotic snail is now the most abundant snail in the Diamond Y Spring
system (Ladd 2010, p. 18). It only occurs in the first 270 m (890 ft)
of the upper watercourse of the Diamond Y Spring system, and it has not
been detected in the lower watercourse (Echelle et al. 2001, p. 26;
Ladd 2010, p. 22).
The mechanism and extent of potential effects of this nonnative
snail on the native invertebrates have not been studied directly.
However, because the snail occurs in relatively high abundances, it is
reasonable to presume that it is likely competing for space and food
resources in the limited habitats within which they occur. Rader et al.
(2003, pp. 651-655) reviewed the biology and possible impacts of red-
rim melania and suggested that the species had already displaced some
native springsnails in spring systems of the Bonneville Basin of Utah.
In the upper

[[Page 49626]]

watercourse where the red-rim melania occurs, only the Gonzales
springsnail occurs there now in very low abundance in the area of
overlap, and the Diamond Y Spring snail does not occur in this reach
any longer (Ladd 2010, p. 19).
The potential impacts of the red-rim melania on the three aquatic
invertebrate species in the Diamond Y Spring system are largely unknown
with the current available information, but the nonnative snail is
presumed to have some negative consequences to the native snails
through competition for space and resources. The effects on the Pecos
amphipod is even less clear, but competition could still be occurring.
The red-rim melania has been present in the upper watercourse since the
mid 1990s, and there is currently nothing preventing the invasion of
the species into Euphrasia Spring in the lower watercourse by an
incidental human introduction or downstream transport during a flood.
Considering the best available information, we conclude that the
presence of this nonnative snail represents a moderate threat to the
Diamond Y Spring snail, Gonzales springsnail, and Pecos amphipod.
Other Nonnative Species
A potential future threat to these species comes from the possible
introduction of additional nonnative species into their habitat. In
general, introduced species are a serious threat to native aquatic
species (Williams et al. 1989, p. 18; Lodge et al. 2000, p. 7). The
threat is moderated by the limited public access to the habitat on The
Nature Conservancy's preserve. Unfortunately, the limited access did
not prevent the introduction of the nonnative sheepshead minnow on two
separate occasions (Echelle et al. 2001, p. 4). In addition,
invertebrates could be inadvertently moved by biologists conducting
studies in multiple spring sites (Echelle et al. 2001, p. 26).
While the introduction of any future nonnative species could
represent a threat to the aquatic invertebrates, the likelihood of this
happening is relatively low because it is only a future possibility. In
addition the extent of the impacts of any future nonnative species on
the Diamond Y Spring snail, Gonzales springsnail, and Pecos amphipod
are unknown at this time.
Small, Reduced Range
One important factor that contributes to the high risk of
extinction for these species is their naturally small range that has
likely been reduced from past destruction of their habitat. The overall
geographic range of the species may have been reduced from the loss of
Comanche Springs (where the snails once occurred and likely the Pecos
amphipod did as well) and from Leon Springs (if they historically
occurred there). And within the Diamond Y Spring system, their
distribution has been reduced as flows from small springs and seeps
have declined and reduced the amount of wetted areas in the spring
outflow. These species are now currently limited to two small spring
outflow areas.
The geographically small range and only two proximate populations
of these invertebrate species increases the risk of extinction from any
effects associated with other threats or stochastic events. When
species are limited to small, isolated habitats, they are more likely
to become extinct due to a local event that negatively effects the
populations (Shepard 1993, pp. 354-357; McKinney 1997, p. 497; Minckley
and Unmack 2000, pp. 52-53). In addition, the species are restricted to
aquatic habitats in small spring systems and have minimal mobility and
no other habitats available for colonization, so it is unlikely their
range will ever expand beyond the current extent. This situation makes
the severity of impact of any possible separate threat very high. In
other words, the resulting effects of any of the threat factors under
consideration here, even if they are relatively small on a temporal or
geographic scale, could result in complete extinction of the species.
While the small, reduced range does not represent an independent threat
to these species, it does substantially increase the risk of extinction
from the effects of other threats, including those addressed in this
analysis, and those that could occur in the future from unknown
sources.
Summary of Factor E
We considered four additional stressors as other natural or manmade
factors that may be affecting these species. The effects from
management actions to control nonnative fish species are considered low
because they occurred in the past, with limited impact, and we do not
expect them to occur in the future. The potential impacts of the
nonnative snail red-rim melania and any future introductions of other
nonnative species on the Phantom Cave snail, Phantom springsnail, and
diminutive amphipod are largely unknown with the current available
information. But the nonnative snail is presumed to have some negative
consequences to the native snails through competition for space and
resources. The effects on the Pecos amphipod are even less clear, but
competition could still be occurring. These nonnative snails have
likely been co-occurring for up to 20 years at one of the two known
locations for these species, and there is currently nothing preventing
the invasion of the species into Euphrasia Spring by an incidental
human introduction or downstream transport during a flood. Considering
the best available information, we conclude that the presence of the
nonnative snail and the potential future introductions of nonnative
species represent a low magnitude threat to the Diamond Y Spring snail,
Gonzales springsnail, and Pecos amphipod. In addition, the effects of
the small, reduced ranges of these species limits the number of
available populations and increases the risk of extinction from other
threats. In combination with the past and future threats from habitat
modification and loss, these factors contribute to the increased risk
of extinction to the three native species.

Proposed Determination--Diamond Y Spring Species

We have carefully assessed the best scientific and commercial
information available regarding the past, present, and future threats
to the Diamond Y Spring snail, Gonzales springsnail, and Pecos
amphipod. We find the species are in danger of extinction due to the
current and ongoing modification and destruction of their habitat and
range (Factor A) from the ongoing and future decline in spring flows,
ongoing and future modification of spring channels, and threats of
future water contamination from oil and gas activities. The most
significant factor threatening these species is a result of historic
and future declines in regional groundwater levels that have caused the
spring system to have reduced surface aquatic habitat and threaten the
remaining habitat with the same fate. We did not find any significant
threats to the species under Factors B or C. We found that existing
regulatory mechanisms that could provide protection to the species
through groundwater management by groundwater conservation districts
and Texas regulations of the oil and gas activities (Factor D) are
inadequate to protect the species from existing and future threats.
Finally, the past management actions for nonnative fishes, the
persistence of the nonnative red-rim melania, and the future
introductions of other nonnative species are other factors that have or
could negatively affect the species (Factor E). The severity of the
impact from the red-rim melania is not known, but it and future
introductions may contribute to

[[Page 49627]]

the risk of extinction from the threats to habitat by reducing the
abundance of the three aquatic invertebrates through competition for
space and resources. The small, reduced ranges (Factor E) of these
species, when coupled with the presence of additional threats, also put
them at a heightened risk of extinction.
The elevated risk of extinction of the Diamond Y Spring snail,
Gonzales springsnail, and Pecos amphipod is a result of the cumulative
nature of the stressors on the species and their habitats. For example,
the past reduction in available habitat from declining surface water in
the Diamond Y Spring system results in lower numbers of individuals
contributing to the sizes of the populations. In addition, the loss of
other spring systems that may have been inhabited by these species
reduced the number of populations that would contribute to the species'
overall viability. In this diminished state, the species are also
facing future risks from the impacts of continuing declining spring
flows, exacerbated by potential extended future droughts resulting from
global climate change, and potential effects from nonnative species.
All of these factors contribute together to heighten the risk of
extinction and lead to our finding that the Diamond Y Spring snail,
Gonzales springsnail, and Pecos amphipod are in danger of extinction
throughout all of their ranges and warrant listing as endangered
species.
The Act defines an endangered species as any species that is ``in
danger of extinction throughout all or a significant portion of its
range'' and a threatened species as any species ``that is likely to
become endangered throughout all or a significant portion of its range
within the foreseeable future.'' We have carefully assessed the best
scientific and commercial information available regarding the past,
present, and future threats to the species, and have determined that
the Diamond Y Spring snail, Gonzales springsnail, and Pecos amphipod
all meet the definition of endangered under the Act. They do not meet
the definition of threatened species, because significant threats are
occurring now and in the foreseeable future, at a high magnitude, and
across the species' entire range, placing them on the brink of
extinction at the present time. Because the threats are placing the
species on the brink of extinction now and not only in the foreseeable
future, we have determined that they meet the definition of endangered
species rather than threatened species. Therefore, on the basis of the
best available scientific and commercial information, we propose
listing the Diamond Y Spring snail, Gonzales springsnail, and Pecos
amphipod as endangered species in accordance with sections 3(6) and
4(a)(1) of the Act.
Under the Act and our implementing regulations, a species may
warrant listing if it is threatened or endangered throughout all or a
significant portion of its range. The species proposed for listing in
this rule are highly restricted in their range, and the threats occur
throughout their ranges. Therefore, we assessed the status of these
species throughout their entire ranges. The threats to the survival of
these species occur throughout the species' ranges and are not
restricted to any particular significant portion of their ranges.
Accordingly, our assessments and proposed determinations apply to these
species throughout their entire ranges.

Available Conservation Measures

Conservation measures provided to species listed as endangered or
threatened under the Act include recognition, recovery actions,
requirements for Federal protection, and prohibitions against certain
practices. Recognition through listing results in public awareness and
conservation by Federal, state, tribal, and local agencies, private
organizations, and individuals. The Act encourages cooperation with the
States and requires that recovery actions be carried out for all listed
species. The protection required by Federal agencies and the
prohibitions against certain activities are discussed, in part, below.
The primary purpose of the Act is the conservation of endangered
and threatened species and the ecosystems upon which they depend. The
ultimate goal of such conservation efforts is the recovery of these
listed species, so that they no longer need the protective measures of
the Act. Subsection 4(f) of the Act requires the Service to develop and
implement recovery plans for the conservation of endangered and
threatened species. The recovery planning process involves the
identification of actions that are necessary to halt or reverse the
species' decline by addressing the threats to its survival and
recovery. The goal of this process is to restore listed species to a
point where they are secure, self-sustaining, and functioning
components of their ecosystems.
Recovery planning includes the development of a recovery outline
shortly after a species is listed, preparation of a draft and final
recovery plan, and revisions to the plan as significant new information
becomes available. The recovery outline guides the immediate
implementation of urgent recovery actions and describes the process to
be used to develop a recovery plan. The recovery plan identifies site-
specific management actions that will achieve recovery of the species,
measurable criteria that determine when a species may be downlisted or
delisted, and methods for monitoring recovery progress. Recovery plans
also establish a framework for agencies to coordinate their recovery
efforts and provide estimates of the cost of implementing recovery
tasks. Recovery teams (comprising species experts, Federal and State
agencies, nongovernmental organizations, and stakeholders) are often
established to develop recovery plans. When completed, the recovery
outline, draft recovery plan, and the final recovery plan will be
available on our Web site (http://www.fws.gov/endangered), or from our
Austin Ecological Services Field Office (see FOR FURTHER INFORMATION
CONTACT).
Implementation of recovery actions generally requires the
participation of a broad range of partners, including other Federal
agencies, States, Tribes, nongovernmental organizations, businesses,
and private landowners. Examples of recovery actions include habitat
restoration (e.g., restoration of native vegetation), research, captive
propagation and reintroduction, and outreach and education. The
recovery of many listed species cannot be accomplished solely on
Federal lands because their range may occur primarily or solely on non-
Federal lands. To achieve recovery of these species requires
cooperative conservation efforts on private, State, and Tribal lands.
If these species are listed, funding for recovery actions will be
available from a variety of sources, including Federal budgets, State
programs, and cost share grants for non-Federal landowners, the
academic community, and nongovernmental organizations. In addition,
pursuant to section 6 of the Act, the State of Texas would be eligible
for Federal funds to implement management actions that promote the
protection and recovery of these species. Information on our grant
programs that are available to aid species recovery can be found at:
http://www.fws.gov/grants.
Although the six aquatic invertebrates are only proposed for
listing under the Act at this time, please let us know if you are
interested in participating in recovery efforts for this species.
Additionally, we invite you to submit any new information on this
species whenever it becomes available and any information you may have
for recovery planning purposes (see FOR FURTHER INFORMATION CONTACT).

