- Dry lake solar energy zone.his technical note is the
product of a collaborative
effort. Many people
representing many
different entities had a hand in its
development. The project occurred
under the leadership of Ray Brady,
Bureau of Land Management
(BLM) Washington Office. The final
content was approved by the BLM
Regional Mitigation Project Team:
Joe Vieira (Lead), Michael Dwyer,
Wendy Seley, and Gordon Toevs.
Special thanks go to the Argonne
National Laboratory project
support team: Heidi Hartmann
(Lead), Laura Fox, David Murphy,
Karen Smith, Shannon Stewart,
Konstance Wescott, and Lee
Walston. Special thanks also go to
John McCarty (BLM Washington
Office), Rochelle Francisco
(BLM Nevada State Office), Fred
Edwards, Mark Slaughter, Kathleen
Sprowl, Boris Poff, and the other
members of the BLM Southern
Nevada District, Pahrump Field
Office Interdisciplinary Team.
Members of the Information and
Publishing Services Section at the
BLM National Operations Center
assisted by providing editorial and
design and layout services. Many
others contributed by attending
or helping conduct one or more of
the workshops conducted to obtain
input from interested parties, by
providing comments on draft
versions of this document, and by
providing management oversight
and/or technical support. Thanks to
all who contributed!
TABSTRACT ___________________________________________________________________________________ 1
1. INTRODUCTION AND PURPOSE ______________________________________________________________ 2
1.1 Purpose of the Strategy ______________________________________________________________________ 2
1.2 Background _____________________________________________________________________________ 3
1.3 Solar Regional Mitigation Strategy Process __________________________________________________________ 4
1.4 Stakeholder Involvement in the Solar Regional Mitigation Strategy Process _______________________________________ 5
2. MITIGATION STRATEGY – DRY LAKE SOLAR ENERGY ZONE _________________________________________ 6
2.1 Description of the Dry Lake Solar Energy Zone and Surrounding Region _________________________________________ 6
2.1.1 General Description of the Solar Energy Zone _____________________________________________________ 6
2.1.2 Landscape Conditions of the Solar Energy Zone and the Region __________________________________________ 6
2.1.3 Regional Setting ______________________________________________________________________ 8
2.1.3.1 General Description _______________________________________________________________ 8
2.1.3.2 Problematic Regional Trends __________________________________________________________ 8
2.2 General Description of Solar Development in the Dry Lake Solar Energy Zone _____________________________________ 18
2.2.1 Description of Existing Rights-of-Way and Impact on Developable Area ____________________________________ 18
2.2.2 Description of Potential Development ________________________________________________________ 18
2.3 Summary of Solar Development Impacts on the Dry Lake Solar Energy Zone _____________________________________ 19
2.4 Mitigation Strategy (Hierarchy) of the Dry Lake Solar Energy Zone ____________________________________________ 20
2.4.1 Avoidance _________________________________________________________________________ 20
2.4.1.1 Dry Wash/Riparian Areas ___________________________________________________________ 20
2.4.1.2 Existing Rights-of-Way, Mining Claims, etc. ________________________________________________ 20
2.4.2 Minimization _______________________________________________________________________ 21
2.4.2.1 Summary of Programmatic Design Features to be Applied _______________________________________ 21
2.4.2.2 Other Required Impact Minimization Measures and/or Stipulations __________________________________ 21
2.4.3 Regional Mitigation ___________________________________________________________________ 21
2.4.3.1 Identification of Unavoidable Impacts ___________________________________________________ 22
2.4.3.2 Unavoidable Impacts that May Warrant Regional Mitigation ______________________________________ 23
2.4.3.2.1 Conceptual Models _________________________________________________________ 23
2.4.3.2.2 Unavoidable Impacts that May Warrant Regional Mitigation ________________________________ 23
2.5 Regional Mitigation Goals ___________________________________________________________________ 24
2.5.1 Background on Regional Goals _____________________________________________________________ 24
2.5.2 Las Vegas Resource Management Plan Goals and Objectives ___________________________________________ 24
2.5.3 Dry Lake Solar Energy Zone Mitigation Goals and Objectives ___________________________________________ 25
2.6 Calculating the Recommended Mitigation Fee for the Dry Lake Solar Energy Zone __________________________________ 26
