[Federal Register Volume 87, Number 231 (Friday, December 2, 2022)]
[Rules and Regulations]
[Pages 73971-73994]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-26237]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R8-ES-2022-0024; FF09E21000 FXES1111090FEDR 234]
RIN 1018-BG21


Endangered and Threatened Wildlife and Plants; Endangered Species 
Status for the Dixie Valley Toad

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service, are listing the Dixie 
Valley toad (Anaxyrus williamsi), a toad species from Nevada, as an 
endangered species under the Endangered Species Act of 1973, as amended 
(Act). This rule continues the protections of the Act applied to the 
Dixie Valley toad under our April 7, 2022, temporary emergency listing 
rule.

DATES: This rule is effective December 2, 2022.

ADDRESSES: This final rule and supporting documents are available on 
the internet at https://www.regulations.gov in Docket No. FWS-R8-ES-
2022-0024.

FOR FURTHER INFORMATION CONTACT: Justin Barrett, Field Supervisor, U.S. 
Fish and Wildlife Service, Reno Fish and Wildlife Office, 1340 
Financial Blvd., Suite 234, Reno, NV 89502; telephone 775-861-6300. 
Individuals in the United States who are deaf, deafblind, hard of 
hearing, or have a speech disability may dial 711 (TTY, TDD, or 
TeleBraille) to access telecommunications relay services. Individuals 
outside the United States should use the relay services offered within 
their country to make international calls to the point-of-contact in 
the United States.

SUPPLEMENTARY INFORMATION:

Executive Summary

    Why we need to publish a rule. Under the Act, a species warrants 
listing if it meets the definition of an endangered species (in danger 
of extinction throughout all or a significant portion of its range) or 
a threatened species (likely to become endangered in the foreseeable 
future throughout all or a significant portion of its range). If we 
determine that a species warrants listing, we must list the species 
promptly and designate the species' critical habitat to the maximum 
extent prudent and determinable. We have determined that the Dixie 
Valley toad meets the

[[Page 73972]]

definition of an endangered species; therefore, we are listing it as 
such. Listing a species as an endangered or threatened species can be 
completed only by issuing a rule through the Administrative Procedure 
Act rulemaking process.
    What this document does. This rule makes final the listing of the 
Dixie Valley toad as an endangered species.
    The basis for our action. Under the Act, we may determine that a 
species is an endangered or threatened species because of any of five 
factors: (A) The present or threatened destruction, modification, or 
curtailment of its habitat or range; (B) overutilization for 
commercial, recreational, scientific, or educational purposes; (C) 
disease or predation; (D) the inadequacy of existing regulatory 
mechanisms; or (E) other natural or manmade factors affecting its 
continued existence. We have determined that the Dixie Valley toad is 
at risk of extinction throughout its range primarily due to the threat 
of geothermal development and its effects to the toad and the habitat 
on which it depends. Other threats to the Dixie Valley toad include 
climate change; chytrid fungus; groundwater pumping associated with 
human consumption, agriculture, and county planning; and predation by 
invasive bullfrogs. In addition, existing regulatory mechanisms may be 
inadequate to protect the species.

List of Acronyms

    We use many acronyms in this rule. For the convenience of the 
reader, we define some of them here:

afy = acre-feet per year
January Environmental Assessment (EA) = January 2021 Draft EA 
(Bureau of Land Management (BLM) 2021a, entire)
January Monitoring and Mitigation Plan = January 2021 Aquatic 
Resources Monitoring and Mitigation Plan (BLM 2021a, Appendix H)
November Environmental Assessment (EA) = November 2021 Final EA (BLM 
2021b, entire)
November Monitoring and Mitigation Plan = November 2021 Aquatic 
Resources Monitoring and Mitigation Plan (BLM 2021b, Appendix H)
BLM = Bureau of Land Management
[deg]C = degrees Celsius
CBD = Center for Biological Diversity
CFR = Code of Federal Regulations
cfs = cubic feet per second
m3/yr = cubic meters per year
DoD = Department of Defense
Act = Endangered Species Act of 1973, as amended (16 U.S.C. 1531 et 
seq.)
EA = environmental assessment
[deg]F = degrees Fahrenheit
NAS Fallon = Fallon Naval Air Station
FR = Federal Register
ft = feet
gpm = gallons per minute
in = inch
km = kilometer
MW = megawatt
m = meter
mm = millimeter
NAC = Nevada Administrative Code
NDOW = Nevada Department of Wildlife
NDNH = Nevada Division of Natural Heritage
NDWR = Nevada Division of Water Resources
Fallon Paiute Shoshone Tribe = Paiute-Shoshone Tribe of the Fallon 
Reservation and Colony
RCP = representative concentration pathway
SSA = species status assessment
Service = U.S. Fish and Wildlife Service
USGS = U.S. Geological Survey

Previous Federal Actions

    We received a petition from the Center for Biological Diversity 
(CBD) on September 18, 2017, requesting that the Dixie Valley toad be 
listed as an endangered or threatened species and that the petition be 
considered on an emergency basis (CBD 2017, entire). The Act does not 
provide a process to petition for emergency listing; therefore, we 
evaluated the petition to determine if it presented substantial 
scientific or commercial information indicating that the petitioned 
action may be warranted. We published a 90-day finding in the Federal 
Register on June 27, 2018 (83 FR 30091), stating that the petition 
presented substantial scientific or commercial information indicating 
that listing the Dixie Valley toad may be warranted.
    On April 7, 2022, we published an emergency rule (87 FR 20336) that 
applies Federal protection under the Act to the Dixie Valley toad for a 
240-day period, ending on December 2, 2022. On April 7, 2022, we 
concurrently published a proposed rule (87 FR 20374) to list the Dixie 
Valley toad as an endangered species under the Act, and we requested 
public comments on that proposal for 60 days, ending June 6, 2022.

Supporting Documents

    A species status assessment (SSA) team prepared an SSA report for 
the Dixie Valley toad. The SSA team was composed of Service biologists, 
in consultation with other scientific experts. The SSA report 
represents a compilation of the best scientific and commercial data 
available concerning the status of the species, including the impacts 
of past, present, and future factors (both negative and beneficial) 
affecting the species.
    In accordance with our joint policy on peer review published in the 
Federal Register on July 1, 1994 (59 FR 34270), and our August 22, 
2016, memorandum updating and clarifying the role of peer review of 
listing actions under the Act, we sought peer review of the SSA report. 
The Service sent the SSA report to four independent peer reviewers and 
received three responses. The purpose of peer review is to ensure that 
our listing determinations are based on scientifically sound data, 
assumptions, and analyses. The peer reviewers have expertise in the 
biology, habitat, and threats to the species. The Service also sent the 
SSA report to three partner agencies, BLM, NDOW, and DoD, and we 
received comments from BLM and NDOW. Comments we received during peer 
and partner review were considered and incorporated into our SSA report 
and this final listing rule.

Summary of Changes From the Proposed Rule

    Based upon our review of the public comments, State agency 
comments, peer and partner review comments, and relevant information 
that became available since the proposed rule published (87 FR 20374; 
April 7, 2022), we updated information in our SSA report, including:
     Adding additional individual toad locations provided by 
NDOW.
     Revising the SSA report to include the Dixie Valley toad 
as a protected species in the State of Nevada.
     Adding information from a newly published scientific paper 
(Rose et al. 2022, entire) regarding occupancy dynamics of the Dixie 
Valley toad and the different environmental conditions adult and larval 
toads require.
     Clarifying the changes from the BLM's January draft 
environmental assessment (EA) to the BLM's November final EA.
     Clarifying how the Dixie Valley toad uses colder springs 
in the wetlands.
     Adding the Traditional Ecological Knowledge provided by 
the Fallon Paiute Shoshone Tribe to section 1.2 of the SSA report.
     Adding information on the differences between Dixie 
Meadows and the McGinness Hills, Tungsten Mountain, and Ngatamariki 
sites.
    We also made changes as appropriate in this final rule. In addition 
to minor clarifying edits and the incorporation of additional 
information on the species' biology, populations, and threats, this 
final rule differs from the proposed rule by clarifying why the changes 
made between the BLM's January draft EA and the BLM's November final EA 
did not change our conclusion that the Dixie Valley toad meets the 
Act's definition of an endangered species.

[[Page 73973]]

Summary of Comments and Recommendations

Peer Reviewer Comments

    As discussed in Supporting Documents, above, we received comments 
from three peer reviewers. We reviewed all comments we received from 
the peer reviewers for substantive issues and new information regarding 
the information contained in the SSA report. The peer reviewers 
generally concurred with our methods and conclusions, and they provided 
support for thorough and descriptive narratives of assessed issues, as 
well as additional information, clarifications, and suggestions to 
improve the final SSA report. Peer reviewer comments are addressed in 
the following summary and were incorporated into the final SSA report 
as appropriate.
    (1) Comment: One peer reviewer stated that chytrid-positive 
bullfrogs do not occur in the southern part of the Dixie Valley toad's 
range. Rather, there is a potential path for introduction of chytrid 
fungus into Dixie Valley toads from chytrid-fungus-positive American 
bullfrogs already occurring in Turley Pond, located about 10 kilometers 
(about 5.7 miles) from Dixie Meadows, to bullfrogs co-occurring with 
Dixie Valley toads in the southern part of the range.
    Our Response: We have clarified that the location of the chytrid-
fungus-positive bullfrogs in Dixie Valley is in Turley Pond, 
approximately 10 kilometers from Dixie Meadows.
    (2) Comment: One peer reviewer asked if the effects of all other 
uses of groundwater and extended drought would be negligible compared 
to the impacts of the geothermal development.
    Our Response: Because the geothermal project constitutes the most 
significant potential localized water-related impact to the springs/
wetland complex providing habitat for the Dixie Valley toad, any 
localized effects of groundwater withdrawals within Dixie Valley, like 
changes in local climatic conditions, are potential secondary 
interacting effects.
    (3) Comment: One peer reviewer suggested we add historical 
baselines to the species needs table to better understand how changes 
in flow and water temperature would affect the species.
    Our Response: There is little or no information on historical 
baselines for springflow and water temperature. We used the best 
available scientific and commercial data from recent studies to 
determine what the Dixie Valley toad's resource needs are, which are 
discussed in section 3.3 of the SSA report.

Comments From Tribes

    We received comments from the Pauite-Shoshone Tribe of the Fallon 
Reservation and Colony, Nevada (hereafter Fallon Paiute Shoshone 
Tribe), expressing support for the listing of the Dixie Valley toad. 
The Fallon Paiute Shoshone Tribe discussed how Dixie Valley is 
ancestral territory where they have lived and prayed for more than 
10,000 years and is one of the most sacred sites in the Tribe's 
culture. The Fallon Paiute Shoshone Tribe's reverence for the site 
includes the ecosystem it supports; thus, they strongly endorse listing 
the Dixie Valley toad as endangered.
    (4) Comment: One Tribal commenter requested that we consider and 
integrate the Fallon Paiute Shoshone Tribe interests into the final 
rule. The Tribal commenter provided numerous reasons documenting why 
the Dixie Meadows ecosystem (also known as Paumu, and including the 
surface waters of the springs, the surrounding wetlands, the 
surrounding uplands, and the endemic toad) is of cultural and spiritual 
significance, such as use of the area for cultural and spiritual 
practices, and the need to safeguard and properly manage the interests 
of Indian Tribes. Further, the Tribe asserted that if the springs cease 
flowing, it would be devastating to both the Dixie Valley toad and the 
Tribe.
    Our Response: We have updated the SSA report to include the 
Traditional Ecological Knowledge provided by the Fallon Paiute Shoshone 
Tribe in section 1.2.
    (5) Comment: One Tribal commenter asserted that the entire proposed 
project must be halted until such time as the BLM consults with the 
Service under section 7 of the Act and highlighted the importance of 
halting construction activities and immediately consulting based on 
Tribal observations of activities detrimental to the Tribe (e.g., 
construction within approximately 500 feet of surface waters, 
construction runoff toward the springs, trash in and around the 
springs, a port-a-potty flowing into the ground, and multiple 
disturbances) and to the Dixie Valley toad (i.e., the risk of crushing 
or harming toads). The Tribe requested government-to-government 
consultation with the Service at its earliest convenience and prior to 
a final determination on the proposed rule.
    Our Response: We are working toward initiating conversations with 
the Fallon Paiute Shoshone Tribe. BLM began informal consultation with 
us on April 7, 2022.

Comments From State Agencies

    (6) Comment: One commenter recommended we get clarification or 
verification that chytrid-fungus-positive results have been limited to 
Turley Pond, which is within Dixie Valley but not within the Dixie 
Valley toad's known range. They stated that recent work evaluating past 
and current chytrid-fungus sampling data to develop monitoring-protocol 
recommendations (including sampling in Dixie Meadows and surrounding 
ponds) is being prepared for journal submission. The commenter 
recommended contacting the authors to incorporate the most up-to-date 
information.
    Our Response: We have clarified the location of the chytrid-fungus-
positive American bullfrogs, as discussed above under our response to 
(1) Comment. The paper referred by the commenter is in review at the 
Journal of Wildlife Diseases; however, the associated data release from 
USGS was used in the SSA report and cited as Kleeman et al. (2021, 
entire).
    (7) Comment: One commenter recommended we include a discussion on 
invasive plants, like Russian olive (Elaeagnus angustifolia) and 
tamarisk (Tamarix spp.), as contributing factors in the cumulative 
analysis, as these species are present within the Dixie Valley toad's 
range.
    Our Response: Section 3.3.3 in the SSA report acknowledges the 
presence of certain invasive plant species within Dixie Meadows. We do 
not have information regarding any population-level threat from these 
invasive plant species.

Public Comments

    We received thousands of comments asserting various opinions, 
including that human-induced threats of geothermal development and 
climate are extensive and irreparably damaging for the Dixie Valley 
ecosystem and pose a threat to the Dixie Valley toad; suggesting that 
alternative sites or type of renewable energy source would be better 
suited to ensure the viability of the Dixie Valley toad; that the 
developer of the geothermal power plant should be denied a permit 
because of the environmental damage it will cause to the Dixie Valley 
toad and its habitat; and that an adequate monitoring plan should be 
developed and implemented for the Dixie Valley toad. The public 
comments overwhelmingly urged us to list the toad as an endangered 
species under the Act. Some of these comments were outside of the scope 
of this final determination; below, we respond to

[[Page 73974]]

substantive comments regarding the listing determination.
    (8) Comment: One commenter asserted that the proposed rule to list 
the Dixie Valley toad as an endangered species would significantly 
adversely affect the social and economic future of Churchill County.
    Our Response: In making a determination as to whether a species 
meets the Act's definition of an endangered or threatened species, 
under section 4(b)(1)(A) of the Act the Secretary is to make that 
determination based solely on the basis of the best scientific and 
commercial data. Therefore, we did not evaluate the social and economic 
impacts of listing the Dixie Valley toad or consider such impacts in 
this final determination. Under the Act, the Service may evaluate 
economic impacts only in association with the designation of critical 
habitat under section 4(b)(2); the Service has concluded that the 
designation of critical habitat for the Dixie Valley toad is not 
determinable at this time and, therefore, is not designating critical 
habitat as part of this rulemaking.
    (9) Comment: One commenter claimed that the analysis of threats was 
incomplete, misrepresented, and did not include all applicable science 
and information. The commenter stated that it is contradictory to say 
that the Dixie Valley toad is thriving while concurrently reporting 
that there is a lack of known water-quality parameters that is 
preferred by the toad.
    Our Response: While we still have much to learn about Dixie Valley 
toads, all monitoring to date indicates that all age classes of the 
toad are present in Dixie Meadows and breeding is occurring annually. 
Water-quality parameters are not known with great detail, as described 
in section 3.3.4 of the SSA report; however, we used the best 
scientific and commercial data available to inform this rule.
    (10) Comment: One commenter stated we should have done an analysis 
on historical wetted area of the wetlands using aerial photography from 
1954 to present, Landsat imagery from 1984-2012, and National 
Agriculture Inventory Program images.
    Our Response: The Service used a Desert Research Institute report 
that analyzed much of the information the commenter is suggesting. This 
information can be found in section 4.2.10 in the SSA report and the 
corresponding report (Albano et al. 2021, entire).
    (11) Comment: One commenter claims our statement that urban 
development, agriculture, and energy production facilities will likely 
place additional demands on already limited water resources is not an 
accurate depiction of activities occurring in Dixie Valley because 
there is limited private land where these activities may occur. The 
commenter stated that the private land that existed in Dixie Valley 
during the 1990s was acquired by the Fallon Naval Air Station, thus 
limiting these activities in Dixie Valley.
    In addition, the commenter stated that we did not incorporate the 
pending DoD/Navy land withdrawals from the Dixie Valley Training Area, 
which would include the entire valley bottom from the south side of 
Dixie Meadows to State Highway 50. The commenter stated that this 
further shows why urban development and agriculture are unlikely to 
occur in Dixie Valley. Additionally, the commenter stated that we 
should have included a map of land ownership in Dixie Valley.
    Our Response: Our statement regarding an increase in urban 
development, agriculture, and energy production facilities was in the 
context of the entire Southwest. Both human settlements and natural 
ecosystems in the southwestern United States are largely dependent on 
groundwater resources, and decreased groundwater recharge may occur as 
a result of climate change (U.S. Global Change Research Program 2009, 
p. 133). Furthermore, the human population in the Southwest is expected 
to increase 70 percent by mid-century (Garfin, 2014, p. 470). Resulting 
increases in urban development, agriculture, and energy production 
facilities will likely place additional demands on already limited 
water resources. Climate change will likely increase water demand while 
at the same time shrink water supply, as water loss may increase 
evapotranspiration rates and run-off during storm events (Archer and 
Predick 2008, p. 25). Overall, demand for water is likely to go up and 
available water resources will likely decrease.
    An example of increased local water demand is the Dixie Valley 
Water Project, which is being proposed to provide more water to the 
neighboring valley experiencing increased urbanization and agriculture 
growth. There is no information on where water will be withdrawn for 
the Dixie Valley Water Project; however, we know that the basin is 
overallocated (NDWR 2021, entire), which could plausibly affect the 
amount of water in Dixie Meadows. According to the NDWR, two water 
right applications are pending in Dixie Meadows, seeking water for 
municipal use, which indicates that there could be increased water 
demand in Churchill County. Although urban development and agriculture 
may not increase within Dixie Valley, increases in urbanization and 
agriculture in surrounding areas may have an impact on water resources 
in Dixie Valley.
    (12) Comment: One commenter stated that we used out-of-date 
information regarding estimates of perennial yield in Dixie Valley. 
They claimed that our estimate of 15,000 acre-feet per year (from an 
abstract on the NDWR website) has been updated on the order of 23,000 
acre-feet per year, pointing out three studies (Garcia et al. 2015, 
entire; Huntington et al. 2014, entire; Smith et al. 2016, entire) that 
were not cited in the proposed rule and that the commenter believes 
should have been incorporated into the expert elicitation panel 
considerations.
    Our Response: We used the best scientific and commercial data 
available, which in this case is the NDWR (NDWR 2021, entire). We could 
not find mention of perennial yield in Huntington et al. (2014, 
entire); however, the author of this scientific paper was one of the 
expert panelists, and, therefore, this information was considered 
during the expert elicitation. We also could not find mention of 
perennial yield in Garcia et al. (2015, entire). Garcia et al. (2015, 
pp. 1, 75, 78, 80) found an estimate of groundwater discharge by 
evapotranspiration to be 23,000 acre-feet, but evapotranspiration does 
not equal perennial yield. Smith et al. (2016, pp. 1, 28, 175) gives a 
potential perennial yield of the combined Dixie-Fairview-Jersey Valley 
system of 23,000 acre-feet per year; however, the 15,000 acre-feet per 
year we cite is from Dixie Valley only. After reviewing the studies 
referenced in this comment, we continue to conclude that the NDWR has 
the best available data because it is the authority on water resources 
in Nevada.
    (13) Comment: One commenter stated that we analyzed and reported 
appropriated water rights in the Dixie Valley as part of our analysis, 
and that we should have reported estimates of actual consumptive use, 
which the commenter stated has decreased since the 1980s.
    Our Response: We used appropriated water rights in the Dixie Valley 
because that is the amount of water that could plausibly be used. 
Because appropriated water is authorized for use and readily available, 
we considered the possibility that it could be used in the future. No 
estimates of consumptive use were provided by the commenter and the 
NDWR does not compile pumping inventories for Dixie Valley.
    (14) Comment: One commenter stated that we included broad 
statements about