[[Page 49628]]

Section 7(a) of the Act requires Federal agencies to evaluate their
actions with respect to any species that is proposed or listed as
endangered or threatened and with respect to its critical habitat, if
any is designated. Regulations implementing this interagency
cooperation provision of the Act are codified at 50 CFR part 402.
Section 7(a)(4) of the Act requires Federal agencies to confer with the
Service on any action that is likely to jeopardize the continued
existence of a species proposed for listing or result in destruction or
adverse modification of proposed critical habitat. If a species is
listed subsequently, section 7(a)(2) of the Act requires Federal
agencies to ensure that activities they authorize, fund, or carry out
are not likely to jeopardize the continued existence of the species or
destroy or adversely modify its critical habitat. If a Federal action
may affect a listed species or its critical habitat, the responsible
Federal agency must enter into formal consultation with the Service.
Federal agency actions within the species habitat that may require
conference or consultation or both as described in the preceding
paragraph include management and any other landscape altering
activities on Federal lands administered by the U.S. Bureau of
Reclamation; issuance of section 404 Clean Water Act permits by the
Army Corps of Engineers; construction and management of gas pipeline
and power line rights-of-way by the Federal Energy Regulatory
Commission; and construction and maintenance of roads or highways by
the Federal Highway Administration.
The Act and its implementing regulations set forth a series of
general prohibitions and exceptions that apply to all endangered
wildlife. The prohibitions of section 9(a)(2) of the Act, codified at
50 CFR 17.21 for endangered wildlife, in part, make it illegal for any
person subject to the jurisdiction of the United States to take
(includes harass, harm, pursue, hunt, shoot, wound, kill, trap,
capture, or collect; or to attempt any of these), import, export, ship
in interstate commerce in the course of commercial activity, or sell or
offer for sale in interstate or foreign commerce any listed species.
Under the Lacey Act (18 U.S.C. 42-43; 16 U.S.C. 3371-3378), it is also
illegal to possess, sell, deliver, carry, transport, or ship any such
wildlife that has been taken illegally. Certain exceptions apply to
agents of the Service and State conservation agencies.
We may issue permits to carry out otherwise prohibited activities
involving endangered and threatened wildlife species under certain
circumstances. Regulations governing permits are codified at 50 CFR
17.22 for endangered species, and at 17.32 for threatened species. With
regard to endangered wildlife, a permit must be issued for the
following purposes: for scientific purposes, to enhance the propagation
or survival of the species, and for incidental take in connection with
otherwise lawful activities.
It is our policy, as published in the Federal Register on July 1,
1994 (59 FR 34272), to identify to the maximum extent practicable at
the time a species is listed, those activities that would or would not
constitute a violation of section 9 of the Act. The intent of this
policy is to increase public awareness of the effect of a proposed
listing on proposed and ongoing activities within the range of species
proposed for listing. The following activities could potentially result
in a violation of section 9 of the Act; this list is not comprehensive:
(1) Unauthorized collecting, handling, possessing, selling,
delivering, carrying, or transporting of the species, including import
or export across State lines and international boundaries, except for
properly documented antique specimens of these taxa at least 100 years
old, as defined by section 10(h)(1) of the Act;
(2) Introduction into the habitat of the six west Texas aquatic
invertebrate species of nonnative species that compete with or prey
upon any of the six west Texas aquatic invertebrate species;
(3) The unauthorized release of biological control agents that
attack any life stage of these species;
(4) Unauthorized modification of the springs or spring outflows
inhabited by the six west Texas aquatic invertebrates; and
(5) Unauthorized discharge of chemicals or fill material into any
waters in which these species are known to occur.
Questions regarding whether specific activities would constitute a
violation of section 9 of the Act should be directed to the Austin
Ecological Services Office (see FOR FURTHER INFORMATION CONTACT).

Critical Habitat

Prudency Determination

Section 4 of the Act, as amended, and implementing regulations (50
CFR 424.12), require that, to the maximum extent prudent and
determinable, the Secretary designate critical habitat at the time the
species is determined to be endangered or threatened. Our regulations
at 50 CFR 424.12(a)(1) state that the designation of critical habitat
is not prudent when one or both of the following situations exist: (1)
The species is threatened by taking or other activity and the
identification of critical habitat can be expected to increase the
degree of threat to the species; or (2) the designation of critical
habitat would not be beneficial to the species.
There is no indication that the six species of west Texas
invertebrates are threatened by collection and there are no likely
increases in the degree of threats to the species if critical habitat
were designated. These species are not targets of collection and the
areas proposed for designation either have restricted public access or
are already readily open to the public (i.e., Balmorhea State Park).
None of the threats identified to the species are associated with human
access to the sites, with the possible exception of the potential for
introducing nonnative species at San Solomon Spring in Balmorhea State
Park. This threat, or any other identified threat, is not expected to
increase as a result of critical habitat designation because the San
Solomon Spring swimming pool is already heavily visited, the Balmorhea
State Park take proactive measures to prevent introduction of non-
native species, and the designation of critical habitat will not change
the situation.
In the absence of finding that the designation of critical habitat
would increase threats to a species, if there are any benefits to a
critical habitat designation, then a prudent finding is warranted. The
potential benefits of critical habitat to the six west Texas
invertebrates include: (1) Triggering consultation under section 7 of
the Act, in new areas for actions in which there may be a Federal nexus
where it would not otherwise occur, because, for example, Federal
agencies were not aware of the potential impacts of an action on the
species; (2) focusing conservation activities on the most essential
features and areas; (3) providing educational benefits to State or
county governments or private entities; and (4) preventing people from
causing inadvertent harm to the species. Therefore, because we have
determined that the designation of critical habitat will not likely
increase the degree of threat to any of the six species and may provide
some measure of benefit, we find that designation of critical habitat
is prudent for the Phantom Cave snail, Phantom springsnail, diminutive
amphipod, Diamond Y Spring snail, Gonzales springsnail, and Pecos
amphipod.

[[Page 49629]]

Background

It is our intent to discuss below only those topics directly
relevant to the designation of critical habitat for six aquatic
invertebrates in this section of the proposed rules.
Critical habitat is defined in section 3 of the Act as:
(1) The specific areas within the geographical area occupied by the
species, at the time it is listed in accordance with the Act, on which
are found those physical or biological features;
(a) Essential to the conservation of the species; and
(b) Which may require special management considerations or
protection; and
(2) Specific areas outside the geographical area occupied by the
species at the time it is listed, upon a determination that such areas
are essential for the conservation of the species.
Conservation, as defined under section 3 of the Act, means to use
and the use of all methods and procedures that are necessary to bring
an endangered or threatened species to the point at which the measures
provided pursuant to the Act are no longer necessary. Such methods and
procedures include, but are not limited to, all activities associated
with scientific resources management such as research, census, law
enforcement, habitat acquisition and maintenance, propagation, live
trapping, and transplantation, and, in the extraordinary case where
population pressures within a given ecosystem cannot be otherwise
relieved, may include regulated taking.
Critical habitat receives protection under section 7 of the Act
through the requirement that Federal agencies ensure, in consultation
with the Service, that any action they authorize, fund, or carry out is
not likely to result in the destruction or adverse modification of
critical habitat. The designation of critical habitat does not affect
land 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 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)
of the Act would apply, but even in the event of a destruction or
adverse modification finding, the obligation of the Federal action
agency and the landowner is not to restore or recover the species, but
to implement reasonable and prudent alternatives to avoid destruction
or adverse modification of critical habitat.
Under the first prong of the Act's definition of critical habitat,
areas within the geographic area occupied by the species at the time it
was listed are included in a critical habitat designation if they
contain physical or biological features (1) which are essential to the
conservation of the species and (2) which may require special
management considerations or protection. For these areas, critical
habitat designations identify, to the extent known using the best
scientific and commercial data available, those physical or biological
features that are essential to the conservation of the species (such as
space, food, cover, and protected habitat). In identifying those
physical and biological features within an area, we focus on the
principal biological or physical constituent elements (primary
constituent elements such as roost sites, nesting grounds, seasonal
wetlands, water quality, tide, soil type) that are essential to the
conservation of the species. Primary constituent elements are the
elements of physical or biological features that, when laid out in the
appropriate quantity and spatial arrangement to provide for a species'
life-history processes, are essential to the conservation of the
species.
Under the second prong of the Act's definition of critical habitat,
we can designate critical habitat in areas outside the geographic 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. For
example, an area currently occupied by the species but that was not
occupied at the time of listing may be essential to the conservation of
the species and may be included in the critical habitat designation. We
designate critical habitat in areas outside the geographic area
occupied by a species only when a designation limited to its range
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 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, other unpublished materials, or
experts' opinions or personal knowledge.
Habitat is dynamic, and species may move from one area to another
over time. We recognize that critical habitat designated at a
particular point in time may not include all of the habitat areas that
we may later determine are necessary for the recovery of the species.
For these reasons, a critical habitat designation does not signal that
habitat outside the designated area is unimportant or may not be needed
for recovery of the species. Areas that are important to the
conservation of the species, both inside and outside the critical
habitat designation, will continue to be subject to: (1) Conservation
actions implemented under section 7(a)(1) of the Act, (2) regulatory
protections afforded by the requirement in section 7(a)(2) of the Act
for Federal agencies to ensure their actions are not likely to
jeopardize the continued existence of any endangered or threatened
species, and (3) the prohibitions of section 9 of the Act if actions
occurring in these areas may affect the species. Federally funded or
permitted projects affecting listed species outside their designated
critical habitat areas may still result in jeopardy findings in some
cases. These protections and conservation tools will continue to
contribute to recovery of this species. Similarly, critical habitat
designations made on the basis of the best available information at the
time of designation will not control the direction and substance of
future recovery plans, habitat conservation plans, or other species
conservation planning efforts if new information available at the time
of these planning efforts calls for a different outcome.