2.7 Management of Solar Regional Mitigation Fees _______________________________________________________ 28
2.8 Evaluation of Mitigation Locations, Objectives, and Actions ________________________________________________ 29
2.9 Mitigation Effectiveness Monitoring and Adaptive Management Plan _________________________________________ 35
2.10 Implementation Strategy ____________________________________________________________________ 43
REFERENCES ________________________________________________________________________________ 45
APPENDIX A: Impact Assessment Summary Table __________________________________________________________ 46
APPENDIX B: Regional and Dry Lake Solar Energy Zone Conceptual Models ___________________________________________ 51
APPENDIX C: Summary Table: Impacts that May Warrant Regional Mitigation for the Dry Lake Solar Energy Zone ____________________ 54
APPENDIX D: BLM Screening of Candidate Regional Mitigation Sites for the Dry Lake Solar Energy Zone _________________________ 57
APPENDIX E: Mitigation of Visual Resource Impacts in the Dry Lake Solar Energy Zone ____________________________________ 632-1 Dry Lake Solar Energy Zone and surrounding area _____________________________________________ 7
2-2 Landscape condition in the Mojave Basin and Range ecoregion __________________________________ 9
2-3 Landscape condition in the Dry Lake Solar Energy Zone ________________________________________ 10
2-4 Dry Lake Solar Energy Zone and surrounding land designations _________________________________ 11
2-5 Land cover types in the Mojave Basin and Range ecoregion _____________________________________ 12
2-6 Land cover types in the vicinity of the Dry Lake Solar Energy Zone _______________________________ 13
2-7 Conceptual diagram for estimating condition and trends of
conservation elements in the Mojave Basin and Range ecoregion
for the Dry Lake Solar Energy Zone Solar Regional Mitigation Strategy ____________________________ 15
2-8 Dry Lake Solar Energy Zone revised developable area __________________________________________ 20
2-9 Steps for calculating per-acre regional mitigation fees _________________________________________ 26
2-10 Gold Butte Area of Critical Environmental Concern ____________________________________________ 31
2-11 Example of a stratified, nonbiased sampling schema for the Dry Lake Solar Energy Zone _____________ 40
2-12 Example of a stratified, nonbiased sampling schema for the Gold Butte Area
of Critical Environmental Concern __________________________________________________________ 41
Tables
2-1 Ecological stressor source, site-impact scores, and distance decay scores implemented
for the landscape condition model for the Mojave Basin and Range _______________________________ 8
2-2 Land cover types and amounts in the vicinity of the Dry Lake Solar Energy Zone ____________________ 14
2-3 Condition and trends assessment for coarse and fine filter conservation elements
in the Mojave Basin and Range relevant to the Dry Lake Solar Energy Zone ________________________ 16
2-4 Estimate of funding needed for management activities to ensure effectiveness and durability _________ 27
2-5 Dry Lake Solar Energy Zone goals and objectives associated with mitigation
in the Gold Butte Area of Critical Environmental Concern _______________________________________ 32
2-6 Priority/order of Gold Butte Area of Critical Environmental Concern
mitigation goals and objectives____________________________________________________________ 34
2-7 Recommended methods and measurements for core and contingent indicators. ___________________ 37
2-8 Quantitative indicators and measurements relevant to each
of the three rangeland health attributes _____________________________________________________ 3
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- 1.1 Purpose of the Strategy
he “Regional Mitigation
Strategy for the Dry
Lake Solar Energy Zone”
recommends a strategy
for compensating for certain
unavoidable impacts that are
expected from the development
of the Dry Lake Solar Energy Zone
(SEZ) in southern Nevada. The
Bureau of Land Management (BLM)
is required to manage the public
lands in a manner that will protect
the quality of ecological and
environmental values and provide
for wildlife habitat in a way that
does not result in the permanent
impairment of the productivity of
the land. While the BLM places a
priority on mitigating impacts to
an acceptable level onsite, there
are times when onsite mitigation
alone may not be sufficient. In these
cases, which are likely to occur with
utility-scale solar development,
which often involves a long-term
commitment of resources over
a relatively large area, the BLM
is considering requirements for
regional mitigation for those
unavoidable impacts that could
exacerbate problematic regional
trends. Accordingly, this pilot
strategy articulates:
1. The unavoidable impacts
expected as a result of
development of the Dry Lake
SEZ.
