71 adjacent roadways as part of the residential development, and the 119 residential units would be expected to develop to City standards in the RL-5, RS-E and RS-1 zones.
Alternative 3 would achieve all Project objectives to some degree, but not to the same extent as the Proposed Project. Alternative 3 would maintain a range of potential housing units consistent with the City’s General Plan (Project Objective A) E. ENVIRONMENTALLY SUPERIOR ALTERNATIVE
Section 15126.6(e)(2) of the State CEQA Guidelines indicates that an analysis of alternatives to a proposed Project shall identify an environmentally superior alternative among the alternatives evaluated in an EIR.
Each sub-section of this alternatives analysis has considered the potential impacts of each alternative and compared them to the proposed Project on a categorical basis.
CEQA Guidelines Section 15126.6 (e)(2) states that if the environmentally superior alternative is the No Project Alternative, then an environmentally superior alternative must be identified from among the other alternatives. In this case, Alternative 1 is the environmentally superior alternative, as it would not result in any impacts and avoids the significant impacts that would result from the proposed Project. Because Alternative 1 is a “No Project” alternative, however, Section 15126.6 (e)(2) requires that an environmentally superior alternative be identified from among the other alternatives.
While identification and disclosure of the environmentally superior alternative is required by CEQA, the City is not required to approve the environmentally superior alternative.
Based on the analysis below, the “environmentally superior” Project alternative is Alternative 3 (per CEQA 15126.6). Alternative 3, however, would not satisfy the Project’s objectives to the degree that the proposed Project would, as described below.
Specifically, Alternative 3 would:
A. Maintain the City’s housing supply.
B. Expand the commercial generation of energy for the City and region, but to a lesser degree than the Project.
C. Provide the City with annual revenue from the solar facility, but to a lesser degree than the Project.
D. Reduce the City’s carbon footprint, but to a lesser degree than the Project.
E. Result in less of a need for renaturalization of the site than the Project.
Neither of the “No Project” alternatives (Alternatives 1 and 2) would satisfy a majority of the Project objectives. Alternative 3, which would include a smaller solar project, meets the majority of Project objectives, but to a lesser degree than the Project. Alternative 3 also does not fully mitigate the significant impacts associated with visual resources identified for the Project, but is the environmentally superior Alternative when balancing impacts and Project objectives.
72 SECTION 11: ADOPTION OF STATEMENT OF OVERRIDING CONSIDERATIONS In compliance with Section 15093 (a)(b) of the State CEQA Guidelines, the City of Twentynine Palms, as Lead Agency, must “balance, as applicable, the economic, legal, social, technological or other benefits of a proposed project against its unavoidable environmental risks when determining whether to approve the project.” The adverse environmental effects may be considered “acceptable” where the benefits of a project outweigh its unavoidable adverse environmental effects. When the Final EIR identifies significant effects that are not avoided or substantially lessened, the Lead Agency must state the specific reasons to support approval
The City Council, having considered the entire administrative record on the Twentynine Palms Solar Project, and having weighed the benefits of the Proposed Project against the unavoidable adverse impacts to aesthetics, specifically visual character of the project site and surrounding area, after mitigation, has determined that each and every one of the following economic and environmental benefits of the Proposed Project individually outweigh all of the potential significant and unavoidable adverse impacts and render those potential adverse environmental impacts acceptable based upon the following overriding considerations:
1. The proposed Solar Project would expand renewable energy generation for the City and region, reducing dependence on fossil fuels and improving grid reliability.
The Solar Project will allow SCE or another regional entity to secure locally generated renewable energy to meet increasing energy demand. Improving regional grid reliability can help reduce rolling blackouts during peak demand;
2. The proposed Solar Project would lower greenhouse gas emissions, supporting the City’s sustainability goals and California’s renewable energy and climate mandates. The proposed Solar Project would further the State of California’s efforts to achieve the Renewable Portfolio Standard under Senate Bill 100 of securing 100% renewable energy by 2045 by creating 50 MW of renewable solar energy;
3. The proposed Solar Project would generate annual revenue for the City via a Community Benefits Package to support essential public services and improve long-term fiscal stability. The Solar Project would generate approximately $5,445,000 in projected General Fund revenue for the City over the anticipated 35- year life of the project, in addition to sales tax and property tax revenue;
4. The proposed Solar Project would create approximately 200 living water jobs during construction of the project. The Project would provide economic benefits to the City and its residents by increased spending in the community as a result of construction and development-related word. It would provide opportunities for local workers to develop their skills and gain experience installing solar facilities and would reduce the amount of time that many workers spend commuting by offering local job opportunities.
73 The City Council hereby declares that each and every one of the foregoing individual benefits provided through approval and implementation of the Twentynine Palms Solar Project outweigh all of the identified significant environmental impacts which cannot be mitigated. The City Council finds that each of the benefits, separately and individually, outweighs the unavoidable adverse environmental effects identified in the EIR and therefore finds those impacts to be acceptable.
