8
THE DESERT TORTOISE

Issue 6 Potential Damaging Effects on the Desert Tortoise Habitat

THE WILSHIRE GROUP POSITION

Wilshire and others (1993) raised the concern that development of the Ward Valley site would have a serious effect upon the habitat of the desert tortoise (Gopherus agassizii) in an area with optimal geology and soils. They did not consider the mitigation plan established by U.S. Ecology, and supported by DHS, to be adequate to balance this loss.

THE DHS/U.S. ECOLOGY POSITION

The plan developed by U.S. Ecology included (1) a relocation plan for approximately 23-30 tortoises in the 36 ha site and other developed areas, a very small percentage of the total Ward Valley population; (2) fencing of about 10.5 km along Highway I-40, which bounds the site to the north, to protect the tortoise from further road kills; (3) use of various measures to reduce or prevent increases in predator populations; (4) speed control of low-level waste transport tracks on the access road; and (5) education of facility employees about desert tortoises. The components of this plan were endorsed by the U.S. Fish and Wildlife Services (USFWS) in its November 21, 1990 Biological Opinion (USFWS, 1990a) and were stated as the Reasonable and Prudent Measures to minimize incidental take. This opinion stated ''that the proposed project is not likely to jeopardize the continued existence of the desert tortoise.''

The Wilshire group also recently raised concern about potential spread of upper respiratory tract disease (URTD) if the tortoise population from the facility site were relocated into the Fenner Desert Wildlife Management Area (DWMA), one that presently is reported to have URTD in its western populations. Department of Health Services responded to this concern by questioning the accuracy of the health data used by the Wilshire group, indicating that the spread may be a result of handling tortoises in the health profile study plots.

THE COMMITTEE'S APPROACH

In our assessment of potential loss or alteration of habitat to evaluate the concerns of the Wilshire group, the committee included not only consideration of the loss of physical space and resources at the disposal site itself, but also possible changes in interactions



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Ward Valley: An Examination of Seven Issues in Earth Sciences and Ecology 8 THE DESERT TORTOISE Issue 6 Potential Damaging Effects on the Desert Tortoise Habitat THE WILSHIRE GROUP POSITION Wilshire and others (1993) raised the concern that development of the Ward Valley site would have a serious effect upon the habitat of the desert tortoise (Gopherus agassizii) in an area with optimal geology and soils. They did not consider the mitigation plan established by U.S. Ecology, and supported by DHS, to be adequate to balance this loss. THE DHS/U.S. ECOLOGY POSITION The plan developed by U.S. Ecology included (1) a relocation plan for approximately 23-30 tortoises in the 36 ha site and other developed areas, a very small percentage of the total Ward Valley population; (2) fencing of about 10.5 km along Highway I-40, which bounds the site to the north, to protect the tortoise from further road kills; (3) use of various measures to reduce or prevent increases in predator populations; (4) speed control of low-level waste transport tracks on the access road; and (5) education of facility employees about desert tortoises. The components of this plan were endorsed by the U.S. Fish and Wildlife Services (USFWS) in its November 21, 1990 Biological Opinion (USFWS, 1990a) and were stated as the Reasonable and Prudent Measures to minimize incidental take. This opinion stated ''that the proposed project is not likely to jeopardize the continued existence of the desert tortoise.'' The Wilshire group also recently raised concern about potential spread of upper respiratory tract disease (URTD) if the tortoise population from the facility site were relocated into the Fenner Desert Wildlife Management Area (DWMA), one that presently is reported to have URTD in its western populations. Department of Health Services responded to this concern by questioning the accuracy of the health data used by the Wilshire group, indicating that the spread may be a result of handling tortoises in the health profile study plots. THE COMMITTEE'S APPROACH In our assessment of potential loss or alteration of habitat to evaluate the concerns of the Wilshire group, the committee included not only consideration of the loss of physical space and resources at the disposal site itself, but also possible changes in interactions