2. The problematic trends in the
Mojave Desert, where the Dry
Lake SEZ is located.
3. A conceptual model that
depicts the relationships
between resources, ecosystem
functions, ecosystem services,
and change agents (including
development, climate change,
wildfire, etc.).
4. The unavoidable impacts that,
in consideration of regional
trends and roles the impacted
resources play, may warrant
regional mitigation.
5. The regional mitigation goals
and objectives recommended
for the Dry Lake SEZ.
6. The regional mitigation
locations and action(s)
recommended for achieving the
mitigation goals and objectives
for the Dry Lake SEZ.
7. The estimated cost of the
mitigation action(s), including
a breakout of acquisition,
restoration, and/or ongoing
management costs to ensure
effectiveness and durability.
8. A recommended method for
calculating a mitigation fee that
could be assessed to developers
and an explanation of how it
was calculated for the Dry Lake
SEZ.
9. A recommendation for how the
BLM fee revenue derived from
development of the Dry Lake
SEZ could be managed.
10. A recommendation for how
the outcomes of the mitigation
actions could be monitored and
what will happen if the actions
are not achieving the desired
results.
This pilot strategy will guide
future decisions for:
• The configuration of lease
parcels within the Dry Lake SEZ.
• The lease stipulations to achieve
avoidance and minimization of
impacts.
• The impacts to be mitigated in
the immediate region.
• Where and how regional
mitigation will occur.
• Monitoring and adaptive
management.
• Developing BLM policy to guide
regional mitigation.
The BLM authorized officer
will make these decisions prior
to leasing and will also take into
consideration:
• The National Environmental
Policy Act (NEPA) analysis
done for the proposed action,
including comments submitted
by the public and other
stakeholders.
• Any changes to the applicable
resource management plan
(RMP) or other plans that affect
management of the SEZ or
possible mitigation sites.
• The input received from
consultation with tribes.
• Any other information that
would update, correct, or
otherwise supplement the
information contained in this
strategy
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- n August 2012, the BLM
initiated the pilot Dry
Lake SEZ Solar Regional
Mitigation Planning Project,
which constitutes the first SRMS
developed for an SEZ. The Dry
Lake SEZ SRMS originated
simultaneously with, and served
as a pilot test case for, the
establishment of BLM guidance
for developing SRMSs for other
SEZs (BLM forthcoming). The effort
was conducted with a significant
amount of public involvement,
including four workshops,
several web-based meetings, and
opportunities to comment on
preliminary and draft versions of
methodologies and strategies.
The Dry Lake SEZ is located
about 15 mi (24 km) northeast of
Las Vegas in Nevada. The process
for developing the Dry Lake SEZ
SRMS largely followed the outline
for regional mitigation planning
outlined in the Final Solar PEIS. In
general, a team of specialists from
the BLM Southern Nevada District
Office, with the support of Argonne
National Laboratory, produced a
preliminary product at each step
in the process, which was then
presented and discussed in a public
forum. The opportunity for written
comments was also extended to the
public. The content and methods
used in this process incorporate
many of the ideas and comments
received from the public.
The mitigation actions
identified in this strategy are
designed to compensate for
the loss of some of the habitat,
visual resources, and ecological
services that are expected from
the development of the Dry
Lake SEZ. For the purpose of this
analysis, it is assumed that all of
the developable land within the
Dry Lake SEZ will be impacted. The
degree of compensation will take
into consideration the condition
of the resource values present in
the Dry Lake SEZ and also consider
the relative costs and benefits of
the use of public lands for solar
energy development, including the
amount of time and effort required
to restore the disturbed area
upon expiration of the lease. The
recommended mitigation actions
are drawn from the “Proposed Las
Vegas Resource Management Plan
and Final Environmental Impact
Statement” (Las Vegas RMP) (BLM
1998). They consist of restoration
and preservation measures
prescribed for the Gold Butte Area
of Critical Environmental Concern
(ACEC), but for which sufficient
resources have been unavailable.
