Endangered and Threatened Wildlife and Plants; Determination of Endangered Species Status for Six West Texas Aquatic Invertebrates, 41227-41258 [2013-16222]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 78, Number 131 (Tuesday, July 9, 2013)]
[Rules and Regulations]
[Pages 41227-41258]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2013-16222]



[[Page 41227]]

Vol. 78

Tuesday,

No. 131

July 9, 2013

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; Determination of 
Endangered Species Status for Six West Texas Aquatic Invertebrates; 
Final Rule

Federal Register / Vol. 78 , No. 131 / Tuesday, July 9, 2013 / Rules 
and Regulations

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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; Determination of 
Endangered Species Status for Six West Texas Aquatic Invertebrates

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service, determine the 
following six west Texas aquatic invertebrate species meet the 
definition of an endangered species under the Endangered Species Act of 
1973: Phantom springsnail (Pyrgulopsis texana), Phantom tryonia 
(Tryonia cheatumi), diminutive amphipod (Gammarus hyalleloides), 
Diamond tryonia (Pseudotryonia adamantina), Gonzales tryonia (Tryonia 
circumstriata), and Pecos amphipod (Gammarus pecos). This final rule 
implements the Federal protections provided by the Endangered Species 
Act for these species. The effect of this regulation is to add these 
species to the lists of Endangered and Threatened Wildlife under the 
Endangered Species Act.

DATES: This rule becomes effective August 8, 2013.

ADDRESSES: This final rule and other supplementary information are 
available on the Internet at https://www.regulations.gov (Docket No. 
FWS-R2-ES-2012-0029) and also at https://www.fws.gov/southwest/es/AustinTexas/. These documents are also available for public inspection, 
by appointment, during normal business hours at: 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.

FOR FURTHER INFORMATION CONTACT: Adam Zerrenner, Field Supervisor, U.S. 
Fish and Wildlife Service, Austin Ecological Services Field Office (see 
ADDRESSES). 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 final rules to list six west Texas 
aquatic invertebrate species as endangered species. The six west Texas 
aquatic invertebrate species are: Phantom springsnail (Pyrgulopsis 
texana), Phantom tryonia (Tryonia cheatumi), diminutive amphipod 
(Gammarus hyalleloides), Diamond tryonia (Pseudotryonia adamantina), 
Gonzales tryonia (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. On August 16, 2012, we published 
proposed rules to list the six west Texas aquatic invertebrates as 
endangered species. In these rules we are finalizing our determinations 
to list these six species as endangered species under the Endangered 
Species Act. The Act requires that a final rule be published in order 
to add species to the lists of endangered and threatened wildlife to 
provide protections under the Act. The table below summarizes the 
status of each species:

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

    These rules will result in all six of these species being listed as 
endangered under the Act. By listing these six species of aquatic 
invertebrates from west Texas as endangered, we are extending the full 
protections of the Act to these species.
    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 have determined that all six species meet the definition of 
endangered species due to 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.
     Other natural or manmade factors, including the presence 
of nonnative snails and the small, reduced ranges of the species.
    Peer review and public comment. With the publication of our August 
16, 2012, proposed rules, we sought comments from independent 
specialists to ensure that our designation is based on scientifically 
sound data, assumptions, and analyses. We received comments from four 
knowledgeable individuals with scientific expertise to review our 
technical assumptions, analysis, and whether or not we had used the 
best available information. These peer reviewers generally concurred 
with our methods and conclusions and provided additional information, 
clarifications, and suggestions to improve this final rule. We also 
considered all comments and information received during two comment 
periods.

Previous Federal Actions

    We proposed all six species be listed as endangered on August 16, 
2012 (77 FR 49602). We also reopened the public comment on the proposed 
rules on February 5, 2013 (78 FR 8096). A complete description of the 
previous Federal actions for these species can be found in the Previous 
Federal Actions section of the August 16, 2012, proposed rules (77 FR 
49602).

[[Page 41229]]

Summary of Comments and Recommendations

    In the proposed rules published on August 16, 2012 (77 FR 49602), 
we requested that all interested parties submit written comments by 
October 15, 2012. We also contacted appropriate Federal and State 
agencies, scientific experts and organizations, and other interested 
parties and invited them to comment on the proposal. We reopened the 
comment period on February 5, 2013 (78 FR 8096), for these proposed 
rules and to accept additional public comment. This second comment 
period closed on March 22, 2013. We received a request for a public 
hearing, and one was held on February 22, 2013, at Balmorhea State Park 
in Toyahvale, Texas. Newspaper notices inviting general public comment 
were published in the Alpine Avalanche and Fort Stockton Pioneer 
newspapers on February 14, 2013.
    During the comment period for the proposed rule, we received 27 
comments addressing the proposed listing and critical habitat for the 
west Texas invertebrates. During the February 22, 2013, public hearing, 
one individual made a comment on the proposed rules. All substantive 
information provided during comment periods has either been 
incorporated directly into our final determinations or addressed below 
in our response to comments. Elsewhere in today's Federal Register, we 
have published a final rule that addresses additional comments on the 
designation of critical habitat for these species.