[[Page 73975]]

the Dixie Valley basin being fully appropriated for consumptive 
groundwater uses in both the emergency listing rule (87 FR 20336; April 
7, 2022) and the SSA report, and that these types of broad statements 
of the status of a basin as large as Dixie Valley can be misguided and 
misleading. The commenter also asserted that water quality in Dixie 
Meadows is very poor for human consumption and there is no interest 
from the County in accessing waters associated with Dixie Meadows.
    Our Response: We were unable to find information on where water 
will be withdrawn from the Dixie Valley Water Project; however, we know 
that the basin is overallocated (NDWR 2021, entire), which could 
plausibly affect the amount of water in Dixie Meadows. According to the 
NDWR, Churchill County has two water right applications in review (6 
cubic feet per second each) in Dixie Meadows for municipal use. 
Citations supporting the assertion that water quality in Dixie Meadows 
is poor for human consumption were not provided. Because the Dixie 
Valley Basin is overallocated and two applications for water rights for 
municipal use are held by the County within Dixie Meadows, we 
considered the potential effects of consumptive groundwater use on the 
Dixie Valley toad.
    (15) Comment: One commenter claimed that Churchill County could 
develop the Dixie Valley Water project in a manner that has minimal 
impact on the Dixie Meadows groundwater resources based on monitoring 
and modeling work completed by the County.
    Our Response: The commenter did not provide data or information on 
monitoring and modeling work done by the County, and we did not find 
any publicly available information that would allow us to take this 
information into consideration in this final rule. We cannot 
incorporate conservation efforts into our analysis that have not been 
confirmed or proven, in accordance with our Policy for Evaluation of 
Conservation Efforts When Making Listing Decisions (68 FR 15100; March 
28, 2003).
    (16) Comment: One commenter disagreed with our statement that Dixie 
Meadows has evolved with little historical variation, claiming our 
statement is not proven or established. The commenter stated that we 
should have analyzed past land use of Dixie Meadows to demonstrate 
previous uses that may have significantly altered habitat. They stated 
that there is a high probability that the meadow was homesteaded, 
farmed, or altered by early settlers and Native Americans.
    Our Response: Section 4.2.10 of the SSA report discusses evidence 
of spring modifications and their potential impacts to the Dixie Valley 
toad and its habitat. Historical water management of Dixie Meadows has 
likely had negative impacts on how water flows through the wetlands as 
evidence of dikes, channelization, and deteriorating pipes can be found 
throughout the area (Stantec 2019, pp. 13, 50-51, 104-105, 132-133; 
Albano et al. 2021, pp. 72-75). However, the needs of the species have 
not changed due to this historical alteration.
    (17) Comment: One commenter stated that we did not take an active 
role in the development of the Aquatic Resources Monitoring and 
Mitigation Plan (hereafter referred to as the Monitoring and Mitigation 
Plan), and the experts participating in our expert elicitation panel 
should have had the opportunity to interface with the Monitoring and 
Mitigation Committee. The commenter also stated that had the Service 
coordinated with Ormat (as well as with other pertinent agencies) to 
improve the Monitoring and Mitigation Plan, then emergency listing the 
Dixie Valley toad would have not been necessary.
    Our Response: Sections 4.2.2 and 4.2.3 of the SSA report summarize 
coordinated efforts between the BLM and the Service on the geothermal 
plant and associated Monitoring and Mitigation Plan, including the 
detailed comments that the Service provided on the January draft EA and 
Monitoring and Mitigation Plan on February 12, 2021.
    (18) Comment: One commenter stated that the primary basis for our 
listing decision was based on the expert panel's predictions on the 
impacts of the Dixie Meadows Project.
    Our Response: The SSA report contains our full analysis of all the 
factors that could affect the continued existence of the Dixie Valley 
toad. Because the Dixie Meadows project is a key factor that could 
affect the species' viability, the expert panel was assembled to help 
characterize the uncertainty around its potential impacts. The panel 
was composed of expert groundwater hydrologists, hydrogeologists, and 
geologists, including one of the foremost experts on geothermal systems 
in Nevada, and their judgments provide a reasonable basis for assessing 
the risk from geothermal development.
    While the risk of changes to the species' habitat from geothermal 
development is one aspect of the assessment and the primary threat to 
the species, the Dixie Valley toad's narrow range, limited 
opportunities for dispersal, risk of exposure to chytrid fungus, and 
projected changes in climate, among other factors, were also considered 
in the listing decision.
    (19) Comment: We received multiple comments on the materials 
provided to the expert panelists for the expert elicitation. Commenters 
stated that the materials provided were inadequate to provide the 
experts with understanding of the Dixie Meadows geothermal project, 
investigations conducted at the site, the hydrogeology of the overall 
area, or the threats to the toad.
    Our Response: The materials provided to the panelists served a 
specific purpose as part of accepted best practices for structured 
expert knowledge elicitation and is only one component of the 
elicitation process (Gosling 2018, entire; O'Hagan 2019, pp. 73-81; 
Oakley and O'Hagan 2019, entire). The expert panelists had access to 
the best available information at the time of the assessment, including 
the January EA, January 2021 Monitoring and Mitigation Plan for the 
Dixie Meadows project, all publicly available related materials, and 
published scientific reports and papers. The expert panelists also have 
significant professional experience in hydrogeology and the Dixie 
Valley region and were provided an opportunity to identify any 
additional studies relevant to the expert knowledge elicitation based 
on their own professional experience in hydrogeology and the Dixie 
Valley region. The information provided is based on credible, published 
scientific sources and is not designed to be an exhaustive reference.
    (20) Comment: One commenter stated that that the materials provided 
to the expert panel that described the location of the major piedmont 
fault at Dixie Meadows as being coincident with the thermal springs, 
and additionally that the same fault is the main producing structure at 
the Comstock and Dixie Valley Power Plant geothermal sites, was a 
``gross over-simplification.'' This led the expert panelists to make 
ill-informed interpretations about the dynamics of fluid flow at Dixie 
Meadows in relation to characteristics of the springflows, and 
consequently toad habitat, and compromised the ability of the panelists 
to make informed decisions based on the ``best available science.'' The 
commenter also stated that the above is clearly incorrect since it 
would also mean that all three geothermal systems/cells are connected, 
which the commenter stated is known not to be the case.

[[Page 73976]]

    Our Response: Geologic and geophysical investigations conducted 
beginning in the 1960s have been interpreted to show that the trace of 
the piedmont fault passes through Dixie Meadows at a location that is 
nearly coincident (just west) of the thermal springs, and that portions 
(sections) of the same piedmont fault, which runs up the west side of 
the valley, are the primary producing structures at the Comstock and 
Dixie Valley Power Plant geothermal sites, respectively; the commenter 
incorrectly interprets this evidence as necessitating that the three 
geothermal cells are hydraulically connected along the length of the 
piedmont fault (AltaRock Energy Inc. 2014ab, entire).
    (21) Comment: One commenter stated that the materials provided to 
the expert panel omitted information describing that dilation zones 
(e.g., at the intersections of faults striking in different directions) 
are determinant of the locations of identifiable, separate geothermal 
cells in Dixie Valley. The commenter stated that each dilation zone is 
``unique.'' The commenter also stated that this led the expert 
panelists to make ill-informed interpretations about the dynamics of 
fluid flow at Dixie Meadows in relation to characteristics of the 
springflows providing habitat for the Dixie Valley toad.
    Our Response: The role of dilation zones as determinant of the 
occurrence of geothermal cells, which are hydraulically separate, on 
the west side of Dixie Valley is published in a major Department of 
Energy-funded study that was available to the expert panelists 
(AltaRock Energy Inc. 2014a, part I). Thus, this information was 
considered in our determination.
    (22) Comment: One commenter expressed concern that the January 11, 
2021, version of the Monitoring and Management Plan was used by the 
expert elicitation panel conducted by the Service in August 2021, 
noting that ``significant changes'' were made in the final version of 
the plan that was published on November 22, 2021. Two commenters stated 
that the changes to the plan and project have specific relevance to 
items of concern identified by us and the expert panelists and 
described in the proposed and emergency listing rules (87 FR 20374 and 
87 FR 20336, both published on April 7, 2022). Specifically, the 
commenters noted the following changes/additions: (a) implementing a 
phased power plant development approach; (b) improving data and 
interpretations regarding the project's flow system and hydrogeologic 
characterization, including enhanced characterization of the long-
recognized basin-fill hydrothermal plume and an enhanced description of 
the 2017 ``flow test'' performed using wells proposed for use in Phase 
1 of the project; and (c) modifying and clarifying the period of 
baseline data collection, clarifying what parameters would be 
monitored, increasing the frequencies of water quality monitoring and 
other field measurements, installing additional monitoring wells in the 
basin-fill hydrothermal plume west of the springs, and/or suspending 
power generation operations should conservation measures be ``non-
satisfactory'' in maintaining the aquatic habitat at Dixie Meadows.
    The commenter(s) stated that the Service did not acknowledge the 
phased power plant development approach and did not analyze or disclose 
how this assumption affected the expert panelists' projections of the 
project's impacts; the new information provided rendered the expert 
panelists' opinions regarding risk(s) posed to the springs/wetlands 
complex supporting the toad marginally relevant, at best; and/or 
changes made between the January Monitoring and Mitigation Plan 
reviewed by the expert panelists and the final version were not 
minimal, disagreeing with our conclusion that changes and additions 
made to the November Monitoring and Mitigation Plan were ``minimal'' 
and did not affect the ability of the plan ``to detect or mitigate 
changes'' (i.e., to provide a robust set of protections).
    Our Response: The SSA considered the possibility of a phased 
approach to development. The expert panelists considered the power 
plant may be managed adaptively (Service 2022, appendix A) when 
thinking about the timeframe of system changes. This information is 
captured in the estimates of uncertainty for the various judgments. 
Even if development is phased, the total production amount approved 
remains a relevant quantity for assessing risk. Expert judgments on 
timeframes were based on the point at which the power plant begins 
operating (Service 2022, appendix A). Moreover, the phased power plant 
development approach results in no significant improvement to the 
efficacy or reliability of the November Monitoring and Mitigation Plan 
or reduction in the potential for adverse project impacts to the 
springs/wetlands (ability to detect or mitigate project-induced 
changes) given that the overall magnitude, number, and specific 
locations of geothermal fluid extraction and injection for each 
operational phase (12- versus 60-MW) will differ greatly. Additionally, 
the Service, in evaluating the threat of geothermal development under 
Factor A (the present or threatened destruction, modification, or 
curtailment of the species' habitat or range) in making a final listing 
decision, fully considered the phased approach described in BLM's 
Decision Record, November final EA, and November Monitoring and 
Mitigation Plan.
    The 2017 ``flow test,'' that is the only field-scale, multi-well 
pumping or injection test performed at the site to date, is of limited 
informational value because test pumping and injection were performed 
simultaneously at comparable rates in relatively close proximity over a 
limited period of time (compared to the proposed 1-year 12-MW 
operation), the test included no bedrock monitoring wells between the 
area of proposed project operations and the springs, depth of water in 
spring pools was monitored rather than more precise/sensitive 
springflows, and efforts to interpret the fate of injected tracers were 
largely unsuccessful.
    Further, changes and additions made in the November Monitoring and 
Mitigation Plan resulted in minimal, if any, improvement in the 
hydrogeologic characterization of the site, refinement of the proposed 
hydrogeologic conceptual model, increase in the capacity of the 
monitoring plan to provide effective warning of the propagation of 
project impacts to the springs and habitat for the toad, or mitigation 
of any such impacts. Although the BLM's Decision Record discusses 
suspension of operations, there is a lack of detail in the November 
Monitoring and Mitigation Plan about a definite schedule for recurring 
review of monitoring results, the timeline for adaptive management 
refinements to occur, and length of time between data collection, lab 
results getting generated, reviewed, and interpreted, and time until a 
decision is made and implemented about if/when/how to mitigate any 
adverse effects.
    (23) Comment: Two commenters stated that the monitoring established 
in the November Monitoring and Mitigation Plan will ensure early 
detection of any changes in the geothermal system prior to the effects 
spreading to the springs, and ``reaction time'' for the detection of 
project-induced changes in hydrologic conditions and ``mitigation 
adjustments'' are misstated in the Service's emergency listing rule (87 
FR 20336; April 7, 2022) based on input from the expert panel that was 
indicative of a lack of understanding of the monitoring plan, including 
its utility

