Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for the Peck's Cave Amphipod, Comal Springs Dryopid Beetle, and Comal Springs Riffle Beetle, 39248-39283 [07-3267]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 72, Number 136 (Tuesday, July 17, 2007)]
[Rules and Regulations]
[Pages 39248-39283]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 07-3267]



[[Page 39247]]

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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; Designation of Critical 
Habitat for the Peck's Cave Amphipod, Comal Springs Dryopid Beetle, and 
Comal Springs Riffle Beetle; Final Rule

Federal Register / Vol. 72 , No. 136 / Tuesday, July 17, 2007 / Rules 
and Regulations

[[Page 39248]]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AU75


Endangered and Threatened Wildlife and Plants; Designation of 
Critical Habitat for the Peck's Cave Amphipod, Comal Springs Dryopid 
Beetle, and Comal Springs Riffle Beetle

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), are 
designating critical habitat for the Peck's cave amphipod (Stygobromus 
pecki), Comal Springs dryopid beetle (Stygoparnus comalensis), and 
Comal Springs riffle beetle (Heterelmis comalensis) in areas of 
occupied, spring-related aquatic habitat in Texas under the Endangered 
Species Act of 1973, as amended (Act). The three listed species are 
known only from four spring systems in central Texas: Comal Springs and 
Hueco Springs in Comal County, and Fern Bank Springs and San Marcos 
Springs in Hays County. The total area designated as critical habitat 
for the amphipod is about 38.5 acres (ac) (15.6 hectares (ha)), for the 
dryopid beetle it is about 39.5 ac (16.0 ha), and for the riffle beetle 
it is about 30.3 ac (12.3 ha).

DATES: This rule becomes effective on August 16, 2007.

FOR FURTHER INFORMATION CONTACT: Adam Zerrenner, Field Supervisor, 
Austin Ecological Services Office, 10711 Burnet Road, Suite 200, 
Austin, TX 78758 (telephone 512-490-0057; facsimile 512-490-0974).

SUPPLEMENTARY INFORMATION:

Background

    It is our intent to discuss only those topics directly relevant to 
the designation of critical habitat in this rule. For more information 
on these species, refer to the final rule listing the Peck's cave 
amphipod, Comal Springs dryopid beetle, and Comal Springs riffle beetle 
that was published in the Federal Register on December 18, 1997 (62 FR 
66295).
    All three of the listed species included in this final rule for 
critical habitat designation are freshwater invertebrates. The Peck's 
cave amphipod is an eyeless, subterranean (below ground) arthropod that 
has been found in Comal Springs and Hueco Springs (also spelled Waco 
Springs). Both spring systems are located in Comal County, Texas. The 
Comal Springs dryopid beetle is a subterranean insect with vestigial 
(poorly developed, non-functional) eyes. The species has been found in 
two spring systems, Comal Springs and Fern Bank Springs, that are 
located in Comal and Hays Counties, respectively. The Comal Springs 
riffle beetle is an aquatic insect that is found in and primarily 
restricted to surface water associated with Comal Springs in Comal 
County and with San Marcos Springs in Hays County.
    The four spring systems (Comal, Fern Bank, Hueco, and San Marcos) 
designated as critical habitat units are produced by discharge of 
aquifer spring water along the Balcones fault zone at the edge of the 
Edwards Plateau in central Texas. The source of water flows for Comal 
Springs and San Marcos Springs is the San Antonio segment of the 
Edwards Aquifer. This aquifer is characterized by highly varied, below 
ground spaces that have been hollowed out within limestone bedrock 
through dissolution by rainwater. Groundwater is held and conveyed 
within these hollowed-out spaces, which range in size from honeycomb-
like pores to large caverns. The San Antonio segment of the aquifer 
occurs in a crescent-shaped section over a distance of 176 miles (mi) 
(283 kilometers (km)), from the town of Brackettville in Kinney County 
on the segment's west side over to the town of Kyle in Hays County at 
the segment's northeast side. Groundwater generally moves from recharge 
areas in the southwest part of the San Antonio segment and travels 
toward discharge areas in the northeast part of the segment, which 
includes Comal Springs and San Marcos Springs. The area that recharges 
groundwater coming to Comal Springs may occur as much as 62 mi (100 km) 
away from the springs (Brune 1981, p. 130). Hueco Springs is recharged 
locally from the local watershed basin and possibly by the San Antonio 
segment of the Edwards Aquifer (Guyton and Associates 1979, p. 2). The 
source of water for Fern Bank Springs has not been determined. Fern 
Bank Springs discharges water from the upper member of the Glen Rose 
Formation, and its flow could originate primarily from that unit; 
however, water discharged from the springs could also be (1) Drainage 
from the nearby Edwards Aquifer recharge zone, (2) water lost from the 
Blanco River, or (3) a combination of all three sources (Veni 2006, 
p.1).
    Comal Springs and San Marcos Springs are the two largest spring 
systems in Texas with respective mean annual flows of 284 and 170 cubic 
feet per second (8 and 5 cubic meters per second) (Fahlquist and 
Slattery 1997, p. 1; Slattery and Fahlquist 1997, p. 1). Both spring 
systems emerge as a series of spring outlets along the Balcones fault 
that follows the edge of the Edwards Plateau in Texas. Fern Bank 
Springs and Hueco Springs have considerably smaller flows and consist 
of one main spring with several satellite springs or seep areas.
    The four spring systems designated for critical habitat are 
characterized by high water quality and relatively constant water 
flows, with temperatures that range from 68 to 75 [deg]F (Fahrenheit) 
(20 to 24 [deg]C (Celsius)). Due to the underlying limestone aquifer, 
discharged water from these springs has a carbonate chemistry (Ogden et 
al. 1986, p. 103). Although flows from San Marcos Springs can vary 
according to fluctuations in the source aquifer, records indicate that 
this spring system has never ceased flowing. San Marcos Springs has 
been monitored since 1894, and has exhibited the greatest flow 
dependability of any major spring system in central Texas (Puente 1976, 
p. 27). Comal Springs has a flow record nearly comparable to that of 
San Marcos Springs; however, Comal Springs ceased flowing from June 13 
to November 3, 1956, during a severe drought (U.S. Army Corps of 
Engineers 1965, p. 59). Water pumping from the aquifer contributed to 
cessation of flow at Comal Springs during the drought period (U.S. Army 
Corps of Engineers 1965, p. 59). Hueco Springs has gone dry a number of 
times in the past during drought periods (Puente 1976, p. 27; Guyton 
and Associates 1979, p. 46). Although flow records are unavailable for 
Fern Bank Springs, the spring system is considered to be perennial 
(Barr 1993, p. 39).
    Each of the four spring systems and related subterranean aquifers 
typically provide adequate resources to sustain life cycle functions 
for resident populations of the Peck's cave amphipod, Comal Springs 
dryopid beetle, and Comal Springs riffle beetle. However, a primary 
threat to the three invertebrate species is the potential failure of 
spring flow due to drought or excessive groundwater pumping, which 
could result in loss of aquatic habitat for the species. Although these 
invertebrate species persisted at Comal Springs in the 1950s despite 
drought conditions (Bowles et al. 2003, p. 379), all three species are 
aquatic and require water to complete their individual life cycles.
    Bowles et al. (2003, p. 379) pointed out that the mechanism by 
which the Comal Springs riffle beetle survived the drought and the 
extent to which its population was negatively impacted are

[[Page 39249]]

uncertain. Bowles et al. (2003, p. 379) speculated that the riffle 
beetle may be able to retreat back into spring openings or burrow down 
to wet areas below the surface of the streambed.
    Barr (1993, p. 55) found Comal Springs dryopid beetles in spring 
flows with low volume discharge as well as high volume discharge and 
suggested that presence of the species did not necessarily depend on a 
high spring flow. However, Barr (1993, p. 61) noted that effects on 
both subterranean species (dryopid beetle and amphipod) from extended 
loss of spring flow and low aquifer levels could not be predicted due 
to limited knowledge about their life cycles.