Peer Review

    In accordance with our peer review policy published on July 1, 1994 
(59 FR 34270), we solicited expert opinion from five knowledgeable 
individuals with scientific expertise that included familiarity with 
the species or their habitats, biological needs, and threats. We 
received comments from four peer reviewers.
    The peer reviewers generally concurred with our methods and 
conclusions and provided additional information, clarifications, and 
suggestions to improve the final rule. Information received from peer 
reviewers has been incorporated into our final rules, and comments are 
addressed in our response to comments below.
    (1) Comment: The common (or vernacular) names applied to the four 
species of snails are not in accord with the ``standardized'' English 
names for North American mollusks as provided in Turgeon et al. (1988, 
1998).
    Our Response: We agree and have revised the common names of the 
four snails throughout the final rules. See ``Summary of Changes from 
Proposed Rule'' sections of the final rules for a list of the changes 
to the common names.
    (2) Comment: We received a number of comments from peer reviewers, 
State agencies, and the public regarding the groundwater origins of the 
spring outflows at Diamond Y Spring. We originally indicated that the 
Rustler Aquifer was the likely source of flows at Diamond Y Spring, 
recognizing a fair amount of uncertainty. We received new information 
from a peer reviewer (U.S. Geological Survey hydrogeologist) indicating 
that, while the Rustler Aquifer may be contributing flow to the 
Edwards-Trinity (Plateau) Aquifer, it cannot be considered the source 
of the spring flow because the spring issues from the Edwards-Trinity 
geologic formation. The Texas Water Development Board provided 
seemingly contradictory comments stating that the strata underlying the 
Edwards-Trinity (Plateau) Aquifer provide most of the spring flow at 
Diamond Y Spring and that the artesian pressure causing the groundwater 
to issue at Diamond Y Spring is likely from below the Rustler Aquifer. 
Finally, the Middle Pecos Groundwater Conservation District also 
commented that Diamond Y Spring is a mixture of discharge from the 
Edwards-Trinity (Plateau) Aquifer and leakage from the other Permian-
age formations, including the Rustler, Salado, Transill, and Yates 
formations and possibly even deeper strata.
    Our Response: The scientific community has not reached consensus 
about the source of spring flows for Diamond Y Spring. We carefully 
reviewed the information provided and substantially revised the 
appropriate sections in the final rules to reflect the uncertainties 
around the best available information.
    (3) Comment: A peer reviewer commented that the Service does not 
discuss how pumping in the Edwards-Trinity (Plateau) Aquifer may affect 
the spring flows at Diamond Y Spring. A related comment from the public 
stated that the Service has not substantiated that pumping from the 
Rustler Aquifer is causing declines in spring flow at Diamond Y Spring. 
The commenter indicates that the Rustler Aquifer levels appear to have 
risen since heavy irrigation from the Rustler Aquifer ceased decades 
ago.
    Our Response: Given the uncertainties about the source aquifer or 
aquifers for Diamond Y Spring, we have revised our discussions of this 
issue to recognize that the source of Diamond Y Spring is unknown. As a 
result, it is not feasible to estimate how pumping from any particular 
aquifer may have affected the spring flows in the past or how future 
pumping will affect future spring flows. However, if substantial 
groundwater is removed in the future from the source aquifer or 
aquifers, wherever they may be, spring flows at Diamond Y Spring are 
very susceptible to loss because they have such a small discharge rate.
    (4) Comment: A peer reviewer commented that spring flows in the San 
Solomon Springs and Diamond Y Spring systems, though they lack 
sufficient studies, are protected by Groundwater Management Area 3 or 
4's desired future conditions, as well as by the groundwater 
conservation districts in the area. A number of other comments from 
State agencies and the public made similar comments indicating that our 
assessment of the ``inadequacy of existing regulatory mechanisms'' was 
not accurate because of the existing groundwater protection provided by 
the groundwater conservation districts and groundwater management 
areas.
    Our Response: We agree that groundwater management areas and 
groundwater conservation districts are vital mechanisms to protect and 
conserve groundwater resources in Texas. We recognize these substantial 
efforts are critical for maintaining future groundwater conditions to 
support both human uses of the groundwater and the ecological 
communities that depend on the outflows from the aquifers. The lack of 
regulatory mechanisms for groundwater conservation is not the only 
reason these species are in danger of extinction. Their extreme rarity 
makes the species particularly vulnerable to all of the threats 
discussed. However, due in part to their extreme rarity, the loss of 
spring flows is a primary concern that contributes to the risk of 
extinction for these species.
    For the San Solomon Spring species, we found that the existing 
regulations from groundwater conservation districts are not serving to 
alleviate or limit the threats to the species because it is uncertain 
whether the planned groundwater declines will allow for maintenance of 
the spring flows that provide habitat for the species. We assume that, 
absent more detailed studies, the large levels of anticipated declines 
in the presumed supporting aquifers are likely to result in continuing 
declines of spring flows in the San Solomon Spring system. We revised 
the final rule discussion under Factor D for the San Solomon Spring 
species with this further explanation.

[[Page 41230]]

    For the Diamond Y Spring species, we found three reasons why the 
existing regulatory mechanisms provided by the groundwater conservation 
districts and groundwater management areas are inadequate to 
sufficiently reduce the threats of spring flow loss to the six species. 
First, the lack of conclusive science on the groundwater systems and 
sources of spring flow for Diamond Y Spring means that we cannot be 
sure which aquifers are the most important to protect. Until we can 
reliably determine the sources of spring flows, it is impossible to 
know if existing regulations are adequate to ensure long-term spring 
flows. Second, and similarly, due to the lack of understanding about 
the relationships between aquifer levels and spring flows, we cannot 
know if the current or future desired future conditions adopted by the 
groundwater management areas are sufficient to provide for the species' 
habitats. To our knowledge, none of the desired future conditions, 
which include large reductions in aquifer levels in 50 years, have been 
used to predict future spring flows at Diamond Y Spring. Finally, other 
sources of groundwater declines outside of the control of the current 
groundwater conservation districts could lead to further loss of spring 
flows. These sources include groundwater pumping not regulated by a 
local groundwater conservation district or climatic changes that alter 
recharge or underground flow paths between aquifers. Therefore, 
although important regulatory mechanisms are in place, such as the 
existence of groundwater conservation districts striving to meet 
desired future conditions for aquifers, we find that the mechanisms may 
not be able to sufficiently reduce the identified threats related to 
future habitat loss. We revised the final rule discussion under Factor 
D for the Diamond Y Spring species with this further explanation.
    (5) Comment: Why did the Service include East Sandia Spring as part 
of the San Solomon Spring System since the spring discharges in the 
alluvial sand and gravel from a shallow groundwater source that is 
different from the other three springs included in this system?
    Our Response: We acknowledge that the East Sandia Spring has a 
different source from the other three springs referred to as the San 
Solomon Spring System. However, we use this term as a common reference 
for the four springs, which are geographically close together and which 
contain similar biological communities. We have clarified our 
discussion of this issue in the final rules.
    (6) Comment: The Service dismisses the potential for contamination 
from agricultural contaminants to the springs because there is 
currently limited agriculture upgradient of the springs and there is an 
informal agreement for continued limitation. The Service might include 
the potential for contamination from agricultural return flows based on 
the hydrogeologic setting if the informal agreement is not honored.
    Our Response: Based on the best available information, we found no 
indication of any agricultural activities in areas that could result in 
contamination in return flows impacting the springs in either the 
Diamond Y Spring System or the San Solomon Spring System. Because the 
agricultural areas are such a large distance from the springs, we 
conclude the chances of effects to the species are remote. The informal 
agreement to avoid use of potential contaminants in the area 
immediately near San Solomon Spring is in areas with limited or no 
agricultural activity so the risk of contamination is remote there as 
well. Therefore, based on the best available information at this time, 
we do think that a significant potential exists for water contamination 
from agricultural sources.
    (7) Comment: The discussion of using toxicants for the management 
of nonnative fish at Diamond Y Spring seems to downplay the likely 
damage that was inflicted upon the invertebrate communities at Diamond 
Y Spring. The possible damage is presented only in terms of the species 
being proposed for listing. However, the entire invertebrate community, 
and its proper functioning, was impacted by the application of fish 
toxicants. Therefore, the damage done may be more at the community or 
even ecosystem level, rather than just the species level.
    Our Response: While there could have been effects that were not 
detectable, monitoring data collected before and after the treatment on 
the target species and other invertebrate species did not find a 
significant effect past the short-term response.