74 SECTION 12: ADOPTION OF THE MITIGATION MONITORING AND REPORTING
PROGRAM
Public Resources Code Section 21081.6 requires that a Mitigation, Monitoring, and Reporting Program be adopted upon certification of an EIR to ensure that the mitigation measures are implemented. The Mitigation, Monitoring, and Reporting Program specifies what the mitigation is, the entity responsible for monitoring the program, and when in the process it should be accomplished.
The City Council hereby adopts the Mitigation Monitoring and Reporting Program attached to this Resolution as Exhibit “A.” Implementation of the Mitigation Measures contained in the Mitigation Monitoring and Reporting Program is hereby made a condition of approval of the Project. In the event of any inconsistencies between the Mitigation Measures set forth herein and the Mitigation Monitoring and Reporting Program, the Mitigation Monitoring and Reporting Program shall control.
SECTION 13: CERTIFICATION OF THE EIR
The City Council finds that it has been presented with the EIR, which it has reviewed and considered, and further finds that the EIR is an accurate and objective statement that has been completed in full compliance with CEQA, the State CEQA Guidelines and the City's Local CEQA Guidelines and that the EIR reflects the independent judgment and analysis of the City Council.
The City Council declares that no evidence of new significant impacts as defined by the State CEQA Guidelines section 15088.5 have been received by the City Council after circulation of the Draft EIR which would require recirculation.
Therefore, the City Council hereby certifies the EIR based on the entirety of the record of proceedings.
75 SECTION 14: CUSTODIAN OF RECORD
The documents and materials that constitute the record of proceedings on which this Resolution has been based are located at The Twentynine Palms City Hall, 6136 Adobe Road, Twentynine Palms, CA 92277. The custodian for these records is the City Clerk of the City of Twentynine Palms or designee. This information is provided in compliance with Public Resources Code section 21081.6.
PASSED, APPROVED, AND ADOPTED by the City Council of the City of Twentynine Palms, California, at its adjourned meeting held on the 23rd of March, 2026, by the following vote, to wit:
AYES:
NOES:
ABSENT:
ABSTAIN:
________________________________
DANIEL L. MINTZ SR., MAYOR
ATTEST:
__________________________________
CINDY VILLESCAS, CITY CLERK
CITY OF TWENTYNINE PALMS, CALIFORNIA
76 Exhibit “A”
Mitigation Monitoring and Reporting Program
MITIGATION MONITORING & REPORTING PROGRAM
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77 Impact Heading Level of Impact After
Mitigation Mitigation Measure Responsible Party/Monitoring Party Implementation Stage Aesthetics
Significant and
Unavoidable
AES-1 Within 60 days of the completion of construction, or at the earliest possible time that is appropriate to achieve plant establishment, as determined by the City and a qualified Project biologist, native plants shall be installed on the Solar Project site as further described in the Habitat Restoration Plan included as Appendix D.3 of the EIR.
City of Twentynine
Palms, Developer,
Project Biologist
Within 60 days of the
completion of
construction, or at the
earliest possible time
that is appropriate to
achieve plant
establishment.
Significant and
Unavoidable
AES-2 Prior to the completion of construction, plant native vegetation along the east and south sides of the perimeter security fence to shield the Solar Project site from potential future residential viewers. Irrigation would be required to assist initial plant growth.
City of Twentynine
Palms, Project
Biologist
Prior to the completion
of construction
Biological
Resources Less than Significant
BIO-1 Construction-Related and Operational-Related Indirect Impacts to Biological Resources.
For each phase of project implementation, including solar decommissioning activities, suitable habitat for special-status species (i.e., all undeveloped land or re-naturalized land within the project site) with potential to occur in the project, the project’s Applicant/Developer shall include the following in the construction contractor’s plans and specifications to address indirect construction-related impacts to special-status species:
• Biological Monitoring. A qualified project biologist shall conduct monthly checks throughout the duration of project construction in order to inspect construction fencing, ensure that practicable measures are being employed to avoid incidental disturbance of habitat, species of concern, and other sensitive biological resources outside the project footprint, and ensure that all applicable requirements from the mitigation measures are being upheld.
• Worker Environmental Awareness Training. Prior to grading, a pre-construction meeting shall be required that includes a training session for project personnel by the biological monitor.
The training shall include (1) a description of the species of concern and its habitats; (2) the general provisions of the applicable regulations pertaining to biological resources, including the Endangered Species Act and the Clean Water Act; (3) the need to adhere to the provisions of the Endangered Species Act, the Clean Water Act, and other applicable
regulations; (4) the penalties associated with violating the City of Twentynine
Palms, Developer,
Project Biologist
Dust Control Plan
reviewed and
approved by Mojave
AQMD
SWPPP submitted to
RWQCB
Prior to and during
construction
This mitigation
measure shall be
included in
construction plans and
specifications for
implementation during
construction
Summary
Biological Monitoring:
monthly checks
throughout the
duration of project
construction.
Worker Environmental
Awareness Training:
Prior to grading.