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Ward Valley: An Examination of Seven Issues in Earth Sciences and Ecology between tortoises living in the vicinity of the facility and humans, native predators, and other tortoises. History of Endangered Species Act Protection Because the desert tortoise is protected as a threatened species by the Endangered Species Act, the listing history of this species is relevant to an assessment of impacts of the proposed facility. The desert tortoise occurs in southwestern North America on flats and bajadas with sandy-gravel soils (Luckenback, 1982). At least two distinct desert tortoise populations have been defined on the basis of genetic (Lamb et al, 1989) and morphometric criteria: the Mojave and Sonoran populations, and a possible third population in southern Sonora and Sinaloa, Mexico (USFWS, 1994a). By the 1980's, desert tortoise populations had disappeared from parts of the western and northern Mojave Desert, and populations had declined in many other areas of the Mojave population's range (Jacobson, 1994; USFWS, 1994a). These declines led to the emergency listing of the entire Mojave desert tortoise population as federally endangered in 1989 (USFWS, 1989), and the final listing of the population as threatened on April 2, 1990 (USFWS, 1990b). The main reasons for this listing included habitat destruction, degradation, and fragmentation; removal or killing of tortoises by humans; increased predation on tortoises by native predators; disease; and failure of existing regulatory mechanisms to protect the desert tortoise and its habitat (USFWS, 1990b; 1994a). The Endangered Species Act mandates the designation of critical habitat and development of a recovery plan for federally listed species (16 U.S.C. § 1533 [1988 and Supp. 1990]). In response to this mandate, the U.S. Fish and Wildlife Service published the final critical habitat designation for the Mojave desert tortoise population on February 8, 1994 (USFWS, 1994b), and approved the final Desert Tortoise (Mojave Population) Recovery Plan (USFWS, 1994a) on June 28, 1994. Critical habitat for the Mojave population was structured in accord with recommendations made in the Recovery Plan to include 14 Desert Wildlife Management Areas (DWMAs) in 6 Recovery Units. A fundamental goal of the Recovery Plan is to maintain the integrity of the distinct populations within each recovery unit, with DWMAs that contain desert tortoise habitat and viable tortoise populations identified in each unit. DWMAs are viewed as reserves, where human activities that negatively impact desert tortoises are restricted (Figure 8.1) (USFWS, 1994a). Ward Valley occupies parts of the Chemehuevi DWMA of the Northern Colorado Recovery Unit, and Fenner DWMA of the Eastern Recovery Unit, as designated in the Desert Tortoise (Mojave Population) Recovery Plan (USFWS, 1994a). The site for the proposed Ward Valley low-level radioactive waste (LLRW) disposal facility is located in the northern end of the Chemehuevi DWMA less than 2 km south of the Fenner DWMA, the two DWMAs being separated by I-40. The site was selected and characterization activities had begun before designation of the area as a desert tortoise critical habitat or identification of the DWMAs.

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Ward Valley: An Examination of Seven Issues in Earth Sciences and Ecology Figure 8.1 DWMAs in the Northern Colorado and Eastern Colorado Recovery Units identified by the Desert Tortoise (Mojave Population) Recovery Plan and approximate locations of the proposed low-level radioactive waste disposal site and the desert tortoise study plots (G, Goffs Health Plot and WV, Upper Ward Valley Demographic Plot) (Modified from USFWS, 1994a, Berry 1994)