Previous Federal Actions

    Information about previous Federal actions for Peck's cave 
amphipod, Comal Springs dryopid beetle, and Comal Springs riffle beetle 
can be found in our proposal to designate critical habitat for these 
species published in the Federal Register on July 17, 2006 (71 FR 
40588). On March 16, 2007, we announced the availability of our draft 
economic analysis, and we reopened the public comment period on the 
proposed rule (72 FR 12585). The reopened public comment period ended 
on April 16, 2007.

Summary of Comments and Recommendations

    We requested written comments from the public on the proposed 
designation of critical habitat for Peck's cave amphipod, Comal Springs 
dryopid beetle, and Comal Springs riffle beetle in the proposed rule 
published on July 17, 2006 (71 FR 40588) and in our March 16, 2007, 
Federal Register notice (72 FR 12585). We also contacted appropriate 
Federal, State, and local agencies; scientific organizations; and other 
interested parties and invited them to comment on the proposed rule.
    During the comment period that opened on July 17, 2006, and closed 
on September 15, 2006, we received eight responses directly addressing 
the proposed critical habitat designation: four from peer reviewers, 
one from a State agency, and three from organizations or individuals. 
The response we received from the State agency, the Texas Department of 
Transportation, indicated that the proposed critical habitat 
designations for these species were ``prudently identified'' by the 
Service. However, that agency did not offer any other comments. After 
completing the draft economic analysis, we reopened the comment period 
between March 16, 2007, and April 16, 2007 (72 FR 12585). During the 
second comment period, we received one comment from a peer reviewer and 
four from organizations; two of which included comments on the economic 
analysis. Responses to all comments were grouped by those from peer 
reviewers, followed by public comments. These comments are addressed in 
the following summary and incorporated into the final rule as 
appropriate. We did not receive any requests for a public hearing and 
thus no public hearing was held.

Peer Review

    In accordance with our policy published on July 1, 1994 (59 FR 
34270), we solicited expert opinions from nine knowledgeable 
individuals with scientific expertise that included familiarity with 
the species, the geographic region in which the species occur, and 
conservation biology principles. We received responses from four of the 
peer reviewers. Although none of the peer reviewers disagreed with our 
methods in designating critical habitat for the Peck's cave amphipod, 
Comal Springs dryopid beetle, and Comal Springs riffle beetle, three of 
the responses indicated that the critical habitat designation failed to 
address the broader issue of maintaining spring flows, ecosystem 
functioning, and groundwater levels within the Edwards Aquifer. Also, 
two of the peer reviewers disagreed with the reasoning we presented in 
our determination of Primary Constituent Element (PCE) 4. Three of the 
peer reviewers' responses provided additional information, 
clarifications, and suggestions to improve the final critical habitat 
rule. We address peer reviewer comments in the following summary and 
have incorporated them into the final rule as appropriate.
    We reviewed all comments received from the peer reviewers and the 
public for substantive issues and new information regarding critical 
habitat for the Peck's cave amphipod, Comal Springs dryopid beetle, and 
Comal Springs riffle beetle, and address them in the following summary.

Peer Reviewer Comments

    1. Comment: One of the critical factors affecting the Peck's cave 
amphipod, Comal Springs dryopid beetle, and Comal Springs riffle beetle 
is continued natural spring flows. Adequate or minimum spring flows 
should be included as a PCE.
    Our Response: We agree that adequate water quantity is necessary 
for the survival of the three invertebrate species. We indicated that 
availability and access to water at the spring sites are important 
factors in maintaining the life history functions of the Peck's cave 
amphipod, the Comal Springs dryopid beetle, and the Comal Springs 
riffle beetle by highlighting the role of water in the descriptions of 
PCEs 1, 2, and 3 of this final rule. We clarified the language for PCE 
3 to highlight the importance of spring flows in maintaining adequate 
dissolved oxygen levels. We also state in the Special Management 
Considerations section of this rule that prolonged cessation of spring 
flows as a result of the loss of hydrological connectivity within the 
aquifer may require special management considerations, such as 
maintenance of sustainable groundwater use and subsurface flows.
    2. Comment: PCE 5 should be corrected to indicate that the 
substrate habitat of the Peck's cave amphipod, Comal Springs dryopid 
beetle, and Comal Springs riffle beetle should also be free of sand and 
silt.
    Our Response: We incorporated this suggestion into PCE 5.
    3. Comment: Riparian vegetation in the immediate vicinity of the 
spring openings are likely not the food source for any of the three 
invertebrate species, as described in PCE 4. Aquatic invertebrates 
typically feed on plant material well after it has been mechanically 
broken down. Flow in the vicinity of spring openings would quickly 
carry away leaf litter and other plant material before it could become 
mechanically broken down. The detritus that comprises the food source 
for the Comal Springs dryopid beetle is most likely introduced into the 
aquifer at recharge points far upstream of the spring openings (i.e., 
within the recharge area of the aquifer). Similarly, the food source 
for the Peck's cave amphipod is likely found within the Edwards 
Aquifer. Specifically, the food source may be composed of material that 
enters through the recharge area of the aquifer and the many other 
organisms that co-occur within the aquifer. Aquatic macrophyte (i.e., 
large plant) roots may be a source of detritus for invertebrates in a 
spring-run downstream of a spring opening. However, the roots are 
likely not the food sources for the Peck's cave amphipod, because the 
amphipod is found only near the spring openings and within the aquifer. 
Because the riparian habitats around the springs are likely not 
influencing these three species, the critical habitat designations only 
represent the smallest part of their habitats or range.
    Our Response: The Comal Springs dryopid beetle has only been 
observed near spring outlets. Adults have been