State Agencies

    We received a number of comments from Texas State agencies, 
including the Texas Governor's Office, the Texas Parks and Wildlife 
Department, the Texas Comptroller's Office, the Texas Water Development 
Board, the Texas Commission on Environmental Quality, the Texas Land 
Commission, and the Texas Department of Agriculture.
    (8) Comment: The Texas Parks and Wildlife Department, while 
indicating they strongly encourage the use of incentive-based 
conservation programs for private land stewardship in Texas, indicated 
they had no additional information beyond what we referenced in the 
proposed rule and agreed that the most significant threat to the 
species' continued survival is the potential failure of spring flow due 
to unmanaged groundwater pumping thresholds, which do not consider 
surface flow and wildlife needs, and prolonged drought.
    Our Response: We concur with the comments and information provided.
    (9) Comment: The Texas Governor's office was concerned that our 
proposal is largely based on conflicting reports, inconclusive data, 
hypothetical scenarios, various assumptions and vast speculation about 
species populations, water quantity and quality, the effect of existing 
regulatory mechanisms and other potential threats. Such information 
fails to provide any sound scientific foundation on which to justify 
the listing and critical habitat designation of these species.
    Our Response: Under the standards of the Act, we are to base our 
determinations of species status on the best available scientific 
information. Often times, scientific data are limited, studies are 
conflicting, or results are seemingly inconclusive. Our review of the 
best available scientific information, including both published 
publications and unpublished scientific reports, supports our 
determinations that these species meet the definition of endangered 
species under the Act. As such we are finalizing critical habitat 
designations for these species as well.
    (10) Comment: Several State and local agencies pointed out that the 
scientific information regarding the groundwater flow systems in this 
region are complex and in need of additional study. This uncertainty 
makes it difficult to predict the responses of spring flows to pumping 
or other stressors on the aquifer.
    Our Response: We agree that more information on the hydrogeology of 
the areas around these spring systems would be very helpful in further 
refining the relationships between pumping, groundwater levels, and 
spring flows. This information will be particularly helpful as we work 
toward conservation of these species in the future. However, the 
uncertainty surrounding these relationships do not alter the facts that 
the habitats of the species are completely dependent upon spring flows 
and that spring flows are dependent upon groundwater levels. These 
groundwater levels, wherever the spring sources may be, are at risk of 
decline through pumping or other stressors such as prolonged drought 
due

[[Page 41231]]

to climate change. These facts put the species in danger of extinction. 
This reasoning is based on the best available information and supports 
our determinations.
    (11) Comment: One State agency pointed out that the data and 
measurements of flow at Diamond Y Spring are lacking and that our 
speculation that the Diamond Y Spring could undergo a similar decline 
as the Leon Springs does not account for the different sources of 
groundwater supplying the two springs.
    Our Response: We did not intend to imply that the Diamond Y Spring 
and Leon Spring are from the same groundwater source. We only intended 
to demonstrate that, should groundwater pumping occur in the source 
aquifer of Diamond Y Spring, the spring could be affected. Leon Springs 
is simply a nearby example of this cause and effect relationship. We 
have revised the final rule to clarify our intent.
    (12) Comment: A State agency suggested that, although data are 
lacking and measurements poorly documented, discharge from Diamond Y 
Spring has been rather constant. Since 1993 they have not observed any 
discernible change in flow at Diamond Y Spring. Another commenter 
suggested that a highly probable cause of decreased extent of the 
shallow water pools at Diamond Y Spring is the proliferation of 
mesquite trees, bulrush, and other water-intensive invasive species 
that have invaded the area.
    Our Response: We agree that data on discharge levels at Diamond Y 
Spring over time are lacking. Because the flow rates are so low, 
observing changes in flow rates without empirical data is very 
difficult; however, we would disagree with the conclusion that flow at 
Diamond Y Spring has undergone no discernible change since 1993. Our 
own field observations and those reported by other researchers have 
noted that the longitudinal extent of surface waters has receded. For 
example, surface flow previously regularly extended downstream of the 
State Highway 18 crossing, but in recent years has not regularly 
extended this far.
    The increase in nearby vegetation could be another contributing 
factor to decreased surface water available at Diamond Y Spring. We are 
not aware of any study evaluating this source of surface water loss, so 
determining the extent of this relationship is difficult. Regardless of 
the reason, any further decline in the spring flows at Diamond Y 
Spring, which are highly susceptible to impact due to their very small 
flow rate, will heighten the risk of extinction of the endemic species 
due to habitat loss.
    (13) Comment: One State agency commented that, while oil and gas 
exploration, extraction, transportation, and processing is active in 
the area, no pollutant or contaminant has ever been found to have 
harmed the aquatic invertebrates that dwell in the springs. Other 
public commenters added that no evidence supports a future catastrophic 
event severely impacting the Diamond Y Spring species. The mere 
speculation of possible future adverse effects cannot be used to 
support a listing determination.
    Our Response: The comment is correct that we are not aware of any 
past contaminant spill that has impacted the species at Diamond Y 
Spring. However, the area is extremely active with oil and gas 
activities; some active wells are immediately adjacent to the springs, 
and some pipelines cross the habitat. This presence of pollutants in 
high quantities presents a constant risk of impact to the species 
either through groundwater or surface water impacts. While we are not 
aware of a formal analysis of the risks posed by the proximity of oil 
and gas operations, to assume that a large magnitude spill is possible, 
even with existing conservation measures in place, and that such a 
spill could have substantial negative impacts on the endemic species is 
reasonable. With only one known location of these species, any possible 
negative impact heightens their risk of extinction. Further, the threat 
from oil and gas activity is only one of several threats that together 
result in these species in danger of extinction.
    (14) Comment: A State agency and others commented that the Service 
did not adequately consider the existing conservation measures and 
Federal and State regulations currently in place to prevent 
contamination from oil and gas activities at Diamond Y Spring.
    Our Response: We understand that existing regulations oversee oil 
and gas activities in Texas. However, the risk of a contaminant event 
that would affect the species at Diamond Y Spring cannot be ruled out 
by the existing conservation efforts and regulations. Because of the 
extremely limited range of these species and their complete dependence 
on the aquatic environment, the potential impacts of contamination will 
remain an ongoing concern at Diamond Y Spring.
    (15) Comment: The Texas Commission on Environmental Quality 
recently issued a statewide general permit (TPDES General Permit No. 
TXG8700000) for point source discharges of pesticide or herbicide made 
into or over surface water. This regulation ensures the protection of 
surface water quality in accordance with applicable State and Federal 
law.
    Our Response: This general permit is helpful to regulate pesticide 
or herbicide use in Texas, and it could provide some limited benefits 
to these invertebrates and other aquatic species in these spring 
systems. However, pesticides and herbicides are not a primary concern 
to these species because of the limited agricultural activities that 
could affect their habitats. Therefore, while we acknowledge this 
statewide permit, we have not revised the final rules to include a 
discussion of this issue relative to the species in this final rule.
    (16) Comment: Because the San Solomon Spring system is in a rural, 
lightly populated area, and exposure to pollutants has been found to be 
limited, no threat to the system's water quality is apparent.
    Our Response: We agree; we did not find substantial concerns for 
water quality at the San Solomon Spring system.
    (17) Comment: The two instances of nonnative snails in the San 
Solomon Spring system have not conclusively been found to have a 
negative impact on the species at issue, and the potential for the 
introduction of other nonnative species is extraordinarily low.
    Our Response: We agree that evidence is not conclusive that the 
nonnative snails are negatively impacting the native species. However, 
to assume that at least some competition for space and resources exists 
between the native and nonnative species is reasonable. We disagree 
with the characterization of the potential for the introduction of 
other nonnative species as extraordinarily low. To the contrary, we 
think the potential is very real of new nonnative species being 
introduced at San Solomon Spring because of the high volume of public 
visitors at Balmorhea State Park. Although the State prohibits the 
release of plants or animals into the Park, people will release 
unwanted aquarium species into natural waters rather than disposing of 
them. The potential for the release of nonnative species is a constant 
risk at San Solomon Spring.
    (18) Comment: Two State agencies and a number of others were 
concerned about the impacts of listing these species and designating 
critical habitat on private property rights, oil and gas development, 
and agricultural activities.
    Our Response: Although the Act does not allow us to consider the 
economic impacts of our listing decisions, we did consider the 
potential economic impacts regarding the designation of critical