Delineation of
Property Boundaries:
Before beginning
activities that would
cause impacts.
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78 Impact Heading Level of Impact After
Mitigation Mitigation Measure Responsible Party/Monitoring Party Implementation Stage provisions of the Endangered Species Act, Clean Water Act, and other applicable regulations; (5) the general measures that are being implemented to conserve the species of concern as they relate to the project; and (6) the access routes to and from disturbance area boundaries within which the project activities must be accomplished. Additionally, the training shall include the measures and mitigation requirements for the applicable resources. Copies of the mitigation measures and any required permits from the resource agencies shall be made available to construction personnel. The video may be recorded so that multiple personnel are able to watch the material. The training shall be provided in alternate languages, as needed. In addition, operations and maintenance personnel shall be required to watch the recorded training prior to entering the Project during operations, with the only exception being emergency situations. Copies of the mitigation measures and any required permits from the resource agencies shall be made available to operations and maintenance personnel. • Delineation of Property Boundaries. Before beginning activities that would cause impacts, the contractor shall, in consultation with the biological monitor, clearly delineate the boundaries with fencing, stakes, or flags, consistent with the grading plan, within which the impacts will take place. All impacts outside the fenced, staked, or flagged areas shall be avoided, and all fencing, stakes, and flags shall be maintained until the completion of impacts in that area. In addition, any avoided environmental resources shall be clearly delineated. Prior to implementing construction activities, the biological monitor shall verify that the flagging clearly delineates the construction limits and any sensitive environmental resources to be
avoided.
• Standard Dust Control Measures. Standard dust control measures as per the Mojave Desert Air Quality Management District shall be implemented to reduce dust impacts on nearby conserved lands, plants, and wildlife. Measures include controlling speed to 15 mph or less on unpaved roads,
replacing ground cover in disturbed areas as quickly as possible, frequently watering active work sites, installation of shaker plates, and suspending excavation and grading
operations during periods of high winds.
Standard Dust Control
Measures:
Implemented during
ground disturbing
activities.
Stormwater Pollution
Prevention Plan: Prior
to issuance of a
grading permit for
construction.
Minimize Spills of
Hazardous Materials:
Regularly throughout
construction period.
Wildlife Hazards:
Throughout
construction period.
Removal of Invasive
Weeds: Throughout
construction period.
Noise Abatement:
Throughout
construction period as
necessary.
Fencing: Upon
completion of
construction and
through the duration
of operation.
Lighting Controls:
Throughout
construction period.
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79 Impact Heading Level of Impact After
Mitigation Mitigation Measure Responsible Party/Monitoring Party Implementation Stage • Stormwater Pollution Prevention Plan. Prior to issuance of a grading permit for construction, the applicant shall submit a stormwater pollution prevention plan (SWPPP) to the City of Twentynine Palms that specifies best management practices to prevent all construction pollutants from contacting
stormwater, with the intent of keeping sedimentation or any other pollutants from moving off site and into receiving waters.
The requirements of the SWPPP shall be incorporated into design specifications and construction contracts.
• Minimize Spills of Hazardous Materials. All vehicles and equipment shall be maintained in proper condition to minimize the potential for fugitive emissions of motor oil, antifreeze, hydraulic fluid, grease, or other hazardous materials.
Hazardous spills and contaminated soil shall be immediately cleaned up and the contaminated soil shall be properly
handled or disposed of at a licensed facility. Servicing of construction equipment shall take place only at a designated staging area. Staging areas shall not be located within the project’s avoidance areas.
• Wildlife Hazards. The following measures shall be
implemented to ensure that wildlife do not become trapped, entangled, injured, or poisoned by construction activities:
o Structures in which wildlife may become trapped
(e.g., open pipes, pits, trenches, etc.) shall be tightly covered at the end of each work day. If covering the
structure is not possible, an escape ramp shall be
provided to allow any wildlife that falls in to safely
escape.
o Debris piles, construction materials, equipment, and
other items that may be used as wildlife refuge shall
be inspected for wildlife at the start of each work day and prior to disturbance. If wildlife is discovered, it shall either be moved out of harm’s way by a qualified
biologist or allowed to move off of the study area on
its own under supervision by a qualified biologist.
o Nets and mesh shall be made of loose-weave
material that is not fused at the intersections of the
weave, as nets with welded weaves present an
entanglement risk.
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Mitigation Mitigation Measure Responsible Party/Monitoring Party Implementation Stage o Toxic materials and garbage shall be removed from
the work site and safely stored or disposed of at the
end of each work day.
• Invasive Weeds. The project applicant shall be required to replant all temporarily impacted areas with native plants and remove invasive plants. The species proposed for replanting shall not include any plants found on the most recent version of the Cal-IPC California Invasive Plant Inventory
(http://www.cal-ipc.org/ip/inventory/index.php).
• Noise. Proposed noise-generating land uses affecting suitable habitat for special-status species shall incorporate setbacks, berms, or walls to minimize the effects of noise on resources pursuant to applicable rules, regulations, and guidelines related to land use noise standards. For planning purposes, wildlife are not expected to be subjected to noise that would exceed rural residential noise standards.