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found on rocks and cotton cloth lures in spring openings. They have 
also been observed on rotting wood above spring upwellings near tree 
roots growing just under the gravel substrate more than 16 feet (ft) (5 
meters (m)) from the shore of Landa Lake (Gibson et al. 2006, p. 3). 
Larvae of this species do not have gills and are considered 
terrestrial, as they typically inhabit moist soil along stream banks 
(Brown 1987, p. 253; Ulrich 1986, p. 325). Because of these 
characteristics, we believe Comal Springs dryopid beetle larvae feed on 
roots and decaying vegetation in areas just above the aquifer (i.e., 
subsurface area) water line. We believe the Peck's cave amphipod likely 
consumes both animals and plants, and feeds both within the aquifer and 
on detritus in areas near spring outlets where plant roots interface 
with spring water (Gibson 2006, p. 1). Therefore, we believe critical 
habitat should include the riparian vegetation as a food source for the 
Peck's cave amphipod and Comal Springs dryopid beetle.
    4. Comment: The designation of 50-ft distances around spring 
openings seems reasonable to protect and maintain the subsurface 
vegetation profile in the immediate area of the springs; however, the 
detrital food base could come from sources at greater distances.
    Our Response: Although there may be some contribution of detrital 
food sources from greater distances within the aquifer, we are unaware 
of any data that indicate this. As explained in our response to Comment 
3 above, there is available information that suggests that riparian 
vegetation near the spring openings is an important habitat component 
for the Peck's cave amphipod, Comal Springs dryopid beetle, and Comal 
Springs riffle beetle, and may provide a source of food for these 
species.
    5. Comment: Under PCE 1, the pesticides mentioned only refer to 
classes such as organochlorines, organophosphates, and chlorinated 
hydrocarbons. The Service should consider pesticide classes such as 
insect growth regulators as well as pharmaceuticals that could enter 
groundwater sources. The Service should clarify the differences between 
these compounds and their potential effects on the listed species.
    Our Response: We have added pharmaceuticals to the list of 
potential pollutants discussed under PCE 1 in response to this comment. 
There are no scientific studies available on the potential effects that 
each of these pollutants have on the Peck's cave amphipod, Comal 
Springs dryopid beetle, and Comal Springs riffle beetle, so we are 
unable to address the potential effects of these pollutants in the 
final rule. We acknowledge the importance of maintaining high water 
quality within the Edwards Aquifer, and we will work to evaluate and 
address the effects of pollutants during the recovery planning and 
implementation processes for these species.
    6. Comment: With regard to PCE 1, Hueco Springs and Fern Bank 
Springs may be influenced by storm water. Can the claim be made that 
the spring systems are characterized by high water quality?
    Our Response: Spring systems in general may have some short-term 
changes in water quality after storm events. Hueco Springs and Fern 
Bank Springs are smaller in size and may have more local recharge 
features than Comal Springs and San Marcos Springs. Although these 
characteristics may make them more susceptible to short-term changes in 
water quality after storm events, the Service has no data to indicate 
that these temporary changes negatively affect the species that occur 
near the spring openings. Comal and San Marcos Springs may also be 
affected by local runoff from storm events based on tracer tests by the 
Edwards Aquifer Authority. We consider all of the spring systems 
occupied by the Peck's cave amphipod, Comal Springs dryopid beetle, and 
Comal Springs riffle beetle to have high water quality.
    7. Comment: There is a strong likelihood that additional 
populations of the Comal Springs riffle beetle occur in or around the 
various spring outlets in the bottoms of Spring Lake and Landa Lake, 
where substrate is sufficiently coarse to serve as habitat.
    Our Response: We believe this is addressed through the designation 
of all aquatic habitat within Landa Lake where springs are present and 
PCEs are known to exist for the Peck's cave amphipod and Comal Springs 
dryopid beetle. However, this point was clarified in the Critical 
Habitat Designation section of this final rule describing the 
designated critical habitat areas within Landa Lake for the Comal 
Springs Unit in Comal County, Texas.
    8. Comment: Paragraph 8 under ``Adverse Modification Standard'' 
states that ``ongoing human activities that occur outside the proposed 
critical habitat are unlikely to threaten the physical and biological 
features of the proposed critical habitat.'' However, if there is an 
increase in pumping water from the aquifer prior to the ruling on 
critical habitat, then that new pumping may impact PCEs 2, 3, and 5.
    Our Response: We agree with the commenter and have clarified the 
language in the Effects of Critical Habitat Designation section that 
groundwater pumping from the Edwards Aquifer may affect critical 
habitat and require section 7 consultation.
    9. Comment: The critical habitat designations may provide benefits 
to the Peck's cave amphipod, Comal Springs dryopid beetle, and Comal 
Springs riffle beetle on a local scale (i.e., in the immediate area of 
the spring openings), but they do not offer protections to the Edwards 
Aquifer ecosystem. Critical habitat for these species should be 
extended to include the entire Edwards Aquifer, including subsurface 
areas. Until parts of the Edwards Aquifer can be shown to not have 
populations of these two species, the most sensible solution is to 
assume that the entire aquifer is critical habitat. Also, there are 
ecosystem processes (e.g., organic matter inputs, interactions with 
other species, nutrient availability) that are not addressed by the 
PCEs and may be addressed by designating the entire Edwards Aquifer.
    Our Response: Organic matter and nutrient availability are 
addressed in PCE 4. We recognize the importance of maintaining 
ecosystem integrity and functionality and implementing strategies to 
protect the entire Edwards Aquifer. However, we reviewed all available 
information that pertains to the occurrence of the Peck's cave 
amphipod, Comal Springs dryopid beetle, and Comal Springs riffle 
beetle. Although the Peck's cave amphipod and the Comal Springs dryopid 
beetle are believed to be subterranean, we have no information 
available to show that the entire Edwards Aquifer ecosystem is occupied 
by the species. Nor do we believe the PCEs are found throughout the 
aquifer. We cannot demonstrate that the entire aquifer is essential to 
the conservation of the species. Although the entire aquifer has not 
been designated as critical habitat, Federal activities outside of 
designated critical habitat areas are subject to review under section 7 
of the Act if these activities may adversely affect the PCEs within the 
critical habitat designation.
    10. Comment: The PCEs do nothing to safeguard the source of the 
water--the Edwards Aquifer, upon which the invertebrates depend. A 
comprehensive plan for the Edwards Aquifer with constraints on 
groundwater pumping and pollution of recharge should be developed.
    Our Response: Designating critical habitat is only one means to aid 
in the habitat conservation of listed species. Efforts to address 
threats to the Edwards Aquifer can be undertaken through the

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recovery implementation process for these and the other federally-
listed species that depend on the aquifer for their survival. For 
example, we are working with a large number of partner agencies and 
organizations, including the Edwards Aquifer Authority, to develop an 
Edwards Aquifer Recovery Implementation Program (RIP) to address 
threats to the Edwards Aquifer. The Edwards Aquifer Authority (EAA) is 
the agency with the responsibility to manage, enhance, and protect the 
Edwards Aquifer system through a variety of mechanisms including the 
issuing of pumping permits for use of water from the aquifer. We intend 
to continue our close work with the EAA and others for conservation of 
the springs that flow from the Edwards Aquifer.