[[Page 73977]]

as a ``rapid response mechanism,'' the locations and frequency of 
monitoring, and ``thresholds'' and ``triggers'' established under the 
November Monitoring and Mitigation Plan. The commenters described the 
November Monitoring and Mitigation Plan as a hydrologic monitoring 
network that will be among the most intensive localized monitoring 
programs in the western United States and noted that it consists of a 
range of mitigation options, including, if necessary, cessation of 
geothermal fluid extraction and injection.
    Our Response: We have concluded that the success of the mitigation 
options described in the November Monitoring and Mitigation Plan are 
highly uncertain given the likelihood and uncertainties of timely and 
effective detection of project impacts to the springs through the 
proposed monitoring, and timely recovery of the springs/wetlands 
complex following any steps taken to remedy impacts. Our conclusions 
are based on a number of considerations, including, but not limited to: 
(a) the concentration of the planned monitoring and mitigation 
thresholds and triggers in the springs/wetland habitat itself, which 
provide no early warning of the spreading of project effects to the 
habitat for the Dixie Valley toad (irrespective of the frequency or 
density of monitoring); and (b) compounded by a delay in the recovery 
of the hydrologic system following, in this case, implementation of any 
mitigation measures involving changes in the location(s) or rate(s) of 
project pumping or injection (Bredehoeft 2011, entire), which will be 
of finite but unknown length and is not recognized or acknowledged in 
the November Monitoring and Mitigation Plan. We note that the November 
Monitoring and Mitigation Plan is an adaptive management document that 
contemplates further refinement of thresholds and triggers and may be 
modified further in the future. The best available information at this 
time is that the monitoring and mitigation plan is not adequate to 
protect the species from extinction due to geothermal development in 
Dixie Valley.
    (24) Comment: One commenter stated that the expert panel did not 
have access to the November Monitoring and Mitigation Plan, which 
included refinements to the hydrogeologic characterization of Dixie 
Valley and their hydrogeologic conceptual model of the Dixie Meadows 
site. The commenter suggests this caused the panelists to be influenced 
by their previously held assumptions about the hydrogeology of Dixie 
Valley, which then influenced their opinions regarding the potential 
impacts of the project.
    Our Response: The November Monitoring and Mitigation Plan contains 
information about the hydrogeology of geothermal systems in Dixie 
Valley (broadly) that was widely available in published sources to the 
expert panel. The panel was composed of expert-level groundwater 
hydrologists/hydrogeologists and a geologist, the latter among the 
foremost experts on geothermal systems in Nevada. The November 
Monitoring and Mitigation Plan did not include significant additional 
data supporting the proposed hydrogeologic conceptual model for the 
Dixie Meadows site and significant uncertainty remains regarding the 
primary and/or significant source or sources of the thermal springs. 
This uncertainty, in turn, has significant ramifications for the 
effectiveness of the proposed monitoring plan and any mitigation 
measures that involve changes to the location(s) or rate(s) of 
geothermal fluid extraction and/or injection, or ceasing them 
altogether as stipulated in BLM's Decision Record.
    (25) Comment: One commenter stated that the proposed listing rule 
(87 FR 20374; April 7, 2022) included unsupported speculation and 
surmise, especially regarding the Dixie Valley toad's habitat needs and 
potential geothermal impacts to its habitats. The commenter disagreed 
with our assessment of the toad's habitat requirements and potential 
impacts to the habitat from the geothermal project.
    Our Response: We considered the best scientific and commercial data 
available regarding the Dixie Valley toad to evaluate its potential 
status under the Act. We solicited peer review of our evaluation of the 
available data, and our peer reviewers supported our analysis. Science 
is a cumulative process, and the body of knowledge is ever-growing. In 
light of this, the Service continually takes new research into 
consideration. If plausible and significant new research supports 
amendment or revision of this rule in the future, the Service will 
consider modifying the rule consistent with the Act as appropriate.
    We address the habitat requirements of the Dixie Valley toad in 
section 3.3 of the SSA report and the potential impacts from geothermal 
development in section 4.2.1 of the SSA report.
    (26) Comment: In discussing sufficient wetted area, one commenter 
stated that in the materials provided to the expert panelists, a USGS 
study (Huntington et al. 2014, pp. 40-49) indicated the average 
proportion of hot geothermal water mixing with cooler basin-fill 
groundwater in Dixie Valley was 10 to 12 percent, although three of the 
hotter temperature springs had 22 to 31 percent mixing. The commenter 
stated that in the unlikely event that all geothermal input to the hot 
springs ceased, 70 to 90 percent of the spring discharge would 
continue, so a complete loss of habitat postulated by the Service does 
not seem plausible. Additionally, the commenter stated that although 
there is a correlation between hot spring discharge, wetted area, and 
toad habitat, a complete loss of habitat would not occur, especially if 
only a small variation in hot spring discharge occurred. The commenter 
referenced table 3.3 in the SSA report to show that there is already a 
large natural variation in springflow from individual springs.
    Our Response: Multiple members of the expert panel suggested that 
changes in surface expression of springs could occur well before 100 
percent of the geothermal input was lost (Service 2022, appendix B), 
leading to the range of plausible values reported by the panel. 
Additionally, a complete loss of the geothermal fluid component of the 
spring discharges would result in a significant decrease in the 
temperature of waters within the springs/wetlands complex with 
potentially substantial negative impacts to the Dixie Valley toad.
    (27) Comment: One commenter stated that the SSA report does not 
provide evidence to support the conclusion that thermally heated waters 
are essential or required for toad habitat or reproduction.
    Our Response: Section 3.3.2 of the SSA report discusses adequate 
water temperature needs of the Dixie Valley toad. Two studies (Halstead 
et al. 2021, entire; Rose et al. 2022, entire) establish the importance 
of thermal waters to Dixie Valley toads. We considered the best 
scientific and commercial data available regarding the Dixie Valley 
toad to evaluate their potential status under the Act. We solicited 
peer review of our evaluation of the available data, and the peer 
reviewers supported our analysis.
    (28) Comment: One commenter discussed how toad sightings in Dixie 
Meadows from 2009 to 2014 (displayed in figure 4.7 in the SSA report) 
show that the toads are distributed throughout the spring-fed wetlands 
but avoid hot water. The commenter stated that many toads were observed 
near Spring Complex 6, the coldest area, which has a temperature 
ranging from 12.7 to 15 [deg]C (55 to 59 [deg]F), and there were no 
toads observed near springs that have a temperature greater than 35 
[deg]C (95 [deg]F). The commenter concludes that the need for hot water 
is unlikely.

[[Page 73978]]

    Our Response: Section 3.3.2 of the SSA report discusses adequate 
water temperature preferred by Dixie Valley toads throughout annual 
seasonal changes. Figure 4.7 in the SSA report depicts toad use between 
2009-2014 during April and May (breeding season) of wetted habitat. The 
Dixie Valley toad uses different parts of the wetlands during different 
times of the year. Because figure 4.7 shows toad use of the wetlands 
during the breeding season only and is not representative of all the 
areas the toad uses throughout the year, it is not appropriate to use 
figure 4.7 to discuss the toad's preference for warm water. Instead, 
please refer to figure 5.1 of the SSA report, which is a more accurate 
description of occupied habitat and shows the Dixie Valley toad occurs 
near spring heads. Additionally, the thermal needs of the Dixie Valley 
toad have been established (Halstead et al. 2021, entire; Rose et al. 
2022, entire).
    Spring Complex 6 is isolated from the other spring complexes and is 
the southern-most wetland within Dixie Meadows. While toads can be 
found in this spring complex, many survey attempts in this area are 
unsuccessful in finding toads and when they are found, few individuals 
are located. Few individuals are found in Spring Complex 6 because it 
has water temperatures cooler than the water temperatures preferred by 
the toad, making it lower-quality habitat. Therefore, although Dixie 
Valley toads can be found in cooler spring complexes, they are low-
quality habitat and do not provide for the needs of the species. We 
conclude that the low abundance of Dixie Valley toads in Spring Complex 
6 supports our conclusion that thermal waters are an essential element 
of the species' continued existence.
    (29) Comment: One commenter stated that employees of Ormat have 
observed tadpoles in ephemeral ponds that fill after storm events that 
have no thermal-water input, indicating that hot spring input is also 
unnecessary for hatching.
    Our Response: Dixie Valley toad larvae need warm water temperatures 
for survival. Dixie Valley toad larvae have been found in water 
temperatures ranging from 20-28 [deg]C (68-82 [deg]F) (Rose et al. 
2022, entire) and have been found close to spring heads and throughout 
the wetland complexes (Rose et al. 2022, entire). Some sites where 
larvae have been found are heated by solar radiation, which may have 
been the case for the anecdotal observation by Ormat employees. Larvae 
likely use a combination of sites heated by solar radiation and thermal 
water input; therefore, reduction in thermal-water input will decrease 
habitat for a life stage with an already highly restricted amount of 
habitat.
    (30) Comment: One commenter disagrees with the correlation between 
thermal characteristics of the Dixie Valley toad habitat and disease 
resistance to chytridiomycosis.
    Our Response: Section 4.2.8 in the SSA report describes potential 
disease impacts from chytridiomycosis and the role that water 
temperature plays in the establishment and severity of 
chytridiomycosis. The best available information indicates that the 
thermal nature of Dixie Valley toad habitat may keep chytrid fungus 
from becoming established; therefore, it is imperative that the water 
maintains its natural thermal characteristics (Forrest et al. 2013, pp. 
75-85; Halstead et al. 2021, pp. 33-35).
    (31) Comment: One commenter stated that because ambient 
temperatures in Dixie Valley are frequently higher than 25 [deg]C (77 
[deg]F), our assertion that it is imperative to maintain precise 
spring-water temperatures is lacking in support.
    Our Response: Available information does not support the assumption 
that warm air temperatures will keep water temperatures high regardless 
of effects from geothermal production. Spring complexes 2, 3, 4, and 5 
(which provide a majority of the wetland habitat for the Dixie Valley 
toad) produce water temperatures greater than 25 [deg]C (77 [deg]F); 
thus, ambient air temperature would not be able to warm water 
temperatures sufficiently. In addition, the commenter only references 
high temperatures in Dixie Valley. If water temperatures in the springs 
are decreased by geothermal production, then winter months with colder 
ambient air temperatures could cool water temperatures to unsuitable 
levels. In summary, the springs are naturally warmer than air 
temperatures because of the geothermal conditions, and if the 
geothermal conditions are removed, the ambient air temperatures would 
be insufficient to raise the water temperatures to the temperatures 
required by the Dixie Valley toad for reproduction and survival.
    (32) Comment: One commenter stated that there is a wide range in 
values for total dissolved solids, dissolved oxygen, and pH across 
Dixie Valley toad aquatic habitat. The commenter asserts that the SSA 
report does not provide evidence that there is a correlation between 
toad distribution and changes in water quality.
    Our Response: The Service recognizes that the exact water-quality 
parameters preferred by Dixie Valley toads are unknown and should be 
studied further. However, after review of the best available 
information, we conclude this species has evolved only in Dixie Meadows 
and is presumed to thrive in the current existing complex mix of water 
emanating from both the basin-fill aquifer and the deep geothermal 
reservoir. See section 3.3.4 of the SSA report for more information 
regarding adequate water quality.
    (33) Comment: One commenter stated that there is no evidence for 
the SSA report's description that the piedmont fault is the source of 
both the cold and hot springs at Dixie Meadows, and that information 
was not provided to the expert panel regarding the presence of the 
basin-fill hydrothermal plume located west of the springs. 
Additionally, the alternative hypothesis regarding the source of the 
springs or other interpretations of the hydrologic significance of the 
piedmont fault were not provided to the expert panelists. The commenter 
then stated that, due to this omission, the panelists were not provided 
with the best available scientific information.
    Our Response: We agree that the Piedmont fault is not the source of 
both cold basin-fill waters and geothermal fluids discharging from the 
springs, subsequently, we revised the SSA report to correct that error. 
Based on the chemistry of waters discharging from the thermal springs, 
we interpret them to be mixtures, to various degrees, of geothermal 
fluids and basin-fill groundwaters (Huntington et al. 2014, entire), 
including those flowing west to east from the foot of the mountains 
toward the springs within the long-recognized basin-fill hydrothermal 
plume.
    In regards to the expert panel, the panelists were composed of 
expert groundwater hydrologists, hydrogeologists, and geologists, 
including one of the foremost experts on geothermal systems in Nevada, 
who are aware of the existence of the basin-fill hydrothermal plume and 
Piedmont fault and their potential roles as sources of waters 
discharging from the springs.
    (34) Comment: One commenter stated that the literature used by the 
Service stating that geothermal energy production is the greatest 
threat to Dixie Valley toads is flawed because some of the scientific 
papers cited did not have the requisite hydrogeological analysis to 
support that assertion. The commenter specifically pointed to Forrest 
et al. (2017), Gordon et al. (2017), and Halstead et al. (2021).
    Our Response: We considered the best scientific and commercial data 
available regarding the Dixie Valley toad to evaluate the species' 
potential status

[[Page 73979]]

under the Act. We solicited peer review of our evaluation of the 
available data, and our peer reviewers supported our analysis. All 
three papers mentioned by the commenter are peer-reviewed journal 
articles. The authors of the three papers provided important 
information on the biology, habitat requirements, and use by the Dixie 
Valley toad within the Dixie Meadow wetlands. All three papers came to 
the same conclusion that geothermal development was the greatest threat 
to the persistence of the toad as described in section 4.2.1 of the SSA 
report. This conclusion was further supported by the expert panel and 
our own analysis of the threats facing the Dixie Valley toad.
    (35) Comment: One commenter stated that the Service recognized that 
every geothermal site is unique, but then considered the impacts of 
geothermal energy projects at four other sites in California and Nevada 
as indicative of the likely impacts of the Dixie Meadows project, 
without analyzing the differences between those projects and the one 
planned at Dixie Meadows, with particular consideration given to 
impacts that have occurred at the Jersey Valley site.
    Our Response: Other geothermal projects were used to inform the 
range of plausible outcomes, but characteristics of projects were not 
directly applied to the Dixie Meadows project, nor were they used to 
determine a most likely outcome. In addition, the expert panelists 
discussed differences in technology and site characteristics between 
other geothermal projects and the Dixie Meadows project when forming 
their opinions (Service 2022, appendix A). The expert panelists used 
these comparisons to narrow down the range of plausible outcomes of the 
Dixie Meadows project, subsequently incorporating the differences 
between other geothermal projects and this project into our analysis.
    (36) Comment: One commenter stated that the expert panelists 
questioned whether those responsible for managing the power plant 
operation would implement the mitigation measures outlined in the 
January Monitoring and Mitigation Plan if/when the measures are counter 
to operational goals. This viewpoint likely influencing the panelists' 
opinions regarding the potential impacts of the project, despite the 
information provided in the November Monitoring and Mitigation Plan.
    Our Response: The expert panel had access to the January Monitoring 
and Mitigation Plan, which substantially described the monitoring and 
mitigation measures, hypotheses concerning the hydrogeology of the 
Dixie Meadows site and source(s) of geothermal fluids discharging from 
the springs, and mitigation measures (including significant 
curtailments of project operations) outlined in the November Monitoring 
and Mitigation Plan. Based on the panelists' evaluation of the above, 
as well as other published information about the hydrogeology and 
surface water resources of the Dixie Meadows site, they collectively 
expressed low confidence in the ability of the January Monitoring and 
Mitigation Plan to detect and mitigate project-induced changes in the 
temperature and/or flow of the springs because of the hydrogeologic 
complexity and natural hydrologic variability of the site, limited 
baseline data, inadequacies in the proposed monitoring and mitigation 
options, and potential interacting effects of climatic change and other 
groundwater-related uses in the valley. After the experts expressed low 
confidence in the ability of the January Monitoring and Mitigation Plan 
to detect and mitigate changes to the springs and wetland complex, they 
additionally expressed concern that mitigation measures might not be 
implemented if the measures ran counter to operational goals. 
Therefore, although the panelists' concern about mitigation measures 
being implemented was one factor, the other factors discussed above had 
a greater influence on the experts' judgements.
    (37) Comment: One commenter claimed that the Service did not 
consider instances where geothermal energy projects have had negligible 
to no impacts on springs or other surface discharges, including the 
geothermal energy projects at the Tungsten Mountain Power Plant and 
McGinness Hills facility in Nevada and the 110-MW Ngatamariki 
geothermal project in New Zealand. The commenter additionally stated 
that a condition of approval of the Ngatamariki project was an 
agreement to preserve surface geothermal features within the Orakei 
Karako thermal system to the northeast.
    Our Response: The expert elicitation panel considered all of these 
projects in their discussions, with the McGinness Hills project 
referenced in the elicitation record (Service 2022, appendix A). The 
Service considered, as part of the expert elicitation and SSA, impacts 
(or the lack thereof) to surface water resources experienced at other 
geothermal energy production in evaluating the potential impacts of the 
project planned at Dixie Meadows. We find that all the other geothermal 
energy projects referenced by the commenter have important differences 
from the Dixie Meadows site, such that we find that it is not 
scientifically supportable to extrapolate their effects to the Dixie 
Meadows project.
    The hydrogeology of the Dixie Meadows site differs significantly 
from that at the McGinness Hills, Tungsten Mountain, and Ngatamariki 
sites in that the Dixie Meadows springs are not hydraulically isolated 
from the underlying geothermal reservoir by one or more low 
permeability layers; e.g., clay or clay-rich strata. Consequently, 
unlike surface water resources at the McGinness Hills, Tungsten 
Mountain, and Ngatamariki sites, the Dixie Meadows springs can be 
impacted by production pumping and/or injection in the underlying 
geothermal reservoir. Additionally, the best available information 
suggests that no hydraulic connection exists between the Orakei Korako 
geothermal system and the Ngatamariki site (O'Brien 2010, p. iii). 
Please refer to section 4.2.1 of the SSA report for further discussion.
    (38) Comment: One commenter stated that the basin-fill hydrothermal 
plume is the only source of geothermal fluids discharging from the 
springs and, as a result, spring flows, including their temperatures, 
could be maintained by reinjecting some of the available cooled 
geothermal fluids into the plume; which could additionally result in an 
increase in the volume of the spring flows. In this respect, the Dixie 
Meadows site/resource is different than other geothermal projects cited 
in the proposed and emergency listing rules (87 FR 20374 and 87 FR 
20336, both published on April 7, 2022).
    Our Response: It is clear from the presence of a major fault scarp 
just west of the springs (at the location of the Piedmont fault) that 
surficial groundwaters flowing west to east through the basin fill, 
including the long-recognized hydrothermal plume (Bergman et al. 2014, 
pp. 74 and 93), contribute to the spring flows; and that the cold water 
component of the basin-fill hydrothermal plume varies seasonally and is 
largely controlled by climatic factors. Additionally, the Piedmont 
fault may be a significant, if not the primary, source of geothermal 
fluids discharging from the springs, a matter of dispute (Bergman et 
al. 2014, entire). The relative contributions of these two potential 
sources, the basin-fill hydrothermal plume and Piedmont fault, to the 
flow and temperatures of the springs are unknown.
    Due to the variable cold-water contribution of the basin-fill 
hydrothermal plume to the discharge and temperatures of the springs, 
which is largely driven by climatic factors

[[Page 73980]]