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Ward Valley: An Examination of Seven Issues in Earth Sciences and Ecology Potential Effects of The Facility on Desert Tortoise Habitat The proposed disposal facility has four main potential effects on desert tortoise habitat. Fragmentation of Desert Tortoise Habitat First, the proposed facility will result in the direct loss of 36 ha and fragmentation of desert tortoise habitat within the DWMA considered by the Recovery Plan (USFWS, 1994a) to contain the largest and most robust of the remaining desert tortoise populations. This area includes 28 ha around the waste containment area itself that will be fenced to exclude tortoises, 3 ha to be occupied by buildings, and 5 ha that will be disturbed during construction of the flood control berms and other project-related facilities. Additional acreage will be lost through widening and upgrading the existing access road, which currently occupies less than 3 ha (USFWS, 1990b), and installation and use of the site-monitoring equipment in the 122 m wide buffer zone surrounding the fenced waste containment area (LA Section 3100.11). Based on reported estimates of tortoise home range size and density in this part of Ward Valley (Karl, 1989), the habitat loss for the facility itself would likely affect 18-20 tortoises, with an additional 5-10 tortoises affected by the access road upgrading (USFWS, 1990b). The fenced facility and the upgrading of the access road may also restrict movement of desert tortoises through part of Ward Valley. While the number of tortoises affected and the habitat area lost are small compared to the whole Ward Valley area, loss of habitat through fencing and road improvement must still be considered habitat fragmentation. Increase In Predator Population Second, the proposed facility may result in increases in the populations of animals that prey on young tortoises. Mortality rates of pre-reproductive tortoises are high, with predation by common ravens (Corvus corax) accounting for a high percentage of deaths (USFWS, 1994a). According to data collected as part of the U. S. Fish and Wildlife Service Breeding Bird Survey Program, raven populations in the Mojave Desert increased 15-fold from 1968 to 1988 (USFWS, 1994a). This population growth has been attributed to increased food supplies and perch and nest sites associated with human activity. An expansion of the local raven population could similarly accompany development of the Ward Valley disposal site. Increased Contact With Humans Third, interactions between tortoises and humans are likely to increase with construction and operation of the disposal facility. The 122 m wide buffer zone surrounding the fenced facility, which is for monitoring, equipment maneuvering, and remediation wells,

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Ward Valley: An Examination of Seven Issues in Earth Sciences and Ecology will still be utilized by tortoises and will likely be a zone of increased contact with humans. The upgrading of the access road may attract additional traffic in the vicinity of the disposal facility (Karl, 1989). Detrimental effects of increased human activity include vehicular mortality along roadways (Nicholson, 1978), stress due to handling and other activities, and collection of tortoises for pets or other purposes (USFWS, 1994a). Increased Competition Among Tortoises Finally, the proposed project may result in increased competition among tortoises. This could occur in several different ways. The project plan currently calls for relocation of tortoises from the site to a nearby area that apparently has lower densities than the facility site (Karl, 1989). This could result in increased densities, and consequently increased competition, in the relocation area. If tortoises from the site itself were not relocated away from the site but merely excluded from their former territory by the fence around the waste containment area, this could similarly result in increased densities in the immediate vicinity of the facility. Even without increased tortoise density, levels of competition could increase if construction and operation of the waste disposal facility degraded the quality of the surrounding habitat and lowered its carrying capacity. ASSESSMENT OF THE PLAN TO REMEDIATE POTENTIAL IMPACTS The project proposal for the Ward Valley site comprises several approaches for mitigating adverse effects on the local desert tortoise population. These were initially based on the Bureau of Land Management (BLM) management plan for desert tortoise habitat (BLM, 1988), and include compensation for lost habitat, reduction of negative impacts on tortoises during facility construction and operation, and research to improve our understanding of desert tortoise ecology (Environmental Impact Report, 1993). These were also included as Reasonable and Prudent Measures in the USFWS November 1990 Biological Opinion. Compensation For Habitat Loss And Fragmentation The licensee intends to compensate for lost tortoise habitat with a two-part plan. Fencing of I-40 The first step calls for fencing Interstate Highway I-40 and upgrading freeway underpasses to improve habitat currently supporting few tortoises and to facilitate movement throughout Ward Valley. The licensee maintains that fencing both sides of the freeway for

