Federal Register, Volume 87 Issue 231 (Friday, December 2, 2022)

[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

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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