The Gold Butte ACEC is in the same
ecological zone (ecoregion) and
subzone as the Dry Lake SEZ and is
of the same vegetation community.
The Gold Butte ACEC provides
habitat for all of the wildlife,
including the special status species,
found in the Dry Lake SEZ.
Under the terms of this strategy,
funding derived from mitigation
fees for the Dry Lake SEZ will not
be sufficient to fund all of the
potential restoration and protection
needs in the Gold Butte ACEC, but
they will allow significant progress
toward achieving the management
objectives for the ACEC: to preserve
the extraordinary resource values
found there while providing for
human use and enjoyment. As
part of the proposed solar energy
program, the solar long-term
monitoring program will be used
to evaluate the effectiveness of
mitigation strategies employed
through regional mitigation plans.
Regional mitigation strategies will
be subject to continued review
and adjustment by the BLM and
its partners to ensure conservation
goals and objectives are being met.
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- 1.4 Stakeholder Involvement in the
Solar Regional Mitigation Strategy Process
he pilot process for
including stakeholder
input in developing the Dry
Lake SEZ SRMS included
four workshops in Las Vegas and
several web-based meetings.
Representatives from federal, state,
and local government agencies;
nongovernmental organizations
concerned with issues such as
environmental or recreational
impacts; representatives from
the solar development industry,
mining industry, and utilities; tribal
representatives; and individual
members of the public who had
been involved in the Solar PEIS
process were invited to attend
these activities. Approximately 70
individuals and representatives
from the previously mentioned
organizations attended the kickoff
workshop held August 29-30,
2012. During the first workshop,
background on regional mitigation
planning and the Solar PEIS impact
assessment for the Dry Lake SEZ
were provided to the attendees.
The subsequent three workshops all
had about 35 attendees, including
individuals and representatives
from agencies, nongovernmental
organizations, the solar industry
and consultants to the industry,
utilities, and tribes.
The second workshop was held
October 24-25, 2012. This workshop
included a field visit to the Dry Lake
SEZ in order to give the participants
a firsthand look at the SEZ. BLM
staff experts were present and
spoke about the range of resources
present in the SEZ and possible
opportunities available to avoid,
minimize, and mitigate potential
impacts related to solar energy
development.
The third workshop was
held January 30-31, 2013. This
workshop focused on regional
trends and conditions, unavoidable
impacts that may warrant regional
mitigation, the establishment of
regional mitigation objectives, the
use of mapping tools and data in
choosing locations for mitigation,
prioritization of mitigation projects,
mitigation costing, and long-term
monitoring.
The fourth workshop, held
on February 27, 2013, focused
on three topics: (1) methods for
establishing mitigation fees in SEZs,
and specifically in the Dry Lake SEZ;
(2) establishing solar mitigation
objectives and priority setting;
and (3) structures for holding and
applying mitigation funds.
Additionally, several webinars
were held to provide information
on: mitigation valuation methods
and mitigation structure options
(December 6, 2012); methods to
identify impacts that may warrant
mitigation (January 1, 2013);
and a proposed mitigation fee
setting method and method to
evaluate candidate mitigation sites
(March 21, 2013).
All presentations from the four
workshops and three webinars are
posted on the project documents
web page on the Dry Lake SEZ
SRMS Project website at: http://
www.blm.gov/nv/st/en/fo/lvfo/
blm_programs/energy/dry_lake_
solar_energy.html. Reports from
the workshops are also available.
Additional materials that were
provided for stakeholder review
are posted on the project website
documents page as well.
Throughout the pilot project,
stakeholders were invited to
comment on interim draft
materials, including the summary
of unavoidable impacts at the
Dry Lake SEZ that may warrant
mitigation, the proposed method
for deriving the mitigation fees, the
method of evaluating candidate
sites for mitigation, and the specific
mitigation sites and activities
proposed for the Dry Lake SEZ.