• Fencing. The solar array site shall include a 7-foot-high perimeter fence upon completion of construction and through the duration of operation to minimize the impact on sensitive or special-status biological resources occurring adjacent to the site.
• Lighting. All construction activities shall be conducted during the daytime, and lights shall not be kept on overnight in the construction area. While night lighting is not currently proposed, if it is required for security purposes during construction activities or operational activities, all exterior lighting along undeveloped land shall be fully shielded and directed downward in a manner that will prevent light spillage or glare into the adjacent avoidance areas. As applicable, emergency maintenance work on the solar arrays at night would be performed using battery or gas-powered light stands that would be directed to the active work area.
Biological Resources Less than Significant
BIO-2 Pre-Construction Nesting Bird Survey.
If construction or solar decommissioning activities must occur during the migratory bird nesting season (typically January 1 through July 31), an avian nesting survey of the Project site and within 500 feet of all impact areas must be conducted to determine the presence/absence of fully protected species, protected migratory birds, and active nests. The avian nesting survey shall be performed by a qualified wildlife biologist Planning Department,
Developer, Project
Biologist
Prior to construction if
construction or solar
decommissioning
occurs between
January 1 through
July 31.
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Mitigation Mitigation Measure Responsible Party/Monitoring Party Implementation Stage within 72 hours prior to the start of construction in accordance with the Migratory Bird Treaty Act and California Fish and Game Code Section 3503, 3503.5, and 3513.
If an active bird nest is found, the nest shall be flagged and mapped on the construction plans along with appropriate buffer established around the nest, which shall be determined by the biologist based on the species’ sensitivity to disturbance (typically 300 feet for passerines and 500 feet for raptors and special status species). The nest area shall be avoided until the nest is vacated, and the juveniles have fledged. The nest area shall be demarcated in the field by flagging and stakes or construction fencing. On-site construction monitoring shall also be conducted when an active nest buffer is in place. No project activities may encroach into established buffers without the consent of a monitoring biologist. The buffer shall remain in place until it is determined the nestlings have fledged and the nest is no longer considered active.
Biological
Resources Less than Significant
BIO-3 Pre-Construction Burrowing Owl Surveys and Avoidance One pre-construction Burrowing Owl survey shall be completed no more than 14 days before initiation of site preparation or grading or solar decommissioning activities and a second survey shall be completed within 24 hours of the start of site preparation or grading or decommissioning activities. If ground-disturbing activities are delayed or suspended for more than 30 days after the preconstruction surveys, the Project site shall be resurveyed. Surveys for Burrowing Owls shall be conducted in accordance with protocols established in the Staff Report on Burrowing Owl Mitigation in 2012 or current version.
If Burrowing Owls are detected, and if impacts to Burrowing Owls cannot be feasibly avoided, the Project applicant will consult with CDFW and obtain appropriate take authorization from the CDFW through the CESA Incidental Take Permit (ITP) process. If requiring an ITP, mitigation for direct impacts to Burrowing Owl shall be fulfilled through compensatory mitigation at a minimum 1:1 habitat replacement of equal or better functions and values to those impacted by the Project, or as otherwise determined through the ITP process.
City of Twentynine
Palms, Developer,
Project Biologist,
California Department
of Fish & Wildlife
One pre-construction
Burrowing Owl survey
shall be completed no
more than 14 days
before initiation of site
preparation or grading
or solar
decommissioning
activities and a
second survey shall
be completed within
24 hours of the start of
site preparation or
grading or
decommissioning
activities. If grounddisturbing activities
are delayed or
suspended for more
than 30 days after the
preconstruction
surveys, the Project
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Mitigation Mitigation Measure Responsible Party/Monitoring Party Implementation Stage site shall be
resurveyed.
Biological
Resources Less than Significant
BIO-4 Pre-Construction Survey for Desert Kit Fox and Avoidance A pre-construction survey for Desert Kit Fox shall be conducted by a Qualified Biologist familiar with desert kit fox within 10 days before initiation of site preparation or grading activities to determine the presence/absence of Desert Kit Fox. The Qualified Biologist shall conduct a pre-project survey to attain 100% visual coverage within the Project area and a minimum 500-foot buffer to determine the presence or absence of desert kit fox individuals, dens, and sign. The project proponent shall provide the results of the survey to CDFW prior to start of Project activities. The survey report should identify the status of all identified dens, include an estimate of occupancy, and detail the methodology utilized to support these conclusions.
If potential dens are located, they shall be monitored by the Qualified Biologist. Trail cameras may be used to assist with observation but shall not be the sole basis upon which the status is determined. Permittee shall provide a determination if active dens can be avoided and buffered from Project activities to prevent take and disturbance with the survey results.