Public Comments

    11. Comment: It seems imprudent to designate critical habitat for 
the Peck's cave amphipod, Comal Springs dryopid beetle, and Comal 
Springs riffle beetle, when this would provide no benefit to the 
species beyond that provided by listing of the species and any 
subsequent evaluation of activities in light of section 7 consultation 
requirements.
    Our Response: The Role of Critical Habitat in Actual Practice of 
Administering and Implementing the Act section in the proposed rule has 
been removed from this final rule. We recognize some benefits to 
critical habitat designations. Federal activities outside of designated 
critical habitat areas are subject to review under section 7 of the Act 
if these activities may adversely affect the PCEs within the critical 
habitat designation. The Ninth Circuit Court's decision in Gifford 
Pinchot Task Force v. United States Fish and Wildlife Service, 378 F.3d 
1059 (9th Cir 2004) (hereinafter Gifford Pinchot) requires 
consideration of the recovery of species. Thus, under this court 
ruling, and our implementation of Section 7 of the Act, critical 
habitat designations may provide greater benefits to the recovery of a 
species. Also, we have found that critical habitat designations serve 
to educate landowners, State and local governments, and the public 
regarding the potential conservation value of the areas designated.
    12. Comment: This critical habitat designation is not beneficial, 
especially in light of a recent initiation of a RIP for the endangered 
species of the Edwards Aquifer under the encouragement of the Service.
    Our Response: In designating critical habitat areas, we have 
reviewed the overall approach to the conservation of the Peck's cave 
amphipod, Comal Springs dryopid beetle, and Comal Springs riffle beetle 
undertaken by local, Federal, and State agencies; and by private 
organizations operating within the species' range since their listing. 
As noted above, we are very supportive of the RIP process; however, 
this process is in its initial stages of development, and therefore we 
were not able to consider the potential conservation benefits of the 
RIP to these species in our critical habitat determination. Also, as 
stated in our response to Comment 11 above, we recognize several 
benefits to designating critical habitat.
    13. Comment: In the Critical Habitat section of the proposed rule, 
the Service understates the extent to which critical habitat 
designations provide additional protection for species above and beyond 
the prohibition of take that comes with federally listing species as 
endangered or threatened. This approach is legally and scientifically 
unsubstantiated, and it shortchanges the goals of the Act to provide 
for the conservation and recovery of listed species.
    Our Response: As discussed above, we agree that the designation of 
critical habitat can serve positive purposes, but we also believe it is 
only one tool for managing listed species' habitat. In addition to the 
designation of critical habitat, we have determined that other 
conservation mechanisms, including the recovery planning process, 
section 6 funding to States, section 7 consultations, management plans, 
Safe Harbor agreements, and other on-the-ground strategies, contribute 
to species' conservation. We will continue to work with local partner 
organizations (such as the Edwards Aquifer Authority, San Antonio Water 
System, local municipalities, Texas Parks and Wildlife Department, and 
others) through the RIP, to develop means for voluntary conservation of 
habitats for these listed species. We believe these other conservation 
measures often provide incentives for project planners and greater 
conservation benefits than critical habitat designation.
    14. Comment: There does not appear to be a clear correlation 
between the needs of the Peck's cave amphipod, Comal Springs dryopid 
beetle, and Comal Springs riffle beetle and particular spring flow 
conditions to require such special management considerations.
    Our Response: There is information to indicate that availability 
and access to water at the spring sites are important factors in 
maintaining the life history functions (i.e., those functions that are 
dependent on high water quality, adequate water temperature, and 
adequate dissolved oxygen levels) of the Peck's cave amphipod, Comal 
Springs dryopid beetle, and Comal Springs riffle beetle, as described 
under PCEs 1, 2, and 3. We believe that prolonged cessation of spring 
flows as a result of the loss of hydrological connectivity within the 
aquifer may require special management considerations, such as 
maintenance of sustainable groundwater use and subsurface flows.
    15. Comment: The proposed rule only designates as critical habitat 
the aquatic areas where the Peck's cave amphipod, Comal Springs dryopid 
beetle, and Comal Springs riffle beetle are found, plus a 50-ft 
distance from the spring outlets. The proposed rule does nothing to 
control water quality impacts from activities occurring in the 
contributing and recharge zones of the aquifer, limiting the critical 
habitat to only a 50-ft buffer beyond the spring outlets to protect the 
species' food sources. Such a buffer would fail to protect the water 
quality in the aquatic habitat. Typical buffers to protect water 
quality tend to be at least 100 ft on each side of sensitive waters. 
The critical habitat should likewise at least accommodate such extended 
buffers to help protect water quality in the aquatic habitat.
    Our Response: We proposed designating critical habitat in areas 
that we have determined are occupied by the Peck's cave amphipod, Comal 
Springs dryopid beetle, and Comal Springs riffle beetle; contain 
sufficient PCEs to support life-history functions essential for the 
conservation of the species; and require special management or 
protection. The 50-ft (15.2-m) distances define the lateral extent of 
critical habitat that contains PCEs with respect to food sources in 
root/water interfaces. Use of a 100-ft (30.4-m) buffer for this 
critical habitat designation would extend the boundary to include areas 
not known to contain the PCEs; therefore, use of this larger buffer is 
not consistent with the criteria used to identify critical habitat.
    The designation of critical habitat requires Federal agencies to 
consult with us when activities they fund, authorize, or carry out may 
affect the critical habitat of a listed species. Consultation is 
required where projects may (indirectly or directly) adversely affect 
critical habitat, even if those projects occur outside designated 
critical habitat (e.g., the contributing and recharge zones of the 
aquifer).
    16. Comment: The final rule should include the minimal spring flow 
rates provided in the EAA's 2005 Draft Habitat Conservation Plan.
    Our Response: The EAA's 2005 Draft Habitat Conservation Plan (HCP) 
has not

[[Page 39252]]