Many of these comments were
discussed during workshops and
used to guide development of this
strategy.
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- 2.1 Description of the Dry Lake Solar
Energy Zone and Surrounding Region
2.1.1 General Description
of the Solar Energy Zone
The Dry Lake SEZ is located in
Clark County in southern Nevada.
The total area of the Dry Lake SEZ,
as shown in Figure 2-1, is 6,187
acres (25 km2
) (BLM and DOE 2012).
In the Final Solar PEIS and the Solar
PEIS ROD, 469 acres (1.9 km2
) of
floodplain and wetland within the
SEZ boundaries were identified
as nondevelopment areas. The
developable area of the SEZ
given in the Final Solar PEIS was
5,717 acres (23 km2
).
The towns of Moapa and
Overton are located 18 mi (29 km)
northeast and 23 mi (37 km) east
of the SEZ, respectively. Nellis Air
Force Base is located approximately
13 mi (21 km) southwest of the SEZ.
The nearest major roads accessing
the proposed Dry Lake SEZ are
Interstate 15, which passes along
the southeastern boundary of the
SEZ, and U.S. Route 93, which runs
from north to south along part of
the southwest border of the SEZ.
The Union Pacific Railroad runs
north to south along a portion of
the eastern SEZ boundary, with
the nearest stop in Las Vegas. The
area around the SEZ is not highly
populated, although Clark County,
with a 2008 population close to
2 million individuals, has a large
number of residents.
The SEZ already contains
rights-of-way and developed
areas, including energy, water,
and transportation infrastructure
facilities. Three designated
transmission corridors pass
through the area, including a
Section 368 energy corridor (of
the Energy Policy Act of 2005),
which contains numerous electric
transmission lines, natural gas and
refined petroleum product lines,
and water lines (see Figure 2-1 for
the designated corridor). A power
generating station is also located
within the area of the SEZ, and two
existing natural gas power plants
are located just southwest of the
SEZ on private land. A minerals
processing plant is located in the
southeastern corner of the SEZ.
The Final Solar PEIS indicated that
in 2012 there were three pending
solar applications within or adjacent
to the SEZ and an additional large
application area located about 2 mi
(3 km) to the east of the SEZ across
Interstate 15.
2.1.2 Landscape
Conditions of the
Solar Energy Zone
and the Region
In 2012, the BLM completed
the “Mojave Basin and Range Rapid
Ecoregional Assessment” for the
Mojave Basin and Range ecoregion
in which the Dry Lake SEZ is located
(NatureServe 2013). The Mojave
Basin and Range REA examines
broad-scale ecological values,
conditions, and trends within the
ecoregion by synthesizing existing
spatial datasets in a meaningful
timeframe. The REAs serve multiple
purposes in an ecoregional
context, including identifying and
answering important management
questions; understanding key
resource values; understanding
the influence of various change
agents; understanding projected
ecological trends; identifying and
mapping key opportunities for
resource conservation, restoration,
and development; and providing
a baseline to evaluate and guide
future actions.
One useful product of the
REAs is the development of
landscape condition models.
These geospatial models have
been created to represent the
condition or level of intactness
throughout the ecoregion at the
time in which the assessments were
initiated (approximately 2010).
The landscape condition model
is a combination of two primary
factors—land use and a distance
decay function from land uses.
Different land use categories were
assigned a relative value between
0 and 1, representing very high
landscape alteration to very little
landscape alteration. For example,
high-density urban areas received
values closer to 0, whereas intact
undisturbed areas received values
closer to 1. The distance decay
function considered the proximity
of each location to human land
uses. Table 2-1 lists a number of
examples of land use and distance
decay scores for various stressor
categories in the Mojave Basin and
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- Range. A full description of the
landscape condition model and
how it was developed can be found
in the “Mojave Basin and Range
Rapid Ecoregional Assessments
Final Memorandum I-3-C.”