Should active Desert Kit Fox dens be present within the Project area that cannot be avoided with an adequate buffer, a Desert Kit Fox Relocation and Mitigation Plan shall be prepared by a qualified biologist in consultation with CDFW, and shall be implemented including protective measures such as the establishment of no disturbance buffer zones for active den and active natal den. No disturbance or relocation of active dens may take place when juveniles may be present and dependent on parental care.
Permittee shall block off inactive dens within the buffer zone with rocks and sticks to discourage use during Project activities and remove when construction is complete. The Qualified Biologist shall periodically check the inactive burrows remain blocked and are not reoccupied During Project activities including construction and decommissioning.
A report to evaluate the success of the relocation efforts and any subsequent re-occupation, if applicable, shall be provided at the end of City of Twentynine
Palms, Developer,
Project Biologist,
California Department
of Fish & Wildlife
Pre-construction
survey for Desert Kit
Fox shall be
conducted within 10
days before initiation
of site preparation or
grading activities.
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Mitigation Mitigation Measure Responsible Party/Monitoring Party Implementation Stage the construction period. Data shall be readily available to the CDFW upon request. If an injured, sick, or dead desert kit fox is detected on any area associated with the project, the designated CDFW personnel at both the Ontario office and the Wildlife Investigation Lab shall be notified as described within the Desert Kit Fox Plan.
Biological
Resources Less than Significant
BIO-5 Desert Tortoise Avoidance and Minimization Measures.
Relocation and/or take of a desert tortoise may not occur without consultation with the USFWS and CDFW. The phrases “authorized biologist” and “desert tortoise monitor,” as used herein, are taken from the most up to date USFWS guidance (USFWS 2009), and the definitions, roles, and responsibilities of each will be adhered to during construction. Also, in accordance with guidance in USFWS (2019), if tortoises or fresh sign are observed during project construction, all activities that could result in take of desert tortoise shall cease immediately until an authorized biologist can confirm that no desert tortoise is present or the desert tortoise moves off the site on its own under the supervision of a qualified biologist.
Desert tortoise exclusion fencing shall be installed around all construction areas prior to the initiation of vegetation clearing. Once the area is fenced, desert tortoises shall be removed from the area by the authorized biologist if the appropriate state and federal permits have been obtained or be allowed to move off site on their own by creating a gap in the fence under the supervision of a qualified biologist. Note that they cannot be “harassed” or otherwise directly encouraged to move off site without obtaining a federal take permit (or as directly authorized/directed by the USFWS and CDFW, if applicable). If the desert tortoise is allowed to move off site on its own, the gap in the exclusion fence will be closed once the tortoise has left the fenced area.
After desert tortoise is no longer inside the fence, the fence shall be maintained in place until construction is completed. The purpose of the fence is to preclude all desert tortoises from the construction impact zone, including desert tortoises that may try to get back to their on-site burrow(s). A minimum of two tortoise-free pre-construction clearance survey passes conducted by the authorized biologist or desert tortoise monitor, after exclusion fencing has been installed, are required to ensure that desert tortoises are no longer on the site and construction may commence. If the fence fails or is subject to gaps then two more tortoise-free survey passes must occur before work can resume.
City of Twentynine
Palms, Developer,
Project Biologist,
United States Fish
and Wildlife Services,
California Department
of Fish & Wildlife
Prior to all ground
disturbing activities.
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Mitigation Mitigation Measure Responsible Party/Monitoring Party Implementation Stage The fence shall be constructed of 0.5-inch mesh hardware cloth and extend 18 inches above ground and 12 inches below ground. Where burial of the fence is not possible, the lower 12 inches shall be folded outward against the ground and fastened to the ground so as to prevent desert tortoise entry. The fence shall be supported sufficiently to maintain its integrity, be checked at least weekly during construction by the authorized biologist or desert tortoise monitor, and maintained when necessary, by the project proponent to ensure its integrity. Access points will be protected by installing the latest specification entrance gates/grates/etc. In all cases, the protection system will not include gaps sufficient for even the smallest hatchling to pass through. Common raven perching deterrents shall be installed as part of the fence construction. If unsupervised gaps are detected, then pre-construction clearance surveys will be required after remediation and prior to resumption of work.
All project-related facilities and construction-related areas, such as staging areas and personnel parking areas, other than the access road and Two Mile Road discussed below, shall occur within the fenced area.
All related infrastructure shall also remain within the fenced area.
As part of the Worker Environmental Awareness Program (WEAP) training, all workers shall be informed to check beneath any parked vehicle immediately prior to moving the vehicle while in desert tortoise habitat outside fenced impact areas. After the desert tortoise-exclusion fence has been installed, all personal vehicles and construction equipment shall be parked inside the fenced area. Vehicular travel outside of established roads (including Samarkand Road, Sunrise Road, and private roads (once constructed) prior to removal of desert tortoises shall be prohibited. If a desert tortoise is found beneath a vehicle, the authorized biologist shall be contacted to move it from harm’s way, if the appropriate state and federal permits have been obtained. Alternatively, the vehicle shall not be moved until the desert tortoise has left of its own accord under supervision of a qualified biologist. The authorized biologist shall be responsible for taking appropriate precautions to ensure that any desert tortoise moved in this manner is not exposed to temperature extremes that could be harmful to the animal.