[[Page 49630]]

Physical or Biological Features

In accordance with section 3(5)(A)(i) and 4(b)(1)(A) of the Act and
regulations at 50 CFR 424.12, in determining which areas within the
geographic area occupied by the species at the time of listing to
designate as critical habitat, we consider the physical or biological
features that are essential to the conservation of the species and
which 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 historical, geographic, and ecological
distributions of a species.
We derive the specific physical or biological features required for
the Phantom Cave snail, Phantom springsnail, Diamond Y Spring snail,
Gonzales springsnail, diminutive amphipod, and Pecos amphipod from
studies of the species' habitat, ecology, and life history as described
below. We have determined that the following physical or biological
features are essential for the Phantom Cave snail, Phantom springsnail,
Diamond Y Spring snail, Gonzales springsnail, diminutive amphipod, and
Pecos amphipod.
Space for Individual and Population Growth and for Normal Behavior
The aquatic environment associated with spring outflow channels and
marshes provide the habitat for Phantom Cave snail, Phantom
springsnail, Diamond Y Spring snail, Gonzales springsnail, diminutive
amphipod, and Pecos amphipod growth and normal behavior. The areas must
contain permanent flowing water to provide for the biological needs of
the species. Each of the species completes all of their life-history
functions in the water and cannot exist for any time outside of the
aquatic environment.
Several habitat parameters of springs, such as temperature,
dissolved carbon dioxide, dissolved oxygen, conductivity, substrate
type, and water depth have been shown to influence the distribution and
abundance of other related species of springsnails (O'Brien and Blinn
1999, pp. 231-232; Mladenka and Minshall 2001, pp. 209-211; Malcom et
al. 2005, p. 75; Martinez and Thome 2006, pp. 12-15; Lysne et al. 2007,
p. 650). Dissolved salts such as calcium carbonate may also be
important factors because they are essential for shell formation for
the snails (Pennak 1989, p. 552). Salinity levels are also relevant,
particularly at Diamond Y Spring because elevated salinity levels (3 to
6 parts per thousand (Hubbs 2001, p. 314) of dissolved salts) may
prevent other more freshwater-adapted species from competing with the
native species adapted to higher salinity levels.
The six invertebrates inhabit springs and spring-fed aquatic
habitats with low variability in water temperatures. For example, Hubbs
(2001, pp. 311-312, 314-315) reported that the spring outflow
temperatures had very low variability with average readings of 20
degrees Celsius ([deg]C) (68 degrees Fahrenheit ([deg]F)) at Diamond Y
Spring and 19[deg]C (66 [deg]F) at East Sandia Spring with a range
between 11 and 25 [deg]C (52 to 77[emsp14][deg]F). Spring measurements
from 2001 to 2003 at the four springs in the San Solomon Spring complex
found water temperatures ranging from 17 to 27 [deg]C (63 to
81[emsp14][deg]F) (Texas Water Development Board 2005, p. 38).
Proximity to spring vents, where water emerges from the ground, plays a
key role in the life history of the six west Texas aquatic
invertebrates. For example, many springsnail species exhibit decreased
abundance farther away from spring vents, presumably due to their need
for stable water chemistry (Hershler 1994, p. 68; Hershler 1998, p. 11;
Hershler and Sada 2002, p. 256; Martinez and Thome 2006, p. 14).
The six west Texas aquatic invertebrates are sensitive to water
contamination. Hydrobiid snails as a group are considered sensitive to
water quality changes, and each species is usually found within
relatively narrow habitat parameters (Sada 2008, p. 59). Taylor (1985,
p. 15) suggested that an unidentified groundwater pollutant may have
been responsible for reductions in abundance of Diamond Y Spring snail
in the headspring and outflow of Diamond Y Spring, although no follow-
up studies have been conducted to investigate the presumption.
Additionally, amphipods generally do not tolerate habitat desiccation
(drying), standing water, sedimentation, or other adverse environmental
conditions; they are considered very sensitive to habitat degradation
(Covich and Thorpe 1991, pp. 676-677).
All six species are most commonly found in flowing water,
presumably where dissolved oxygen levels are higher. The species are
often found in moderate flowing water along the spring outflow margins
rather than in central channels. Water depths where the species occur
are generally very shallow, usually less than 1 m (3 ft) deep. An
exception to this is the bottom of the San Solomon Spring pool where,
because of the construction of the swimming pool, water depths are much
greater, exceeding 5 m (15 ft). In San Solomon, Giffin, and Phantom
Lake Springs, the habitats for the species are limited to the spring
outflow channels because past alteration of the system (building of
ditches) has eliminated any small spring openings. However, at Diamond
Y Spring (and to a limited extent, East Sandia Spring) the spring
outflows have not been severely modified so that small springs, seeps,
and marshes still provide diffuse shallow flowing water habitat
associated with emergent bulrush and saltgrass (Taylor 1987, p. 38;
Echelle et al. 2001, p. 5). While these areas are more difficult to
map, measure, and survey, these small springs and seeps are important
habitat for the three invertebrate species at Diamond Y Spring as long
as they provide flowing water.
Therefore, based on the information above, we identify permanent,
flowing, unpolluted water (free from contamination) within natural
temperature variations, emerging from the ground and flowing on the
surface, to be a physical or biological feature necessary for these
species.
Food, Water, Air, Light, Minerals, or Other Nutritional or
Physiological Requirements
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). 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 six species depend as
a food resource. Abundant sunlight is necessary to promote the growth
of algae upon which all six west Texas aquatic invertebrates feed.
All four snails are presumably fine-particle feeders on detritus
(organic material from decomposing organisms) and periphyton (mixture
of algae and other microbes attached to submerged surfaces) associated
with the substrates (mud, rocks, and vegetation) (Allan 1995, p. 83;
Hershler and Sada 2002, p. 256; Lysne et al. 2007, p. 649). Dundee and
Dundee (1969, p. 207) found diatoms (a group of single-celled algae)

[[Page 49631]]

to be the primary component in the digestive tract of the Phantom Cave
snail and Phantom springsnail, indicating diatoms are a primary food
source. Spring ecosystems occupied by these snail species must support
the periphyton upon which springsnails graze. Additionally, submergent
vegetation contributes the necessary nutrients, detritus, and bacteria
on which these species forage.
Amphipods are omnivorous, feeding on algae, submergent vegetation,
and decaying organic matter (Smith 2001, p. 572). Both species of
amphipod are often found in beds of submerged aquatic plants (Cole
1976, p. 80), indicating that they probably feed on a surface film of
algae, diatoms, bacteria, and fungi (Smith 2001, p. 572). Young
amphipods depend on microbial foods, such as algae and bacteria,
associated with aquatic plants (Covich and Thorp 1991, p. 677).
Therefore, based on the information above, we identify the presence
of abundant food, consisting of algae, bacteria, decaying organic
material, and submergent vegetation that contributes the necessary
nutrients, detritus, and bacteria on which these species forage to be a
physical or biological feature for these species.
Sites for Cover or Shelter and for Breeding, Reproduction, or Rearing
(or Development) of Offspring
The six west Texas aquatic invertebrates occur across a wide range
of substrate types. The Phantom Cave snail is most commonly attached to
hard surfaces, especially large algae-covered rocks, submerged
vegetation, or even concrete walls of the irrigation ditches, and found
in areas of higher water velocities (Bradstreet 2011, pp. 73, 91). The
other springsnails may also be attached to hard surfaces but will also
often be found in the softer substrate at the margins of the stream
flows. Suitable substrates for egg laying by the snails are typically
firm, characterized by cobble, gravel, sand, woody debris, and aquatic
vegetation. These substrates increase productivity by providing
suitable egg-laying sites for the snails.
The amphipods, in the absence of predatory fishes, will swim over
any open substrate on the channel bottom, but in circumstances where
fishes are abundant they may be found in greater abundance underneath
large rocks, embedded in gravels, or associated with submerged
vegetation. Amphipods do not lay eggs upon a surface; instead, the eggs
are held within a marsupium (brood pouch) within the female's
exoskeleton.
Therefore, based on the information above, we identify substrates
that include cobble, gravel, pebble, sand, silt, and aquatic
vegetation, for breeding, egg laying, maturing, feeding, and escape
from predators to be a physical or biological feature for these
species.
Habitats Protected From Disturbance or Representative of the
Historical, Geographic, and Ecological Distributions of the Species
The Phantom Cave snail, Phantom springsnail, Diamond Y Spring
snail, Gonzales springsnail, diminutive amphipod, and Pecos amphipod
have a very restricted geographic distribution. Endemic species whose
populations exhibit a high degree of isolation are extremely
susceptible to extinction from both random and nonrandom catastrophic
natural or human-caused events. Therefore, it is essential to maintain
the spring systems in which they are currently found and upon which
these species depend. Adequate spring sites, free of inappropriate
disturbance, must exist to promote population expansion and viability.
This means protection from disturbance caused by water depletion, water
contamination, springhead alteration, or nonnative species. These
species must, at a minimum, sustain their current distributions if
ecological representation of these species is to be ensured.
As discussed above (see Factor E: Other Natural or Manmade Factors
Affecting Its Continued Existence), introduced species are a moderate
threat to native aquatic species (Williams et al. 1989, p. 18; Lodge et
al. 2000, p. 7), including the six west Texas aquatic invertebrates.
The red-rim melania already competes with all six species where they
occur, and the quilted melania has been introduced into habitats
occupied by the San Solomon Spring species. Feral hogs cause local
spring channel destruction within the Diamond Y Spring system. Because
the distribution of the Phantom Cave snail, Phantom springsnail,
Diamond Y Spring snail, Gonzales springsnail, diminutive amphipod, and
Pecos amphipod is so limited, and their habitat so restricted,
introduction of additional nonnative species into their habitat could
be devastating.
Therefore, based on the information above, we identify either an
absence of nonnative predators and competitors or nonnative predators
and competitors at low population levels to be a physical or biological
feature necessary for these species.