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Ward Valley: An Examination of Seven Issues in Earth Sciences and Ecology 10.5 km where it crosses Ward Valley would enhance 1684 ha of tortoise habitat. This estimate is based on previous reports of reduced tortoise densities in the corridor adjacent to major highways (Nicholson, 1978; Karl, 1989), which has been attributed to increased roadkill and collecting. The estimate assumes the zone of strong freeway influence and low tortoise density is 0.8 km wide on either side of I-40. The Committee's View of Fencing This aspect of the mitigation plan has advantages and in all likelihood will reduce highway mortality and improve the potential for population increases in areas adjacent to the highway. However, the expected carrying capacity of the newly enhanced habitat along the highway remains unclear. Prior to selection of a specific site for the facility, the licensee performed a census of tortoises throughout section 34, the section that would have to be transferred to the state of California by the Department of the Interior (DOI) for construction of the facility. Based on those tortoise density data, the licensee selected one of the least dense parts of section 34 for the waste disposal facility (Karl, 1989). Facility construction and operation on the selected site would therefore affect fewer tortoises than on other possible sites in the immediate vicinity. The fencing of I-40 and improvement of underpasses would likely facilitate north-south movement within the valley, because the freeway currently serves as a barrier to movement, with few tortoises using the existing underpasses (Karl, 1989). Although fencing would also probably reduce vehicular mortality, it is not clear whether traffic negatively affects tortoises in other ways that might limit occupation of the fenced habitat. For example, desert tortoises have been observed emerging from burrows in response to ground vibrations (USFWS, 1994a). Abnormal behavior, such as premature emergence from subterranean burrows or the apparent inability to detect and flee from predators, has been detected in other reptiles after experimental exposure to sounds of slightly lower intensities than those generated by off-highway vehicles (Brattstrom and Bondello, 1983). Even with a reduction in vehicular mortality from fencing, the area adjacent to the freeway may remain as suboptimal habitat for desert tortoises. Relocation of Tortoises The second part of the plan to compensate for lost habitat calls for relocating tortoises displaced during site construction into the protected habitat north of I-40 created through fencing along the highway. Approximately 23-30 tortoises will be moved as part of the relocation effort (USFWS, 1990b), including individuals removed from the fenced construction site and the area disturbed for berm construction. Other tortoises whose burrows are disturbed during construction will be relocated as determined at the time (USFWS, 1990a).

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Ward Valley: An Examination of Seven Issues in Earth Sciences and Ecology The Committee's View of Relocation Although the relocation site will have geology and soils similar to the waste facility site, the committee sees several problems associated with the relocation plan. First, previous desert tortoise relocation studies have shown only limited success (e.g., Fusari et al., 1984; Burge et al., 1985; Baxter and Stewart, 1986). A combination of factors contributes to the generally low success rate of tortoise relocations: 1) the tendency of relocated tortoises to move long distances from the relocation site in either an erratic pattern or back towards their point of origin, 2) increased mortality among relocated individuals, 3) interference with the social structure of host tortoises, 4) increased stress on host and guest tortoises through competition and handling during relocation, and 5) introduction or enhanced transmission of disease (Fusari et al., 1984; Berry, 1986; Science Applications International Corporation, 1993; USFWS, 1994a). Second, according to the guidelines for tortoise translocation in the Desert Tortoise (Mojave Population) Recovery Plan (USFWS, 1994a), displaced tortoises should not be released in DWMAs until relocation is much better understood. The proposed relocation, which would move tortoises from one DWMA (Chemehuevi) 2-3 km away to a different DWMA (Fenner) in a different Recovery Unit (Eastern Mojave), would be in opposition to this recommendation. The Recovery Plan encourages research on experimental relocation, but only outside DWMAs. A third problem with the relocation plan is that the carrying capacity of the relocation habitat and the social structure of the host tortoise population are presently unknown. The Recovery Plan recommends that host tortoise populations be studied for at least two years before introducing tortoises into an area already inhabited by tortoises (USFWS, 1994a). Based on the abundance of tortoise signs tallied in strips along I-40 in Ward Valley, tortoises presently occupy the belt adjacent to the freeway, with the most dramatic depression of density north of I-40 being limited to the 0.40 km closest to the freeway (Karl, 1989). Without fencing to keep relocated tortoises in the strip of habitat along the freeway, guest tortoises are likely to wander into the home ranges of host individuals (either farther to the north or to the south on the other side of the freeway), where they may interfere with the social structure of hosts and compete with them for food and burrows (Berry, 1986). Finally, the relocation plan could facilitate the transmission of disease from tortoises in the Fenner DWMA to individuals in the Chemehuevi DWMA. Desert tortoises in parts of the Mojave population are affected by an upper respiratory tract disease (URTD) and two shell diseases that have begun to receive intensive study only within the last five years. Disease has contributed to high mortality rates observed recently in the western Mojave Desert (USFWS, 1994a; Jacobson, 1994). Attention was focused on URTD by a severe outbreak of the disease in Desert Tortoise Natural Area in Kern County, CA, where 43 percent of 468 tortoises studied in 1989 showed signs of the disease, with a mortality rate of close to 25 percent (Jacobson et al., 1991). URTD may have been spread to wild tortoise populations by the illegal release of captive tortoises (Jacobson, 1993). A higher incidence of URTD has been reported near urban areas, which often have concentrations of captive desert tortoises, but the disease appears to be spreading (USFWS, 1994a). Habitat deterioration, poor nutrition,