(including seasonal variations, such as the amount and timing of 
snowmelt), as well as the unspecified location(s), rate(s), and timing 
of the described reinjection of cooled geothermal fluids into the 
plume, we have low confidence that the measure described by the 
commenter could be used to reproduce the temperatures and flow rates of 
various springs at Dixie Meadows.
    Likewise, any resulting increases in the flow of the springs are 
likely to be accompanied by a decrease in the temperature of the 
springs (in that sense, a depletion of the spring flows).
    Regarding the geologic (and hydrogeologic) characteristics of the 
Dixie Meadows site, it is not unique among the geothermal energy 
project sites considered in the emergency listing rule (87 FR 20336; 
April 7, 2022). The Dixie Valley Power Plant site in northern Dixie 
Valley is situated within the same Dixie Valley Fault Zone with many of 
the same major faults; a hydrothermal plume also exists within the 
overlying basin fill at that site. One or more thermal springs were 
once present in the vicinities of the Steamboat Springs and Jersey 
Valley geothermal projects, also referenced in the emergency listing 
rule.
    (39) Comment: One commenter stated that there will be no net 
depletion of water within the overall hydrologic/hydrogeologic system 
because consumptive use of the geothermal fluids will be negligible.
    Our Response: We agree the overall water balance of the larger 
(area-wide) hydrologic/hydrogeologic system may not be affected to any 
significant degree by the combined geothermal extraction and injection 
during operations due to the use of binary technology within the power 
plant. However, the transport of geothermal fluids to the springs, 
which ultimately depends on the movement of geothermal fluids along 
discrete permeable structures in faulted/fractured bedrock, may be 
altered by the project pumping and/or injection in ways that cannot be 
anticipated in this fractured-rock environment; impacting, in 
particular, the temperatures of the springs, despite maintenance of the 
overall water balance within the system. Because water temperature is a 
key component of Dixie Valley toad survival and reproduction, we are 
most concerned about the impacts of the project on water temperatures 
within the toad's habitat.
    (40) Comment: One commenter stated that the hydrogeology of the 
Dixie Meadows site, including the geothermal reservoir, is unique; 
reasonably well understood and defined based on exploration drilling, 
flow testing, and spring analyses conducted to date; and not comparable 
to other geothermal systems in Dixie Valley or elsewhere in the region.
    Our Response: The hydrogeology of the geothermal system at Dixie 
Meadows has many geologic, hydrogeologic, and thermal characteristics 
in common with other geothermal systems/cells identified and studied on 
the west side of Dixie Valley within the Dixie Valley Fault Zone (area 
of the Comstock Mine and long-time Dixie Valley Power Plant) based on 
geothermal investigations beginning in the 1960s (Bergman et al. 2014, 
entire), including the presence of basin-fill hydrothermal plumes 
emanating from the vicinity of the range-bounding Dixie Valley Fault. 
In addition to the Dixie Valley Power Plant site, one or more thermal 
springs were once present in the vicinities of the Steamboat Springs 
and Jersey Valley geothermal projects, also referenced in the emergency 
listing rule (87 FR 20336; April 7, 2022).
    The distinguishing (unique) feature of the Dixie Meadows geothermal 
system is the presence of numerous thermal springs, numbering well in 
excess of 20, that provide habitat for an endemic species, the Dixie 
Valley toad. With respect to the current understanding of the 
geothermal system/site, its hydrogeology is poorly characterized to 
date, due, in particular, to limited bedrock exploratory drilling and 
field-scale multi-well pumping and injection testing. This paucity of 
information hinders the development of a conceptual hydrogeologic model 
that includes identification/confirmation of the source(s) of the 
thermal spring discharges, as well as the development of an effective 
early-warning monitoring program and mitigation measures, both of which 
depend on the identification of the source(s) of the thermal spring 
discharges.

I. Final Listing Determination

Background

    A thorough review of the taxonomy, life history, and ecology of the 
Dixie Valley toad (Anaxyrus williamsi) is presented in the SSA report 
(Service 2022, entire).
    The Dixie Valley toad was described as a distinct species in the 
western toads (Anaxyrus boreas) species complex in 2017, due to 
morphological differences, genetic information, and its isolated 
distribution (Gordon et al. 2017, entire). Forrest et al. (2017, 
entire) also published a paper describing Dixie Valley toad and came up 
with similar results but stopped short of concluding that it is a 
unique species. We evaluated both papers and concluded the Gordon et 
al. (2017, entire) paper provided a better sampling design to answer 
species-level genetic questions and conducted a more thorough 
morphological analysis. Additionally, the Dixie Valley toad has been 
accepted as a valid species by the two leading authoritative amphibian 
internet sites: (1) amphibiaweb.org (AmphibiaWeb 2022, website) and (2) 
Amphibian Species of the World (Frost 2021, website). Because both the 
larger scientific community and our own analysis of the best available 
scientific information indicate that the findings of Gordon et al. 
(2017 entire) are well supported, we are accepting their conclusions 
that the Dixie Valley toad is a unique species (Anaxyrus williamsi). 
Therefore, we have determined that the Dixie Valley toad is a listable 
entity under the Act.
    Limited information is available specific to the life history of 
the Dixie Valley toad; therefore, closely associated species are used 
as surrogates where appropriate. Breeding (denoted by observing a male 
and female in amplexus, egg masses, or tadpoles) occurs annually 
between March and May (Forrest 2013, p. 76). Breeding appears 
protracted due to the thermal nature of the habitat and can last up to 
3 months (March-May), with toads breeding early in the year in habitats 
closer to the thermal spring sources and then moving downstream into 
habitats as they warm throughout spring and early summer. Other toad 
species typically have a much more contracted breeding season of 3 to 4 
weeks (e.g., Sherman 1980, pp. 18-19, 72-73). Dixie Valley toad 
tadpoles hatch shortly after being deposited; time to hatching is not 
known but is likely dependent on water temperature (e.g., black toad 
(Anaxyrus exsul) tadpoles hatch in 7 to 9 days; Sherman 1980, p. 97). 
Fully metamorphosed Dixie Valley toadlets were observed 70 days after 
egg laying (Forrest 2013, pp. 76-77).
    The Dixie Valley toad is a narrow-ranging endemic (highly local and 
known to exist only in their place of origin) known from one population 
in the Dixie Meadows area of Churchill County, Nevada. The species 
occurs primarily on Department of Defense (Fallon Naval Air Station) 
lands (90 percent) and Bureau of Land Management (BLM) lands (10 
percent). The wetlands located in Dixie Meadows cover 307.6 hectares 
(ha) (760 acres (ac)) and are fed by geothermal springs. The potential 
area of occupancy is estimated to be 146 ha (360 ac) based on the 
extent of wetland-associated vegetation. The species is heavily reliant 
on these

[[Page 73981]]

wetlands, as it is rarely encountered more than 14 meters (m) (46 feet 
(ft)) from aquatic habitat (Halstead et al. 2021, p. 7).

Regulatory and Analytical Framework

Regulatory Framework

    Section 4 of the Act (16 U.S.C. 1533) and the implementing 
regulations in title 50 of the Code of Federal Regulations set forth 
the procedures for determining whether a species is an endangered 
species or a threatened species, issuing protective regulations for 
threatened species, and designating critical habitat for threatened and 
endangered species. In 2019, jointly with the National Marine Fisheries 
Service, the Service issued final rules that revised the regulations in 
50 CFR parts 17 and 424 regarding how we add, remove, and reclassify 
threatened and endangered species and the criteria for designating 
listed species' critical habitat (84 FR 45020 and 84 FR 44752; August 
27, 2019). At the same time the Service also issued final regulations 
that, for species listed as threatened species after September 26, 
2019, eliminated the Service's general protective regulations 
automatically applying to threatened species the prohibitions that 
section 9 of the Act applies to endangered species (collectively, the 
2019 regulations).
    As with the proposed rule, we are applying the 2019 regulations for 
this final rule because the 2019 regulations are the governing law just 
as they were when we completed the proposed rule. Although there was a 
period in the interim--between July 5, 2022, and September 21, 2022--
when the 2019 regulations became vacated and the pre-2019 regulations 
therefore governed, the 2019 regulations are now in effect and govern 
listing and critical habitat decisions (see Center for Biological 
Diversity v. Haaland, No. 4:19-cv-05206-JST, Doc. 168 (N.D. Cal. July 
5, 2022) (CBD v. Haaland) (vacating the 2019 regulations and thereby 
reinstating the pre-2019 regulations)); In re: Cattlemen's Ass'n, No. 
22-70194 (9th Cir. Sept. 21, 2022) (staying the district court's order 
vacating the 2019 regulations until the district court resolved a 
pending motion to amend the order); Center for Biological Diversity v. 
Haaland, No. 4:19-cv-5206-JST, Doc. Nos. 197, 198 (N.D. Cal. Nov. 16, 
2022) (granting plaintiffs' motion to amend July 5, 2022 order and 
granting government's motion for remand without vacatur). The Act 
defines an ``endangered species'' as a species that is in danger of 
extinction throughout all or a significant portion of its range, and a 
``threatened species'' as a species that is likely to become an 
endangered species within the foreseeable future throughout all or a 
significant portion of its range. The Act requires that we determine 
whether any species is an endangered species or a threatened species 
because of any of the following factors:
    (A) The present or threatened destruction, modification, or 
curtailment of its habitat or range;
    (B) Overutilization for commercial, recreational, scientific, or 
educational purposes;
    (C) Disease or predation;
    (D) The inadequacy of existing regulatory mechanisms; or
    (E) Other natural or manmade factors affecting its continued 
existence.
    These factors represent broad categories of natural or human-caused 
actions or conditions that could have an effect on a species' continued 
existence. In evaluating these actions and conditions, we look for 
those that may have a negative effect on individuals of the species, as 
well as other actions or conditions that may ameliorate any negative 
effects or may have positive effects.
    We use the term ``threat'' to refer in general to actions or 
conditions that are known to or are reasonably likely to negatively 
affect individuals of a species. The term ``threat'' includes actions 
or conditions that have a direct impact on individuals (direct 
impacts), as well as those that affect individuals through alteration 
of their habitat or required resources (stressors). The term ``threat'' 
may encompass--either together or separately--the source of the action 
or condition or the action or condition itself.
    However, the mere identification of any threat(s) does not 
necessarily mean that the species meets the statutory definition of an 
``endangered species'' or a ``threatened species.'' In determining 
whether a species meets either definition, we must evaluate all 
identified threats by considering the species' expected response and 
the effects of the threats--in light of those actions and conditions 
that will ameliorate the threats--on an individual, population, and 
species level. We evaluate each threat and its expected effects on the 
species, then analyze the cumulative effect of all of the threats on 
the species as a whole. We also consider the cumulative effect of the 
threats in light of those actions and conditions that will have 
positive effects on the species, such as any existing regulatory 
mechanisms or conservation efforts. The Secretary determines whether 
the species meets the definition of an ``endangered species'' or a 
``threatened species'' only after conducting this cumulative analysis 
and describing the expected effect on the species now and in the 
foreseeable future.
    The Act does not define the term ``foreseeable future,'' which 
appears in the statutory definition of ``threatened species.'' Our 
implementing regulations at 50 CFR 424.11(d) set forth a framework for 
evaluating the foreseeable future on a case-by-case basis. The term 
``foreseeable future'' extends only so far into the future as the 
Services can reasonably determine that both the future threats and the 
species' responses to those threats are likely. In other words, the 
foreseeable future is the period of time in which we can make reliable 
predictions. ``Reliable'' does not mean ``certain''; it means 
sufficient to provide a reasonable degree of confidence in the 
prediction. Thus, a prediction is reliable if it is reasonable to 
depend on it when making decisions.
    It is not always possible or necessary to define foreseeable future 
as a particular number of years. Analysis of the foreseeable future 
uses the best scientific and commercial data available and should 
consider the timeframes applicable to the relevant threats and to the 
species' likely responses to those threats in view of its life-history 
characteristics. Data that are typically relevant to assessing the 
species' biological response include species-specific factors such as 
lifespan, reproductive rates or productivity, certain behaviors, and 
other demographic factors.

Analytical Framework

    The SSA report documents the results of our comprehensive 
biological review of the best scientific and commercial data regarding 
the status of the species, including an assessment of the potential 
threats to the species (Service 2022, entire). The SSA report does not 
represent our decision on whether the species should be listed as an 
endangered or threatened species under the Act. However, it does 
provide the scientific basis that informs our regulatory decisions, 
which involve the further application of standards within the Act and 
its implementing regulations and policies. The following is a summary 
of the key results and conclusions from the SSA report; the full SSA 
report can be found at Docket No. FWS-R8-ES-2022-0024 on https://www.regulations.gov.
    To assess the Dixie Valley toad's viability, we used the three 
conservation biology principles of resiliency, redundancy, and 
representation (Shaffer

[[Page 73982]]

and Stein 2000, pp. 306-310). Briefly, resiliency supports the ability 
of the species to withstand environmental and demographic stochasticity 
(for example, wet or dry, warm or cold years), redundancy supports the 
ability of the species to withstand catastrophic events (for example, 
droughts, large pollution events), and representation supports the 
ability of the species to adapt over time to long-term changes in the 
environment (for example, climate changes). In general, the more 
resilient and redundant a species is and the more representation it 
has, the more likely it is to sustain populations over time, even under 
changing environmental conditions. Using these principles, we 
identified the species' ecological requirements for survival and 
reproduction at the individual, population, and species levels, and 
described the beneficial and risk factors influencing the species' 
viability.
    The SSA process can be categorized into three sequential stages. 
During the first stage, we evaluated the individual species' life-
history needs. The next stage involved an assessment of the historical 
and current condition of the species' demographics and habitat 
characteristics, including an explanation of how the species arrived at 
its current condition. The final stage of the SSA involved making 
predictions about the species' responses to positive and negative 
environmental and anthropogenic influences. Throughout all of these 
stages, we used the best available information to characterize 
viability as the ability of a species to sustain populations in the 
wild over time. We used this information to inform our regulatory 
decision.
    We note that, by using the SSA framework to guide our analysis of 
the scientific information documented in the SSA report, we have not 
only analyzed individual effects on the species, but we have also 
analyzed their potential cumulative effects. We incorporate the 
cumulative effects into our SSA analysis when we characterize the 
current and future condition of the species. To assess the current and 
future condition of the species, we undertake an iterative analysis 
that encompasses and incorporates the threats individually and then 
accumulates and evaluates the effects of all the factors that may be 
influencing the species, including threats and conservation efforts. 
Because the SSA framework considers not just the presence of the 
factors, but to what degree they collectively influence risk to the 
entire species, our assessment integrates the cumulative effects of the 
factors and replaces a standalone cumulative effects analysis.

Summary of Biological Status and Threats

    In this discussion, we review the biological condition of the 
species and its resources, and the threats that influence the species' 
current and future condition, in order to assess the species' overall 
viability and the risks to that viability.

Species Needs

Wetted Area
    Dixie Meadows contains 122 known spring and seep sources and 
discharges approximately 1,109,396 cubic meters per year (m\3\/yr) (900 
acre-feet per year (afy)) (BLM 2021b, appendix H, pp. 1-2), which 
distributes water across the wetland complex then flows out to the 
playa or is collected in a large ephemeral pond in the northeast 
portion of the wetland complex. Some of the larger springs have 
springbrooks that form channels while in other areas the water spreads 
out over the ground or through wetland vegetation creating a thin layer 
of water or wet soil that helps maintain the wetland. Spring discharge 
is inherently linked to the amount of wetted area within the wetland 
complex. Spring discharge is important for the viability of the Dixie 
Valley toad because changes to discharge rates likely impact the 
ability of the toad to survive in a particular spring complex.
    Dixie Valley toad is a highly aquatic species rarely found more 
than 14 m (46 ft) away from water (Halstead et al. 2021, pp. 28, 30). 
The species needs wetted area for shelter, feeding, reproduction, and 
dispersal. Any change in the amount of wetted area will directly 
influence the amount of habitat available to the Dixie Valley toad. Due 
to the already restricted range of the habitat, the species needs to 
maintain the entirety of the 1.46-square-kilometer (km\2\) (360-ac) 
potential area of occupancy, based on the extent of the wetland-
associated vegetation.
Adequate Water Temperature
    In addition to the Dixie Valley toad being highly aquatic, the 
temperature of the water is also important to its life history. The 
species needs warm temperatures for shelter and reproduction. The Dixie 
Valley toad selects water or substrate that is warmer compared to 
nearby random paired locations, particularly in spring, fall, and 
winter months (Halstead et al. 2021, pp. 30, 33-34). During spring, 
they select areas with warmer water for breeding (oviposition sites), 
which allows for faster egg hatching and time to metamorphosis 
(Halstead et al. 2021, pp. 30, 33-34). During fall, they select warmer 
areas (closer to thermal springs with dense vegetation), which 
satisfies their thermal preferences as nighttime temperatures decrease 
(Halstead et al. 2021, pp. 30, 33-34). As winter approaches, toads find 
areas with consistent warm temperatures during brumation (hibernation 
for cold-blooded animals), so they do not freeze (Halstead et al. 2021, 
pp. 30, 33-34). This affinity for warm water temperature during 
brumation is unique to the Dixie Valley toad as compared to other 
species within the western toad species complex, which select burrows, 
rocks, logs, or other structures to survive through winter (Browne and 
Paszkowski 2010, pp. 53-56; Halstead et al. 2021, p. 34). Therefore, 
although the exact temperatures are unknown (range between 10-41 [deg]C 
(50-106 [deg]F), Dixie Valley toad requires water temperatures warm 
enough to successfully breed and survive colder months during the year.
Wetland Vegetation
    The most common wetland vegetation found within Dixie Meadows 
includes Juncus balticus (Baltic rush), Schoenoplectus spp. 
(bulrushes), Phragmites australis (common reed), Eleocharis spp. 
(spikerushes), Typha spp. (cattails), Carex spp. (sedges), and 
Distichlis spicata (saltgrass) (AMEC Environment and Infrastructure 
2014, p. I-1; Tierra Data 2015, pp. 2-25-2-29; BLM 2021b, appendix H, 
pp. 50-52, 93-99). Several species of invasive and nonnative plants 
also occur in Dixie Meadows, including Cicuta maculata (water hemlock), 
Cardaria draba (hoary cress), Lepidium latifolium (perennial 
pepperweed), Elaeagnus angustifolia (Russian olive), and Tamarix 
ramosissima (saltcedar) (AMEC Environment and Infrastructure 2014, p. 
3-59). The Dixie Valley toad needs sufficient wetland vegetation to use 
as shelter. At a minimum, maintaining the current heterogeneity of the 
wetland vegetation found in Dixie Meadows is a necessary component for 
maintaining the resiliency of the Dixie Valley toad (Halstead et al. 
2021, p. 34).
Adequate Water Quality
    Amphibian species spend all or part of their life cycle in water; 
therefore, water quality characteristics directly affect amphibians. 
Dissolved oxygen, potential hydrogen (pH), salinity, water 
conductivity, and excessive nutrient concentrations (among other water 
quality metrics) all have direct and indirect impacts to the survival, 
growth, maturation, and physical development

[[Page 73983]]

of amphibian species when found to be outside of naturally occurring 
levels for any particular location (Sparling 2010, pp. 105-117).
    Various water quality data have been collected from a few springs 
within Dixie Meadows and from wells drilled during geothermal 
exploration activities (BLM 2021b, appendix H, pp. 57-64). The exact 
water quality parameters preferred by the Dixie Valley toad are 
unknown; however, this species has evolved only in Dixie Meadows and is 
presumed to thrive in the current existing, complex mix of water 
emanating from both the basin-fill aquifer and the deep geothermal 
reservoir. Within the unique habitat in Dixie Meadows, and given the 
life history and physiological strategies employed by the species, a 
good baseline of existing environmental water quality factors that are 
most important for all life stages should be studied (Rowe et al. 2003, 
p. 957). The Dixie Valley toad needs the natural variation of the 
current water quality parameters found in Dixie Meadows to maintain 
resiliency.