Primary Constituent Elements

Under the Act and its implementing regulations, we are required to
identify the physical or biological features essential to the
conservation of the Phantom Cave snail, Phantom springsnail, Diamond Y
Spring snail, Gonzales springsnail, diminutive amphipod, and Pecos
amphipod in areas occupied at the time of listing, focusing on the
features' primary constituent elements. We consider primary constituent
elements to be the elements of physical or biological features that
provide for a species' life-history processes and are essential to the
conservation of the species.
Based on our current knowledge of the physical or biological
features and habitat characteristics required to sustain the species'
life-history processes, we determine that the primary constituent
elements specific to the Phantom Cave snail, Phantom springsnail,
diminutive amphipod, Diamond Y Spring snail, Gonzales springsnail, and
Pecos amphipod are springs and spring-fed aquatic systems that contain:
a. Permanent, flowing, unpolluted water (free from contamination)
emerging from the ground and flowing on the surface;
b. Water temperatures that vary between 11 and 27 [deg]C (52 to
81[emsp14][deg]F) with natural seasonal and diurnal variations slightly
above and below that range;
c. Substrates that include cobble, gravel, pebble, sand, silt, and
aquatic vegetation, for breeding, egg laying, maturing, feeding, and
escape from predators;
d. Abundant food, consisting of algae, bacteria, decaying organic
material, and submergent vegetation that contributes the necessary
nutrients, detritus, and bacteria on which these species forage; and
e. Either an absence of nonnative predators and competitors or
nonnative predators and competitors at low population levels.
With this proposed designation of critical habitat, we intend to
identify the physical or biological features essential to the
conservation of the species, through the identification of the
appropriate quantity and spatial arrangement of the primary constituent
elements sufficient to support the life-history processes of the
species. All units and subunits proposed to be designated as critical
habitat are currently occupied by the Phantom Cave snail, Phantom
springsnail, Diamond Y Spring snail, Gonzales springsnail, diminutive
amphipod, and Pecos amphipod and contain the

[[Page 49632]]

primary constituent elements in the appropriate quantity and spatial
arrangement sufficient to support the life history needs of the
species.

Special Management Considerations or Protection

When designating critical habitat, we assess whether the specific
areas within the geographic area occupied by the species at the time of
listing contain features that are essential to the conservation of the
species and which may require special management considerations or
protection. The features essential to the conservation of the Phantom
Cave snail, Phantom springsnail, Diamond Y Spring snail, Gonzales
springsnail, diminutive amphipod, and Pecos amphipod may require
special management considerations or protection to reduce threats, such
as reducing or eliminating water in suitable or occupied habitat
through drought or groundwater pumping; introducing pollutants to
levels unsuitable for the species; and introducing nonnative species
into the inhabited spring systems such that suitable habitat is reduced
or eliminated. Special management considerations or protection are
required within critical habitat areas to address these threats (See
Summary of Factors Affecting the Species). Management activities that
could ameliorate these threats include management of groundwater levels
to ensure the springs remain flowing (all spring sites), managing oil
and gas activities to eliminate the threat of groundwater or surface
water contamination (Diamond Y Spring), maintaining the pump within
Phantom Lake Spring to ensure consistent flow, managing existing
nonnative species, red-rim melania, quilted melania, and feral hogs
(San Solomon, Giffin, Phantom Lake, and Diamond Y Springs), and
preventing the introduction of additional nonnative species (all spring
sites).

Criteria Used To Identify Critical Habitat

As required by section 4(b)(2) of the Act, we use the best
scientific data available to designate critical habitat. We review
available information pertaining to the habitat requirements of the
species. In accordance with the Act and its implementing regulation at
50 CFR 424.12(e), we consider whether designating additional areas--
outside those currently occupied as well as those occupied at the time
of listing--are necessary to ensure the conservation of the species. We
are not currently proposing to designate any areas outside the
geographic area occupied by the species because none of the
historically occupied areas (or those that may have been occupied) were
found to be essential for the conservation of the species (see
discussion below).
We relied on information from knowledgeable biologists and
recommendations contained in state wildlife resource reports (Dundee
and Dundee 1969, entire; Cole and Bousfield 1970, entire; Cole 1976,
entire; Cole 1985, entire; Taylor 1985, entire; Henry 1992, entire;
Bowles and Arsuffi 1993, entire; Seidel et al. 2009, entire; Hershler
et al. 2010, entire; Ladd 2010, entire; Allan 2011, entire; Bradstreet
2011, entire; Hershler 2011, p. 1) in making this determination. We
also reviewed the available literature pertaining to habitat
requirements, historic localities, and current localities for these
species. This includes regional geographic information system (GIS)
coverages.
Areas Occupied at the Time of Listing
For the purpose of designating critical habitat for the Phantom
Cave snail, Phantom springsnail, Diamond Y Spring snail, Gonzales
springsnail, diminutive amphipod, and Pecos amphipod, we defined the
occupied area based on the most recent surveys available, which
includes the Diamond Y and San Solomon Spring systems. We then
evaluated whether these areas contain the primary constituent elements
for the species and whether they require special management. Next we
considered areas historically occupied, but not currently occupied.
While the west Texas aquatic invertebrates may have inhabited other
springs in the area (such as Saragosa and Toyah Springs, for the San
Solomon Spring species, and Leon and Comanche Springs for the Diamond Y
Spring species), we only have confirmation that the Diamond Y Spring
snail and Gonzales springsnail occurred in Comanche Spring at some
point in the past. We evaluated these areas to determine whether they
were essential for the conservation of the species.
To determine if currently occupied areas contain the primary
constituent elements, we assessed the life-history components of the
species as they relate to habitat. All of the west Texas aquatic
invertebrate species require unpolluted spring water in the springheads
and spring outflows; periphyton and decaying organic material for food;
a combination of soft and hard substrates for maturation, feeding, egg
laying by snails, and escape from predators; and absence of nonnative
predators and competitors (see discussion on Physical or Biological
Features).
Areas Unoccupied at the Time of Listing
To determine if the sites that may have been historically occupied
by the Phantom Cave snail, Phantom springsnail, Diamond Y Spring snail,
Gonzales springsnail, diminutive amphipod, and Pecos amphipod are
essential for their conservation, we considered: (1) The importance of
the site to the overall status of the species to prevent extinction and
contribute to future recovery of each species; (2) whether the area
could be restored to contain the necessary physical and biological
features to support the species; and (3) whether a population of the
species could be reestablished at the site.
The Phantom Cave snail, Phantom springsnail, and diminutive
amphipod occur in the San Solomon Spring system, which includes San
Solomon Spring, Giffin Spring, East Sandia Spring, and Phantom Spring.
These species may have occurred in other springs within the system,
including Saragosa, Toyah, and West Sandia Springs. These springs now
lack water flow and the physical or biological features necessary to
support the San Solomon Spring system invertebrates--mainly the lack of
flowing water. We do not foresee these features being restorable to the
point where populations of the Phantom Cave snail, Phantom springsnail,
and diminutive amphipod could be reestablished. These springs are not
restorable because we do not foresee an opportunity for groundwater
levels to rise sufficiently in the future to restore permanent spring
flows because the supporting aquifers are of ancient origin and do not
receive substantial modern recharge. Therefore, even if current pumping
activities were to be managed for the benefit of spring flows, it is
doubtful that aquifer levels would rise sufficiently to provide
restoration of permanent aquatic habitat at these sites. For these
reasons, we are not proposing Saragosa Spring, Toyah Spring, or West
Sandia Spring or any other unoccupied areas as critical habitat for the
San Solomon Spring system invertebrates.
The Diamond Y Spring snail, Gonzales springsnail, and Pecos
amphipod occur in the Diamond Y Spring system. The Diamond Y Spring
snail and Gonzales springsnail historically occurred at Comanche
Spring, and the Pecos amphipod may have occurred there as well. All
three species may have occurred at Leon Spring. Both Comanche Spring
and Leon Spring, which have aquifer

[[Page 49633]]

sources that may be different or more localized than that of Diamond Y
Spring, are dry or nearly so and have been altered to such a degree
that they no longer contain the physical or biological features
necessary to support the Diamond Y Spring invertebrates--mainly the
lack of flowing water. Natural flow conditions from these springs do
not appear to be restorable to the point where populations of the
Diamond Y Spring snail, Gonzales springsnail, and Pecos amphipod could
be reestablished. For these reasons, we are not proposing Leon Spring
or Comanche Spring as critical habitat for the Diamond Y Spring
invertebrates.
Mapping
For the areas we are proposing as critical habitat, we plotted the
known occurrences of the Phantom Cave snail, Phantom springsnail,
Diamond Y Spring snail, Gonzales springsnail, diminutive amphipod, and
Pecos amphipod in springheads and spring outflows on 2010 aerial
photography from U.S. Department of Agriculture, National Agriculture
Imagery Program base maps using ArcMap (Environmental Systems Research
Institute, Inc.), a computer geographic information system (GIS)
program. We drew the boundaries around the water features that make up
the critical habitat in each area. Other than at San Solomon Spring,
there are no known developed areas such as buildings, paved areas, and
other structures that lack the biological features for the springsnail
within the proposed critical habitat areas.
When determining proposed critical habitat boundaries, we made
every effort to avoid including developed areas such as lands covered
by buildings, pavement, and other structures because such lands lack
physical or biological features for the species. The scale of the maps
we prepared under the parameters for publication within the Code of
Federal Regulations may not reflect the exclusion of such developed
lands within Balmorhea State Park at San Solomon Spring. Any such lands
left inside critical habitat boundaries shown on the maps of these
proposed rules (such as the asphalt and concrete-paved dry surfaces in
Balmorhea State Park) have been excluded by text in these proposed
rules and are not proposed for designation as critical habitat.
Therefore, if the critical habitat is finalized as proposed, a Federal
action involving these lands would not trigger section 7 consultation
with respect to critical habitat and the requirement of no adverse
modification unless the specific action would affect the physical or
biological features in the adjacent critical habitat.
Summary
We are proposing for designation of critical habitat lands that we
have determined are occupied at the time of listing and contain
sufficient elements of physical or biological features to support life-
history processes essential for the conservation of the species. Units
were proposed for designation based on sufficient elements of physical
or biological features being present to support the Phantom Cave snail,
Phantom springsnail, Diamond Y Spring snail, Gonzales springsnail,
diminutive amphipod, and Pecos amphipod life-history processes. Some
units contain all of the identified elements of physical or biological
features and supported multiple life-history processes. Some segments
contained only some elements of the physical or biological features
necessary to support the Phantom Cave snail, Phantom springsnail,
Diamond Y Spring snail, Gonzales springsnail, diminutive amphipod, and
Pecos amphipod particular use of that habitat.

Proposed Critical Habitat Designation

We are proposing four areas as critical habitat for the Phantom
Cave snail, Phantom springsnail, and diminutive amphipod. We are
proposing one area as critical habitat for the Diamond Y Spring snail,
Gonzales springsnail, and Pecos amphipod. The critical habitat areas we
describe below constitute our current best assessment of areas that
meet the definition of critical habitat for the species. The five areas
we propose as critical habitat are: (1) San Solomon Spring, (2) Giffin
Spring, (3) East Sandia Spring, (4) Phantom Lake Spring, and (5) the
Diamond Y Spring System. Phantom Cave snail, Phantom springsnail, and
diminutive amphipod all occur in the first 4 units and they are listed
in Table 1. Diamond Y Spring snail, Gonzales springsnail, and Pecos
amphipod occur in the Diamond Y Spring Unit and it is listed in Table
2.