The desert tortoise exclusion fence during construction shall have as part of its design either a desert-tortoise-proof cattle guard, desert
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Mitigation Mitigation Measure Responsible Party/Monitoring Party Implementation Stage tortoise exclusion gate, exclusion grate, or a breakaway portion of fence that can be opened and closed to allow vehicle access. The gate or modified fence shall remain closed at all times during construction except to allow vehicles to enter or leave the site. This measure may be modified if the desert tortoise monitor, based on surveys of surrounding areas, determines that there is little or no likelihood of desert tortoises entering the site through the opening. If the authorized biologist determines that the gate may be left open and subsequently finds that a desert tortoise has entered the construction area through that opening, a gate or modified fence shall be installed and kept closed after desert tortoise has left the site.
Prior to installing the fence, the authorized biologist shall survey the area along which the fence will be installed, with the goal of establishing a fenced area that allows for as many desert tortoise burrows to remain outside the fenced area while still accommodating project construction.
The authorized biologist shall consider the direction of the burrow and know that burrows may be 30 to 40 feet long. So, not only the burrow opening, but also the burrow's end, shall be considered and excluded if the fence line is to be altered. Any desert tortoise burrows found within the proposed fence line that cannot be avoided shall be hand excavated by the authorized biologist prior to clearing of the fence line or installation of the fence. Burrow excavation procedures are discussed in Desert Tortoise Council (1999). The authorized biologist or desert tortoise monitors shall remain on-site to monitor the installation of the fence.
After installing the fence, and before any other activities occur within the fenced area, the authorized biologist shall survey the site for desert tortoises. If possible, the surveys shall occur immediately after installation of the fence and several days prior to brushing or grading activities. The site shall be searched at least two consecutive times with a negative survey result, meaning if the site is searched and desert tortoise are found, two additional surveys must be completed until the result is negative. Burrows shall either be excavated as they are found or flagged for excavation later. Each burrow shall also be carefully checked for viable desert tortoise eggs. If found, the authorized biologist shall have a plan for disposition of these eggs outside the impact zone but within the adjacent area and move the eggs in such a way that the viability of the eggs is not adversely affected by their movement (Desert Tortoise Council 1999). Handling of desert tortoise eggs would require
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Mitigation Mitigation Measure Responsible Party/Monitoring Party Implementation Stage consultation with CDFW and the USFWS. Security fencing shall be placed inside of the desert tortoise exclusion fencing, which shall remain in place for the duration of project operations (e.g., excluding all wildlife from entering the Project), as recommended by USFWS and CDFW (Lalumiere, pers. comm. 2025).
Prior to conducting vegetation clearing or grading activities in desert tortoise habitat outside permanently fenced areas of the project site (i.e., off-site access road, gen-tie alignment, and substation), the authorized biologist or desert tortoise monitor under the supervision of an authorized biologist will survey the access road impact area immediately prior to conducting these activities to ensure that no desert tortoises are present. Because of the linear nature of the access road, the applicant may conduct surveys at any time of year but shall avoid impacts to potential and known desert tortoise burrows, in addition to avoiding impacts to desert tortoises. Potential burrows will be buffered by 30 feet unless they can be shown to be unoccupied, or the authorized biologist believes a smaller buffer is appropriate in order to protect underground burrows. Examples of situations where smaller buffers may be appropriate may include the following: burrow entrances are obviously oriented away from the impact area; the type of activity near the burrow is not likely to impact desert tortoise (e.g., the activity will not have the potential to crush a burrow); the burrow is adjacent to an existing thoroughfare that receives vehicle use already and the proposed activity is similar in nature; etc. Temporary desert tortoise exclusion fencing will be installed along the access road. Once construction along the access road is completed, the desert tortoise exclusion fencing shall be removed. No vehicle or equipment parked outside any of the fenced areas will be moved prior to inspecting the ground beneath the vehicle or equipment for the presence of desert tortoise. If present, the desert tortoise will be left to move on its own under supervision by a qualified biologist.
The WEAP required under Mitigation Measure BIO-1 shall also include the following information and requirements specific to protection of desert tortoise:
- A description of the desert tortoise, including adults and juveniles - Color photographs of desert tortoise
- Protections to the desert tortoise under the ESA and CESA and potential penalties for violating the ESA and CESA
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Mitigation Mitigation Measure Responsible Party/Monitoring Party Implementation Stage - Measures implemented under the project to protect desert tortoises and to conserve their habitat
- The requirement that all workers shall check beneath any parked vehicle immediately prior to moving the vehicle while in desert tortoise habitat outside fenced impact areas and what to do if a desert tortoise is found
- Information for contacting the authorized biologist or desert tortoise monitor in case personnel observe one or more desert tortoises on the project site
- All trash that may attract desert tortoise predators (e.g., ravens, domestic dogs) shall be removed from the work site at the end of each day.