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Ward Valley: An Examination of Seven Issues in Earth Sciences and Ecology drought, and stress may all make tortoises more susceptible to URTD through immunosuppression (Jacobson et al., 1991). In 1993, desert tortoises in the Goffs Health Profile study plot, approximately 13 km northwest of the proposed Ward Valley disposal site (Figure 8.1), tested seropositive for Mycoplasma agassizii when given ELISA tests (Berry, 1994). Schumacher et al. (1993) found ELISA tests to be an effective diagnostic tool for identifying the presence of Mycoplasma agassizii, a newly described mycoplasma that causes URTD in desert tortoises (Brown et al., 1994). Widespread shell abnormalities have also been observed in the Goffs Health Profile study plot (Berry, 1994), but the causes and effects of shell disease are not well understood (Jacobson et al., 1994). To date, URTD and shell disease have not been recorded at BLM's Upper Ward Valley study plot, located about 18 km south-southeast of the proposed disposal facility (Berry, 1994). The site licensors suggest that the presence of URTD at the Goffs study plot could represent localized transmission or aggravation of the disease caused by handling during research rather than a regional infection (Brandt, 1994). Although localized aggravation of the disease cannot be ruled out, introduction of desert tortoises from the proposed Ward Valley disposal site into an area closer to the Goffs study plot where disease has been detected is inadvisable. Particularly in view of the homing tendency of tortoises and their capability of moving long distances after relocation (as much as 7.3 km) (Berry, 1986), relocated tortoises could facilitate the spread of disease if they were exposed to ill tortoises near the Goffs plot, then moved back toward their original home range south of I-40. Minimization of Predatory Population Growth The mitigation plan for the Ward Valley LLRW site includes several measures aimed at minimizing the growth in raven populations that has been associated with increases in human activities in the Mojave Desert (Environmental Impact Report, 1993). The top of the fence surrounding the waste containment area will be electrified to prevent the perching of ravens and other avian predators. Electrical transmission lines to the site will be buried, similarly to minimize the addition of perches for avian predators. Food waste and other garbage will be contained and roadkills along the access road will be collected daily to minimize the attraction of additional predators to the site. Bimonthly raven counts will be made and submitted annually to the U. S. Fish and Wildlife Service to monitor the size of local raven populations (USFWS 1990a). Some increase in raven populations can be anticipated in the vicinity of the disposal facility, but the measures that will be implemented by US Ecology are likely to keep the increase small. Monitoring the raven population will allow a reevaluation and possible alteration of mitigation procedures if predator populations show a significant increase.