Table 1--Proposed Critical Habitat Units for Phantom Cave Snail, Phantom
Springsnail, and Diminutive Amphipod
[Area estimates reflect all land within critical habitat unit
boundaries]
------------------------------------------------------------------------
Land ownership by Size of unit in
Critical habitat unit type hectares (acres)
------------------------------------------------------------------------
San Solomon Spring............ State--Texas Parks 1.8 (4.4)
and Wildlife
Department.
Giffin Spring................. Private.............. 0.7 (1.7)
East Sandia Spring............ Private--The Nature 1.2 (3.0)
Conservancy.
Phantom Lake Spring........... Federal--Bureau of 0.02 (0.05)
Reclamation.
------------------
Total..................... ..................... 3.7 (9.2)
------------------------------------------------------------------------
Note: Area sizes may not sum due to rounding.

Table 2--Proposed Critical Habitat Unit for Diamond Y Spring Snail,
Gonzales Springsnail, and Pecos Amphipod
[Area estimate reflects all land within critical habitat unit
boundaries]
------------------------------------------------------------------------
Land ownership by Size of unit in
Critical habitat unit type hectares (acres)
------------------------------------------------------------------------
Diamond Y Spring System....... Private--The Nature 178.6 (441.4)
Conservancy.

Total..................... ..................... 178.6 (441.4)
------------------------------------------------------------------------

[[Page 49634]]

We present brief descriptions of all units, and reasons why they
meet the definition of critical habitat below.
San Solomon Spring Unit
The San Solomon Spring Unit consists of 1.8 ha (4.4 ac) that is
currently occupied by the Phantom Cave snail, Phantom springsnail, and
diminutive amphipod and contains all of the features essential to the
conservation of these species. It is located in Reeves County, near
Balmorhea, Texas. San Solomon Spring provides the water for the large
swimming pool at Balmorhea State Park, which is owned and managed by
Texas Parks and Wildlife Department. The proposed designation includes
all springs, seeps, and outflows of San Solomon Spring, including the
part of the concrete-lined pool that has a natural substrate bottom and
irrigation ditch, and two constructed ci[eacute]negas. While the
ditches do not provide all of the physical or biological features (such
as submerged vegetation), there are sufficient features (including
natural substrates on the ditch bottoms) to provide for the life-
history processes of the species. Habitat in this unit is threatened by
future declining spring flows due to drought or groundwater
withdrawals, the presence of nonnative snails, and the introduction of
other nonnative species. Therefore, the primary constituent elements in
this unit may require special management considerations or protection
to minimize impacts resulting from these threats.
Giffin Spring Unit
Giffin Spring Unit consists of 0.7 ha (1.7 ac) that is currently
occupied by the Phantom Cave snail, Phantom springsnail, and diminutive
amphipod and contains all of the features essential to the conservation
of these species. It is located on private property in Reeves County,
near Balmorhea, Texas, and its waters are captured in irrigation
earthen channels for agricultural use. The proposed designation
includes all springs, seeps, sinkholes, and outflows of Giffin Spring.
The unit contains most all of the identified physical and biological
features. Habitat in this unit is threatened by declining spring flows
due to drought or groundwater withdrawals, the presence of nonnative
snails, the introduction of other nonnative species, and further
modification of spring outflow channels. Therefore, the primary
constituent elements in this unit may require special management
considerations or protection to minimize impacts resulting from these
threats.
East Sandia Spring Unit
East Sandia Spring consists of 1.2 ha (3.0 ac) that is currently
occupied by the Phantom Cave snail, Phantom springsnail, and diminutive
amphipod and contains all of the features essential to the conservation
of these species. This unit is included within a preserve owned and
managed by The Nature Conservancy (Karges 2003, p. 145) in Reeves
County just east of Balmorhea, Texas. The proposed designation includes
the springhead itself and surrounding seeps and outflows. The unit
contains all of the identified physical and biological features.
Habitat in this unit is threatened by declining spring flows due to
drought or groundwater withdrawals, the introduction of nonnative
species, and modification of spring outflow channels. Therefore, the
primary constituent elements in this unit may require special
management considerations or protection to minimize impacts resulting
from these threats.
Phantom Lake Spring Unit
Phantom Lake Spring consists of a small pool about 0.02 ha (0.05
ac) in size that is currently occupied by the Phantom Cave snail,
Phantom springsnail, and diminutive amphipod and contains the features
essential to the conservation of these species. Phantom Lake Spring is
owned by the U.S. Bureau of Reclamation about 6 km (4 mi) west of
Balmorhea State Park in Jeff Davis County, Texas. The proposed
designation includes only the springhead pool. The physical or
biological features of the habitat at Phantom Lake Spring have been
maintained since 2000 by a pumping system and subsequent reconstruction
of the spring pool. Although artificially maintained, the site
continues to provide sufficient physical or biological features to
provide for all the life-history processes of the three invertebrate
species. Habitat in this unit is threatened by future declining spring
flows due to drought or groundwater withdrawals, the presence of
nonnative snails, and the introduction of other nonnative species.
Therefore, the primary constituent elements in this unit may require
special management considerations or protection to minimize impacts
resulting from these threats.
Diamond Y Spring Unit
Diamond Y Spring Unit consists of 178.6 ha (441.4 ac) that is
currently occupied by the Diamond Y Spring snail, Gonzales springsnail,
and Pecos amphipod and contains all of the features essential to the
conservation of these species. Diamond Y Spring and surrounding lands
are owned and managed by The Nature Conservancy. The proposed
designation includes the Diamond Y Spring and approximately 6.8 km (4.2
mi) of its outflow, including both upper and lower watercourses, ending
at approximately 0.8 km (0.5 mi) downstream of the State Highway 18
bridge crossing. Also included in this proposed unit is approximately
0.8 km (0.5 mi) of Leon Creek upstream of the confluence with Diamond Y
Draw. The boundaries of this unit extend out laterally beyond the
mapped spring outflow channels to incorporate any and all small springs
and seeps that may not be mapped or surveyed but are expected to
contain the species and the necessary physical or biological features.
The unit contains all of the identified physical and biological
features. Habitat in this unit is threatened by declining spring flows
due to drought or groundwater withdrawals, subsurface drilling and
other oil and gas activities that could contaminate surface drainage or
aquifer water, the presence of nonnative snails and feral hogs, the
introduction of other nonnative species, and modification of spring
outflow channels. Therefore, the primary constituent elements in this
unit may require special management considerations or protection to
minimize impacts resulting from these threats.

Effects of Critical Habitat Designation

Section 7 Consultation

Section 7(a)(2) of the Act requires Federal agencies, including the
Service, to ensure that any action they fund, authorize, or carry out
is not likely to jeopardize the continued existence of any endangered
species or threatened species or result in the destruction or adverse
modification of designated critical habitat of such species. In
addition, section 7(a)(4) of the Act requires Federal agencies to
confer with the Service on any agency action that is likely to
jeopardize the continued existence of any species proposed to be listed
under the Act or result in the destruction or adverse modification of
proposed critical habitat.
Decisions by the 5th and 9th Circuit Courts of Appeals have
invalidated our regulatory definition of ``destruction or adverse
modification'' (50 CFR 402.02) (see Gifford Pinchot Task Force v. U.S.
Fish and Wildlife Service, 378 F. 3d 1059 (9th Cir. 2004) and Sierra
Club v. U.S. Fish and Wildlife Service et al., 245

[[Page 49635]]

F.3d 434, 442 (5th Cir. 2001)), and we do not rely on this regulatory
definition when analyzing whether an action is likely to destroy or
adversely modify critical habitat. Under the statutory provisions of
the Act, we determine destruction or adverse modification on the basis
of whether, with implementation of the proposed Federal action, the
affected critical habitat would continue to serve its intended
conservation role for the species.
If a Federal action may affect a listed species or its critical
habitat, the responsible Federal agency (action agency) must enter into
consultation with us. Examples of actions that are subject to the
section 7 consultation process are actions on State, tribal, local, or
private lands that require a Federal permit (such as a permit from the
U.S. Army Corps of Engineers under section 404 of the Clean Water Act
(33 U.S.C. 1251 et seq.) or a permit from the Service under section 10
of the Act) or that involve some other Federal action (such as funding
from the Federal Highway Administration, Federal Aviation
Administration, or the Federal Emergency Management Agency). Federal
actions not affecting listed species or critical habitat, and actions
on State, tribal, local, or private lands that are not federally funded
or authorized, do not require section 7 consultation.
As a result of section 7 consultation, we document compliance with
the requirements of section 7(a)(2) through our issuance of:
(1) A concurrence letter for Federal actions that may affect, but
are not likely to adversely affect, listed species or critical habitat;
or
(2) A biological opinion for Federal actions that may affect, or
are likely to adversely affect, listed species or critical habitat.
When we issue a biological opinion concluding that a project is
likely to jeopardize the continued existence of a listed species and/or
destroy or adversely modify critical habitat, we provide reasonable and
prudent alternatives to the project, if any are identifiable, that
would avoid the likelihood of jeopardy and/or destruction or adverse
modification of critical habitat. We define ``reasonable and prudent
alternatives'' (at 50 CFR 402.02) as alternative actions identified
during consultation that:
(1) Can be implemented in a manner consistent with the intended
purpose of the action,
(2) Can be implemented consistent with the scope of the Federal
agency's legal authority and jurisdiction,
(3) Are economically and technologically feasible, and
(4) Would, in the Director's opinion, avoid the likelihood of
jeopardizing the continued existence of the listed species and/or avoid
the likelihood of destroying or adversely modifying critical habitat.
Reasonable and prudent alternatives can vary from slight project
modifications to extensive redesign or relocation of the project. Costs
associated with implementing a reasonable and prudent alternative are
similarly variable.
Regulations at 50 CFR 402.16 require Federal agencies to reinitiate
consultation on previously reviewed actions in instances where we have
listed a new species or subsequently designated critical habitat that
may be affected and the Federal agency has retained discretionary
involvement or control over the action (or the agency's discretionary
involvement or control is authorized by law). Consequently, Federal
agencies sometimes may need to request reinitiation of consultation
with us on actions for which formal consultation has been completed, if
those actions with discretionary involvement or control may affect
subsequently listed species or designated critical habitat.
Application of the ``Adverse Modification'' Standard
The key factor related to the adverse modification determination is
whether, with implementation of the proposed Federal action, the
affected critical habitat would continue to serve its intended
conservation role for the species. Activities that may destroy or
adversely modify critical habitat are those that alter the physical or
biological features to an extent that appreciably reduces the
conservation value of critical habitat for the Phantom Cave snail,
Phantom springsnail, Diamond Y Spring snail, Gonzales springsnail,
diminutive amphipod, and Pecos amphipod. As discussed above, the role
of critical habitat is to support the life-history needs of the species
and provide for the conservation of the species.
Section 4(b)(8) of the Act requires us to briefly evaluate and
describe, in any proposed or final regulation that designates critical
habitat, activities involving a Federal action that may destroy or
adversely modify such habitat, or that may be affected by such
designation.
Activities that may affect critical habitat, when carried out,
funded, or authorized by a Federal agency, should result in
consultation for the Phantom Cave snail, Phantom springsnail, Diamond Y
Spring snail, Gonzales springsnail, diminutive amphipod, and Pecos
amphipod. These activities include, but are not limited to:
(1) Actions that would reduce the quantity of water flow within the
spring systems proposed as critical habitat.
(2) Actions that would contaminate or cause significant degradation
of water quality within the spring systems proposed as critical
habitat, including surface drainage water or aquifer water quality.
(3) Actions that would modify the springheads or outflow channels
within the spring systems proposed as critical habitat.
(4) Actions that would reduce or alter the availability of aquatic
substrates within the spring systems that are proposed as critical
habitat.
(5) Actions that would reduce the occurrence of native aquatic
periphyton within the spring systems proposed as critical habitat.
(6) Actions that would introduce, promote, or maintain nonnative
predators and competitors within the spring systems proposed as
critical habitat.