been finalized, nor have we issued a permit for the EAA. We have not 
analyzed spring flow rates from the 2005 Draft HCP for effects to the 
Peck's cave amphipod, Comal Springs dryopid beetle, and Comal Springs 
riffle beetle. In addition, flow from Fern Bank Springs is from the 
Trinity Aquifer, not the Edwards Aquifer. Thus, the draft EAA HCP does 
not address the maintenance of Fern Bank Springs habitat and that 
population of the Comal Springs dryopid beetle.
    17. Comment: The economic analysis should include the benefits of 
designating critical habitat for the invertebrate species. Without 
estimating the benefits to designation, the costs seem unreasonably 
high, and therefore paint the conservation effort in a negative light. 
A full benefits analysis should include direct, indirect, and non-use 
benefits.
    Our Response: As stated in Chapter 1 of the final economic 
analysis, a potential direct benefit of the rulemaking is the potential 
to enhance conservation of the species. The published economics 
literature has documented that social welfare benefits can result from 
the conservation and recovery of endangered and threatened species. 
However, in its guidance for implementing Executive Order 12866, OMB 
acknowledges that it may not be feasible to monetize, or even quantify, 
the benefits of environmental regulations due to either an absence of 
defensible, relevant studies or a lack of resources on the implementing 
agency's part to conduct new research. Rather than rely on economic 
measures, we believe that the direct benefits of the proposed rule are 
best expressed in biological terms that can be weighed against the 
expected cost impacts of the rulemaking.
    Where data are available, the economic analysis does discuss and 
attempt to measure the net economic impacts of this rulemaking. For 
example, Chapter 2 discusses the reduction in net economic benefit to 
municipal and industrial water users that may occur with pumping 
restrictions. The analysis also discusses the fact that higher 
springflow levels are anticipated to contribute to river flows 
downstream of the aquifer, which will make more water available to 
municipalities, industries, and farmers who use river water. Whether 
the users will use the water to an economic benefit depends on a myriad 
of factors that are beyond the scope of the economic analysis; however, 
the analysis notes that increased springflows are likely to generate 
potentially significant ecological and/or recreational benefits.
    18. Comment: Section 1.34(c) of the EAA Act of 1993, as amended, 
notes that a ``holder of a permit for irrigation use may not lease more 
than 50 percent of the irrigation rights initially permitted. The 
user's remaining irrigation water rights must be used in accordance 
with the original permit and must pass with transfer of the irrigated 
land.'' Paragraph 83 of the economic analysis makes it unclear whether 
this restriction on irrigation transfers was considered in the 
analysis.
    Our Response: The analysis predicts that water users, when faced 
with lowered water permit availability, will sell or lease their water 
rights to higher-valued uses. The value of water in the planning area 
is assumed to rise faster than the profitability of irrigated crops, 
and thus agricultural water will be traded from agriculture to 
municipal and industrial use, as has been common in the western United 
States. Despite the current restriction on the sale and lease of 
irrigation rights in the Edwards Aquifer, the analysis assumes that the 
Edwards Aquifer Authority will be able to purchase and retire 
sufficient agricultural water rights for the purposes of maintaining 
aquifer levels in the future. While this assumption was implicit in the 
draft economic analysis, it is now stated explicitly in the final 
economic analysis.
    19. Comment: PCE 5 concludes that a gravel substrate is necessary 
for the Comal Springs riffle beetle because specimens were not found in 
Spring Run 4 where the substrate was primarily sand and not gravel. The 
Service has drawn this conclusion from a preliminary correlation 
reported in a study done by Bowles et al. (2003), and therefore, a 
definitive conclusion may inaccurately represent the findings. A number 
of abiotic and biotic factors, including flow rates, competition with 
other species, and other life-history traits may all have been 
contributing factors to the absence of the beetle in Spring Run 4.
    Our Response: In reviewing the best available information, we found 
that additional searches for the Comal Springs riffle beetle in Spring 
Run 3 and the western shoreline habitat of Landa Lake yielded results 
similar to those found by Bowles et al. (2003) with regard to the 
occurrence of this species on gravel, cobble, and rock substrates 
outside of areas with sedimentation or silt buildup (BIO-WEST 2002a, p. 
11). We included this additional reference within the discussion of PCE 
5. By referencing the survey results of Bowles et al. (2003), it was 
not our intention to imply that the Comal Springs riffle beetle could 
never be found in smaller sized substrates. Although we cannot 
determine the full scope of substrate habitat restrictions for the 
Comal Springs riffle beetle from the information provided in the above 
referenced reports, it does indicate that gravel, cobble, and rock 
substrates that are free of silt and sedimentation are essential 
features of the habitat for this species.
    20. Comment: ``Global warming'' is another impact to consider in 
protecting water quantity in the habitat of the Peck's cave amphipod, 
Comal Springs dryopid beetle, and Comal Springs riffle beetle. At least 
one science team has predicted higher temperatures, and thus, higher 
evaporation rates, and reduced rainfall for central Texas as a result 
of global warming.
    Our Response: We recognize that global climate change may affect 
global temperatures, and that this in turn can cause other climatic 
changes, such as changes in the amount and pattern of precipitation. 
However, the consequences of such changes to the Peck's cave amphipod, 
Comal Springs dryopid beetle, and Comal Springs riffle beetle are 
unknown. We therefore believe this issue to be outside the scope of the 
critical habitat designation for these species.

Summary of Changes From Proposed Rule

    Based upon our review of the peer review and public comments, 
economic analysis, and any new relevant information that may have 
become available since the publication of the proposal, we reevaluated 
our proposed critical habitat designation for the Peck's cave amphipod, 
Comal Springs dryopid beetle, and Comal Springs riffle beetle. We made 
no changes to the critical habitat designation as described in the 
proposed rule. Other than minor clarifications and incorporation of 
additional information on the species' biology, status, and threats, 
this final rule differs from the proposal by the following:
    (1) We modified the primary constituent elements for clarity and to 
reflect additional information received during the public comment 
period. Specifically we added, ``other compounds containing 
surfactants'' and ``pharmaceuticals and veterinary medicines,'' under 
the list of potential pollutants under PCE 1. Under PCE 3, we added the 
phrase, ``that allows for adequate spring flows'' to clarify the intent 
of the hydrologic regime. For PCE 4, we added, ``living plant material, 
algae, fungi, bacteria and other

[[Page 39253]]

microorganisms,'' to the list of potential food items.
    (2) We made technical corrections to some of the information found 
in the Primary Constituent Elements, Background, and Criteria Used to 
Identify Critical Habitat sections of this rule.