[[Page 41232]]

habitat. Critical habitat only directly affects actions funded, 
permitted, or carried out by a Federal agency, and Federal activities 
that could affect the habitat in these areas are very limited. As a 
result, we found only extremely small potential indirect effects from 
the proposed designation of critical habitat. For critical habitat, our 
economic analysis found the incremental administrative economic impacts 
related to consultations on the critical habitat of the six west Texas 
invertebrates are expected to amount to an estimated $41,000 over 20 
years ($3,600 on an annualized basis), assuming a discount rate of 
seven percent.
    In addition, at this time we do not anticipate noticeable impacts 
to private property rights, oil and gas development, or agricultural 
activities from either the listing or the designation of critical 
habitat for these species. Other listed species have been in these 
areas for more than 30 years with very few, if any, conflicts with 
economic development. However, if future conflicts arise, we will work 
closely with the potentially affected parties to find cooperative 
solutions for conservation of these species while striving to minimize 
potential effects on economic activities.

Summary of Changes from Proposed Rule

    One important change we made in this final rule is the revision to 
the common names of the four species of snails to conform to 
scientifically accepted nomenclature (Turgeon et al. 1998, pp. 75-76). 
These changes were suggested by a peer reviewer of the proposed rule. 
Table 1 lists the names used in the proposed rules and the revised 
names used in the final rules. We have used the revised names of all 
the snails throughout these final rules. No changes were made to the 
scientific names.

                       Table 1--Revised Common Names for the Six West Texas Invertebrates
----------------------------------------------------------------------------------------------------------------
                                           Common name used in proposed
             Scientific name                           rules             Revised common name used in final rules
----------------------------------------------------------------------------------------------------------------
Pyrgulopsis texana.......................  Phantom cave snail..........  Phantom springsnail.
Tryonia cheatumi.........................  Phantom springsnail.........  Phantom tryonia.
Gammarus hyalleloides....................  Diminutive amphipod.........  No change.
Pseudotryonia adamantina.................  Diamond Y Spring snail......  Diamond tryonia.
Tryonia circumstriata....................  Gonzales springsnail........  Gonzales tryonia.
Gammarus pecos...........................  Pecos amphipod..............  No change.
----------------------------------------------------------------------------------------------------------------

    Other minor changes were made in the SUPPLEMENTARY INFORMATION 
section of these final rules to correct and update discussions of 
issues raised by peer and public commenters. No changes were made to 
the 50 CFR Part 17 section of the rules.

Background

    We intend to discuss below only those topics directly relevant to 
the listing of the six west Texas aquatic invertebrates as endangered 
species. 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 
springsnail, Phantom tryonia, diminutive amphipod, Diamond tryonia, 
Gonzales tryonia, 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) deposits. 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 final 
rules.
    Both spring systems associated with San Solomon Spring and Diamond 
Y Spring represent discharge from groundwater flow systems that have 
little modern recharge and were formed in the Pleistocene when the 
climate was cooler and wetter than today (French 2013, p. 1). Both 
groundwater systems are not well understood, especially at the local 
scale, because they include both lateral and vertical flow between 
multiple aquifers (French 2013, p. 1).
    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 final 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,

[[Page 41233]]

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; the farthest two (East Sandia Spring and 
Phantom Lake Spring) are about 13 kilometers (km) (8 miles (mi)) apart, 
and all but East Sandia Spring likely originate from the same 
groundwater source (see discussion below). 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 using either water issued from the springs or pumped 
groundwater.
    The base flows from 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 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, pp. 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). Substantial uncertainty exists 
about the precise nature of this regional groundwater flow system and 
its contribution to the San Solomon Spring system.
    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 stormwater 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 springsnail, Phantom 
tryonia, 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

[[Page 41234]]

an elevation similar to San Solomon Spring. Brune (1981, p. 385) 
reported flow from Giffin Spring ranged 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 combined flow rates from 
both springs, which ranged from 0.12 to 0.01 cms (4.07 cfs to 0.45 
cfs), 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. Whether the six aquatic invertebrates 
discussed in this document occurred in these now dry spring sites is 
unconfirmed, 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 the tributary drainage of 
Diamond Y Draw/Leon Creek that drains 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 discharge from Diamond Y Spring is extremely 
small; between 2010 and 2013, the U.S. Geological Survey measured flows 
from Diamond Y Spring ranging from 0.0009 to 0.002 cms (0.03 to 0.09 
cfs) (U.S. Geological Survey 2013, p. 1). 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; farther downstream the drainage is again 
named Leon Creek. 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.
    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 extensively developed for oil and gas extraction. In addition, a 
natural gas