The landscape condition
model developed for the Mojave
Basin and Range was developed
as a raster dataset of 100-m cells.
The model illustrates landscape
condition values throughout the
ecoregion (Figure 2-2). The resulting
map provides a composite view of
the relative impacts of land uses
across the entire ecoregion. Darker
green areas indicate apparently
least impacted areas (most intact)
and orange-red areas are the most
impacted (least intact). According
to this landscape condition model,
most of the impacts occur near
urban areas (e.g., Las Vegas) and
along roadways. However, most
of the Mojave Basin and Range is
still relatively intact. The landscape
condition within the Dry Lake SEZ is
shown in Figure 2-3.
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- 2.1.3 Regional Setting
2.1.3.1 General Description
The Dry Lake SEZ is situated
within 5 mi (8 km) of several other
federally owned or administered
lands. The Moapa River Indian
Reservation is approximately 4 mi
(6.4 km) northeast of the revised
SEZ boundary. The Coyote Springs
ACEC, which is also designated
critical habitat for the federally
threatened desert tortoise, is
located within 0.5 mi (0.8 km) west
of the SEZ. Farther west of the
Coyote Springs ACEC is the U.S.
Fish and Wildlife Service Desert
National Wildlife Refuge, which is
approximately 3 mi (4.8 km) west
of the SEZ. The Muddy Mountains
Wilderness Area is approximately
8 mi (12.9 km) southeast of the SEZ
(Figure 2-4).
The Dry Lake SEZ is located
in a relatively undeveloped rural
area, bounded on the west by the
Arrow Canyon Range and on the
southeast by the Dry Lake Range.
The topography of the land within
the SEZ is arid basin dominated
by creosote and white bursage
vegetation communities. Land
cover types2
within the ecoregion
are presented in Figure 2-5. At a
more local scale, land cover types in
the vicinity of the Dry Lake SEZ are
shown in Figure 2-6. In total, there
are 10 natural land cover types
and 2 disturbance land cover types
predicted to occur in the vicinity
(i.e., within 5 mi, or 8 km) of the
Dry Lake SEZ (Table 2-2). There are
three land cover types that occur
in the developable portion of the
SEZ (Table 2-2). Listed in order of
dominance, these land cover types
are: Sonora-Mojave Creosote-White
Bursage Desert Scrub (98.8% of the
developable area), Sonora-Mojave
2
Geospatial data for land cover types were obtained from the
Southwest Regional Gap Analysis Project (http://earth.gis.usu.edu/
swgap/) and the California Gap land cover mapping project (http://
gap.uidaho.edu/index.php/california-land-cover/).
2.1.3.2 Problematic Regional Trends
The Mojave Basin and Range
REA presents a framework for
determining the condition and
trend of various resource values
and conservation elements in the
ecoregion. The Mojave Basin and
Mixed Salt Desert Scrub (0.8% of
the developable area), and North
American Warm Desert Wash (0.4%
of the developable area). Other land
cover types expected to occur in
the nondevelopable area of the SEZ
include Developed, Medium – High
Intensity and North American Warm
Desert Pavement (Table 2-2).
Table 2-1. Ecological stressor source, site-impact scores, and distance decay scores implemented for
the landscape condition model for the Mojave Basin and Range.