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Ward Valley: An Examination of Seven Issues in Earth Sciences and Ecology Measures To Reduce Impact of Tortoise/Human Interaction Planned measures to reduce the impact of increased interaction between tortoises and humans include a speed limit and escort for transport vehicles on the access road, fencing of the 10.5-km segment of I-40 where it crosses Ward Valley, an education program for employees of the disposal facility, and monitoring of tortoise mortality. The upgrading of the access road may attract increased traffic other than waste transport vehicles to the site (Karl, 1989). Other vehicles may not observe posted speed limits, which could result in occasional mortality of tortoises from roadkill. Increased traffic on the access road could also facilitate illegal collecting of tortoises. On the other hand, reduction in mortality from fencing I-40 will likely more than compensate for incidental mortality along the access road. The plans for monitoring tortoise mortality will permit the adoption of additional roadkill reduction measures, such as the installation of speed bumps, if the present plan proves to be inadequate for preventing roadkill mortality. CONCLUSIONS AND RECOMMENDATIONS The committee has two primary concerns about potential effects of the proposed facility on desert tortoise habitat: (1) limited habitat degradation and fragmentation associated with development of the facility, and (2) the unknown consequences of the relocation plan. The Recovery Plan and the critical habitat designation were both based on the fundamental principle of conservation biology that large, unfragmented habitat reserves are more effective in preventing extinction than small, fragmented ones (Simberloff and Abele, 1982; Wilcove et al., 1986). The Chemehuevi DWMA, which includes the proposed waste disposal facility, is the only DWMA in the Northern Colorado Recovery Unit and contains one of the largest and most robust desert tortoise populations in the Mojave Desert (USFWS, 1994a). It is currently the least fragmented and least disturbed DWMA and is considered to be a vital area for recovery of the desert tortoise (USFWS, 1994a). The Recovery Plan recommends the prohibition within DWMAs of surface disturbances that reduce the ability of the habitat to support tortoises (USFWS, 1994a). The acreage of habitat that will be permanently lost during construction and operation of the waste facility is small relative to the overall size of the Chemehuevi DWMA, but even small critical habitat losses may hinder recovery of the desert tortoise, as noted in the U. S. Fish and Wildlife Service's 1990 Biological Opinion pertaining to the proposed site (USFWS, 1990a, p. 18): Development of such facilities within areas that may be deemed important for the recovery of the tortoise by the Recovery Plan or the Bureau's habitat management plans sets a biologically unsound precedent for future management actions. • The committee commends U.S. Ecology for its plans to decrease desert tortoise mortality in Ward Valley, but it recommends that the relocation plan be

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Ward Valley: An Examination of Seven Issues in Earth Sciences and Ecology reevaluated in light of the Desert Tortoise (Mojave Population) Recovery Plan (USFWS, 1994a) and the paucity of data on successful tortoise relocations. The Recovery Plan recommends that no displaced tortoises be released in DWMAs until relocation is better understood. Many unknowns remain about this particular relocation plan, in addition to the general uncertainties about relocation. These unknowns include the carrying capacity of the relocation habitat, the social structure and density of the host desert tortoise population, and the extent of infectious disease in the vicinity of the relocation area. The Recovery Plan recommends restricting relocations to areas outside DWMAs and, if the relocation area already supports tortoises, only after a 2-year study of the recipient habitat and population. • If tortoise relocation remains as part of the mitigation measures for construction and operation of the Ward Valley facilities, the committee supports the recommendation of the U.S. Fish and Wildlife Service to establish a research program designed to study the effects of tortoise relocation and further recommends that relocation be made only outside DWMAs. As part of the conditions in the Biological Opinion (USFWS 1990a), the U.S. Fish and Wildlife Service required establishment of a research program tied to relocation of the tortoises. If the research program is well designed, including intensive monitoring of tortoises relocated outside DWMAs, much could be learned about tortoise relocation and tortoise population interactions. • As a possible alternative for the relocation plan, the committee suggests that consideration be again given to (1) evaluating impacts on the adjacent tortoise population of a plan that would exclude, but not relocate, resident individuals from all locations of facility construction and operation activities, or (2) consultation with the U.S. Fish and Wildlife Service about designating all individuals lost during construction as "incidental take". Incidental take was addressed in the Biological Opinion, but in the opinion it referred to those tortoises lost after relocation of all collectable individuals. The committee feels that sacrifice of the tortoises on site or collection for adoption may ultimately have fewer adverse effects on the tortoise population in the vicinity of the facility than the proposed relocation. • Finally, the committee recommends reinitiation of formal consultation with the U. S. Fish and Wildlife Service on the low-level radioactive waste disposal site at Ward Valley. Reinitiation of consultation is required if one of the following conditions occurs: (1) the amount or extent of incidental take that was agreed upon is reached; (2) new information reveals effects of the agency action that may adversely affect listed species or critical habitat in