Threats Analysis

    We reviewed the potential risk factors (i.e., threats, stressors) 
that may be currently affecting the Dixie Valley toad. In this rule, we 
discuss only those factors in detail that could meaningfully affect the 
status of the species.
    The primary threats affecting the status of the Dixie Valley toad 
are geothermal development and associated groundwater pumping (Factor 
A); establishment of Batrachochytrium dendrobatidis (Bd; hereafter 
referred to as amphibian chytrid fungus), which causes the disease 
chytridiomycosis (Factor C); predation by the invasive American 
bullfrog (Lithobates catesbeianus) (Factor C); groundwater pumping 
associated with human consumption, agriculture, and county planning 
(Factor A); and climate change (Factor A). Climate change may further 
influence the degree to which these threats, individually or 
collectively, may affect the Dixie Valley toad. The risk factors that 
are unlikely to have significant effects on the Dixie Valley toad, such 
as livestock grazing and historical spring modifications, are not 
discussed here but are evaluated in the current condition assessment of 
the SSA report.
Geothermal Development
    Geothermal resources are reservoirs of hot water or steam found at 
different temperatures and depths below the ground. These geothermal 
reservoirs can be used to produce energy by drilling a well and 
bringing the heated water or steam to the surface. Geothermal energy 
plants use the steam or heat created by the hot water to drive turbines 
that produce electricity. Three main technologies are being used today 
to convert geothermal water into electricity: dry steam, flash steam, 
and binary cycle. Binary technology is the focus for this analysis 
because that type of geothermal power technology has been approved for 
development at Dixie Meadows.
    Binary cycle power plants use the heat of geothermal fluids 
extracted from (pumped out of) geothermal reservoirs to heat a 
secondary fluid (e.g., butane) that generally has a much lower boiling 
point than water. This process is accomplished through a heat 
exchanger, and the secondary fluid is flashed into vapor by the heat 
from the geothermal fluid; the vapor then drives the turbines to 
generate electricity. The cooled geothermal fluid is subsequently 
reinjected back into the ground to maintain pressures within the 
geothermal reservoir and to be reheated, incurring for all practical 
purposes no losses to evaporation. Consequently, binary cycle power 
plants do not affect the overall amount of water within the hydrologic 
system or, optimally, pressures within the geothermal reservoir 
(despite the project pumping). However, in the case of the Dixie 
Meadows site, the transport of geothermal fluids to the springs, which 
ultimately depends on the movement of geothermal fluids along discrete 
permeable structures in faulted/fractured bedrock, may be altered by 
the project pumping and/or injection at specific locations in ways that 
cannot be anticipated in this fractured-rock environment; impacting, in 
particular, the temperatures of the springs, despite maintenance of the 
overall water balance within the system.
    General impacts from geothermal production facilities are presented 
below. Because every geothermal field is unique, it is difficult to 
predict what effects from geothermal production may occur.
    Prior to geothermal development, the flow path of water underneath 
the land surface is usually not known with sufficient detail to 
understand and prevent impacts to the surface wetlands dependent upon 
those flows (Sorey 2000, p. 705). Changes in surface waters connected 
to underground thermal waters as a result of geothermal production are 
common and are expected. Typical changes seen include changes in water 
temperature, flow, and water quality, which are all resource needs of 
the Dixie Valley toad that could be negatively affected by geothermal 
production (Sorey 2000, entire; Bonte et al. 2011, pp. 4-8; Kaya et al. 
2011, pp. 55-64; Chen et al. 2020, pp. 2-6).
    Steam discharge, land subsidence (i.e., gradual settling or sudden 
sinking of the ground surface due to the withdrawal of large amounts of 
groundwater), and changes in water temperature and flow have all been 
documented from geothermal production areas throughout the western 
United States (Sorey 2000, entire). For example:
    (1) Long Valley Caldera near Mammoth, California. Geothermal 
pumping in the period 1985-1998 resulted in several springs ceasing to 
flow and declines in pressure of the geothermal reservoir, which caused 
reductions of 10-15 [deg]C (50-59 [deg]F) in the reservoir temperature 
and a localized decrease of approximately 80 [deg]C (176 [deg]F) near 
the reinjection zone (Sorey 2000, p. 706).
    (2) Steamboat Springs near Reno, Nevada. Geothermal development 
resulted in the loss of surface discharge (geysers and springs) on the 
main terrace and a reduction of thermal water discharge to Steamboat 
Creek by 40 percent (Sorey 2000, p. 707).
    (3) Northern Dixie Valley near Reno, Nevada. Steam discharge and 
land subsidence occurred at an existing 56-MW geothermal plant in 
northern Dixie Valley, Nevada, which has been in production since 1985 
(Sorey 2000, p. 708; Huntington et al. 2014, p. 5). To remedy the 
subsidence, the plant began pumping water from the cold basin fill 
aquifer (local aquifer) and reinjecting it above the hot geothermal 
reservoir (regional aquifer) (Huntington et al. 2014, p. 5). This 
approach may have led to other detrimental impacts as the depth to 
groundwater increased from 1.8 m (6 ft) in 1985 to 4.3-4.6 m (14-15 ft) 
in 2009-2011 (Albano et al. 2021, p. 78).
    (4) Jersey Valley near Reno, Nevada. In 2011, a 23.5-MW geothermal 
power plant started production in Jersey Valley, just north of Dixie 
Valley. Springflow at a perennial thermal spring began to decline 
almost immediately after the power plant began operation (BLM 2022, p. 
1; Nevada Division of Water Resources (NDWR) 2022, unpublished data). 
By 2014, the Jersey Valley Hot Spring ceased flowing (BLM 2022, p. 1; 
NDWR 2022, unpublished data). The loss of aquatic insects from the 
springbrook has diminished the foraging ability of eight different bat 
species that occur in the area (BLM 2022, p. 28). To mitigate for the 
spring going dry, the BLM proposed to pipe

[[Page 73984]]

geothermal fluid to the spring source (BLM 2022, p. 8); however, 
mitigation has not yet occurred. If a similar outcome were to occur in 
Dixie Meadows, resulting in the complete drying of the springs, the 
Dixie Valley toad would likely be extirpated if mitigation to prevent 
the drying of the springs is not satisfactorily or timely achieved.
    In an effort to minimize changes in water temperature, quantity, 
and quality, and to maintain pressure of the geothermal reservoir, 
geothermal fluids are reinjected into the ground, although reinjected 
water is at a lower temperature than when it was pumped out of the 
ground. This practice entails much trial and error in an attempt to 
equilibrate subsurface reservoir pressure. It can take several years to 
understand how a new geothermal field will react to production and 
reinjection wells; however, reinjection does not always have the 
desired effect (Kaya et al. 2011, pp. 55-64).
    Geothermal energy production is considered the greatest threat to 
the persistence of Dixie Valley toad (Forrest et al. 2017, pp. 172-173; 
Gordon et al. 2017, p. 136; Halstead et al. 2021, p. 35). Geothermal 
environments often harbor unique flora and fauna that have evolved in 
these rare habitats (Boothroyd 2009, entire; Service 2019, entire). 
Changes to these rare habitats often cause declines in these endemic 
organisms or even result in the destruction of their habitat (Yurchenko 
2005, p. 496; Bayer et al. 2013, pp. 455-456; Service 2019, pp. 2-3). 
Because the Dixie Valley toad relies heavily on wetted area and warm 
water temperature to remain viable, reduction of these two resource 
needs could cause significant declines in the population and changes to 
its habitat that are detrimental to the species and result in it being 
in danger of extinction.
Disease
    Over roughly the last four decades, pathogens have been associated 
with amphibian population declines, mass die-offs, and extinctions 
worldwide (Bradford 1991, pp. 174-176; Muths et al. 2003, pp. 359-364; 
Weldon et al. 2004, pp. 2,101-2,104; Rachowicz et al. 2005, pp. 1,442-
1,446; Fisher et al. 2009, pp. 292-302; Knapp et al. 2011, pp. 8-19). 
One pathogen strongly associated with dramatic declines on all 
continents that harbor amphibians is chytridiomycosis caused by 
amphibian chytrid fungus (Rachowicz et al. 2005, pp. 1,442-1,446). 
Chytrid fungus has now been reported in amphibian species worldwide 
(Fellers et al. 2001, pp. 947-952; Rachowicz et al. 2005, pp. 1,442-
1,446). Early doubt that this particular pathogen was responsible for 
worldwide die-offs has largely been overcome by the weight of evidence 
documenting the appearance, spread, and detrimental effects to affected 
populations (Vredenburg et al. 2010, pp. 9,690-9,692).
    Clinical signs of chytridiomycosis and diagnosis include abnormal 
posture, lethargy, and loss of righting reflex (the ability to correct 
the orientation of the body when it is not in its normal upright 
position) (Daszak et al. 1999, p. 737). Chytridiomycosis also causes 
gross lesions, which are usually not apparent and consist of abnormal 
epidermal sloughing and ulceration, as well as hemorrhages in the skin, 
muscle, or eye (Daszak et al. 1999, p. 737). Chytridiomycosis can be 
identified in some species of amphibians by examining the oral discs 
(tooth rows) of tadpoles that may be abnormally formed or lacking 
pigment (Fellers et al. 2001, pp. 946-947).
    Despite the acknowledged impacts of chytridiomycosis to amphibians, 
little is known about this disease outside of mass die-off events. 
There is high variability between species of amphibians in response to 
being infected, including within the western toad species complex. Two 
long-term study sites have documented differences in apparent survival 
of western toads between two different sites in Montana and Wyoming 
(Russell et al. 2019, pp. 300-301). The chytrid-positive western toad 
population in Montana was reduced by 19 percent compared to chytrid-
negative toads in that area--in comparison to the western toad 
population in Wyoming, which was reduced by 55 percent (Russell et al. 
2019, p. 301). Various diseases are confirmed to be lethal to Yosemite 
toads (Anaxyrus canorus) (Green and Sherman 2001, p. 94), and research 
has elucidated the potential role of chytrid fungus infection as a 
threat to Yosemite toad populations (Dodge 2013, pp. 6-10, 15-20; 
Lindauer and Voyles 2019, pp. 189-193). These various diseases and 
infections, in concert with other factors, have likely contributed to 
the decline of the Yosemite toad (Sherman and Morton 1993, pp. 189-197) 
and may continue to pose a risk to the species (Dodge 2013, pp. 10-11; 
Lindauer and Voyles 2019, pp. 189-193). Amargosa toads (Anaxyrus 
nelsoni) are known to have high infection rates and high chytrid fungus 
loads; however, they do not appear to show adverse impacts from the 
disease (Forrest et al. 2015, pp. 920-922). Not all individual 
amphibians that test positive for chytrid fungus develop 
chytridiomycosis.
    Dixie Valley toad was sampled for chytrid fungus in 2011-2012 
(before it was recognized as a species) and 2019-2021 (Forrest 2013, p. 
77; Kleeman et al. 2021, entire); chytrid fungus was not found during 
either survey. However, chytrid fungus has been documented in bullfrogs 
in Turley Pond, located approximately 10 km south of Dixie Meadows 
(Forrest 2013, p. 77), and bullfrogs are a known vector species for 
spreading chytrid fungus and diseases to other species of amphibians 
(Daszak et al. 2004, pp. 203-206; Urbina et al. 2018, pp. 271-274; Yap 
et al. 2018, pp. 4-8).
    The best available information indicates that the thermal nature of 
the Dixie Valley toad habitat may keep chytrid fungus from becoming 
established; therefore, it is imperative that the water maintains its 
natural thermal characteristics (Forrest 2013, pp. 75-85; Halstead et 
al. 2021, pp. 33-35). Western toads exposed to chytrid fungus survive 
longer when exposed to warmer environments (mean 18 [deg]C (64 [deg]F)) 
as compared to western toads in cooler environments (mean 15 [deg]C (59 
[deg]F)) (Murphy et al. 2011, pp. 35-38). Additionally, chytrid fungus 
zoosporangia grown at 27.5 [deg]C (81.5 [deg]F) remain metabolically 
active; however, no zoospores are produced, indicating no reproduction 
at this high temperature (Lindauer et al. 2020, pp. 2-5). Generally, 
chytrid fungus does not seem to become established in water warmer than 
30 [deg]C (86 [deg]F) (Forrest and Schlaepfer 2011, pp. 3-7). Dixie 
Meadows springhead water temperatures range from 13 [deg]C (55 [deg]F) 
to 74 [deg]C (165 [deg]F), although the four largest spring complexes 
(springs that create the largest wetland areas and are inhabited by a 
majority of the Dixie Valley toad population) range from 16 [deg]C (61 
[deg]F) to 74 [deg]C (165 [deg]F) with median temperatures of at least 
25 [deg]C (77 [deg]F). Additionally, water temperatures measured in 
2019 at toad survey sites throughout Dixie Meadows (i.e., not at 
springheads) ranged from 10 to 41 [deg]C (50 to 106 [deg]F) (Halstead 
and Kleeman 2020, entire). Any reduction in water temperature, 
including reductions caused by geothermal development, would not only 
affect the ability of Dixie Valley toads to survive during cold months, 
but could also make the species vulnerable to chytrid fungus.
Predation
    Predation has been reported in species similar to the Dixie Valley 
toad and likely occurs in Dixie Meadows; however, predation of Dixie 
Valley toads has not been documented. Likely predators on the egg and 
aquatic larval

[[Page 73985]]