Critical Habitat

    Critical habitat is defined in section 3 of the Act as--(i) The 
specific areas within the geographical area occupied by a species, at 
the time it is listed in accordance with the Act, on which are found 
those physical or biological features (I) Essential to the conservation 
of the species and (II) that may require special management 
considerations or protection; and (ii) specific areas outside the 
geographical area occupied by a species at the time it is listed, upon 
a determination that such areas are essential for the conservation of 
the species. Conservation, as defined under section 3 of the Act means 
to use and the use of all methods and procedures that are necessary to 
bring any endangered species or threatened species to the point at 
which the measures provided under the Act are no longer necessary. Such 
methods and procedures include, but are not limited to, all activities 
associated with scientific resources management such as research, 
census, law enforcement, habitat acquisition and maintenance, 
propagation, live trapping, and transplantation, and, in the 
extraordinary case where population pressures within a given ecosystem 
cannot be otherwise relieved, may include regulated taking.
    Critical habitat receives protection under section 7 of the Act 
through the prohibition against destruction or adverse modification of 
critical habitat with regard to actions carried out, funded, or 
authorized by a Federal agency. Section 7 of the Act requires 
consultation on Federal actions that are likely to result in the 
destruction or adverse modification of critical habitat. The 
designation of critical habitat does not affect land ownership or 
establish a refuge, wilderness, reserve, preserve, or other 
conservation area. Such designation does not allow government or public 
access to private lands. Section 7 of the Act is a purely protective 
measure and does not require implementation of restoration, recovery, 
or enhancement measures.
    To be included in a critical habitat designation, the habitat 
within the area occupied by the species must first have features that 
are essential to the conservation of the species. Critical habitat 
designations identify, to the extent known using the best scientific 
data available, habitat areas that provide essential life cycle needs 
of the species (i.e., areas on which are found the primary constituent 
elements (PCEs), as defined at 50 CFR 424.12(b)).
    Occupied habitat may be included in critical habitat only if the 
essential features thereon may require special management or 
protection. Furthermore, when the best available scientific data do not 
demonstrate that the conservation needs of the species require 
additional areas, we cannot designate critical habitat in areas outside 
the geographical area occupied by the species at the time of listing. 
However, an area currently occupied by the species but not occupied at 
the time of listing, will likely be essential to the conservation of 
the species and, therefore, may be included in the critical habitat 
designation.
    The Service's Policy on Information Standards Under the Endangered 
Species Act, published in the Federal Register on July 1, 1994 (59 FR 
34271), and Section 515 of the Treasury and General Government 
Appropriations Act for Fiscal Year 2001 (Pub. L. 106-554; H.R. 5658) 
and the associated Information Quality Guidelines issued by the 
Service, provide criteria, establish procedures, and provide guidance 
to ensure that decisions made by the Service represent the best 
scientific data available. They require Service biologists, to the 
extent consistent with the Act and with the use of the best scientific 
data available, to use primary and original sources of information as 
the basis for recommendations to designate critical habitat. When 
determining which areas are critical habitat, a primary source of 
information is generally the listing package for the species. 
Additional information sources may include the recovery plan for the 
species, articles in peer-reviewed journals, conservation plans 
developed by States and counties, scientific status surveys and 
studies, biological assessments, or other unpublished materials and 
expert opinion or personal knowledge. All information is used in 
accordance with the provisions of Section 515 of the Treasury and 
General Government Appropriations Act for Fiscal Year 2001 (Pub. L. 
106-554; H.R. 5658) and the associated Information Quality Guidelines 
issued by the Service.
    Section 4 of the Act requires that we designate critical habitat on 
the basis of the best scientific and commercial data available. Habitat 
is often dynamic, and species may move from one area to another over 
time. Furthermore, we recognize that designation of critical habitat 
may not include all of the habitat areas that may eventually be 
determined to be necessary for the recovery of the species. For these 
reasons, critical habitat designations do not signal that habitat 
outside the designation is unimportant or may not be required for 
recovery.
    Areas that support populations, but are outside the critical 
habitat designation, will continue to be subject to conservation 
actions implemented under section 7(a)(1) of the Act and to the 
regulatory protections afforded by the section 7(a)(2) jeopardy 
standard, as determined on the basis of the best available information 
at the time of the action. Federally funded or permitted projects 
affecting listed species outside their designated critical habitat 
areas may still result in jeopardy findings in some cases. Similarly, 
critical habitat designations made on the basis of the best available 
information at the time of designation will not control the direction 
and substance of future recovery plans, habitat conservation plans, or 
other species conservation planning efforts if new information 
available to these planning efforts calls for a different outcome.

Primary Constituent Elements

    In accordance with section 3(5)(A)(i) of the Act and regulations at 
50 CFR 424.12, in determining which areas to designate as critical 
habitat, we consider those physical and biological features (known as 
primary constituent elements) that are essential to the conservation of 
the species, and within areas occupied by the species at the time of 
listing, that may require special management considerations or 
protection. These include, but are not limited to: (1) Space for 
individual and population growth, and for normal behavior; (2) food, 
water, air, light, minerals, or other nutritional or physiological 
requirements; (3) cover or shelter; (4) sites for breeding, 
reproduction, and rearing (or development) of offspring; and (5) 
habitats that are protected from disturbance or are representative of 
the historic geographical and ecological distributions of a species.
    The specific primary constituent elements required for the Peck's 
cave amphipod, Comal Springs dryopid beetle, and Comal Springs riffle 
beetle are derived from the biological needs of these species as 
described in the Background section of this final rule and in the 
December 18, 1997, final rule listing these species (62 FR 66295).
    Pursuant to the Act and its implementing regulations, we are 
required to identify the known physical

[[Page 39254]]