[[Page 41235]]

gathering and treating plant is located within 0.8 km (0.5 mi) upslope 
of the headpool in the upper watercourse of Diamond Y Spring (Hoover 
2013, p. 2). 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.
    Substantial scientific uncertainty exists regarding the aquifer 
sources that provide the source water to the Diamond Y Springs. 
Preliminary 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). However, more recent studies by the U.S. 
Geological Survey suggest that the Rustler Aquifer only contributes 
some regional flow mixing with the larger Edwards-Trinity (Plateau) 
Aquifer in this area through geologic faulting and artesian pressure, 
as the Rustler Aquifer is deeper than the Edwards-Trinity Aquifer 
(Bumgarner 2012, p. 46; Ozuna 2013, p. 1). In contrast, the Texas Water 
Development Board indicates that the strata underlying the Edwards-
Trinity (Plateau) Aquifer provide most of the spring flow at Diamond Y 
Spring and that the artesian pressure causing the groundwater to issue 
at Diamond Y Spring is likely from below the Rustler Aquifer (French 
2013, pp. 2-3). The Middle Pecos Groundwater Conservation District 
suggested that Diamond Y Spring is a mixture of discharge from the 
Edwards-Trinity (Plateau) Aquifer and leakage from the other Permian-
age formations, including the Rustler, Salado, Transill, and Yates 
formations and possibly even deeper strata below the Edwards-Trinity 
(Plateau) Aquifer (Gershon 2013, p. 6). Obviously, substantial 
uncertainty exists as to the exact nature of the groundwater sources 
for Diamond Y Spring.
    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, we have evidence that at least the two snails 
(Diamond tryonia and Gonzales tryonia) 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 final rules: Phantom springsnail (P. 
texana), Phantom tryonia (T. cheatumi), Diamond tryonia (P. 
adamantina), and Gonzales tryonia (T. circumstriata). The Phantom 
springsnail is classified in the family Hydrobiidae (Hershler 2010, p. 
247), and the other three snails are in the family Cochliopidae 
(Hershler et al. 2011, p. 1), formerly a subfamily of Hydrobiidae. All 
of the snails are strictly aquatic with respiration occurring through 
an internal gill. These type of snails (snails in the former family 
Hydrobiidae) 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 
genus Pyrgulopsis (Phantom springsnail) 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 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

[[Page 41236]]

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. Currently no nonnative fishes occur in the springs where 
the species occur, so no unnatural predation pressure from fish is 
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 Springsnail, Pyrgulopsis texana (Pilsbry 1935)
    The Phantom springsnail was first described by Pilsbry (1935, pp. 
91-92) as Cochliopa texana. 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 classified 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 springsnail 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 springsnails 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 springsnail meets the 
definition of a species under the Act.
    The Phantom springsnail occurs only 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 springsnail 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 springsnails can exist 
in very high densities. Dundee and Dundee (1969, pp. 207) described the 
abundance of the Phantom springsnails 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 springsnail 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 
springsnails (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 springsnails can reach tremendous 
population sizes in very small areas.
    Phantom springsnails 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 within Phantom Cave 
proper, but only within the outflow of Phantom Lake Spring. Bradstreet 
(2011, p. 55) found the highest abundances of Phantom springsnails 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 springsnails prefer 
substrates harder and larger in size (Bradstreet 2011, p. 91).
Phantom Tryonia, Tryonia cheatumi (Pilsbry 1935)
    The Phantom tryonia 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 tryonia meets the definition of a species under the Act.
    The Phantom tryonia occurs only 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 tryonia 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 tryonia can have 
moderate densities of abundance, but have never been recorded as high 
as the Phantom springsnail. In the 1980s, Taylor (1987, p. 40) 
described Phantom tryonia 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

[[Page 41237]]

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 that more than 460,000 individuals of 
this species may be at San Solomon Spring (Bradstreet 2011, p. 55). 
Lang (2011) reports the following densities (not population estimates) 
of Phantom tryonia (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 tryonia can reach high population 
sizes in very small areas with favorable conditions.
    Phantom tryonia 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, p. 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 Tryonia, Pseudotryonia adamantina (Taylor 1987)
    The Diamond tryonia 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 
tryonia being reclassified into the new genus Pseudotryonia (Hershler 
2001, p. 16). Based on these published studies, we conclude that 
Diamond tryonia meets the definition of a species 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 
tryonia 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 tryonia 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 tryonia 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 tryonia in the upper watercourse. 
However, neither researcher surveyed extensively in the lateral spring 
seeps downstream from the main spring outflow.
    The Diamond tryonia 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 tryonia 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 tryonia 
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 tryonia was historically common in the 
upper watercourse and absent from the lower watercourse. Currently it 
is very 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 tryonia 
(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 Tryonia, Tryonia circumstriata (Leonard and Ho 1960)
    The Gonzales tryonia 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 
tryonia meets the definition of a species under the Act.
    Taylor (1985, pp. 18-19; 1987, p. 38) found Gonzales tryonia 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 tryonia no longer 
occurred in the lower watercourse and had been replaced by Diamond 
tryonia. 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

[[Page 41238]]

outflow channel of the lower watercourse.
    Gonzales tryonia 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 tryonia 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 tryonia appears to have replaced the Diamond tryonia in some 
of the habitat in the upper watercourse (Brown 2008, p. 489) since 
1991.
    Taylor (1985, p. 19) calculated densities for Gonzales tryonia 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 tryonia 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 tryonia in the upper watercourse 
to be only about 11,000 individuals.
    As with the Diamond tryonia, the historic distribution of the 
Gonzales tryonia may have been larger than the present distribution. 
Other area springs nearby such as Leon and Comanche Springs may have 
harbored the species. The identification of one collection of dead 
shells of the species that was made from Comanche Springs in 1998 
(Worthington 1998, unpublished data) was recently confirmed as Gonzales 
tryonia (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 final 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, these freshwater amphipods are thought to have 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 occur only in 
desert spring outflow channels on substrates, often within interstitial 
spaces on and 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).
    The literature has some disparity 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

[[Page 41239]]

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 final 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 to meet the 
definition of a species 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 occurs only in the four springs from the 
San Solomon Spring system (Gervasio et al. 2004, pp. 520-522). 
Available information does not indicate 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 meets the 
definition of a species 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 system (Echelle et al. 2001, p. 20; Lang et al. 2003, 
p. 51; Allan 2011, p. 2; Lang 2011, entire). Available information does 
not allow us 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 our determinations for each species.