- If desert tortoises occur in a work area and will not leave of their own accord, then it will be necessary to coordinate with the USFWS and CDFW. Physical relocation of a desert tortoise may not occur unless approved by the wildlife agencies, and this may require authorizations pursuant to Incidental Take Permits from the USFWS and CDFW.
- The biological monitors shall have the authority to stop work at all times, if proper avoidance measures are not in place or project activities may potentially result in impacts to desert tortoises. - A speed limit of 15 mph shall be maintained at all times except on county/state roads.
- Work shall be restricted to daylight hours at all times when working within or adjacent to desert tortoise habitat, except in an emergency, to avoid vehicle traffic when tortoise may be on access roads at times of poor visibility.
This mitigation measure would also be applied in the event of future construction of roads subject to the future road dedications.
Biological
Resources Less than Significant
BIO-6 Desert Tortoise Habitat Compensatory Mitigation.
The project applicant shall implement habitat mitigation for 142.1± acres of permanent impacts to occupied desert tortoise habitat. Impacts are to be compensated at a minimum 1:1 ratio either through one or a combination of the following:
Option 1: Purchase of off-site habitat mitigation lands that contain suitable habitat for desert tortoise.
City of Twentynine
Palms, Developer,
Project Biologist,
United States Fish
and Wildlife Services,
California Department
of Fish & Wildlife
Prior to the issuance
of grading permits.
MITIGATION MONITORING & REPORTING PROGRAM
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88 Impact Heading Level of Impact After
Mitigation Mitigation Measure Responsible Party/Monitoring Party Implementation Stage Option 2: Purchase of mitigation credits at a mitigation bank for desert tortoise.
The applicant shall submit a document outlining the permanent impacts to desert tortoise habitat, along with a compensatory mitigation plan, to the USFWS and CDFW for review and approval. The Project applicant shall also be required to obtain an Incidental Take Permit (ITP) from the CDFW and USFWS where the ITP includes an analysis of whether Project impacts would jeopardize the continued existence of the species, provide suitable avoidance and minimization measures to reduce potential impacts, and adequately mitigate through conservation or mitigation banking. Unavoidable impacts to occupied suitable habitat shall be compensated at a minimum of 1:1, as described above, in addition to implementing all other measures and condition of the ITPs.
This mitigation measure would also be applied in the event of future construction of roads subject to the future road dedications Biological
Resources Less than Significant
BIO-7 Focused Surveys, Avoidance and Mitigation Outside of Solar BSA
Development proposed for any portion of the site outside the Solar Project BSA shall be required to conduct the following surveys prior to issuance of grading permits: a general biological reconnaissance survey, including vegetation mapping, special-status plant survey, western Joshua Tree focused survey, desert native plant survey, desert tortoise (Gopherus agassizii) protocol-level survey, burrowing owl (Athene cunicularia) protocol-level survey, and an aquatic resources delineation. Focused surveys shall be conducted in accordance with the methods described in Section 3.2.4, Special-Status and Regulated Resources, of the project-specific Biological Resources Technical Report.
If the results of the general biological reconnaissance survey determine there are biological resources that are not evaluated in the Biological Resources Technical Report, then additional CEQA documentation would be required by the project applicant. If the general biological reconnaissance survey determines there are sensitive natural vegetation communities, and if jurisdictional aquatic resources, and/or desert native plants, desert tortoise, or burrowing owl are determined present, then the following applicable mitigation measures from Section 7 of the Project BRTR referenced below shall be implemented:
Mitigation Measure BIO-2 (Construction-Related and OperationalRelated Indirect Impacts to Biological Resources), Mitigation Measure City of Twentynine
Palms, Developer,
Project Biologist
MITIGATION MONITORING & REPORTING PROGRAM
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89 Impact Heading Level of Impact After
Mitigation Mitigation Measure Responsible Party/Monitoring Party Implementation Stage BIO-3 (Desert Tortoise Avoidance and Minimization Measures), Mitigation Measure BIO-4 (Desert Tortoise Habitat Compensatory Mitigation), Mitigation Measure BIO-5 (Pre-Construction Burrowing Owl Surveys and Avoidance), Mitigation Measure BIO-6 (Pre-Construction Survey for Desert Kit Fox and Avoidance), Mitigation Measure BIO-7 (Pre-Construction Nesting Bird Survey), Mitigation Measure BIO-8 (Sensitive Vegetation Communities and Jurisdictional Resources Mitigation), Mitigation Measure BIO-9 (Avoidance and Minimization to Potential Jurisdictional Aquatic Resources), and Mitigation Measure BIO-10 (Desert Native Plants Removal Permit).
Should special-status plant species and/or western Joshua Tree be determined present, then the following additional mitigation measures shall be implemented:
Special-Status Plants
Impacts to special-status plant occurrences shall be avoided to the greatest extent possible and minimized where avoidance is not feasible.
Where impacts to special-status plant species cannot be avoided, mitigation is required. For direct impacts to special-status plant species, one or a combination of the following strategies shall be implemented:
- Avoidance and Minimization. Impacts to special-status plant occurrences shall be avoided to the greatest extent possible and minimized where avoidance is not feasible.