forms of Dixie Valley toad include predacious diving beetles (Dytiscus 
spp.) and dragonfly larvae (Odonata). Common ravens (Corvus corax) and 
other corvids are known to feed on juvenile and adult black toads and 
Yosemite toads (Sherman 1980, pp. 90-92; Sherman and Morton 1993, pp. 
194-195). Raven populations are increasing across the western United 
States and are clearly associated with anthropogenic developments, such 
as roads and power lines (Coates and Delehanty 2010, pp. 244-245; Howe 
et al. 2014, pp. 44-46). Ravens are known to nest within Dixie Valley 
(Environmental Management and Planning Solutions 2016, pp. 3-4).
    The American bullfrog, a ranid species native to much of central 
and eastern North America, now occurs within Dixie Meadows (Casper and 
Hendricks 2005, pp. 540-541; Gordon et al. 2017, p. 136). Bullfrogs are 
recognized as one of the 100 worst invasive species in the world 
(Global Invasive Species Database 2021, pp. 1-17). Bullfrogs are known 
to compete with and prey on other amphibian species (Moyle 1973, pp. 
19-21; Kiesecker et al. 2001, pp. 1,966-1,969; Pearl et al. 2004, pp. 
16-18; Casper and Hendricks 2005, pp. 543-544; Monello et al. 2006, p. 
406; Falaschi et al. 2020, pp. 216-218).
    Bullfrogs are a gape-limited predator, which means they eat 
anything they can swallow (Casper and Hendricks 2005, pp. 543-544). The 
Dixie Valley toad is the smallest toad species in the western toad 
species complex and can easily be preyed upon by bullfrogs. Smaller 
bullfrogs eat mostly invertebrates (Casper and Hendricks 2005, p. 544) 
and thus may compete with Dixie Valley toad for food resources. Within 
Dixie Valley, bullfrogs are known to occur at Turley Pond and in one 
area of Dixie Meadows adjacent to occupied Dixie Valley toad habitat 
(Forrest 2013, pp. 74, 87; Rose et al. 2015, p. 529; Halstead et al. 
2021, p. 24).
Climate Change
    Both human settlements and natural ecosystems in the southwestern 
United States are largely dependent on groundwater resources, and 
decreased groundwater recharge may occur as a result of climate change 
(U.S. Global Change Research Program 2009, p. 133). Furthermore, the 
human population in the Southwest is expected to increase 70 percent by 
mid-century (Garfin 2014, p. 470). Resulting increases in urban 
development, agriculture, and energy-production facilities will likely 
place additional demands on already limited water resources. Climate 
change will likely increase water demand and shrink water supply, since 
water loss may increase evapotranspiration rates and runoff during 
storm events (Archer and Predick 2008, p. 25).
    In order to identify changing climatic conditions more specific to 
Dixie Meadows, we conducted a climate analysis using the Climate Mapper 
web tool (Hegewisch et al. 2020, online). The Climate Mapper is a web 
tool for visualizing past and projected climate and hydrology of the 
contiguous United States. This tool maps real-time conditions, current 
forecasts, and future projections of climate information across the 
United States to assist with decisions related to agriculture, climate, 
fire conditions, and water.
    For our analysis, we analyzed mean annual temperature and percent 
precipitation using the historical period of 1971-2000 and the 
projected future time period 2040-2069. We examined emission scenarios 
that used representative concentration pathways (RCPs) 4.5 and 8.5 
using ArcGIS Pro.
    Our analysis predicts increased air temperatures in Dixie Meadows, 
along with a slight increase in precipitation. Annual mean air 
temperature is projected to increase between 2.5 and 3.4 [deg]C (4.5 
and 6.1 [deg]F) and result in average temperatures 3.0 [deg]C (5.3 
[deg]F) warmer throughout Dixie Meadows between 2040 and 2069 
(Hegewisch et al. 2020, Geographic Information System (GIS) data). 
Under the two emission scenarios, annual precipitation is projected to 
increase by 4.5 to 7.7 percent (Hegewisch et al. 2020, GIS data).
    Climate change may impact the Dixie Valley toad and its habitat in 
two main ways: (1) reductions in springflow as a result of changes in 
the amount, type, and timing of precipitation, increased 
evapotranspiration rates, and reduced aquifer recharge; and (2) 
reductions in springflow as a result of changes in human behavior in 
response to climate change (e.g., increased groundwater pumping as 
surface water resources disappear). A reduction in springflow could be 
exacerbated by the greater severity of droughts being experienced in 
the southwestern United States, including Nevada (Snyder et al. 2019, 
pp. 2-4; Williams et al. 2020, pp. 1-5). Higher temperatures and drier 
conditions could result in greater evapotranspiration, leading to 
increased drying of wetland habitat. Impacts vary geographically and 
identifying the vulnerability of individual springs is challenging. For 
example, each spring studied in Arches National Park in Utah responded 
to local precipitation and recharge differently, despite similarities 
in topographic setting, aquifer type, and climate exposure (Weissinger 
2016, p. 9).
    Predicting individual spring response to climate change is further 
complicated by the minimal information available about the large 
hydrological connections for most sites and the high degree of 
uncertainty inherent in future precipitation models. Regardless, the 
best available data indicate that the Dixie Valley toad may be 
vulnerable to climate change, but the best available science currently 
does not allow for us to predict where and to what degree impacts may 
manifested.
Groundwater Pumping
    The basin is fully appropriated for consumptive groundwater uses 
(18,758,663 cubic meters per year (m\3\/yr) (15,218 acre-feet per year 
(afy)) of an estimated 18,489,943 m\3\/yr (15,000 afy) perennial yield; 
NDWR 2021, entire), and the proposed Dixie Valley groundwater export 
project by Churchill County is seeking an additional 12,326,628-
18,489,943 m\3\/yr (10,000-15,000 afy) (Huntington et al. 2014, p. 2). 
Total geothermal water rights appropriated in Dixie Valley as of 2020 
are 15,659,749 m\3\/yr (12,704 afy) (BLM 2021b, pp. 2-28).
    Increased groundwater pumping in Nevada is primarily driven by 
human water demand for municipal purposes; irrigation; and development 
for oil, gas, geothermal resources, and minerals. Many factors 
associated with groundwater pumping can affect whether or not an 
activity will impact a spring. These factors include the amount of 
groundwater pumped, period of pumping, the proximity of pumping to a 
spring, depth of pumping, and characteristics of the aquifer being 
impacted. Depending on these factors, groundwater withdrawal may result 
in no measurable impact to springs or may reduce spring discharge, 
change the temperature of the water, reduce free-flowing water, dry 
springs, alter Dixie Valley toad habitat size and heterogeneity, or 
create habitat that is more suited to nonnative species than to native 
species (Sada and Deacon 1994, p. 6). Pumping rates that exceed 
perennial yield can lower the water table, which in turn will likely 
affect riparian vegetation (Patten 2008, p. 399).
    Determining when groundwater withdrawal exceeds perennial yield is 
difficult to ascertain and reverse due to inherent delays in detection 
of pumping impacts and the subsequent lag time required for recovery of 
discharge at a spring (Bredehoeft 2011, p. 808). Groundwater pumping 
initially captures stored groundwater near the pumping area until water 
levels decline and a

[[Page 73986]]

cone of depression expands, potentially impacting water sources to 
springs or streams (Dudley and Larson 1976, p. 38). Spring aquifer 
source and other aquifer characteristics influence the ability and rate 
at which a spring fills and may recover from groundwater pumping (Heath 
1983, pp. 6, 14). Depending on aquifer characteristics and rates of 
pumping, recovery of the aquifer is variable and may take several years 
or even centuries (Heath 1983, p. 32; Halford and Jackson 2020, p. 70). 
Yet where reliable records exist, most springs fed by even the most 
extensive aquifers are affected by exploitation, and springflow 
reductions relate directly to quantities of groundwater removed (Dudley 
and Larson 1976, p. 51).
    The most extreme potential effects of groundwater withdrawal on the 
Dixie Valley toad are likely desiccation and extirpation or extinction. 
If groundwater withdrawal occurs but does not cause a spring to dry, 
there can still be adverse effects to Dixie Valley toads or their 
habitat because reduction in springflow reduces both the amount of 
water and amount of occupied habitat. If the withdrawals also coincide 
with altered precipitation and temperature from climate change, even 
less water will be available. Cumulatively, these conditions could 
result in a delay in groundwater recharge at springs, which may then 
result in a greater effect to the Dixie Valley toad than the effects of 
the individual threats acting alone. Across the Dixie Meadows springs, 
discharge varies greatly, with some springs with low discharge at the 
current time likely due to a combination of influences, both natural 
and anthropogenic. Although there is much uncertainty around the 
magnitude and timing of groundwater withdrawal, and thus the possible 
effects on the Dixie Meadows spring system, we anticipate that the 
future effects of groundwater withdrawal could have significant effects 
on the Dixie Meadows spring system.

Current Condition

Redundancy, Representation, and Resiliency
    Population estimates are not available for the Dixie Valley toad. 
Time-series data of toad abundance are available from various surveys 
conducted by the Service and the Nevada Department of Wildlife (NDOW) 
during the period 2009-2012 (before the Dixie Valley toad was 
recognized as a species); however, differences in sample methodology 
between years and low recapture rates of marked toads make it difficult 
to infer temporal trends or population size. In addition to adult 
toads, surveys recorded eggs, tadpoles, and juveniles in all survey 
years, suggesting consistent reproduction is occurring.
    Adult toads currently have high occupancy rates and are generally 
more likely than not to occur across the Dixie Meadows wetlands (Rose 
et al. 2022, p. entire). Dixie Valley toad larvae were more likely 
detected areas with high surface water, low emergent vegetation, and 
water temperatures between 20-28 [deg]C (68-82.4 [deg]F) (Rose et al. 
2022, entire).
    Larvae are detected less often than adults and warmer water 
temperatures strongly influence the probability of reproduction 
(Halstead et al. 2019, pp. 10-11). This finding suggests that adult 
toads are seeking out a subset of habitat for reproduction based in 
part on water temperature. The percentage of the range currently 
occupied by adults remained similarly high throughout 2018-2022 and 
across seasons (Rose et al. 2022, entire). The high occupancy rate 
observed from 2018 through 2022, and evidence of reproduction observed 
in the period 2009-2022, indicate that the Dixie Valley toad is 
currently maintaining resilience to the historical and current 
environmental stochasticity present at Dixie Meadows (Rose et al. 2022, 
entire). However, the narrowly distributed, isolated nature of the 
single population of the species indicates that the Dixie Valley toad 
has little ability to withstand stochastic or catastrophic events 
through dispersal. Because the species evolved in a unique spring 
system with little historical variation, we conclude that it has low 
potential to adapt to environmental changes to its habitat. As a 
single-site endemic with no dispersal opportunities outside the current 
range, the species has inherently low redundancy and representation and 
depends entirely on the continued availability of habitat in Dixie 
Meadows.
    Below, we discuss the potential impacts the Dixie Meadows 
Geothermal Utilization Project could have on both the current and 
future status of the Dixie Valley toad. Based on an expert knowledge 
elicitation (discussed further below) conducted on the potential 
outcomes of this geothermal project, peak change to the spring system 
could occur as early as year 1 of geothermal pumping, with a 90 percent 
chance that peak change will occur within 10 years of the start of 
geothermal pumping (Service 2022, pp. 42-43).
Dixie Meadows Geothermal Project
    In addition to 50 active geothermal leases within Dixie Valley in 
Churchill County, two geothermal exploration projects were approved in 
Dixie Meadows in 2010 and 2011 (BLM 2010, entire; BLM 2011, entire). 
Most recently, on November 23, 2021, BLM approved and permitted the 
Dixie Meadows Geothermal Utilization Project (BLM 2021b, entire) after 
issuing two draft environmental assessments, receiving extensive 
comments from the Service and NDOW, and developing a Monitoring and 
Mitigation Plan. This project will consist of up to two 30-MW 
geothermal power plants on 6.5 ha (16 ac) each; up to 18 well pads 
(107x114 m (350x375 ft)), upon which up to three wells per pad may be 
drilled for exploration, production, or injection; pipelines to carry 
geothermal fluid between well fields and the power plant(s); and either 
a 120-kilovolt (kV) or a 230-kV transmission gen-tie and associated 
access roads and structures (BLM 2021b, p. 1-1). The project proponent 
(Ormat Nevada Inc. (Ormat)) began construction on the first geothermal 
plant the week of February 14, 2022, and plans to begin geothermal 
production by 2024 after completing 12 months of monitoring as 
described in the Monitoring and Mitigation Plan (BLM 2021b, appendix 
H). To see a more detailed overview of the approved and permitted 
project, refer to the BLM November final EA.
    As mentioned above, two geothermal exploration projects were 
approved by the BLM in 2010 and 2011 (BLM 2010, entire; BLM 2011, 
entire); however, required monitoring and baseline environmental 
surveys for those exploration projects did not occur (BLM 2021a, pp. 3-
17-3-18). As a result, key environmental information (e.g., water 
quality metrics data such as flow, water temperature, and water 
pressure) is lacking to determine the effects of the projects on the 
surrounding environment. Most of the information collected during this 
timeframe consisted of singular measurements taken quarterly or 
annually, which do not characterize the variability in environmental 
conditions observed in Dixie Meadows. The lack of robust baseline 
environmental information is part of why we, along with experts from 
the expert knowledge elicitation workshop panel (described below), 
conclude that the November Monitoring and Mitigation Plan associated 
with the Dixie Meadows Geothermal Utilization Project needs further 
refinement to adequately detect and respond to changes in the wetlands 
and toad populations. The ability of the November Monitoring and 
Mitigation Plan to detect changes in baseline conditions, and mitigate 
those changes, is discussed below.

[[Page 73987]]

Expert Knowledge Elicitation
    An expert knowledge elicitation workshop was carried out during the 
period August 17-20, 2021, using the then proposed Dixie Meadows 
Geothermal Utilization Project January draft EA and Monitoring and 
Mitigation Plan, along with a summary of all existing data, to 
determine the range of outcomes of the approved project. This workshop 
followed established best practices for eliciting expert knowledge 
(Gosling 2018, entire; O'Hagan 2019, pp. 73-81; Oakley and O'Hagan 
2019, entire). The expert panel consisted of a multidisciplinary group 
with backgrounds in the geologic structure of basin and range systems, 
various components of deep and shallow groundwater flow, as well as 
geothermal exploration and development. All panelists have direct 
experience in the Great Basin, and most in Dixie Valley and Dixie 
Meadows, specifically. The panelists were asked questions regarding the 
time until peak changes to the spring system would occur, the ability 
of the January Monitoring and Mitigation Plan to detect and mitigate 
change, the amount of time it would take to mitigate change if 
mitigation is possible, and what the peak changes to springflow and 
spring temperature could be. For a detailed overview of the expert 
knowledge elicitation process, refer to the SSA report (Service 2022, 
appendix A).
    The expert panelists concluded that the Dixie Meadows spring system 
will change quickly, and detrimentally, once geothermal energy 
production begins, with a median response time of roughly 4 years and a 
90 percent chance that the largest magnitude changes will occur within 
10 years (Service 2022, appendix A). Uncertainty within individual 
judgments on response time was related to the efficacy of mitigation 
measures and interactions between short-term impacts from geothermal 
development and longer-term impacts from climate change and consumptive 
water use.
    Experts had low confidence in the ability of the January Monitoring 
and Mitigation Plan to both detect and mitigate changes to the 
temperature and flow of surface springs in Dixie Meadows. Although the 
aggregated distribution for the ability to detect changes ranged from 0 
to 100 percent, the median expectation was a roughly 38 percent chance 
of detecting changes (Service 2022, appendix A). These judgments 
reflect an expectation that there is less than 50 percent confidence 
from the experts that the January Monitoring and Mitigation Plan could 
detect changes in the spring system due to the complexity and natural 
variability of the system, limited baseline data, and perceived 
inadequacies of the January Monitoring and Mitigation Plan. The January 
Monitoring and Mitigation Plan was perceived as inadequate due in part 
to limited monitoring locations, low frequency of monitoring and 
reporting, and lack of a statistical approach for addressing 
variability and uncertainty. The degree of confidence in the ability to 
mitigate environmental impacts of the project was even lower (median of 
roughly 29 percent; Service 2022, appendix A) based on previously 
stated concerns about the plan, lack of information on how water 
quality would be addressed, interacting effects of climate change and 
extractive water use, and questions about the motivation to mitigate if 
measures ran counter to other operating goals of the plant.
    The expert panel was asked what timeframe would be required to 
fully mitigate changes in spring temperature and springflow once 
detected--assuming that changes have been detected, it is technically 
feasible to mitigate the problem, and there is a willingness to 
participate from all parties. Based on those assumptions, the experts 
judged that it could take multiple years to mitigate perturbations once 
detected, with a median expectation of 4 years (Service 2022, appendix 
A).
    At the time the expert knowledge elicitation occurred, the Dixie 
Meadows Geothermal Utilization Project was not approved. However, in 
the discussion about expected peak change in spring temperature and 
springflow, the experts considered how the spring system would change 
if the geothermal project was not approved or the January Monitoring 
and Mitigation Plan was improved. Expert judgments on expected peak 
change in spring temperature and springflow that considered the 
geothermal project not getting approved and an improvement in the 
January Monitoring and Mitigation Plan were not considered in our 
analysis because the geothermal project was approved in November 2021. 
Additionally, although the November Monitoring and Mitigation Plan 
included significant revisions to the frequency of monitoring, those 
revisions did not substantially affect the ability of the plan to 
detect or mitigate changes in the spring system. Therefore, it is 
unlikely the results of the expert knowledge elicitation completed on 
the January draft EA and the then-existing Monitoring and Mitigation 
Plan would have changed meaningfully in response to the November final 
approved EA and Monitoring and Mitigation Plan.
    Although there is considerable uncertainty in the magnitude of 
expected changes from the approved project, there is a high degree of 
certainty that geothermal energy development will have severe and 
negative effects on the geothermal springs relied upon by the Dixie 
Valley toad, including reductions in spring temperature and springflow, 
which directly affect the resource needs of the species. The plausible 
range of changes to spring temperatures ranged from a decrease of 10 
[deg]C (18 [deg]F) to 55 [deg]C (99 [deg]F) (Service 2022, appendix A). 
This range is due to the wide spatial variation in spring temperatures 
across the spring system and reflects the expectation that the spring 
temperatures could plausibly drop to ambient levels (i.e., a complete 
loss of geothermal contributions). Similarly, the experts considered it 
plausible that springs in Dixie Meadows could dry up (no surface 
discharge) as the geothermal contribution was reduced, with up to a 31 
percent decrease in surface discharge. These judgments reflect the 
range of operations that may be implemented under the phased power 
plant approach, perceived inadequacies with the January Monitoring and 
Mitigation Plan, and the fact that drying of surface springs has been 
documented at other nearby geothermal development projects (BLM 2022, 
p. 1) indicates this may be a plausible outcome.

Scenario Considerations for Current and Future Conditions

    In the SSA report, we analyzed four scenarios based on the expert 
knowledge elicitation. As mentioned earlier, these scenarios could 
plausibly affect both the current and future condition of the species. 
Three of the scenarios (scenarios 1-3) assume the Dixie Meadows 
Geothermal Utilization Project will begin construction as approved, 
while scenario 4 assumes there will be no geothermal development or the 
November Monitoring and Mitigation Plan will be significantly improved 
before project implementation. Scenario 4 was not considered in this 
decision given the approval of the geothermal project, the beginning of 
construction on the project, and the lack of substantive improvements 
to the November Monitoring and Mitigation Plan. As discussed above 
under ``Expert Knowledge Elicitation,'' we have low confidence in the 
ability of the November Monitoring and Mitigation Plan to detect or 
mitigate changes to the spring system, or to adequately mitigate for 
potential effects from the project.