San Solomon Spring Species--Phantom springsnail, Phantom tryonia, 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 springsnail, Phantom tryonia, 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

[[Page 41240]]

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 flow declines, 
available aquatic habitat is reduced and altered. If one spring ceases 
to flow continually, all habitats for the Phantom springsnail, Phantom 
tryonia, 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 discharge 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 historically a 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; 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. 
More than 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

[[Page 41241]]

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 overpumping 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 (through opening of fractures or 
conduits through dissolution, tectonic activity, or changing sediment 
storage in conduits) that may affect regional 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) conducted 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 pumping (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 pumping 
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 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 is expected to result 
in continued lowering of the groundwater levels in the Salt

[[Page 41242]]

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). No studies have evaluated the effects of this level of anticipated 
drawdown on spring flows. The aquifer in the Wild Horse Flat area (a 
likely spring source for the San Solomon Spring system) 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. This decline in spring flows 
will further limit habitat available to the invertebrate species and 
increase their risk of extinction.
    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 springsnail, Phantom tryonia, 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 
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 springsnail, Phantom tryonia, 
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 pollution can occur 
either directly into surface water or indirectly through contamination 
of groundwater that discharges into spring run habitats used by the 
species. The main source 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 and has 
little to no agricultural activities. While more agricultural 
activities occur far upstream in the aquifer source area, available

[[Page 41243]]

information does not lead to concern about contaminants from those 
sources.
    In addition, the 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 springsnail, Phantom tryonia, 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 
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.
    Conservation efforts have attempted to maintain suitable spring 
habitat conditions at Phantom Lake Spring. Here 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 springsnail 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 springsnail, Phantom tryonia, 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 vulnerability 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.

[[Page 41244]]

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 springsnail, Phantom tryonia, 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 the 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 habitat loss and modification of the Phantom springsnail, 
Phantom tryonia, and diminutive amphipod is a threat that has 
significant effects on the populations of these species. 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)
    Very few people 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. We know of no 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 tryonia, 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 various species of crayfishes 
are known predators of snails (Hershler 1998, p. 14; Dillon 2000, pp. 
293-294). 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 threats 
that have a significant effect on the Phantom Lake snail, Phantom 
tryonia, and diminutive amphipod. We have no indication that this 
threat will have an increased effect on these species 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

[[Page 41245]]

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 provides 
some protection to the spring outflow channels only 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 provides 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).
    In the area west of the springs, currently four local groundwater 
districts could possibly manage groundwater to protect spring flows in 
the San Solomon Spring system (Texas Water Development Board 2011, p. 
1). 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, which occur outside the geographic boundaries of the 
groundwater districts, prevents any direct benefits of their management 
plans for the three aquatic invertebrates.
    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 presumed 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) over 
the next 50 years 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 by the Texas Water 
Development Board (Beach et al. 2004, pp. 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. We are not aware of any information or studies that have 
accessed the impacts on spring flows associated with the drawdown from 
the desired future condition. However, the drawdown levels could be 
substantial compared to the available groundwater, which receives 
little natural recharge beyond regional flow. 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

[[Page 41246]]

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 springsnail, Phantom 
tryonia, and diminutive amphipod.

Summary of Factor D

    Some regulatory mechanisms are in place, such as the existence of 
groundwater conservation districts, which address the primary threat to 
the Phantom springsnail, Phantom tryonia, or diminutive amphipod of 
habitat loss due to spring flow decline. However, we find that these 
mechanisms are not serving to alleviate or limit the threats to the 
species because it is uncertain whether the planned groundwater 
declines will allow for the maintenance of the spring flows that 
provide habitat for the species. We assume that, absent more detailed 
studies, the large levels of anticipated declines are likely to result 
in continuing declines of spring flows in the San Solomon Spring 
system. We, therefore, conclude that these existing regulatory 
mechanisms are inadequate to sufficiently reduce the identified threats 
associated with groundwater decline and spring flow losses that provide 
habitat for the Phantom springsnail, Phantom tryonia, 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, to presume that they are likely competing for space and 
food resources in the limited habitats in which they occur is 
reasonable. 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 springsnail, Phantom tryonia, 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 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, p. 48). In 
spite of these efforts, the risk, which cannot be fully determined, 
remains 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 
springsnail, Phantom tryonia, 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

[[Page 41247]]

that has been reduced from past destruction of their habitat. While the 
overall extent of the 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 springsnail, 
Phantom tryonia, and diminutive amphipod are largely unknown with the 
currently 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 
currently nothing will prevent 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 springsnail, Phantom tryonia, 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.

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 springsnail, Phantom tryonia, 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 threaten the remaining springs with the same fate. We did 
not find any threats with significant effects to the species under 
Factors B or C. We found that existing regulatory mechanisms are 
inadequate to provide protection to the species habitat from existing 
and future threats through groundwater management by groundwater 
conservation districts (Factor D). 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 springsnail, Phantom 
tryonia, 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 springsnail, Phantom tryonia, and 
diminutive 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 Phantom springsnail, Phantom tryonia, and diminutive amphipod all 
meet the definition of endangered species 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. This makes them in danger of 
extinction now, so 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 
are listing the Phantom springsnail, Phantom tryonia, 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 being listed in these 
rules 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

[[Page 41248]]

significant portion of that range. Accordingly, our assessment and 
determination applies to the species throughout their entire range.

Diamond Y Spring Species--Diamond tryonia, Gonzales tryonia, 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 tryonia, Gonzales tryonia, 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). 
While these springs likely originate from a different aquifer source 
than Diamond Y Spring, the situation demonstrates the potential for 
spring losses in this area.
    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.
    No one has made 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 attain. Recent measurements of outflows from the Diamond Y 
Spring headspring between 2010 and 2013 have showed a discharge range 
from 0.0009 to 0.003 cms (0.03 to 0.09 cfs) (U.S. Geological Survey 
2013, p. 1). 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 declining 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 tryonia, Gonzales tryonia, and the Pecos amphipod.
    The precise reason for the declining spring flows remains uncertain 
but 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. Local conditions 
related to vegetation growth and limited local precipitation may also 
be contributing factors.
    Substantial scientific uncertainty exists regarding the aquifer 
sources that provide the source water to the Diamond Y Springs. 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 supported that the Rustler Aquifer is instead 
more likely the chief source of water (Boghici 1997, p. 107). However, 
more recent studies by the U.S. Geological Survey suggest that the 
Rustler Aquifer only contributes some regional flow mixing with the 
larger Edwards-Trinity (Plateau) Aquifer in this area through geologic 
faulting and artesian pressure, as the Rustler Aquifer is deeper than 
the Edwards-Trinity Aquifer (Bumgarner 2012, p. 46; Ozuna 2013, p. 1). 
In contrast, the Texas Water Development Board indicates that the 
strata underlying the Edwards-Trinity (Plateau) Aquifer provide most of 
the spring flow at Diamond Y Spring and that the artesian pressure 
causing the groundwater to issue at Diamond Y Spring is likely from 
below the Rustler Aquifer (French 2013, pp. 2-3). The Middle Pecos 
Groundwater Conservation District suggested that Diamond Y Spring is a 
mixture of discharge from the Edwards-Trinity (Plateau) Aquifer and 
leakage from the other Permian-age formations, including the Rustler 
and possibly other formations below the Edwards-Trinity (Plateau) 
Aquifer (Gershon 2013, p. 6). Obviously, we have substantial 
uncertainty as to the exact nature of the groundwater sources for 
Diamond Y Spring, but based on the best available information, we 
presume the springflows originate from some combination of the Rustler 
and Edwards-Trinity (Plateau) Aquifers.
    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 Broekhoven 2001, pp. 
218-219). Groundwater planning for the Rustler aquifer anticipates no 
annual recharge (Middle Pecos Groundwater Conservation District 2010b, 
p. 18).