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Ward Valley: An Examination of Seven Issues in Earth Sciences and Ecology a manner or to an extent not considered in the opinion; (3) the agency action is subsequently modified in a manner that causes an effect to a listed species or critical habitat that was not considered in the opinion, and (4) a new species is listed or critical habitat designated that may be affected by this action (50 CFR 402.16). The original Biological Opinion was made by the Service on November 21, 1990. Since that time, critical habitat that includes the proposed disposal site has been designated (USFWS, 1994b) and a recovery plan for the Mojave population of the desert tortoise has been developed and approved (USFWS, 1994a). REFERENCES Baxter, R. J., and G. R. Stewart. 1986. Report of continuing field work on the desert tortoise at Twenty-nine Palms Marine Corps Air Ground Combat Center, Spring 1985. Proceedings of the Desert Tortoise Council Symposium 1986. Berry, K. H. 1986. Desert tortoise (Gopherus agassizii) relocation: Implications of social behavior and movements. Herpetologica 42:113-25. Berry, K. 1994. Desert tortoise issues, in Ward Valley proposed low-level radioactive waste site: A report to the National Academy of Sciences: Presentations made to the National Academy of Sciences Review Panel, July 7 and 9 and August 30 to September 1, 1994, Needles, California, Wilshire, H., D. Miller, K. Howard, K. Berry, W. Bianchi, D. Cehrs, I. Friedman, D. Huntley, M. Liggett, and G. Smith, eds. pp. XV1-XV22. Brandt, E. C. 1994. Summary submittal of the California Department of Health Services to National Academy of Sciences Committee to Review Specific Scientific and Technical Safety Issues Related to the Ward Valley, California , Low-level Radioactive Waste Site, October 7, 1994, Sacramento, California. Brattstrom, B. H., and M. C. Bondello. 1983. Effects of off-road vehicle noise on desert vertebrates. Pp. 167-206, in Environmental effects of off-road vehicles: Impacts and management in arid regions, R. H. Webb and H. G. Wilshire, eds. Springer-Verlag, New York, New York. Brown, M. B., I. M. Schumacher, P. A. Klein, K. Harris, T. Correll, and E. R. Jacobson. 1994. Mycoplasma agassizii causes upper respiratory tract disease in the desert tortoise. Infection and Immunity 62:4580-86. Bureau of Land Management. 1988. Desert tortoise habitat management on the public lands: A rangewide plan. Washington, D.C.: U.S. Department of the Interior. Burge, B. L., G. R. Stewart, J. E. Roberson, K. Kirtland, R. J. Baxter, and D. C. Pearson. 1985. Excavation of winter burrows and relocation of desert tortoises at the Twenty-nine Palms Marine Corps Air Ground Combat Center. Proceedings of the Desert Tortoise Council Symposium 1985:32-39. Environmental Impact Report. 1993. Vol. 6 [14866-012], Section 2.1.6.1. in Administrative Record, California Low-Level Radioactive Waste Disposal Facility. Prepared for Department of Health Services/Bureau of Land Management by Dames & Moore.