[[Page 73988]]

Therefore, only scenarios 1-3 were considered for this decision.
    The scenarios incorporated the following considerations from the 
expert knowledge elicitation: the efficacy of the November Monitoring 
and Mitigation Plan; how the surficial spring system will respond to 
geothermal production; and changes in temperature, evapotranspiration, 
and extreme precipitation events related to climate change. For all 
scenarios, we project that the basin will remain over-allocated. The 
lower bound of scenarios (scenario 1) projects that the November 
Monitoring and Mitigation Plan is ineffective; the springs dry 
completely; and there are increases in air temperature, 
evapotranspiration, and extreme precipitation events seen under RCP 
8.5. This scenario represents the low confidence the experts have in 
the November Monitoring and Mitigation Plan and reflects the results in 
a similar situation that occurred in Jersey Valley where geothermal 
production caused the spring system to go dry within 3 years of the 
start of operation (BLM 2022, p. 1; NDWR 2022, unpublished data). The 
upper bound of scenarios (scenario 3) projects that the November 
Monitoring and Mitigation Plan is moderately effective; geothermal 
production has moderate effects on the surficial spring system; and 
increases in temperature, evapotranspiration, and moderate changes in 
precipitation seen under RCP 4.5 occur. Because the experts expressed 
less than 50 percent confidence in the ability of the November 
Monitoring and Mitigation Plan to both detect and mitigate change, it 
was logical for this scenario to represent the upper bound of 
plausibility. Put another way, the experts did not consider it likely 
that geothermal production would have minor or negligible effects on 
the surface spring system.
    These scenarios include the range of peak changes to spring 
temperature and springflow as discussed earlier (a decrease of 10 
[deg]C (18 [deg]F) to 55 [deg]C (99 [deg]F) in spring temperature, and 
a 31-100 percent decrease in springflow). These projected changes in 
spring temperature and flow were used as inputs into a multistate, 
dynamic occupancy model, which is described further in the SSA report 
(Service 2022, pp. 61-64). Scenario 1 results in complete reproductive 
failure because of the drying of springs, and scenarios 2 and 3 project 
a risk of reproductive failure after 1 year of geothermal production. 
Under scenario 2, the mean percentage of the range occupied by larvae 
drops to 0 percent by year 4 of geothermal production. Scenario 3 
projects a mean of 1 percent of the range occupied by larvae by year 6 
of geothermal production. All scenarios result in a high level of risk 
of reproductive failure for the Dixie Valley toad in the near future.
    Although the occupancy model described above represents the best 
available projection framework for the Dixie Valley toad, not all 
demographic and risk factors relevant to understanding species 
viability are included. One major threat not accounted for by the model 
is the synergistic effect of changes in temperature with the risk posed 
by exposure to the fungal pathogen chytrid fungus that causes the 
disease chytridiomycosis (see ``Disease,'' above). Chytrid fungus 
growth and survival are sensitive to both cold and hot temperatures, 
with optimal growth conditions in culture occurring between 15 and 25 
[deg]C (59 and 77 [deg]F). There is equivocal evidence on whether 
colder temperatures limit the effects of chytrid fungus (Voyles et al. 
2017, pp. 367-369); however, hot geothermal waters above 25 [deg]C (77 
[deg]F) appear to provide protection against chytrid fungus by allowing 
individuals to raise body temperatures through behavioral fever 
(Forrest and Schlaepfer 2011, entire; Murphy et al. 2011, p. 39). This 
information indicates that future decreases in water temperature 
associated with scenarios 2 and 3 are likely to increase the risk that 
chytrid fungus could become established within the Dixie Valley toad 
population. If chytrid fungus becomes established within the Dixie 
Valley toad population, there would be negative, and plausibly 
catastrophic, effects to the species.
    The seasonal timing of changes in water temperature is also 
particularly important. Dixie Valley toads strongly rely on aquatic 
environments throughout their life cycle (Halstead et al. 2021, 
entire). Unlike western toads that may be found hundreds to thousands 
of meters from aquatic breeding sites, in surveys, Dixie Valley toads 
are almost always found in water (Halstead et al. 2021, pp. 30-31). 
When not detected in water, Dixie Valley toads are found 4.2 m (13.8 
ft) from water on average and are found both in and above water during 
brumation (Halstead et al. 2021, p. 30). Toads select autumn brumation 
sites that are warmer than random locations available, and toads are 
1.3 times more likely to select sites for each 1 [deg]C (1.8 [deg]F) 
increase in water temperature (Halstead et al. 2021, p. 30). Because 
toads are found closer to spring heads in autumn compared to sites 
selected during other times of year, it is likely that they are 
selecting areas where water temperatures will remain stable throughout 
the winter (Halstead et al. 2021, p. 34). The selection of areas with 
stable, warm water temperatures indicates that reductions in geothermal 
contributions during winter could lead to thermal stress, reductions in 
available habitat as waters cool, or even mortality if geothermal 
contributions are removed completely or reduced to a level that toads 
are unable to adapt their brumation strategies.

Conservation Efforts and Regulatory Mechanisms

    The Dixie Valley toad occurs only on Federal lands (the DoD's 
Fallon Naval Air Station and BLM). Various laws, regulations, policies, 
and management plans may provide conservation or protections for Dixie 
Valley toads. As such, the following management plans are the existing 
conservation tools driving the management of Dixie Valley toads and 
their habitat:
     As required by the Sikes Act (16 U.S.C. 670 et seq., as 
amended), the DoD has an integrated natural resources management plan 
(INRMP) (AMEC Environmental and Infrastructure, Inc., 2014, entire) in 
place for supporting both the installation mission as well as 
protecting and enhancing installation resources for multiple use, 
sustainable yield, and biological integrity. The INRMP is being updated 
to incorporate the DoD's National Strategic Plan for amphibian and 
reptile conservation and management (Lovich et al. 2015, entire), which 
will include specific management for Dixie Meadows and the Dixie Valley 
toad.
     As required by the Federal Land Policy and Management Act 
of 1976 (43 U.S.C. 1701 et seq.), BLM has a resource management plan 
for all actions and authorizations involving BLM-administered lands and 
resources.
    In compliance with the National Environmental Policy Act of 1970, 
as amended (42 U.S.C. 4321 et seq.), which is a procedural statute, for 
projects that Federal agencies fund, authorize, or carry out, BLM, with 
input from Ormat, developed a Monitoring and Mitigation Plan for the 
Dixie Meadows Geothermal Utilization Project; it is an appendix in 
BLM's November final EA. The goal of the November Monitoring and 
Mitigation Plan is to identify hydrologic and biologic resources, 
spring-dependent ecosystems, aquatic habitat, and species that could be 
affected by geothermal exploration, production, and injection in the 
Dixie Meadows area. The November Monitoring and Mitigation Plan will 
describe the plan Ormat will implement to monitor and mitigate 
potential effects to those

[[Page 73989]]

resources, ecosystems, habitat, and species.
    The November Monitoring and Mitigation Plan includes adaptive 
management and mitigation measures that Ormat would implement if 
changes are detected in baseline conditions and threshold values are 
exceeded. Management actions may include geothermal reservoir pumping 
and injection adjustments (e.g., redistribution of injection between 
shallow and deep aquifers). Other more aggressive actions include 
augmenting affected springs with geothermal fluids or fresh water to 
restore preproduction temperature, flow, stage, and water chemistry. 
The November Monitoring and Mitigation Plan states that if mitigation 
actions are not sufficient for the protection of species and aquatic 
habitat, pumping and injection would be suspended until appropriate 
mitigation measures are identified, implemented, and shown to be 
effective.
    We, along with other interested parties (e.g., Department of the 
Navy, NDOW) provided comments to the BLM regarding the November 
Monitoring and Mitigation Plan, which was first made available to the 
public in January 2021. We have low confidence in the ability of the 
November Monitoring and Mitigation Plan to adequately detect and 
respond to changes because of the complexity and natural variability of 
the spring system, limited baseline data, and perceived inadequacies of 
the plan. We determined the November Monitoring and Mitigation Plan is 
inadequate because of the inadequate time to collect relevant baseline 
information prior to beginning operation of the plant, limited 
monitoring locations, lack of a statistical approach for addressing 
variability and uncertainty, lack of information on how water quality 
would be addressed, interacting effects of climate change and 
extractive water use, and uncertainty about the feasibility of certain 
mitigation measures and implementation of mitigation if measures ran 
counter to other operating goals of the plant.
    The changes made between the January 2021 and November 2021 
versions of the Monitoring and Mitigation Plan did not change our view 
that the plan is inadequate to detect potential changes to the spring 
system or mitigate for potential effects from project operations. We 
address the changes made between the two versions under Public 
Comments, above (see, in particular, Comments 24, 25, 26, 40, and 42). 
The issues mentioned in the previous paragraph remain; therefore, our 
conclusion that the plan in its current form is not sufficient to 
protect the Dixie Valley toad and its habitat remain the same.
     Nevada Administrative Code (NAC) at section 503.075(2)(b) 
lists the Dixie Valley toad as a protected amphibian in the State of 
Nevada. Under the NAC at section 503.093(1), there is no open season on 
those species of amphibian classified as protected by the State: 
``[e]xcept as otherwise provided . . . , a person shall not hunt or 
take any wildlife which is classified as protected, or possess any part 
thereof, without first obtaining the appropriate license, permit or 
written authorization from the [NDOW].'' Under the NAC at section 
503.0935, the State may issue a special permit to allow a person to 
handle, move, or temporarily possess any wildlife which is classified 
as protected for the purpose of reducing or eliminating the risk of 
harm to the wildlife that may result from any lawful activity conducted 
on land where the wildlife is located. Under the NAC at section 
503.094, the State issues permits for the take and possession of any 
species (including protected species) of wildlife only for scientific 
or educational purposes.
    The Nevada Department of Conservation and Natural Resources 
includes the Nevada Division of Natural Heritage (NDNH), which tracks 
the species status of plants and animals in Nevada. The NDNH recognizes 
Dixie Valley toads as critically imperiled, rank S1. Ranks of S1 are 
defined as species with very high risks of extirpation in the 
jurisdiction due to very restricted range, very few populations or 
occurrences, very steep declines, severe threats, or other factors.

Determination of Dixie Valley Toad's Status

    Section 4 of the Act (16 U.S.C. 1533) and its implementing 
regulations (50 CFR part 424) set forth the procedures for determining 
whether a species meets the definition of endangered species or 
threatened species. The Act defines an ``endangered species'' as a 
species in danger of extinction throughout all or a significant portion 
of its range and a ``threatened species'' as a species likely to become 
an endangered species within the foreseeable future throughout all or a 
significant portion of its range. The Act requires that we determine 
whether a species meets the definition of an endangered species or a 
threatened species because of any of the following factors: (A) The 
present or threatened destruction, modification, or curtailment of its 
habitat or range; (B) overutilization for commercial, recreational, 
scientific, or educational purposes; (C) disease or predation; (D) the 
inadequacy of existing regulatory mechanisms; or (E) other natural or 
manmade factors affecting its continued existence.
    In conducting our status assessment of the Dixie Valley toad, we 
evaluated all identified threats under the Act's section 4(a)(1) 
factors and assessed how the cumulative impact of all threats acts on 
the viability of the species as a whole. That is, all the anticipated 
effects from both habitat-based and direct mortality-based threats are 
examined in total and then evaluated in the context of what those 
combined negative effects will mean to the future condition of the 
Dixie Valley toad.

Status Throughout All of Its Range

    After evaluating threats to the species and assessing the 
cumulative effect of the threats under the Act's section 4(a)(1) 
factors, we determined that the Dixie Valley toad is currently at risk 
of extinction throughout its range primarily due to the approval and 
commencement of geothermal development (Factor A). Other threats 
identified in this status determination include increased severity of 
drought due to climate change (Factor A); the threat of chytrid fungus 
establishing itself in the population (Factor C); groundwater pumping 
associated with human consumption, agriculture, and county planning 
(Factor A); and predation by invasive bullfrogs (Factor C). These other 
threats will likely exacerbate the main threat of geothermal 
development. Existing regulatory mechanisms do not address the primary 
threat to the species (Factor D).
    Construction of the Dixie Meadows Geothermal Utilization Project 
has begun, and the first phase of geothermal production is planned to 
begin before the end of 2024. Based upon the best available scientific 
and commercial information as described in this determination, the 
Service has a high degree of certainty that geothermal production will 
have severe, negative effects on the geothermal springs the species 
relies upon for habitat (Factor A). These negative effects include 
reductions in spring temperature and springflow, which directly affect 
the needs of the species (i.e., adequate water temperature, sufficient 
wetted areas, sufficient wetland vegetation, including vegetation 
cover, and adequate water quality (see Species Needs, above)). The best 
available information indicates that a complete reduction in springflow 
and significant reduction of water temperature are plausible outcomes 
of the geothermal project, and these conditions could result in the 
species no

[[Page 73990]]

longer persisting (i.e., becoming extinct or functionally extinct as a 
result of significant habitat degradation, or no reproduction due to 
highly isolated, non-recruiting individuals).
    The narrowly distributed, isolated nature of the single, small 
population of the species indicates that the Dixie Valley toad will 
have no ability to withstand stochastic or catastrophic events through 
dispersal. Because the species occurs in only one spring system and has 
not experienced habitat changes of the magnitude or pace projected, it 
may have low potential to adapt to a fast-changing environment. As a 
single-site endemic with no dispersal opportunities outside the current 
range and low adaptive capacity, the species has inherently low 
redundancy and representation, and depends entirely on the continued 
availability of wetland habitat in Dixie Meadows. Low redundancy and 
representation make the Dixie Valley toad particularly vulnerable to 
fast-paced change to its habitat and catastrophic events, any of which 
could plausibly result from the permitted Dixie Meadows Geothermal 
Utilization Project.
    The Dixie Valley toad exists in one population that will likely be 
directly affected to a significant degree by geothermal production in a 
short timeframe, resulting in a high risk that the species could become 
extinct.
    In addition to the current development of the geothermal project, a 
combination of threats will act synergistically to exacerbate effects 
from geothermal production on the Dixie Meadows spring system. A 
reduction in springflow could be exacerbated by the greater severity of 
droughts being experienced in the southwestern United States, including 
Nevada (Snyder et al. 2019, pp. 2-4; Williams et al. 2020, pp. 1-5). 
Higher temperatures and drier conditions could result in greater 
evapotranspiration, leading to increased drying of wetland habitat. A 
reduction in water temperature could allow chytrid fungus to become 
established and negatively impact the Dixie Valley toad population. 
Chytrid fungus would likely be catastrophic to Dixie Valley toads, as 
it has caused severe declines in other amphibian species, and the 
fungus has been found in another known vector species (bullfrog) in 
Turley Pond, which is about 10 km (6.2 mi) from the southern range of 
the Dixie Valley toad (Forrest 2013, p. 77). Bullfrogs themselves are a 
threat to the species, as Dixie Valley toads could be easily preyed 
upon because of their small size. If bullfrogs were to become 
established throughout the Dixie Valley toad's habitat, there would 
likely be a reduction in Dixie Valley toad abundance.
    Thus, after assessing the best available information, we conclude 
that the Dixie Valley toad is currently in danger of extinction 
throughout all of its range due to the immediacy of the threat of 
geothermal production, including negative effects such as reductions in 
spring temperature and springflow, which would directly affect the 
needs of the species (i.e., adequate water temperature, sufficient 
wetted areas, sufficient wetland vegetation, including vegetation 
cover, and adequate water quality), and low confidence in the ability 
of the Mitigation and Monitoring Plan to effectively minimize and 
mitigate for potential effects that are likely to manifest in the near 
term. We find that threatened species status is not appropriate because 
the threat of extinction is imminent as opposed to being likely to 
develop within the foreseeable future.

Status Throughout a Significant Portion of Its Range

    Under the Act and our implementing regulations, a species may 
warrant listing if it is in danger of extinction or likely to become so 
in the foreseeable future throughout all or a significant portion of 
its range. We have determined that the Dixie Valley toad is in danger 
of extinction throughout all of its range and, accordingly, did not 
undertake an analysis of any significant portion of its range. Because 
the Dixie Valley toad warrants listing as endangered throughout all of 
its range, our determination does not conflict with the decision in 
Center for Biological Diversity v. Everson, 435 F. Supp. 3d 69 (D.D.C. 
2020), because that decision related to significant-portion-of-the-
range analyses for species that warrant listing as threatened, not 
endangered, throughout all of their range.

Determination of Status

    Our review of the best available scientific and commercial 
information indicates that the Dixie Valley toad meets the Act's 
definition of an endangered species. Therefore, we are listing the 
Dixie Valley toad as an endangered species in accordance with sections 
3(6) and 4(a)(1) of the Act.