Exemptions

Application of Section 4(a)(3) of the Act

The National Defense Authorization Act for Fiscal Year 2004 (Pub.
L. 108-136) amended the Act to limit areas eligible for designation as
critical habitat on some Department of Defense lands. There are no
Department of Defense lands within or near the proposed critical
habitat designation, so section 4(a)(3)(B)(i) of the Act does not
apply.

Exclusions

Application of Section 4(b)(2) of the Act

Section 4(b)(2) of the Act states that the Secretary shall
designate and make revisions to critical habitat on the basis of the
best available scientific data after taking into consideration the
economic impact, national security impact, and any other relevant
impact of specifying any particular area as critical habitat. The
Secretary may exclude an area from critical habitat if he determines
that the benefits of such exclusion outweigh the benefits of specifying
such area as part of the critical habitat, unless he determines, based
on the best scientific data available, that the failure to designate
such area as critical habitat will result in the extinction of the
species. In making that determination, the statute on its face, as well
as the legislative history, are clear that the Secretary has broad
discretion regarding

[[Page 49636]]

which factor(s) to use and how much weight to give to any factor.
Under section 4(b)(2) of the Act, we may exclude an area from
designated critical habitat based on economic impacts, impacts on
national security, or any other relevant impacts. In considering
whether to exclude a particular area from the designation, we identify
the benefits of including the area in the designation, identify the
benefits of excluding the area from the designation, and evaluate
whether the benefits of exclusion outweigh the benefits of inclusion.
If the analysis indicates that the benefits of exclusion outweigh the
benefits of inclusion, the Secretary may exercise his discretion to
exclude the area only if such exclusion would not result in the
extinction of the species.
Exclusions Based on Economic Impacts
Under section 4(b)(2) of the Act, we consider the economic impacts
of specifying any particular area as critical habitat. In order to
consider economic impacts, we are preparing an analysis of the economic
impacts of the proposed critical habitat designation and related
factors. Potential land use sectors that may be affected by critical
habitat designation include oil and gas development near the Diamond Y
Spring system and agriculture (irrigated lands using groundwater
withdrawals) at both spring systems. We also consider any social
impacts that might occur because of the designation.
We will announce the availability of the draft economic analysis as
soon as it is completed, at which time we will seek public review and
comment. At that time, copies of the draft economic analysis will be
available for downloading from the Internet at http://www.regulations.gov, or by contacting the Austin Ecological Services
Field Office directly (see FOR FURTHER INFORMATION CONTACT section).
During the development of a final designation, we will consider
economic impacts, public comments, and other new information, and areas
may be excluded from the final critical habitat designation under
section 4(b)(2) of the Act and our implementing regulations at 50 CFR
424.19.
Exclusions Based on National Security Impacts
Under section 4(b)(2) of the Act, we consider whether there are
lands owned or managed by the Department of Defense where a national
security impact might exist. In preparing this proposal, we have
determined that the lands within the proposed designation of critical
habitat for the Phantom Cave snail, Phantom springsnail, Diamond Y
Spring snail, Gonzales springsnail, diminutive amphipod, and Pecos
amphipod are not owned or managed by the Department of Defense, and,
therefore, we anticipate no impact on national security. Consequently,
the Secretary does not propose to exert his discretion to exclude any
areas from the final designation based on impacts on national security.
Exclusions Based on Other Relevant Impacts
Under section 4(b)(2) of the Act, we consider any other relevant
impacts, in addition to economic impacts and impacts on national
security. We consider a number of factors, including whether the
landowners have developed any habitat conservation plans or other
management plans for the area, or whether there are conservation
partnerships that would be encouraged by designation of, or exclusion
from, critical habitat. In addition, we look at any tribal issues, and
consider the government-to-government relationship of the United States
with tribal entities. We also consider any social impacts that might
occur because of the designation.
We are not proposing any exclusions at this time from the proposed
critical habitat designation under section 4(b)(2) of the Act based on
partnerships, management, or protection afforded by cooperative
management efforts. However, we are considering excluding the San
Solomon Spring Unit that is currently covered under a habitat
conservation plan with Texas Parks and Wildlife Department for the
Phantom Cave snail, Phantom springsnail, and diminutive amphipod for
management activities at Balmorhea State Park. This permit authorizes
``take'' of the invertebrates (which were candidates at the time of
issuance) in the State Park for ongoing management activities while
minimizing impacts to the aquatic species. The activities included in
the habitat conservation plan are a part of Texas Parks and Wildlife
Department's operation and maintenance of the State Park, including the
drawdowns associated with cleaning the swimming pool and vegetation
management within the refuge canal and ci[eacute]nega. The habitat
conservation plan also calls for restrictions and guidelines for
chemical use in and near aquatic habitats to avoid and minimize impacts
to the three aquatic invertebrate species (Service 2009a, pp. 9, 29-
32). The habitat conservation plan, however, provides no protection
from the main threat to this critical habitat unit--future declining
spring flows due to drought or groundwater withdrawals. In these
proposed rules, we are seeking input from the public as to whether or
not the Secretary should exclude the area within this habitat
conservation plan or other such areas under management that benefit the
Phantom Cave snail, Phantom springsnail, Diamond Y Spring snail,
Gonzales springsnail, diminutive amphipod, and Pecos amphipod from the
final critical habitat designation. (Please see the Public Comments
section of this document for instructions on how to submit comments).

Peer Review

In accordance with our joint policy on peer review published in the
Federal Register on July 1, 1994 (59 FR 34270), we will seek the expert
opinions of at least three appropriate and independent specialists
regarding these proposed rules. The purpose of peer review is to ensure
that our critical habitat designation is based on scientifically sound
data, assumptions, and analyses. We have invited these peer reviewers
to comment during this public comment period on our specific
assumptions and conclusions in these proposed designations of critical
habitat.
We will consider all comments and information received during this
comment period on these proposed rules during our preparation of a
final determination. Accordingly, the final decision may differ from
this proposal.

Public Hearings

Section 4(b)(5) of the Act provides for one or more public hearings
on this proposal, if requested. Requests must be received within 45
days after the date of publication of these proposed rules in the
Federal Register. Such requests must be sent to the address shown in
FOR FURTHER INFORMATION CONTACT. We will schedule public hearings on
this proposal, if any are requested, and announce the dates, times, and
places of those hearings, as well as how to obtain reasonable
accommodations, in the Federal Register and local newspapers at least
15 days before the hearing.

Required Determinations

Regulatory Planning and Review--Executive Orders 12866 and 13563

Executive Order 12866 provides that the Office of Information and
Regulatory Affairs (OIRA) will review all significant rules. The Office
of Information and Regulatory Affairs has determined that this rule is
not significant.
Executive Order 13563 reaffirms the principles of E.O. 12866 while
calling for improvements in the nation's regulatory system to promote
predictability, to reduce uncertainty,

[[Page 49637]]

and to use the best, most innovative, and least burdensome tools for
achieving regulatory ends. The executive order directs agencies to
consider regulatory approaches that reduce burdens and maintain
flexibility and freedom of choice for the public where these approaches
are relevant, feasible, and consistent with regulatory objectives. E.O.
13563 emphasizes further that regulations must be based on the best
available science and that the rulemaking process must allow for public
participation and an open exchange of ideas. We have developed this
rule in a manner consistent with these requirements.

Regulatory Flexibility Act (5 U.S.C. 601 et seq.)

Under the Regulatory Flexibility Act (RFA; 5 U.S.C. 601 et seq.) as
amended by the Small Business Regulatory Enforcement Fairness Act
(SBREFA) of 1996 (5 U.S.C 801 et seq.), whenever an agency must publish
a notice of rulemaking for any proposed or final rule, it must prepare
and make available for public comment a regulatory flexibility analysis
that describes the effects of the rule on small entities (small
businesses, small organizations, and small government jurisdictions).
However, no regulatory flexibility analysis is required if the head of
the agency certifies the rule will not have a significant economic
impact on a substantial number of small entities. The SBREFA amended
the RFA to require Federal agencies to provide a certification
statement of the factual basis for certifying that the rule will not
have a significant economic impact on a substantial number of small
entities.
At this time, we lack the available economic information necessary
to provide an adequate factual basis for the required RFA finding.
Therefore, we defer the RFA finding until completion of the draft
economic analysis prepared under section 4(b)(2) of the Act and
Executive Order 12866. This draft economic analysis will provide the
required factual basis for the RFA finding. Upon completion of the
draft economic analysis, we will announce availability of the draft
economic analysis of the proposed designation in the Federal Register
and reopen the public comment period for the proposed designation. We
will include with this announcement, as appropriate, an initial
regulatory flexibility analysis or a certification that the rule will
not have a significant economic impact on a substantial number of small
entities accompanied by the factual basis for that determination. We
have concluded that deferring the RFA finding until completion of the
draft economic analysis is necessary to meet the purposes and
requirements of the RFA. Deferring the RFA finding in this manner will
ensure that we make a sufficiently informed determination based on
adequate economic information and provide the necessary opportunity for
public comment.

Energy Supply, Distribution, or Use--Executive Order 13211

Executive Order 13211 (Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use) requires
agencies to prepare Statements of Energy Effects when undertaking
certain actions. We do not expect the designation of this proposed
critical habitat to significantly affect energy supplies, distribution,
or use due to the small amount of habitat we are proposing for
designation and the lack of Federal activities that would be affected
by the designation. Therefore, this action is not a significant energy
action, and no Statement of Energy Effects is required. However, we
will further evaluate this issue as we conduct our economic analysis,
and review and revise this assessment as necessary.

Unfunded Mandates Reform Act (2 U.S.C. 1501 et seq.)