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Ward Valley: An Examination of Seven Issues in Earth Sciences and Ecology Fusari, M., D. Beck, K. H. Berry, M. Coffeen, J. Diemer, and J. St. Amant. 1984. Problems with release of captive tortoises. Proceedings of the Desert Tortoise Council Symposium 1984:136-46. Jacobson, E. R. 1993. Implications of infectious diseases for captive propagation and introduction programs of threatened/endangered reptiles. Journal of Zoo and Wildlife Medicine 24:245-55. ——— 1994. Causes of mortality and diseases in tortoises: A review. Journal of Zoo and Wildlife Medicine 25:2-17. Jacobson, E. R., J. M. Gaskin, M. B. Brown, R. K. Harris, C. H. Gardiner, J. L. LaPointe, H. P. Adams, and C. Reggiardo. 1991. Chronic upper respiratory tract disease of free-ranging desert tortoises (Xerobates agassizii). Journal of Wildlife Diseases 27:296-316. Jacobson, E. R., T. J. Wronski, J. Schumacher, C. Reggiardo, and K. H. Berry. 1994. Cutaneous dyskeratosis in free-ranging desert tortoises, Gopherus agassizii, in the Colorado Desert of southern California . Journal of Zoo and Wildlife Medicine 25:68-81. Karl, A. E. 1989. Investigations of the desert tortoise at the California Department of Health Services proposed low-level radioactive waste facility site in Ward Valley, California, Report submitted to US Ecology and C. Robert Feldmeth, July 8, 1989. Lamb, T., J. C. Arise, and J. W. Gibbons. 1989. Phylogeographic patterns in mitochondrial DNA of the desert tortoise (Xerobates agassizii) [sic], and evolutionary relationships among the North American gopher tortoises. Evolution 43:76-87. Luckenback, R. A. 1982. Ecology and management of the desert tortoise (Gopherus agassizii) in California. In North American tortoises: Conservation and ecology, R. B. Bury, ed. U.S. Department of the Interior Fish and Wildlife Service, Washington, D.C., Wildlife Research Report 12, pp. 1-37. Nicholson, L. 1978. The effects of roads on desert tortoise populations. Proceedings of the Desert Tortoise Council Symposium 1978:127-29. Schumacher, I. M., M. B. Brown, E. R. Jacobson, B. R. Collins, and P. A. Klein. 1993. Detection of antibodies to a pathogenic mycoplasma in desert tortoises (Gopherus agassizii) with upper respiratory tract disease. Journal of Clinical Microbiology 31:1454-60. Science Applications International Corporation. 1993. American Honda tortoise relocation project: Final report. Science Applications International Corporation, Santa Barbara, California. Simberloff, D., and L. G. Abele. 1982. Refuge design and island biogeographic theory: Effects of fragmentation. American Naturalist 120:41-50. U.S. Fish and Wildlife Service. 1989. Endangered and threatened wildlife and plants; emergency determination of endangered status for the Mojave population of the desert tortoise. Federal Register 54(149):32326. ——— 1990a. Biological opinion for the proposed low-level radioactive waste disposal facility, Ward Valley, San Bernardino County, California, (6840 CA-932.5) (1-6-90-F-41), November 21, 1990.

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Ward Valley: An Examination of Seven Issues in Earth Sciences and Ecology ——— 1990b. Endangered and threatened wildlife and plants; determination of threatened status for the Mojave population of the desert tortoise. Federal Register 55(63):12178-91. ——— 1994a. Desert tortoise (Mojave population) recovery plan. U.S. Fish and Wildlife Service, Portland, Oregon. ——— 1994b. Endangered and threatened wildlife and plants; determination of critical habitat for the Mojave population of the desert tortoise. Federal Register 59(26):5820-66. Wilcove, D. S., C. H. McLellan, and A. P. Dobson. 1986. Habitat fragmentation in the temperate zone. Pp. 237-56 in Conservation biology: The science of scarcity and diversity , M. E. Soulé, ed. Sinauer Associates, Sunderland, Maryland. Wilshire, H., K. Howard, and D. Miller. 1993. Memorandum to Secretary Bruce Babbitt, dated June 2. pp 3.

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