Range REA defines conservation
elements as resources of
conservation concern within an
ecoregion. These elements could
include habitat or populations
for plant and animal taxa, such
as threatened and endangered
species, or ecological systems and
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- Ecological Stressor Source
Site
Impact
Score
Presumed
Relative
Stress
Distance
Decay
Score
Impact
Approaches
Negligible
Transportation
Dirt roads, 4-wheel drive 0.7 Low 0.5 200 m
Local, neighborhood and connecting roads 0.5 Medium 0.5 200 m
Secondary and connecting roads 0.2 High 0.2 500 m
Primary highways with limited access 0.05 Very High 0.1 1,000 m
Primary highways without limited access 0.05 Very High 0.05 2,000 m
Urban and Industrial Development
Low-density development 0.6 Medium 0.5 200 m
Medium-density development 0.5 Medium 0.5 200 m
Powerline/transmission lines 0.5 Medium 0.9 100 m
Oil/gas wells 0.5 Medium 0.2 500 m
High-density development 0.05 Very High 0.05 2,000 m
Mines 0.05 Very High 0.2 500 m
Managed and Modified Land Cover
Ruderal forest and upland 0.9 Very Low 1 0 m
Native vegetation with introduced species 0.9 Very Low 1 0 m
Pasture 0.9 Very Low 0.9 100 m
Recently logged 0.9 Very Low 0.5 200 m
Managed tree plantations 0.8 Low 0.5 200 m
Introduced tree and shrub 0.5 Medium 0.5 200 m
Introduced upland grass and forb 0.5 Medium 0.5 200 m
Introduced wetland 0.3 High 0.8 125 m
Cultivated agriculture 0.3 High 0.5 200 m
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- plant communities of regional
importance. A list of conservation
elements could also include other
resource values, such as highly
erodible soils; populations of
wild horses and burros; scenic
viewsheds; or designated sites
of natural, historical, or cultural
significance. There are two basic
types of conservation elements in
the Mojave Basin and Range:
• Coarse filter conservation
elements, which typically include
all of the major ecosystem types
within the assessment landscape
and represent all of the
predominant natural ecosystem
functions and services in the
ecoregion.
• Fine filter conservation elements,
which complement the first
set of elements by including a
limited subset of focal species
assemblages and individual
species.
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- Table 2-2. Land cover types and amounts in the vicinity of the Dry Lake Solar Energy Zone.
Description Acres Within SEZ
Developable Area1
Acres Within Entire SEZ
(Developable and
Nondevelopable)2
Acres Within
5-Mile Buffer
Around SEZ3
Natural Land Cover Types
Sonora-Mojave Creosotebush-White
Bursage Desert Scrub 3,427 (98.8%) 5,879 (95.0%) 83,300 (84.1%)
Sonora-Mojave Mixed Salt Desert Scrub 30 (0.8%) 38 (0.6%) 645 (0.7%)
North American Warm Desert Wash 14 (0.4%) 141 (2.3%) 2,618 (2.6%)
North American Warm Desert
Pavement 21 (0.3%) 1,694 (1.7%)
North American Warm Desert Bedrock
Cliff and Outcrop 5,144 (5.2%)
Mojave Mid-Elevation Mixed
Desert Scrub 4,651 (4.7%)
North American Warm Desert Playa 287 (0.3%)
Inter-Mountain Basins Semi-Desert
Shrub Steppe 147 (0.1%)
Open Water 1 (<0.1%)
North American Warm Desert Riparian
Mesquite Bosque 1 (<0.1%)
Disturbance Land Cover Types
Developed, Medium - High Intensity 108 (1.8%) 495 (0.5%)
Invasive Southwest Riparian Woodland
and Shrubland 11 (<0.1%)
TOTAL (acres): 3,471 6,187 98,994
1 Values in parentheses represent the percent acreage relative to the entire developable area
(3,471 acres).
2
Values in parentheses represent the percent acreage relative to the entire SEZ (6,187 acres).
3
Values in parentheses represent the percent acreage relative to the entire 5-mile buffer area (98,994 acres).
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- A full list and explanation
of the coarse filter conservation
elements within the Mojave
Basin and Range can be found in
Appendix 2 of the Mojave Basin
and Range REA. In brief, the core
conservation elements include 19
coarse filter conservation elements
that represent terrestrial and
aquatic ecological system types and
communities and more than 600
fine filter conservation elements
that represent individual species or
species assemblages.
Problematic trends are
understood by forecasting the
response of conservation elements
to one of four change agents in
the ecoregion. The four change
agents include fire, invasive species,
climate change, and human
development. Of these change
agents, the conservation element
responses to human development
are the easiest to predict in a
meaningful timeframe for SRMSs
because solar energy development
represents an anthropogenic
disturbance, and the impacts of
human development are likely to
affect all conservation elements
similarly.