In accordance with the Unfunded Mandates Reform Act (2 U.S.C. 1501
et seq.), we make the following findings:
(1) This rule will not produce a Federal mandate. In general, a
Federal mandate is a provision in legislation, statute, or regulation
that would impose an enforceable duty upon State, local, or tribal
governments, or the private sector, and includes both ``Federal
intergovernmental mandates'' and ``Federal private sector mandates.''
These terms are defined in 2 U.S.C. 658(5)-(7). ``Federal
intergovernmental mandate'' includes a regulation that ``would impose
an enforceable duty upon State, local, or tribal governments'' with two
exceptions. It excludes ``a condition of Federal assistance.'' It also
excludes ``a duty arising from participation in a voluntary Federal
program,'' unless the regulation ``relates to a then-existing Federal
program under which $500,000,000 or more is provided annually to State,
local, and tribal governments under entitlement authority,'' if the
provision would ``increase the stringency of conditions of assistance''
or ``place caps upon, or otherwise decrease, the Federal Government's
responsibility to provide funding,'' and the State, local, or tribal
governments ``lack authority'' to adjust accordingly. At the time of
enactment, these entitlement programs were: Medicaid; Aid to Families
with Dependent Children work programs; Child Nutrition; Food Stamps;
Social Services Block Grants; Vocational Rehabilitation State Grants;
Foster Care, Adoption Assistance, and Independent Living; Family
Support Welfare Services; and Child Support Enforcement. ``Federal
private sector mandate'' includes a regulation that ``would impose an
enforceable duty upon the private sector, except (i) a condition of
Federal assistance or (ii) a duty arising from participation in a
voluntary Federal program.''
The designation of critical habitat does not impose a legally
binding duty on non-Federal Government entities or private parties.
Under the Act, the only regulatory effect is that Federal agencies must
ensure that their actions do not destroy or adversely modify critical
habitat under section 7. While non-Federal entities that receive
Federal funding, assistance, or permits, or that otherwise require
approval or authorization from a Federal agency for an action, may be
indirectly impacted by the designation of critical habitat, the legally
binding duty to avoid destruction or adverse modification of critical
habitat rests squarely on the Federal agency. Furthermore, to the
extent that non-Federal entities are indirectly impacted because they
receive Federal assistance or participate in a voluntary Federal aid
program, the Unfunded Mandates Reform Act would not apply, nor would
critical habitat shift the costs of the large entitlement programs
listed above onto State governments.
(2) We do not believe that this rule will significantly or uniquely
affect small governments because the land proposed for designation is
either privately owned or owned by U.S. Bureau of Reclamation or the
State of Texas. None of these government entities fit the definition of
``small governmental jurisdiction.'' Therefore, a Small Government
Agency Plan is not required. However, we will further evaluate this
issue as we conduct our economic analysis, and review and revise this
assessment if appropriate.

Takings--Executive Order 12630

In accordance with Executive Order 12630 (Government Actions and
Interference with Constitutionally Protected Private Property Rights),
we will analyze the potential takings implications of designating
critical habitat for the Phantom Cave snail, Phantom springsnail,
Diamond Y Spring snail, Gonzales springsnail, diminutive amphipod, and
Pecos amphipod in a

[[Page 49638]]

takings implications assessment. Critical habitat designation does not
affect landowner actions that do not require Federal funding or
permits, nor does it preclude development of habitat conservation
programs or issuance of incidental take permits to permit actions that
do require Federal funding or permits to go forward. The takings
implications assessment will analyze whether this proposed designation
of critical habitat for the Phantom Cave snail, Phantom springsnail,
Diamond Y Spring snail, Gonzales springsnail, diminutive amphipod, and
Pecos amphipod poses significant takings implications for lands within
or affected by the designation.

Federalism--Executive Order 13132

In accordance with Executive Order 13132 (Federalism), these
proposed rules do not have significant Federalism effects. A Federalism
assessment is not required. In keeping with Department of the Interior
and Department of Commerce policy, we requested information from, and
coordinated development of, these proposed critical habitat
designations with appropriate State resource agencies in Texas. The
designation of critical habitat in areas currently occupied by the
Phantom Cave snail, Phantom springsnail, Diamond Y Spring snail,
Gonzales springsnail, diminutive amphipod, and Pecos amphipod imposes
no additional restrictions to those currently in place and, therefore,
has little incremental impact on State and local governments and their
activities. The designation may have some benefit to these governments
because the areas that contain the physical or biological features
essential to the conservation of the species are more clearly defined,
and the elements of the features of the habitat necessary to the
conservation of the species are specifically identified. This
information does not alter where and what federally sponsored
activities may occur. However, it may assist local governments in long-
range planning (rather than having them wait for case-by-case section 7
consultations to occur).
Where State and local governments require approval or authorization
from a Federal agency for actions that may affect critical habitat,
consultation under section 7(a)(2) would be required. While non-Federal
entities that receive Federal funding, assistance, or permits, or that
otherwise require approval or authorization from a Federal agency for
an action, may be indirectly impacted by the designation of critical
habitat, the legally binding duty to avoid destruction or adverse
modification of critical habitat rests squarely on the Federal agency.

Civil Justice Reform--Executive Order 12988

In accordance with Executive Order 12988 (Civil Justice Reform),
the Office of the Solicitor has determined that the rule does not
unduly burden the judicial system and that it meets the requirements of
sections 3(a) and 3(b)(2) of the Order. We have proposed designating
critical habitat in accordance with the provisions of the Act. These
proposed rules use standard mapping technology and identify the
elements of physical or biological features essential to the
conservation of the Phantom Cave snail, Phantom springsnail, Diamond Y
Spring snail, Gonzales springsnail, diminutive amphipod, and Pecos
amphipod within the designated areas to assist the public in
understanding the habitat needs of the species.

Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.)

This rule does not contain any new collections of information that
require approval by OMB under the Paperwork Reduction Act of 1995 (44
U.S.C. 3501 et seq.). This rule will not impose recordkeeping or
reporting requirements on State or local governments, individuals,
businesses, or organizations. An agency may not conduct or sponsor, and
a person is not required to respond to, a collection of information
unless it displays a currently valid OMB control number.

National Environmental Policy Act (42 U.S.C. 4321 et seq.)

We have determined that environmental assessments and environmental
impact statements, as defined under the authority of the National
Environmental Policy Act (NEPA; 42 U.S.C. 4321 et seq.), need not be
prepared in connection with listing a species as endangered or
threatened under the Endangered Species Act. We published a notice
outlining our reasons for this determination in the Federal Register on
October 25, 1983 (48 FR 49244).
It is our position that, outside the jurisdiction of the U.S. Court
of Appeals for the Tenth Circuit, we do not need to prepare
environmental analyses pursuant to NEPA in connection with designating
critical habitat under the Endangered Species Act. We published a
notice outlining our reasons for this determination in the Federal
Register on October 25, 1983 (48 FR 49244). This position was upheld by
the U.S. Court of Appeals for the Ninth Circuit (Douglas County v.
Babbitt, 48 F.3d 1495 (9th Cir. 1995), cert. denied 516 U.S. 1042
(1996)). The range of the Phantom Cave snail, Phantom springsnail,
Diamond Y Spring snail, Gonzales springsnail, diminutive amphipod, and
Pecos amphipod does not occur in the Tenth Circuit, so a NEPA analysis
will not be conducted.

Clarity of the Rule

We are required by Executive Orders 12866 and 12988 and by the
Presidential Memorandum of June 1, 1998, to write all rules in plain
language. This means that each rule we publish must:
(1) Be logically organized;
(2) Use the active voice to address readers directly;
(3) Use clear language rather than jargon;
(4) Be divided into short sections and sentences; and
(5) Use lists and tables wherever possible.
If you feel that we have not met these requirements, send us
comments by one of the methods listed in the ADDRESSES section. To
better help us revise the rule, your comments should be as specific as
possible. For example, you should tell us the numbers of the sections
or paragraphs that are unclearly written, which sections or sentences
are too long, the sections where you feel lists or tables would be
useful, etc.

Government-to-Government Relationship with Tribes

In accordance with the President's memorandum of April 29, 1994
(Government-to-Government Relations with Native American Tribal
Governments; 59 FR 22951), Executive Order 13175 (Consultation and
Coordination with Indian Tribal Governments), and the Department of the
Interior's manual at 512 DM 2, we readily acknowledge our
responsibility to communicate meaningfully with recognized Federal
Tribes on a government-to-government basis. In accordance with
Secretarial Order 3206 of June 5, 1997 (American Indian Tribal Rights,
Federal-Tribal Trust Responsibilities, and the Endangered Species Act),
we readily acknowledge our responsibilities to work directly with
tribes in developing programs for healthy ecosystems, to acknowledge
that tribal lands are not subject to the same controls as Federal
public lands, to remain sensitive to Indian culture, and to make
information available to tribes.
We determined that there are no tribal lands within or near the
current or historic ranges of the Phantom Cave snail, Phantom
springsnail, Diamond Y

[[Page 49639]]

Spring snail, Gonzales springsnail, diminutive amphipod, and Pecos
amphipod that contain the features essential for conservation of the
species. Therefore, we are not proposing to designate critical habitat
on tribal lands.

References Cited

A complete list of references cited in this rulemaking is available
on the Internet at http://www.regulations.gov at Docket No. FWS-R2-ES-
2012-0029 and upon request from the Austin Ecological Services Field
Office (see FOR FURTHER INFORMATION CONTACT).

Authors

The primary authors of this package are the staff members of the
Southwest Region of the Service.

List of Subjects in 50 CFR Part 17

Endangered and threatened species, Exports, Imports, Reporting and
recordkeeping requirements, Transportation.

Proposed Regulation Promulgation

Accordingly, we propose to amend part 17, subchapter B of chapter
I, title 50 of the Code of Federal Regulations, as set forth below:

PART 17--[AMENDED]

1. The authority citation for part 17 continues to read as follows:

Authority: 16 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C.
4201-4245; Pub. L. 99-625, 100 Stat. 3500; unless otherwise noted.

2. In Sec. 17.11(h) add entries for ``Snail, Diamond Y Spring'',
``Snail, Phantom Cave'', ``Springsnail, Gonzales'', and ``Springsnail,
Phantom'' under ``SNAILS'' and ``Amphipod, diminutive'' and ``Amphipod,
Pecos'' under ``CRUSTACEANS'' to the List of Endangered and Threatened
Wildlife in alphabetical order to read as follows:

Sec. 17.11 Endangered and threatened wildlife.

* * * * *
(h) * * *

--------------------------------------------------------------------------------------------------------------------------------------------------------
Species Vertebrate
--------------------------------------------------------- population where Critical Special
Historic range endangered or Status When listed habitat rules
Common name Scientific name threatened
--------------------------------------------------------------------------------------------------------------------------------------------------------

* * * * * * *
Snails:

* * * * * * *
Snail, Diamond Y Spring........ Pseudotryonia U.S.A. (TX)........... NA............... E......... ............ 17.95(f).... NA
adamantina.