[[Page 41249]]

    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.
    The Edwards-Trinity (Plateau) Aquifer underlies about 109,000 
square km (42,000 square miles) of west-central Texas, extending from 
Travis to Brewster Counties (Baker and Ardis 1996, pp. B2-B3). The 
aquifer underlies much of the region around Diamond Y Spring in Pecos 
County and about 50 percent of the aquifer ranges from 71 to 110 m (234 
to 362 ft) thick (Bumgarner et al. 2012, p. 47). The 2009 estimate of 
the annual amount of groundwater used in Pecos County for irrigation 
was 143 million cm (115,650 af), and the majority of the water comes 
from the Edwards-Trinity (Plateau) Aquifer (Middle Pecos Groundwater 
Conservation District 2010b, pp. 18, Appendix D).
    Future groundwater withdrawals may further impact spring flow rates 
if they occur in areas of the Rustler or Edwards-Trinity (Plateau) 
Aquifers 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 aquifers. 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 2010b, pp. 15-16). 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. The latest plans from Groundwater Management Area 7 
(the planning group covering the relevant portion of the Edwards-
Trinity (Plateau) Aquifer) allows for a groundwater withdrawal in the 
Edwards-Trinity (Plateau) Aquifer not to exceed 3.6 m (12 ft) in the 
year 2060 (Middle Pecos Groundwater Conservation District 2010b, p. 
10). This level of drawdown will accommodate 294 million cm (238,000 
af) of annual withdrawals by pumping, including withdrawals from both 
the Edwards-Trinity (Plateau) and Pecos Valley Aquifers (Middle Pecos 
Groundwater Conservation District 2010b, p. 11). This level of pumping 
would be about twice more than the long-term average withdrawals. 
Therefore, based on these expected increasing levels of groundwater 
drawdown, we anticipate continued declines in spring flow rates in the 
Diamond Y Spring system.
    In addition to pumping within the groundwater district, surrounding 
counties that do not have a groundwater district conduct groundwater 
withdrawals from the Edwards-Trinity (Plateau) Aquifer). This 
unregulated pumping could also contribute to aquifer level declines and 
impact spring flow rates.
    The exact relationship between aquifer levels and spring flow rates 
has not been quantified and represents an area of substantial 
uncertainty. However, we think that the anticipated increase in 
groundwater withdrawals, if occurring in an area contributing water to 
the Diamond Y Spring system, would have a negative impact on habitat 
availability for these species and significantly increase their risk of 
extinction.
    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. Many semiarid areas like the western United 
States are likely to 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

[[Page 41250]]

Water Development Board 2012c, p. 231).
    In conclusion, the Diamond tryonia, Gonzales tryonia, and Pecos 
amphipod are vulnerable to the effects of habitat loss because of the 
past and expected future 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 the entire range of the 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 the species 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 pollution 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, within the Diamond Y Preserve were 45 active and 
plugged wells, and an estimated 800 to 1,000 wells perforated the 
aquifers within the springs' drainage basins (Veni 1991, p. 83). At 
this time many active wells are still 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 2013, p. 1). Taylor (1985, p. 15) 
suggested that an unidentified groundwater pollutant may have been 
responsible for reductions in abundance of Diamond tryonia in the 
headspring and outflow of Diamond Y Spring, although no follow-up 
studies were ever 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, pp. 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. No regular monitoring 
of the water quality for these species or their habitats currently 
occurs, so it is unlikely that the effects would be detected quickly to 
allow for a timely response.
    These invertebrates are sensitive to water contamination. 
Springsnails 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 tryonia 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, we have 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

[[Page 41251]]

following The Nature Conservancy assuming 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 snails have not been found in this section for some time.
    Dense bulrush stands may alter habitat for the invertebrates in 
several ways. 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 found 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 they use 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 
outflow areas from Diamond Y Spring have 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 the 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

[[Page 41252]]

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 habitat loss and modification for the Diamond tryonia, 
Gonzales tryonia, and Pecos amphipod is a threat that has significant 
effects on individuals and populations of these species. 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)
    Very few people 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. We know of no 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 tryonia, Gonzales tryonia, and Pecos amphipod, 
and 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. We know of no nonnative predatory fishes 
within their spring habitats, but there are crayfish, which are known 
predators of snails (Hershler 1998, p. 14; Dillon 2000, pp. 293-294). 
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 tryonia, Gonzales tryonia, 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 provides some protection to the spring outflow 
channels only 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 a groundwater district is 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).
    Currently one local groundwater district in the area could likely 
manage groundwater to protect spring flows in the Diamond Y Spring 
system (Texas Water Development Board 2011, p. 1). The Middle Pecos 
Groundwater Conservation District covers all of Pecos County and was 
confirmed as a district 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,

[[Page 41253]]

economy and environment of the District'' (Middle Pecos Groundwater 
Conservation District 2010b, p. 1). However, the management plan does 
not provide specific objectives to maintain spring flow at Diamond Y 
Spring. 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 Edwards-Trinity (Plateau) and Rustler Aquifers 
that may be related to the source aquifers of Diamond Y Spring--
identify the desired future condition of aquifer drawdown compared to 
2010 levels in the next 50 years (2060) for each aquifer and county. 
The desired future condition for the Rustler Aquifer was not to exceed 
a 90-m (300-ft) drawdown (Middle Pecos Groundwater Conservation 
District 2010a, p. 24). 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). For the Edwards-Trinity (Plateau) Aquifer, the 
desired future condition is for an average drawdown in 50 years of 
about 9 m (28 ft) (Middle Pecos Groundwater Conservation District 
2010a, p. 20). 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.
    Researchers have large uncertainty related to determining source 
aquifers of Diamond Y Spring; therefore, determining what effects 
management of these aquifers will have on spring flows is difficult. 
Without better understanding of the interrelationships of the aquifers 
and the spring flows, we cannot confidently predict whether or not the 
existing groundwater management for the desired future conditions will 
provide the necessary flows to maintain the species' habitat. In 
addition, the Edwards-Trinity (Plateau) Aquifer is larger in geographic 
extent than the Rustler Aquifer and extends beyond the boundaries of 
the Middle Pecos Groundwater Conservation District into counties 
without a groundwater district. Unmanaged groundwater withdrawals in 
those areas, outside of the management of a groundwater conservation 
district, could also affect spring flows at Diamond Y Spring. For these 
reasons, we find that the regulatory mechanisms directing future 
groundwater withdrawal rates from the nearby aquifers that may support 
spring flows in the Diamond Y Spring system are inadequate to protect 
against ongoing and future modification of habitat for the Diamond 
tryonia, Gonzales tryonia, and Pecos amphipod.

