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CFR Citation: 50 CFR Part 17

RIN ID: RIN 1018-AU75

NOTICE: Part III

DOCUMENT ACTION: Final rule.

SUBJECT CATEGORY: 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

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

DOCUMENT 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, springrelated 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).

SUMMARY: Interior Department, Fish and Wildlife Service,

SUPPLEMENTAL INFORMATION

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, nonfunctional) 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 hollowedout spaces, which range in size from honeycomb like pores to large caverns. The San Antonio segment of the aquifer occurs in a crescentshaped 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
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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 cooccur within the aquifer. Aquatic macrophyte (i.e., large plant) roots may be a source of detritus for invertebrates in a springrun 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 50ft 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 shortterm 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 shortterm 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 waterthe 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 [[Page 39251]]
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 ontheground 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 50ft 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 50ft 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 lifehistory functions essential for the conservation of the species; and require special management or protection. The 50ft (15.2m) distances define the lateral extent of critical habitat that contains PCEs with respect to food sources in root/water interfaces. Use of a 100ft (30.4m) 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
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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 nonuse 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 highervalued 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 lifehistory 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 (BIOWEST 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
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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. 106554; 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 peerreviewed 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. 106554; 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
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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. Highquality 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 semivolatile 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 springadapted aquatic species live in highquality unpolluted groundwater and spring outflows that have low levels of salinity and turbidity. Highquality 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. 34; Groeger et al. 1997, pp. 282283). 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 wellaerated 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. 1718).

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 (detritusfeeding animals) that consume detrital materials in springinfluenced riparian zones (Brown 1987, p. 262; Randy
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Gibson 2006, pp. 12). 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) (8128 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 (8128 mm). Collection efforts in areas of high sedimentation generally do not yield riffle beetles (Bowles et al. 2003, p. 376). Similarly, BIOWEST (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 (BIOWEST 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 midJune 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 nonnative species (e.g., biological control, sport fish stocking). To address the threats affecting these three invertebrate species, certain special management actions may be requiredfor 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 peerreviewed 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), BIOWEST (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 nongovernmental organizations operating within the species' range since their listing in 1997.

Peck's cave amphipodThe 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) (8kilometer (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 belowground 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 50ft (15.2m) 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 50ft 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 50ft 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 computerbased Geographical Information System (GIS). Designated critical habitat does not
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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 beetleThe 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, airfilled chambers, such as caves (Barr and Spangler 1992, pp. 5152). 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 50ft (15.2m) distance from spring outlets of Comal Springs and Fern Bank Springs. The 50ft (15.2m) 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 50ft (15.2m) 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 beetleFor 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 found within the same lake (excluding a slough (slack water) portion that lacks spring outlets). Apart from the slough portion, the approximate linear distance of Spring Lake at its greatest length is 0.2 mi (0.3 km). We are designating about 19.8 ac (8.0 ha) of aquatic habitat in Landa Lake and about 10.5 ac (4.3 ha) of aquatic habitat in Spring Lake as critical habitat. These areas contain PCEs necessary for lifehistory functions of the Comal Springs riffle beetle. We did not include the 50ft (15.2m) lateral extent around springs because, unlike the other two species, the riffle beetle is believed to occur on the surface and not subterranean. The acreages were estimated by calculating the crosshatched polygon area in two map figures of these lakes using 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.

When determining critical habitat boundaries, we made every effort to avoid including within those boundaries of the maps contained within this final rule developed areas such as buildings, paved areas, and other structures that lack PCEs for the Peck's cave amphipod, Comal Springs dryopid beetle, or Comal Springs riffle beetle. These efforts included overlaying critical habitat boundaries onto aerial photos to determine the percentage of buildings, lawns, and paved areas that were located within the critical habitat designations. In the few instances that this occurred, these areas were excluded in the text of the critical habitat unit descriptions in the Critical Habitat Designation section of this final rule. The estimated acreages for these areas were so small (i.e., approximately 2 percent or less of the critical habitat units involved), it was not practical to exclude them from the GIS coordinates provided for the designated critical habitat units in this final rule. We believe that eliminating buildings, lawns, and paved areas in the text of the critical habitat descriptions was the most feasible means of excluding these areas from the designations and provided a clearer indication of the exclusions for the public. The scale of the maps prepared under the parameters for publication within the Code of Federal Regulations may not reflect the exclusion of such developed areas. Any such structures and the surface under them inadvertently left inside critical habitat boundaries shown on the maps of this final rule have been excluded by text in the final rule and are not designated as critical habitat. Therefore, Federal actions limited to these areas would not trigger

FOR FURTHER INFORMATION CONTACT Adam Zerrenner, Field Supervisor, Austin Ecological Services Office, 10711 Burnet Road, Suite 200, Austin, TX 78758 (telephone 5124900057; facsimile 5124900974).