* * * * * * *
Snail, Phantom Cave............ Pyrgulopsis texana..... U.S.A. (TX)........... NA............... E......... ............ 17.95(f).... NA

* * * * * * *
Springsnail, Gonzales.......... Tryonia circumstriata.. U.S.A. (TX)........... NA............... E......... ............ 17.95(f).... NA

* * * * * *
Springsnail, Phantom........... Tryonia cheatumi....... U.S.A. (TX)........... NA............... E......... ............ 17.95(f).... NA

* * * * * * *
Crustaceans:
Amphipod, diminutive........... Gammarus hyalleloides.. U.S.A. (TX)........... NA............... E......... ............ 17.95(h).... NA

* * * * * * *
Amphipod, Pecos................ Gammarus pecos......... U.S.A. (TX)........... NA............... E......... ............ 17.95(h).... NA

* * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------

3. Amend Sec. 17.95 by:
a. In paragraph (f), adding an entry for ``Diamond Y Spring snail
(Pseudotryonia adamantina) and Gonzales springsnail (Tryonia
circumstriata)'' followed by an entry for ``Phantom Cave snail
(Pyrgulopsis texana) and Phantom springsnail (Tryonia cheatumi)'' after
the entry for ``Interrupted Rocksnail (Leptoxis foremani)'', to read as
follows:
b. In paragraph (h), adding an entry for ``Diminutive amphipod
(Gammarus hyalleloides)'' and an entry for ``Pecos amphipod (Gammarus
pecos)'' in the same alphabetical order that these species appear in
the table at Sec. 17.11(h), to read as follows.

Sec. 17.95 Critical habitat--fish and wildlife.

* * * * *
(f) Clams and Snails.
* * * * *

Diamond Y Spring snail (Pseudotryonia adamantina) and Gonzales
springsnail (Tryonia circumstriata)

(1) A critical habitat unit is depicted for Pecos County, Texas, on
the map below.
(2) Within this area, the primary constituent elements of the
physical or biological features essential to the conservation of
Diamond Y Spring snail and Gonzales springsnail are springs and spring-
fed aquatic systems that contain:
(i) Permanent, flowing, unpolluted water (free from contamination)
emerging from the ground and flowing on the surface;
(ii) Water temperatures that vary between 11 and 27 [deg]C (52 to
81[emsp14][deg]F) with natural seasonal and diurnal variations slightly
above and below that range;
(iii) Substrates that include cobble, gravel, pebble, sand, silt,
and aquatic vegetation, for breeding, egg laying, maturing, feeding,
and escape from predators;
(iv) Abundant food, consisting of algae, bacteria, decaying organic
material, and submergent vegetation that contributes the necessary
nutrients, detritus, and bacteria on which these species forage; and
(v) Either an absence of nonnative predators and competitors or
nonnative

[[Page 49640]]

predators and competitors at low population levels.
(3) Critical habitat does not include manmade structures (such as
buildings, aqueducts, runways, roads, and other paved areas) and the
land on which they are located existing within the legal boundaries on
the effective date of this rule.
(4) Critical habitat map unit. Data layers defining the map unit
were created on 2010 aerial photography from U.S. Department of
Agriculture, National Agriculture Imagery Program base maps using
ArcMap (Environmental Systems Research Institute, Inc.), a computer
geographic information system (GIS) program. The maps in this entry, as
modified by any accompanying regulatory text, establish the boundaries
of the critical habitat designation. The coordinates or plot points or
both on which each map is based are available to the public at the
Service's internet site, (http://www.fws.gov/southwest/es/AustinTexas/
), Regulations.gov (http://www.regulations.gov at Docket No. FWS-R2-ES-
2012-0029) and at the field office responsible for this designation.
You may obtain field office location information by contacting one of
the Service regional offices, the addresses of which are listed at 50
CFR 2.2.
(5) Diamond Y Spring Unit, Pecos County, Texas. Map of Diamond Y
Spring Unit follows:
BILLING CODE 4310-55-P

[[Page 49641]]

[GRAPHIC] [TIFF OMITTED] TP16AU12.015

Phantom Cave snail (Pyrgulopsis texana) and Phantom springsnail
(Tryonia cheatumi)

(1) Critical habitat units are depicted for Jeff Davis County and
Reeves County, Texas, on the maps below.
(2) Within these areas, the primary constituent elements of the
physical or biological features essential to the conservation of
Phantom Cave snail and Phantom springsnail are springs and spring-fed
aquatic systems that contain:
(i) Permanent, flowing, unpolluted water (free from contamination)
emerging from the ground and flowing on the surface;
(ii) Water temperatures that vary between 11 and 27 [deg]C (52 to
81[emsp14][deg]F) with natural seasonal and diurnal variations slightly
above and below that range;
(iii) Substrates that include cobble, gravel, pebble, sand, silt,
and aquatic vegetation, for breeding, egg laying, maturing, feeding,
and escape from predators;
(iv) Abundant food, consisting of algae, bacteria, decaying organic
material, and submergent vegetation that contributes the necessary
nutrients, detritus, and bacteria on which these species forage; and

[[Page 49642]]

(v) Either an absence of nonnative predators and competitors or
nonnative predators and competitors at low population levels.
(3) Critical habitat does not include manmade structures (such as
buildings, aqueducts, runways, roads, and other paved areas) and the
land on which they are located existing within the legal boundaries on
the effective date of this rule.
(4) Critical habitat map units. Data layers defining map units were
created on 2010 aerial photography from U.S. Department of Agriculture,
National Agriculture Imagery Program base maps using ArcMap
(Environmental Systems Research Institute, Inc.), a computer geographic
information system (GIS) program. The maps in this entry, as modified
by any accompanying regulatory text, establish the boundaries of the
critical habitat designation. The coordinates or plot points or both on
which each map is based are available to the public at the Service's
Internet site (http://www.fws.gov/southwest/es/AustinTexas/),
Regulations.gov (http://www.regulations.gov at Docket No. FWS-R2-ES-
2012-0029) and at the field office responsible for this designation.
You may obtain field office location information by contacting one of
the Service regional offices, the addresses of which are listed at 50
CFR 2.2.
(5) San Solomon Spring Unit, Reeves County, Texas. Map of San
Solomon Spring Unit follows:

[[Page 49643]]

[GRAPHIC] [TIFF OMITTED] TP16AU12.016

(6) Giffin Spring Unit, Reeves County, Texas. Map of Giffin Spring
Unit is provided at subparagraph (5) of this entry.
(7) East Sandia Spring Unit, Jeff Davis County, Texas. Map of East
Sandia Spring Unit follows:

[[Page 49644]]

[GRAPHIC] [TIFF OMITTED] TP16AU12.017

(8) Phantom Lake Spring Unit, Jeff Davis County, Texas. Map of
Phantom Lake Spring Unit follows:

[[Page 49645]]

[GRAPHIC] [TIFF OMITTED] TP16AU12.018

* * * * *
(h) Crustaceans.

Diminutive amphipod (Gammarus hyalleloides)

(1) Critical habitat units are depicted for Jeff Davis County and
Reeves County, Texas, on the maps below.
(2) Within these areas, the primary constituent elements of the
physical or biological features essential to the conservation of
diminutive amphipod are springs and spring-fed aquatic systems that
contain:
(i) Permanent, flowing, unpolluted water (free from contamination)
emerging from the ground and flowing on the surface;
(ii) Water temperatures that vary between 11 and 27 [deg]C (52 to
81[emsp14][deg]F) with natural seasonal and diurnal variations slightly
above and below that range;
(iii) Substrates that include cobble, gravel, pebble, sand, silt,
and aquatic vegetation, for breeding, maturing, feeding, and escape
from predators;
(iv) Abundant food, consisting of algae, bacteria, decaying organic
material, and submergent vegetation that contributes the necessary
nutrients, detritus, and bacteria on which these species forage; and

[[Page 49646]]

[[Page 49647]]

[GRAPHIC] [TIFF OMITTED] TP16AU12.019

(6) Giffin Spring Unit, Reeves County, Texas. Map of Giffin Spring
Unit is provided at paragraph (5) of this entry.
(7) East Sandia Spring Unit, Jeff Davis County, Texas. Map of East
Sandia Spring Unit follows:

[[Page 49648]]

[GRAPHIC] [TIFF OMITTED] TP16AU12.020

(8) Phantom Lake Spring Unit, Jeff Davis County, Texas. Map of
Phantom Lake Spring Unit follows:

[[Page 49649]]

[GRAPHIC] [TIFF OMITTED] TP16AU12.021

* * * * *
Pecos amphipod (Gammarus pecos)

(1) The critical habitat unit is depicted for Pecos County, Texas,
on the map below.
(2) Within this area, the primary constituent elements of the
physical or biological features essential to the conservation of Pecos
amphipod are springs and spring-fed aquatic systems that contain:
(i) Permanent, flowing, unpolluted water (free from contamination)
emerging from the ground and flowing on the surface;
(ii) Water temperatures that vary between 11 and 27 [deg]C (52 to
81[emsp14][deg]F) with natural seasonal and diurnal variations slightly
above and below that range;
(iii) Substrates that include cobble, gravel, pebble, sand, silt,
and aquatic vegetation, for breeding, maturing, feeding, and escape
from predators;
(iv) Abundant food, consisting of algae, bacteria, decaying organic
material, and submergent vegetation that contributes the necessary
nutrients, detritus, and bacteria on which these species forage; and
(v) Either an absence of nonnative predators and competitors or
nonnative

[[Page 49650]]

predators and competitors at low population levels.
(3) Critical habitat does not include manmade structures (such as
buildings, aqueducts, runways, roads, and other paved areas) and the
land on which they are located existing within the legal boundaries on
the effective date of this rule.
(4) Critical habitat map units. Data layers defining map units were
created on 2010 aerial photography from U.S. Department of Agriculture,
National Agriculture Imagery Program base maps using ArcMap
(Environmental Systems Research Institute, Inc.), a computer geographic
information system (GIS) program. The maps in this entry, as modified
by any accompanying regulatory text, establish the boundaries of the
critical habitat designation. The coordinates or plot points or both on
which each map is based are available to the public at the Service's
Internet site (http://www.fws.gov/southwest/es/AustinTexas/),
Regulations.gov (http://www.regulations.gov at Docket No. FWS-R2-ES-
2012-0029) and at the field office responsible for this designation.
You may obtain field office location information by contacting one of
the Service regional offices, the addresses of which are listed at 50
CFR 2.2.
(5) Diamond Y Spring Unit, Pecos County, Texas. Map of Diamond Y
Spring Unit follows:

[[Page 49651]]

[GRAPHIC] [TIFF OMITTED] TP16AU12.022

* * * * *

Dated: August 2, 2012.
Eileen Sobeck,
Deputy Assistant Secretary for Fish and Wildlife and Parks.
[FR Doc. 2012-19829 Filed 8-15-12; 8:45 am]
BILLING CODE 4310-55-C