Understanding the problematic
conservation element trends
relevant to the Dry Lake SEZ
was accomplished through
(1) a geospatial analysis of
available ecoregional data and
(2) expert opinion by the BLM
interdisciplinary team. Figure 2-7
presents a conceptual illustration
of the geospatial framework for
determining the condition and
trends of conservation elements
in the ecoregion. The geospatial
data used in this assessment are
available publicly from open
sources. These data include the
BLM’s landscape condition model
for the Mojave Basin and Range,
modeled land cover types, and
species-specific habitat suitability
models. The Mojave Basin and
Range landscape condition
model can be used as a proxy for
landscape intactness. Evaluating
condition and trends of coarse and
fine filter conservation elements
(land cover and habitat models)
in an ecoregional context will
provide a better understanding
of the impacts of solar energy
development within the Dry Lake
SEZ relative to the rest of the
ecoregion.
The geospatial process for
quantitatively evaluating condition
and trends for conservation
elements (Figure 2-7) begins
with a characterization of the
distribution of the conservation
element within identified analysis
areas: (1) the entire Mojave Basin
and Range ecoregion, (2) vicinity
of the Dry Lake SEZ, and (3) within
the Dry Lake SEZ developable
area. These areas are then clipped
to current and anticipated future
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- Geospatial Data
1. Landscape Condition Model1
2. Habitat Suitablity Models2
3. Land Cover Types3
Characterize Distribution:
1. In the ecoregion
2. Within vicinity of the SEZ (5-mi buffer)
3. Within SEZ developable area
Geospatial Overlay Analysis4
:
1. Current Development Footprint5
2. 2025 Development Footprint6
CONDITION
TRENDS/
FORECAST
human development footprints3
and forecast trends. Trends are
understood by using the current
and future human development
footprints to evaluate the
expected future distribution of the
conservation element relative to its
current distribution.
An example table showing the
condition and trends of various
coarse and fine filter conservation
elements in the Mojave Basin and
Range is shown in Table 2-3. Due
to the large number of fine scale
conservation elements that could
potentially be evaluated, the BLM
determined that a trends analysis of
coarse filter land cover types would
be a suitable habitat-based proxy
3
Geospatial data for current and future human development
footprints are described in more detail in the Mojave Basin and
Range REA (NatureServe 2013).
for geospatial trends of fine scale
conservation elements (individual
species). In Table 2-3, coarse filter
conservation elements evaluated
include the Mojave Basin and
Range landscape condition model
and the Southwest Regional Gap
Analysis Project modeled land cover
types.
The only fine filter conservation
element presented in Table 2-3
is the Mojave population of the
desert tortoise (Gopherus agassizii),
which is listed in the table due
to its threatened status under
the Endangered Species Act and
known presence in potentially
suitable habitat on the Dry Lake
SEZ. Based on the results presented
in Table 2-3, it was concluded that
all conservation elements are
expected to experience a declining
trend in the Mojave Basin and
Range, as all conservation elements
are expected to experience some
level of range contraction due to
human development in the future.
Landscape condition within the
Mojave Basin and Range is also
expected to decline in the future.
Because the Sonora-Mojave
Creosotebush-White Bursage
Desert Scrub comprised the largest
portion of the Dry Lake SEZ (98.8%),
the cumulative expected future
loss of this conservation element
of 10.26% was considered to be
a problematic trend among all
conservation elements relative to
the Dry Lake SEZ.
1
The landscape condition model is available from and described in the BLM Mojave Basin and Range Rapid Ecoregional Assessment.
2
Habitat suitability models are available from the Southwest Regional Gap Analysis Project.
3
Land cover types are available from the Southwest Regional Gap Analysis Project.
4
The overlay change agent/conservation element analysis was conducted to determine geospatial trends. Geospatial data for the change agent were
overlayed with the distribution of conservation elements to determine current and future distributions of the conservation elements.
5
Geospatial data for the current human development footprint model are available from and described in the BLM Mojave Basin and Range Rapid
Ecoregional Assessment.
6
Geospatial data for the future (approximately 2025) human development footprint model are available from and described in the BLM Mojave Basin
and Range Rapid Ecoregional Assessment.
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