and biological features (PCEs) within the geographical area occupied at 
the time of listing that are essential to the conservation of the 
Peck's cave amphipod, Comal Springs dryopid beetle, and Comal Springs 
riffle beetle, which may require special management considerations or 
protections. All areas designated as critical habitat for Peck's cave 
amphipod, Comal Springs dryopid beetle, and Comal Springs riffle beetle 
are occupied, within the species' historic geographic ranges, and 
contain sufficient PCEs to support at least one life history function.
    Based on our current knowledge of the life history, biology, and 
ecology of these species, and the habitat requirements for sustaining 
the essential life history functions of these species, we have 
determined that the Peck's cave amphipod, Comal Springs dryopid beetle, 
and Comal Springs riffle beetle require the PCEs described below. The 
PCEs apply to all three species unless otherwise noted.
    PCE 1. High-quality water with no or minimal levels of pollutants, 
such as soaps and detergents (Brown 1987, p. 261) and other compounds 
containing surfactants, heavy metals, pesticides, fertilizer nutrients, 
petroleum hydrocarbons, pharmaceuticals and veterinary medicines, and 
semi-volatile compounds, such as industrial cleaning agents, and 
including:
    (a) Low salinity with total dissolved solids that generally range 
from about 307 to 368 milligrams per liter (mg/L); and
    (b) Low turbidity that generally is less than 5 nephelometric 
(measurement of turbidity in a water sample by passing light through 
the sample and measuring the amount of the light that is deflected) 
turbidity units (NTUs).
    These spring-adapted aquatic species live in high-quality 
unpolluted groundwater and spring outflows that have low levels of 
salinity and turbidity. High-quality discharge water from springs and 
adjacent subterranean areas also help sustain habitat components, such 
as riparian vegetation, that are essential to the Peck's cave amphipod, 
Comal Springs dryopid beetle, and Comal Springs riffle beetle. The two 
beetle species are thought to require water with adequate levels of 
dissolved oxygen for respiration (Brown 1987, p. 260; Arsuffi 1993, p. 
18). Amphipods generally require relatively high concentrations of 
oxygen and may serve as an indicator of good water quality (Arsuffi 
1993, p. 15). While definitive studies on the limits of tolerance and 
preference for these aquatic invertebrates have not been completed, the 
aquatic invertebrates are exclusively found in aquatic habitats with 
constant temperature, low salinity, low turbidity, and extremely low 
levels of pollutants. In particular, respiration in the riffle beetle 
may be inhibited by pollutants such as soaps and detergents that can 
affect its respiratory mechanism (Brown 1987, p. 261). The dryopid 
beetle may also be affected by these particular pollutants, since this 
species shares a similar respiratory structure (Arsuffi 1993, p. 18). 
However, biological tolerances for this species are not understood due 
to its existence within a subterranean habitat.
    Based on available literature, we believe that the PCE for high 
water quality in the critical habitat for these species should have an 
approximate range of salinity of about 307 to 368 mg/L and a turbidity 
of less than 5 NTUs. Fahlquist and Slattery (1997, p. 3) reported a low 
salinity (as measured by total dissolved solids) as low as 307 mg/L at 
Comal Springs, and Slattery and Fahlquist (1997, p. 4) found that San 
Marcos Springs had a low salinity of 328 mg/L. The two springs also 
have a low turbidity of less than 5 NTUs (Fahlquist and Slattery 1997, 
p. 3; Slattery and Fahlquist 1997, p. 4). Brune (1975, p. 94) reported 
a salinity for Hueco Springs of 322 mg/L. The highest salinity (as 
determined by analysis of total dissolved solids) that we have found 
associated with any of these invertebrates was 368 mg/L, which was 
reported from Fern Bank Springs on April 28, 2005 (Texas Water 
Development Board 2006, p. 1).
    PCE 2. Aquifer water temperatures that range from approximately 68 
to 75 [deg]F (20 to 24 [deg]C).
    The three listed invertebrate species complete their life cycle 
functions within a relatively narrow temperature range; water 
temperatures outside of this range could be harmful to these 
invertebrates. The temperature of spring water emerging from the 
Edwards Aquifer at Comal Springs and San Marcos Springs ordinarily 
occurs within a narrow range of approximately 72 to 75 [deg]F (22 to 24 
[deg]C) (Fahlquist and Slattery 1997, pp. 3-4; Groeger et al. 1997, pp. 
282-283). Hueco Springs and Fern Bank Springs have temperature records 
of 68 to 71 [deg]F (20 to 22 [deg]C) (George 1952, p. 52; Brune 1975, 
p. 94; Texas Water Development Board 2006, p. 1).
    PCE 3. A hydrologic regime that allows for adequate spring flows 
that provide levels of dissolved oxygen in the approximate range of 4.0 
to 10.0 mg/L for respiration of the Comal Springs riffle beetle and 
Comal Springs dryopid beetle.
    Respiration in most beetle species belonging to the family Elmidae 
(which includes the Comal Springs riffle beetle) typically requires 
flowing waters highly saturated with dissolved oxygen (Brown 1987, p. 
260). As a consequence, riffle beetles are most commonly associated 
with flowing water that has shallow riffles (small waves) or rapids 
(Brown 1987, p. 253). Although there are not available data to support 
a correlation between minimum spring flows and survival or other 
sublethal, adverse effects of low or no spring flows on these species, 
there is information to indicate that availability and access to water 
at the spring sites are important factors in their respiration. For 
example, riffle beetles are known to be restricted to waters with high 
dissolved oxygen due to their reliance on a plastron (a thin sheet of 
air) that is held next to the underside of the body surface by a mass 
of minute, hydrophobic (tending to repel and not absorb water) hairs. 
The plastron functions as a gill by allowing oxygen to diffuse 
passively from water into the plastron and replace oxygen absorbed 
during respiration (Brown 1987, p. 260). Beetle species in the Elmidae 
family are generally limited to well-aerated water environments since 
gaseous exchange with a plastron can actually be reversed in oxygen-
depleted waters (Brown 1987, p. 260; Ward 1992, p. 130). The Comal 
Springs dryopid beetle also relies on a plastron for respiration, and 
this beetle species may also be affected by changes in oxygen levels 
caused by habitat modification (Arsuffi 1993, pp. 17-18).
    PCE 4. Food supply that includes detritus (decomposed materials), 
leaf litter, living plant material, algae, fungi, bacteria and other 
microorganisms, and decaying roots.
    Feeding ecology in the Elmidae family varies among species, but 
most riffle beetles, as larvae and adults, feed on algae and detritus 
scraped from the substrates within their habitat (Brown 1987, p. 262). 
Specific food requirements for each of the three invertebrate species 
are unknown. However, the Peck's cave amphipod and dryopid beetle are 
most commonly found in areas where plant roots are inundated or 
otherwise influenced by aquifer water. Potential food sources for all 
three species in these areas include detritus (decomposed materials), 
leaf litter, and decaying roots; however, it is possible that these 
species feed on bacteria and fungi associated with decaying plant 
material. Both beetle species may be detritivores (detritus-feeding 
animals) that consume detrital materials in spring-influenced riparian 
zones (Brown 1987, p. 262; Randy

[[Page 39255]]

Gibson 2006, pp. 1-2). The best information available indicates the 
Peck's cave amphipod is an omnivore (a species capable of consuming 
both animals and plants), which would enable the amphipod to exist as a 
scavenger or predator inside the aquifer in addition to using detritus 
in areas near spring outlets where plant roots interface with spring 
water (Gibson 2006, p. 1).
    Trees and shrubs in riparian areas adjacent to the spring system 
may provide plant growth necessary to maintain food sources such as 
decaying material for these invertebrates. Roots from trees and shrubs 
in proximity to spring outlets are most likely to penetrate underground 
down to the water pools, where these roots can serve as habitat for the 
amphipod and dryopid beetle. We believe relatively intact riparian 
areas with trees and shrubs may provide an important function within 
areas designated for critical habitat of the two subterranean species. 
According to patterns of plant canopies as determined from aerial 
photographs, trees and shrubs (and their root systems) are generally 
within 50 ft (15.2 m) of the edge of water in these spring systems.
    PCE 5. Bottom substrate in surface water habitat of the Comal 
Springs riffle beetle that is free of sand and silt, and is composed of 
gravel and cobble ranging in size between 0.3 to 5.0 inches (in) (8-128 
millimeters (mm)).
    Although Comal Springs riffle beetles occur in conjunction with a 
variety of bottom substrates in surface water habitat, Bowles et al. 
(2003, p. 372) found that these beetles mainly occurred in areas with 
gravel and cobble ranging between 0.3 to 5.0 in (8-128 mm). Collection 
efforts in areas of high sedimentation generally do not yield riffle 
beetles (Bowles et al. 2003, p. 376). Similarly, BIO-WEST (2002, p. 11) 
conducted surveys for the Comal Springs riffle beetle in the Comal 
system and found that individuals of this species were restricted to 
habitat areas that consisted of rocks and gravel. They also observed 
that riffle beetles were only found in areas that were largely silt-
free (BIO-WEST 2002, p.11).
    This designation is designed for the conservation of PCEs necessary 
to support the life history functions that were the basis for the 
proposal and the areas containing those PCEs. Because not all life 
history functions require all of the PCEs, not all of the designated 
critical habitat may contain all the PCEs.
    Units are designated based on sufficient PCEs being present to 
support at least one of each of the species' life history functions. 
Some units contain all PCEs and support multiple life processes, while 
some units contain only a portion of the PCEs necessary to support the 
species' particular use of that habitat. Where a subset of the PCEs is 
present at the time of designation, this rule protects those PCEs and 
thus the conservation function of the habitat.