Available Conservation Measures

    Conservation measures provided to species listed as endangered or 
threatened species under the Act include recognition, recovery actions, 
requirements for Federal protection, and prohibitions against certain 
practices. Recognition through listing results in public awareness, and 
conservation by Federal, State, Tribal, and local agencies, private 
organizations, and individuals. The Act encourages cooperation with the 
States and requires that recovery actions be carried out for listed 
species. The protection required by Federal agencies and the 
prohibitions against certain activities are discussed, in part, below.
    The primary purpose of the Act is the conservation of endangered 
and threatened species and the ecosystems upon which they depend. The 
ultimate goal of such conservation efforts is the recovery of these 
listed species, so that they no longer need the protective measures of 
the Act. Section 4(f) of the Act calls for the Service to develop and 
implement recovery plans for the conservation of endangered and 
threatened species. The recovery planning process involves the 
identification of actions that are necessary to halt or reverse the 
species' decline by addressing the threats to its survival and 
recovery. The goal of this process is to restore listed species to a 
point where they are secure, self-sustaining, and functioning 
components of their ecosystems.
    Recovery planning includes the development of a recovery outline 
shortly after a species is listed and preparation of a draft and final 
recovery plan. The recovery outline guides the immediate implementation 
of urgent recovery actions and describes the process to be used to 
develop a recovery plan. Revisions of the plan may be done to address 
continuing or new threats to the species, as new substantive 
information becomes available. The recovery plan identifies site-
specific management actions that set a trigger for review of the five 
factors that control whether a species remains endangered or may be 
reclassified from endangered to threatened (``downlisted'') or removed 
from protected status (``delisted'') and methods for monitoring 
recovery progress. Recovery plans also establish a framework for 
agencies to coordinate their recovery efforts and provide estimates of 
the cost of implementing recovery tasks. Recovery teams (composed of 
species experts, Federal and State agencies, nongovernmental 
organizations, and stakeholders) are often established to develop 
recovery plans. When completed, the recovery outline, draft recovery 
plan, and the final recovery plan will be available on our website 
(https://www.fws.gov/program/endangered-species) (see FOR FURTHER 
INFORMATION CONTACT).
    Implementation of recovery actions generally requires the 
participation of a

[[Page 73991]]

broad range of partners, including other Federal agencies, States, 
Tribes, nongovernmental organizations, businesses, and private 
landowners. Examples of recovery actions include habitat restoration 
(e.g., restoration of native vegetation), research, captive propagation 
and reintroduction, and outreach and education. The recovery of many 
listed species cannot be accomplished solely on Federal lands because 
their range may occur primarily or solely on non-Federal lands. To 
achieve recovery of these species requires cooperative conservation 
efforts on private, State, and Tribal lands.
    Following publication of this final rule, funding for recovery 
actions will be available from a variety of sources, including Federal 
budgets, State programs, the academic community, and nongovernmental 
organizations. In addition, pursuant to section 6 of the Act, the State 
of Nevada will be eligible for Federal funds to implement management 
actions that promote the protection or recovery of the Dixie Valley 
toad. Information on our grant programs that are available to aid 
species recovery can be found at: https://www.fws.gov/service/financial-assistance.
    Please let us know if you are interested in participating in 
recovery efforts for this species. Additionally, we invite you to 
submit any new information on this species whenever it becomes 
available and any information you may have for recovery planning 
purposes (see FOR FURTHER INFORMATION CONTACT).
    Section 7(a) of the Act requires Federal agencies to evaluate their 
actions with respect to any species that is listed as an endangered or 
threatened species and with respect to its critical habitat, if any is 
designated. Regulations implementing this interagency cooperation 
provision of the Act are codified at 50 CFR part 402. Section 7(a)(4) 
of the Act requires Federal agencies to ensure that activities they 
authorize, fund, or carry out are not likely to jeopardize the 
continued existence of any endangered or threatened species or destroy 
or adversely modify its critical habitat. If a Federal action may 
affect a listed species or its critical habitat, the responsible 
Federal agency (action agency) must enter into consultation with us.
    Federal agency actions within the species' habitat that may require 
conference or consultation or both as described in the preceding 
paragraph may include, but are not limited to:
     Management planning and permitting on Federal lands, such 
as fire management plans, mining permits, integrated natural resources 
management plans, land resource management plans, oil and natural gas 
permits, and geothermal project approvals; and
     Landscape-altering activities on Federal lands, such as 
aquatic habitat restoration, fire suppression, fuel reduction 
treatments, renewable energy development, renewable and alternative 
energy projects, and geothermal project implementation.
    The Act and its implementing regulations set forth a series of 
general prohibitions and exceptions that apply to endangered wildlife. 
The prohibitions of section 9(a)(1) of the Act, codified at 50 CFR 
17.21, make it illegal for any person subject to the jurisdiction of 
the United States to take (which includes harass, harm, pursue, hunt, 
shoot, wound, kill, trap, capture, or collect; or to attempt any of 
these) endangered wildlife within the United States or on the high 
seas. In addition, it is unlawful to import; export; deliver, receive, 
carry, transport, or ship in interstate or foreign commerce in the 
course of commercial activity; or sell or offer for sale in interstate 
or foreign commerce any species listed as an endangered species. It is 
also illegal to possess, sell, deliver, carry, transport, or ship any 
such wildlife that has been taken illegally. Certain exceptions apply 
to employees of the Service, the National Marine Fisheries Service, 
other Federal land management agencies, and State conservation 
agencies.
    We may issue permits to carry out otherwise prohibited activities 
involving endangered wildlife under certain circumstances. Regulations 
governing permits are codified at 50 CFR 17.22. With regard to 
endangered wildlife, a permit may be issued for the following purposes: 
for scientific purposes, to enhance the propagation or survival of the 
species, and for incidental take in connection with otherwise lawful 
activities. The statute also contains certain exemptions from the 
prohibitions, which are found in sections 9 and 10 of the Act.
    It is our policy, as published in the Federal Register on July 1, 
1994 (59 FR 34272), to identify to the maximum extent practicable at 
the time a species is listed those activities that would or would not 
constitute a violation of section 9 of the Act. The intent of this 
policy is to increase public awareness of the effect of a final listing 
on proposed and ongoing activities within the range of a listed 
species. Based on the best available information, the following actions 
are unlikely to result in a violation of section 9, if these activities 
are carried out in accordance with existing regulations and permit 
requirements; this list is not comprehensive:
    (1) Vehicle use on existing roads and trails in compliance with the 
BLM Carson City District's resource management plan.
    (2) Recreational use with minimal ground disturbance (e.g., hiking, 
walking).
    Based on the best available information, the following activities 
may potentially result in a violation of section 9 of the Act if they 
are not authorized in accordance with applicable law, including the 
Act; this list is not comprehensive:
    (1) Unauthorized handling or collecting of the species;
    (2) Unauthorized livestock grazing that results in direct mortality 
and direct or indirect destruction of vegetation and aquatic habitat;
    (3) Destruction/alteration of the species' habitat by draining, 
ditching, stream channelization or diversion, or diversion or 
alteration of surface or ground water flow into or out of the wetland;
    (4) Introduction of nonnative species that compete with or prey 
upon the Dixie Valley toad or wetland vegetation;
    (5) The unauthorized release of biological control agents that 
attack any life stage of the Dixie Valley toad;
    (6) Modification of the vegetation components on sites known to be 
occupied by the Dixie Valley toad; and
    (7) Modification of spring and wetland water temperatures.
    Questions regarding whether specific activities would constitute a 
violation of section 9 of the Act should be directed to the Reno 
Ecological Services Field Office (see FOR FURTHER INFORMATION CONTACT).

II. Critical Habitat

Background

    Critical habitat is defined in section 3 of the Act as:
    (1) The specific areas within the geographical area occupied by the 
species, at the time it is listed in accordance with the Act, on which 
are found those physical or biological features
    (a) Essential to the conservation of the species, and
    (b) Which may require special management considerations or 
protection; and
    (2) Specific areas outside the geographical area occupied by the 
species at the time it is listed, upon a determination that such areas 
are essential for the conservation of the species.

[[Page 73992]]

    Our regulations at 50 CFR 424.02 define the geographical area 
occupied by the species as an area that may generally be delineated 
around species' occurrences, as determined by the Secretary (i.e., 
range). Such areas may include those areas used throughout all or part 
of the species' life cycle, even if not used on a regular basis (e.g., 
migratory corridors, seasonal habitats, and habitats used periodically, 
but not solely by vagrant individuals).
    Conservation, as defined under section 3 of the Act, means to use 
and the use of all methods and procedures that are necessary to bring 
an endangered or threatened species to the point at which the measures 
provided pursuant to the Act are no longer necessary. Such methods and 
procedures include, but are not limited to, all activities associated 
with scientific resources management such as research, census, law 
enforcement, habitat acquisition and maintenance, propagation, live 
trapping, and transplantation, and, in the extraordinary case where 
population pressures within a given ecosystem cannot be otherwise 
relieved, may include regulated taking.
    Critical habitat receives protection under section 7 of the Act 
through the requirement that Federal agencies ensure, in consultation 
with the Service, that any action they authorize, fund, or carry out is 
not likely to result in the destruction or adverse modification of 
critical habitat. The designation of critical habitat does not affect 
land ownership or establish a refuge, wilderness, reserve, preserve, or 
other conservation area. Such designation also does not allow the 
government or public to access private lands. Such designation does not 
require implementation of restoration, recovery, or enhancement 
measures by non-Federal landowners. Where a landowner requests Federal 
agency funding or authorization for an action that may affect a listed 
species or critical habitat, the Federal agency would be required to 
consult with the Service under section 7(a)(2) of the Act. However, 
even if the Service were to conclude that the proposed activity would 
result in destruction or adverse modification of the critical habitat, 
the Federal action agency and the landowner are not required to abandon 
the proposed activity, or to restore or recover the species; instead, 
they must implement ``reasonable and prudent alternatives'' to avoid 
destruction or adverse modification of critical habitat.
    Under the first prong of the Act's definition of critical habitat, 
areas within the geographical area occupied by the species at the time 
it was listed are included in a critical habitat designation if they 
contain physical or biological features (1) which are essential to the 
conservation of the species and (2) which may require special 
management considerations or protection. For these areas, critical 
habitat designations identify, to the extent known using the best 
scientific and commercial data available, those physical or biological 
features that are essential to the conservation of the species (such as 
space, food, cover, and protected habitat).
    Under the second prong of the Act's definition of critical habitat, 
we can designate critical habitat in areas outside the geographical 
area occupied by the species at the time it is listed, upon a 
determination that such areas are essential for the conservation of the 
species.
    Section 4 of the Act requires that we designate critical habitat on 
the basis of the best scientific data available. Further, our Policy on 
Information Standards Under the Endangered Species Act (published in 
the Federal Register on July 1, 1994 (59 FR 34271)), the Information 
Quality Act (section 515 of the Treasury and General Government 
Appropriations Act for Fiscal Year 2001 (Pub. L. 106-554; H.R. 5658)), 
and our associated Information Quality Guidelines provide criteria, 
establish procedures, and provide guidance to ensure that our decisions 
are based on the best scientific data available. They require our 
biologists, to the extent consistent with the Act and with the use of 
the best scientific data available, to use primary and original sources 
of information as the basis for recommendations to designate critical 
habitat.
    When we are determining which areas should be designated as 
critical habitat, our primary source of information is generally the 
information from the SSA report and information developed during the 
listing process for the species. Additional information sources may 
include any generalized conservation strategy, criteria, or outline 
that may have been developed for the species; the recovery plan for the 
species; articles in peer-reviewed journals; conservation plans 
developed by States and counties; scientific status surveys and 
studies; biological assessments; other unpublished materials; or 
experts' opinions or personal knowledge.
    Habitat is dynamic, and species may move from one area to another 
over time. We recognize that critical habitat designated at a 
particular point in time may not include all of the habitat areas that 
we may later determine are necessary for the recovery of the species. 
For these reasons, a critical habitat designation does not signal that 
habitat outside the designated area is unimportant or may not be needed 
for recovery of the species. Areas that are important to the 
conservation of the species, both inside and outside the critical 
habitat designation, will continue to be subject to: (1) conservation 
actions implemented under section 7(a)(1) of the Act; (2) regulatory 
protections afforded by the requirement in section 7(a)(2) of the Act 
for Federal agencies to ensure their actions are not likely to 
jeopardize the continued existence of any endangered or threatened 
species; and (3) the prohibitions found in section 9 of the Act for 
endangered species or the 4(d) rule (for threatened species). Federally 
funded or permitted projects affecting listed species outside their 
designated critical habitat areas may still result in jeopardy findings 
in some cases. These protections and conservation tools will continue 
to contribute to recovery of the species. Similarly, critical habitat 
designations made on the basis of the best available information at the 
time of designation will not control the direction and substance of 
future recovery plans, habitat conservation plans, or other species 
conservation planning efforts if new information available at the time 
of those planning efforts calls for a different outcome.

Prudency Determination

    Section 4(a)(3) of the Act, as amended, and implementing 
regulations (50 CFR 424.12) require that, to the maximum extent prudent 
and determinable, the Secretary shall designate critical habitat at the 
time the species is determined to be an endangered or threatened 
species. Our regulations (50 CFR 424.12(a)(1)) state that the Secretary 
may, but is not required to, determine that a designation would not be 
prudent in the following circumstances:
    (i) The species is threatened by taking or other human activity and 
identification of critical habitat can be expected to increase the 
degree of such threat to the species;
    (ii) The present or threatened destruction, modification, or 
curtailment of a species' habitat or range is not a threat to the 
species, or threats to the species' habitat stem solely from causes 
that cannot be addressed through management actions resulting from 
consultations under section 7(a)(2) of the Act;
    (iii) Areas within the jurisdiction of the United States provide no 
more than

[[Page 73993]]

negligible conservation value, if any, for a species occurring 
primarily outside the jurisdiction of the United States;
    (iv) No areas meet the definition of critical habitat; or
    (v) The Secretary otherwise determines that designation of critical 
habitat would not be prudent based on the best scientific data 
available.
    As discussed in the SSA report, there is currently no imminent 
threat of collection or vandalism identified under Factor B for this 
species, and identification and mapping of critical habitat is not 
expected to initiate any such threat. In our SSA report and the 
emergency listing rule for the Dixie Valley toad (87 FR 20336; April 7, 
2022), we determined that the present or threatened destruction, 
modification, or curtailment of habitat or range is a threat to Dixie 
Valley toad and that those threats in some way can be addressed by the 
Act's section 7(a)(2) consultation measures. The species occurs wholly 
in the jurisdiction of the United States, and we are able to identify 
areas that meet the definition of critical habitat. Therefore, because 
none of the circumstances enumerated in our regulations at 50 CFR 
424.12(a)(1) have been met and because the Secretary has not identified 
other circumstances for which this designation of critical habitat 
would be not prudent, we have determined that the designation of 
critical habitat is prudent for the Dixie Valley toad.

Critical Habitat Determinability

    Having determined that designation is prudent, under section 
4(a)(3) of the Act we must find whether critical habitat for the Dixie 
Valley toad is determinable. Our regulations at 50 CFR 424.12(a)(2) 
state that critical habitat is not determinable when one or both of the 
following situations exist:
    (i) Data sufficient to perform required analyses are lacking, or
    (ii) The biological needs of the species are not sufficiently well 
known to identify any area that meets the definition of ``critical 
habitat.''
    We reviewed the available information pertaining to the biological 
needs of the species and habitat characteristics where this species is 
located. Careful assessments of the economic impacts that may occur due 
to a critical habitat designation are not yet complete. Therefore, data 
sufficient to perform required analyses are lacking, and we conclude 
that the designation of critical habitat for the Dixie Valley toad is 
not determinable at this time. The Act allows the Service an additional 
year to publish a critical habitat designation that is not determinable 
at the time of listing (16 U.S.C. 1533(b)(6)(C)(ii)).

Administrative Procedure Act

    The April 7, 2022, emergency rule (87 FR 20336) that implemented 
temporary (240-day) protections for the Dixie Valley toad expires on 
December 2, 2022. Given the immediate threat geothermal development 
poses to the species, we conclude that it is necessary to establish 
immediate and seamless protection under the Act for the Dixie Valley 
toad. Therefore, we have determined that, under the exemption provided 
in the Administrative Procedure Act (5 U.S.C. 553(d)(3)), ``good 
cause'' exists to make these regulations effective upon publication 
(see DATES, above).

Required Determinations

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

    It is our position that, outside the jurisdiction of the U.S. Court 
of Appeals for the Tenth Circuit, we do not need to prepare 
environmental analyses pursuant to the National Environmental Policy 
Act (42 U.S.C. 4321 et seq.) in connection with regulations adopted 
pursuant to section 4(a) of the Act. We published a notice outlining 
our reasons for this determination in the Federal Register on October 
25, 1983 (48 FR 49244). This position was upheld by the U.S. Court of 
Appeals for the Ninth Circuit (Douglas County v. Babbitt, 48 F.3d 1495 
(9th Cir. 1995), cert. denied 516 U.S. 1042 (1996)).

Government-to-Government Relationship With Tribes

    In accordance with the President's memorandum of April 29, 1994 
(Government-to-Government Relations with Native American Tribal 
Governments; 59 FR 22951), Executive Order 13175 (Consultation and 
Coordination with Indian Tribal Governments), and the Department of the 
Interior's manual at 512 DM 2, we readily acknowledge our 
responsibility to communicate meaningfully with recognized Federal 
Tribes on a government-to-government basis. In accordance with 
Secretarial Order 3206 of June 5, 1997 (American Indian Tribal Rights, 
Federal-Tribal Trust Responsibilities, and the Endangered Species Act), 
we readily acknowledge our responsibilities to work directly with 
Tribes in developing programs for healthy ecosystems, to acknowledge 
that Tribal lands are not subject to the same controls as Federal 
public lands, to remain sensitive to Indian culture, and to make 
information available to Tribes. We requested information from the 
Paiute-Shoshone Tribe of the Fallon Reservation and Colony during the 
SSA process. We received a request for a government-to-government 
consultation from the Paiute-Shoshone Tribe of the Fallon Reservation 
and Colony during the public comment period and are working toward 
initiating conversations with the tribe. We will continue to work with 
Tribal entities in the future, including during development of a 
critical habitat designation for the Dixie Valley toad.

References Cited

    A complete list of references cited in this rulemaking is available 
on the internet at https://www.regulations.gov and upon request from 
the Reno Fish and Wildlife Office (see FOR FURTHER INFORMATION 
CONTACT).

Authors

    The primary authors of this rule are the staff members of the Fish 
and Wildlife Service's Species Assessment Team and the Reno Fish and 
Wildlife Office.

List of Subjects in 50 CFR Part 17

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

Regulation Promulgation

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

PART 17--ENDANGERED AND THREATENED WILDLIFE AND PLANTS

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

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


0
2. In Sec.  17.11, amend paragraph (h) by adding an entry for ``Toad, 
Dixie Valley'' to the List of Endangered and Threatened Wildlife in 
alphabetical order under AMPHIBIANS to read as follows:


Sec.  17.11  Endangered and threatened wildlife.

* * * * *
    (h) * * *

[[Page 73994]]



----------------------------------------------------------------------------------------------------------------
                                                                                          Listing citations and
           Common name              Scientific name      Where listed         Status         applicable rules
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------
                                                   Amphibians
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
Toad, Dixie Valley..............  Anaxyrus williamsi  Wherever found....  E              87 FR [Insert Federal
                                                                                          Register page where
                                                                                          the document begins],
                                                                                          12/2/2022.
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------


Stephen Guertin,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. 2022-26237 Filed 12-1-22; 8:45 am]
BILLING CODE 4333-15-P