Texas Regulations for Oil and Gas Activities

    The Railroad Commission of Texas has regulations that oversee 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 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. With only one known location of these species, any 
possible negative impact heightens their risk of extinction. 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

    Some regulatory mechanisms are in place, such as the existence of 
groundwater conservation districts that address the primary threat to 
the Diamond tryonia, Gonzales tryonia, or Pecos amphipod of habitat 
loss due to spring flow decline. However, we find that these mechanisms 
are not serving to alleviate or limit the threats to the species for 
three reasons. First, the lack of conclusive science on the groundwater 
systems and sources of spring flow for Diamond Y means that we cannot 
be sure which aquifers are the most important to protect. Until we can 
reliably determine the sources of spring flows, we cannot know if 
existing regulations are adequate to ensure long-term spring flows. 
Second, and similarly, due to the lack of understanding about the 
relationships between aquifer levels and spring flows, we cannot know 
if the current or future desired future conditions adopted by the 
groundwater management areas are sufficient to provide for the species' 
habitats. To our knowledge, none of the desired future conditions, 
which include large reductions in aquifer levels in 50 years, have been 
used to predict future spring flows at Diamond Y Spring. Finally, other 
sources of groundwater declines outside of the control of the current 
groundwater conservation districts could lead to further loss of spring 
flows. These sources include groundwater pumping not regulated by a 
local groundwater conservation district or climatic changes that alter 
recharge or underground flow paths between aquifers. Therefore, 
although important regulatory mechanisms are in place, such as the 
existence of groundwater conservation districts striving to meet 
desired future conditions for aquifers, we find that the mechanisms may 
not be able to sufficiently reduce the identified threats related to 
future habitat loss.
    Although regulatory mechanisms overseeing oil and gas operations 
are in place, even a small risk of a contaminant spill presents a high 
risk of resulting extinction of these species because of their 
extremely limited range. We, therefore, conclude that these existing 
regulatory mechanisms are inadequate to sufficiently reduce the 
identified threats to the Phantom springsnail, Phantom tryonia, and 
diminutive amphipod now and in the future.
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, a 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

[[Page 41254]]

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 tryonia 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).
    No information is available on the impacts of the initial rotenone 
treatment, but we suspect that, like the later Antimycin A treatment, 
at least short-term effects resulted 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 tryonia 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 tryonia occurs in this area of the upper watercourse in a 
very narrow stretch of the outflow channel from Diamond Y Spring, and 
the Diamond tryonia 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 tryonia is unknown. 
However, these actions could have contributed to the current absence of 
the Diamond tryonia from this reach and the restricted distribution of 
the Gonzales tryonia 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 occurs only 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, to 
presume that it is likely competing for space and food resources in the 
limited habitats within which they occur is reasonable. 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 watercourse where the red-rim melania occurs, only the 
Gonzales tryonia occurs there now in very low abundance in the area of 
overlap, and the Diamond tryonia 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 currently 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 nothing currently would prevent 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 tryonia, 
Gonzales tryonia, 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 tryonia, Gonzales tryonia, 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

[[Page 41255]]

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 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 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 springsnail, Phantom tryonia, 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 nothing is currently 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 is a threat with a low-magnitude impact on the populations of 
the Diamond tryonia, Gonzales tryonia, 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.

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 tryonia, Gonzales tryonia, 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 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 tryonia, Gonzales 
tryonia, 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 tryonia, Gonzales 
tryonia, 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 tryonia, Gonzales tryonia, 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. This situation makes them in danger of 
extinction now, so 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 
are listing the Diamond tryonia, Gonzales tryonia, 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 we are listing in this 
rule are highly restricted in their

[[Page 41256]]

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 
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 (https://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 the species' 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: 
https://www.fws.gov/grants.
    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.
    Our policy, as published in the Federal Register on July 1, 1994 
(59 FR 34272), is 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 listing on 
proposed and ongoing activities within the range of listed species. The 
following activities

[[Page 41257]]

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).

Required Determinations

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).

References Cited

    A complete list of references cited in this rulemaking is available 
on the Internet at https://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.

Regulation Promulgation

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

PART 17--[AMENDED]

0
1. The authority citation for part 17 continues to read as follows:

    Authority: 16 U.S.C. 1361-1407; 1531-1544; and 4201-4245, unless 
otherwise noted.


0
2. In Sec.  17.11(h), add entries for ``Springsnail, Phantom'', 
``Tryonia, Diamond'', ``Tryonia, Gonzales'', and ``Tryonia, Phantom'' 
under ``Snails'' and ``Amphipod, diminutive'' and ``Amphipod, Pecos'' 
under ``Crustatceans'' 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
 
                                                                      * * * * * * *
    Springsnail, Phantom.........  Pyrgulopsis texana..  U.S.A. (TX).........  NA.................  E                      812     17.95(f)           NA
 
                                                                      * * * * * * *
    Tryonia, Diamond.............  Pseudotryonia         U.S.A. (TX).........  NA.................  E                      812     17.95(f)           NA
                                    adamantina.
    Tryonia, Gonzales............  Tryonia               U.S.A. (TX).........  NA.................  E                      812     17.95(f)           NA
                                    circumstriata.
    Tryonia, Phantom.............  Tryonia cheatumi....  U.S.A. (TX).........  NA.................  E                      812     17.95(f)           NA
 
                                                                      * * * * * * *
Crustaceans
    Amphipod, diminutive.........  Gammarus              U.S.A. (TX).........  NA.................  E                      812     17.95(h)           NA
                                    hyalleloides.
 
                                                                      * * * * * * *
    Amphipod, Pecos..............  Gammarus pecos......  U.S.A. (TX).........  NA.................  E                      812     17.95(h)           NA
 
                                                                      * * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------


[[Page 41258]]

* * * * *

    Dated: June 25, 2013.
Daniel M. Ashe,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 2013-16222 Filed 7-8-13; 8:45 am]
BILLING CODE 4310-55-P