Special Management Considerations or Protections

    When designating critical habitat, we assess whether the areas 
determined to be occupied at the time of listing contain the features 
essential to the conservation that may require special management 
considerations or protections. Primary threats to the spring systems 
designated as critical habitat for the three invertebrate species that 
may require special management are summarized in Table 2. The threats 
for individual springs vary according to the degree of urbanization and 
availability of aquifer source water, but possible threats generally 
include prolonged cessation of spring flows (in 1956, Comal Springs at 
New Braunfels did not flow from mid-June to November (U.S. Army Corps 
of Engineers 1965)) as a result of the loss of hydrological 
connectivity within the aquifer (e.g., groundwater pumping, excavation, 
concrete filling), pollutants (e.g., stormwater drainage, pesticide 
use), and non-native species (e.g., biological control, sport fish 
stocking). To address the threats affecting these three invertebrate 
species, certain special management actions may be required--for 
example, maintenance of sustainable groundwater use and subsurface 
flows, use of adequate buffers for water quality protection, selection 
of appropriate pesticides, and implementation of integrated pest 
management plans.

Criteria Used To Identify Critical Habitat

    As required by section 4(b)(1)(A) of the Act, we use the best 
scientific and commercial data available in determining areas that 
contain the features that are essential to the conservation of the 
Peck's cave amphipod, Comal Springs dryopid beetle, and Comal Springs 
riffle beetle.
    We reviewed available information that pertains to the presence and 
habitat requirements of these three invertebrate species, such as 
research published in peer-reviewed articles, data in reports submitted 
during section 7 consultations, contracted surveys, agency reports and 
databases, and aerial photographs. Information that has been reviewed 
includes, but is not limited to: Holsinger (1967), Bosse et al. (1988), 
Barr and Spangler (1992), Arsuffi (1993), Barr (1993), BIO-WEST (2001, 
2002a, 2002b, 2003, 2004), Bowles et al. (2003), Fries et al. (2004), 
and Krejca (2005). As part of the process, we also reviewed the overall 
approach to conservation of these species undertaken by local, State, 
and Federal agencies, and private and non-governmental organizations 
operating within the species' range since their listing in 1997.
    Peck's cave amphipod--The Peck's cave amphipod has been found in 
Comal Springs and Hueco Springs, which are both located in Comal 
County. While limited data have been collected on the extent to which 
this subterranean species exists below ground away from outlets of 
spring systems, other species within the genus Stygobromus are known to 
be widely distributed in groundwaters and cave systems (Holsinger 1972, 
p. 65). Although this species could possibly range throughout the 4-
mile (mi) (8-kilometer (km)) distance between the two habitat spring 
systems through the ``honeycomb'' pores and conduits of the Edwards 
Aquifer, it is not known to what extent below-ground connections 
between Comal Springs and Hueco Springs are inhabited by the amphipod. 
The only specific location information we have for this species 
regarding its distribution in the aquifer, aside from where they exit 
the aquifer via spring openings, is an observation of Peck's cave 
amphipods at the bottom of a well (Panther Canyon well) that is located 
approximately 360 ft (110 m) away from the head outlet of Spring Run 
No. 1 (as designated in Barr and Spangler 1992, Fig. 1 on p. 42) in the 
Comal Springs complex (Krejca 2005, p. 83).
    We are designating critical habitat for the Peck's cave amphipod in 
aquatic habitat associated with both Comal Springs and Hueco Springs. 
To include amphipod food sources in root/water interfaces around spring 
outlets, we also are designating an area consisting of a 50-ft (15.2-m) 
distance from spring outlets of both Comal Springs and Hueco Springs 
(including several satellite springs that are located between the main 
outlet of Hueco Springs and the Guadalupe River). We believe that this 
50-ft distance defines the lateral extent of critical habitat that 
contains PCEs necessary to provide for life functions of the Peck's 
cave amphipod with respect to roots that can penetrate into the 
aquifer. Based on the 50-ft distance, the areas designated for the 
amphipod critical habitat are about 38.1 ac (15.4 ha) at Comal Springs 
and 0.4 ac (0.2 ha) at Hueco Springs. The acreages were calculated with 
a computer-based Geographical Information System (GIS). Designated 
critical habitat does not

[[Page 39256]]

include areas where PCEs do not occur for this species, such as 
buildings, roads, sidewalks, campgrounds, and lawns. Where lakes are 
designated, critical habitat is only designated in a radius of 50 ft 
(15.2 m) around springs and does not include other areas of the lake 
bottom where springs do not occur.
    Comal Springs dryopid beetle--The Comal Springs dryopid beetle has 
been found in only two spring systems, Comal Springs and Fern Bank 
Springs, located in Comal and Hays Counties, respectively. The 
subterranean species is primarily collected near spring outlets (Barr 
and Spangler 1992, p. 41). While the extent to which the dryopid beetle 
inhabits subterranean areas away from spring outlets is unknown, this 
species does not swim and may be limited to relatively short ranges 
within the aquifer. In addition, immature stages of the species are 
thought to be terrestrial (Barr 1993, p. 56); however, they may also 
exist in spring outlets and in subterranean, air-filled chambers, such 
as caves (Barr and Spangler 1992, pp. 51-52). Barr and Spangler (1992, 
p. 41) collected larvae of the dryopid beetle near spring outlets of 
Comal Springs and believed that the larvae were associated with 
ceilings of spring orifices. Extension of the dryopid beetle into the 
aquifer may also be limited by the lack of food materials associated 
with decaying plant roots that occur near spring orifices.
    For critical habitat of the Comal Springs dryopid beetle, we are 
designating aquatic habitat and a 50-ft (15.2-m) distance from spring 
outlets of Comal Springs and Fern Bank Springs. The 50-ft (15.2-m) 
distance is based on evaluations of aerial photographs showing tree and 
shrub canopies occurring in proximity to spring outlets at both spring 
systems. These plant canopies reflect approximate distances where plant 
root systems interface with water flows of the two spring systems. 
Based on the 50-ft (15.2-m) distance, the area designated for dryopid 
beetle critical habitat at Comal Springs is about 38.1 ac (15.4 ha), 
and 1.4 ac (0.6 ha) at Fern Bank Springs. These acreages include 
occupied areas that contain PCEs necessary for life history functions 
of the Comal Springs dryopid beetle. The acreages were calculated with 
GIS. Designated critical habitat does not include areas where PCEs do 
not occur for this species, such as lawns, buildings, roads, parking 
lots, and sidewalks. Where lakes are designated, critical habitat is 
only designated in a radius of 50 ft (15.2 m) around springs and does 
not include other areas of the lake bottom where springs do not occur.
    Comal Springs riffle beetle--For the Comal Springs riffle beetle, 
habitat is primarily restricted to surface water in two impounded 
spring systems that are located within Comal and Hays Counties in 
central Texas. In Comal County, the aquatic beetle species is found in 
various spring outlets and seeps of Comal Springs that occur within the 
spring runs of Landa Lake and within Landa Lake itself, over a linear 
distance of about 0.9 mi (1.4 km). The species has also been found in 
outlets of San Marcos Springs in the upstream portion of Spring Lake in 
Hays County. However, populations of Comal Springs riffle beetles may 
exist elsewhere in Spring Lake since spring systems within the lake are 
interconnected, and sampling to date for the species within the lake 
has been limited.
    For critical habitat of the Comal Springs riffle beetle, we are 
designating an area that encompasses all of the spring outlets that are 
fou