- Salvage. If a qualified ecologist determines that impacts to special-status plants cannot be avoided and it is feasible to effectively salvage the plants, that ecologist shall develop a restoration and mitigation plan based on the life history of the species impacted, as necessary, to mitigate project impacts. The plan shall include, at minimum, (a) collection/salvage measures for plants and/or seed banks to retain intact soil conditions and maximize success likelihood; (b) details regarding storage of plants and/or seed banks; (c) location of the proposed recipient site and detailed site preparation and plant introduction techniques details for top soil storage, as applicable; (d) time of year that the salvage and replanting or seeding shall occur and the methodology of the replanting; (e) a description of the irrigation, if used; (f) success criteria; and (g) a detailed monitoring program, commensurate with the plan’s goals.
Western Joshua Tree
MITIGATION MONITORING & REPORTING PROGRAM
TWENTYNINE PALMS SOLAR 2024021042
90 Impact Heading Level of Impact After
Mitigation Mitigation Measure Responsible Party/Monitoring Party Implementation Stage If impacts to western Joshua tree cannot be avoided, mitigation is required. If avoidance is not feasible, and construction will result in direct removal of western Joshua tree, a Westen Joshua Tree Conservation Act Incidental Take Permit or a Section 2081 Incidental Take Permit from CDFW shall be required prior to construction.
Biological
Resources Less than Significant
BIO-8 Avoidance and Minimization of Impacts to Potential Jurisdictional Aquatic Resources.
A 1602 Agreement shall be secured, if necessary, should Project designs change and affect jurisdictional waters identified in the Draft EIR. The following avoidance and minimization measures would be implemented when ground-disturbing activities occur within 25 feet of waters of the state and/or jurisdictional streambeds (i.e., jurisdictional aquatic resources):
• All jurisdictional aquatic resources within 25 feet of project activities shall be fenced or flagged as environmentally sensitive areas prior to any ground disturbance.
• A biological monitor shall be present during construction activities within 25 feet of jurisdictional aquatic resources to ensure avoidance.
• Best Management Practices shall be implemented to avoid indirect impacts to jurisdictional waters, including:
- Water containing mud, silt, or other pollutants from grading or other activities shall not be allowed to enter jurisdictional aquatic resources or be placed in locations that may be subjected to high storm flows.
- Spoil sites shall not be located within jurisdictional aquatic resources or in locations that may be subject to high storm flows, where spoils might be washed into drainages.
- Raw cement/concrete or washings thereof, asphalt, paint or other coating material, oil or other petroleum products, or any other substances that could be hazardous, resulting from project-related activities, shall be prevented from entering jurisdictional aquatic resources.
- Equipment maintenance shall occur outside jurisdictional aquatic resources and in such a manner that no petroleum products or other pollutants from the equipment enters on- or off-site state-jurisdictional aquatic resources either directly or indirectly.
City of Twentynine
Palms, Developer,
Project Biologist
When grounddisturbing activities
occur within 25 feet of
waters of the state
and/or jurisdictional
streambeds.
MITIGATION MONITORING & REPORTING PROGRAM
TWENTYNINE PALMS SOLAR 2024021042
91 Impact Heading Level of Impact After
Mitigation Mitigation Measure Responsible Party/Monitoring Party Implementation Stage Biological
Resources Less than Significant
BIO-9 Sensitive Vegetation Communities and Jurisdictional Resources Mitigation Outside of Solar BSA
If the Residential GPA site and future road dedications are constructed, prior to issuance of a grading permit, permanent impacts to the sensitive vegetation community (e.g., desert willow–smoketree wash woodland), will be mitigated at not less than a 1:1 ratio through preservation of the same vegetation community either on site, off site, or through a CDFW approved mitigation bank. Areas outside the solar BSA shall also mitigate to ensure no-net-loss of jurisdictional aquatic resources at a minimum of 1:1 with purchase of credits at an approved mitigation bank including Regional Water Quality Control Board/California Department of Fish and Wildlife jurisdiction. Mitigation shall be completed through use of a mitigation bank (e.g., Black Mountain Conservation Bank) or other applicant-sponsored mitigation either on site or off site. Final mitigation ratios and credits shall be determined in consultation with the resource agencies but will be no less than a 1:1 mitigation ratio. Should applicant-sponsored mitigation be implemented, a Habitat Mitigation and Monitoring Plan (HMMP) shall be prepared. The HMMP shall include a conceptual planting plan including planting zones, grading, and irrigation, as applicable; a conceptual planting plant palette; a longterm maintenance and monitoring plan; annual reporting requirements; and proposed success criteria. Any applicant-sponsored mitigation shall be conserved and managed in perpetuity.
Best management practices shall be implemented to avoid any indirect impacts on jurisdictional waters and sensitive vegetation communities as described in Mitigation Measure BIO-8 (Avoidance and Minimization of Impacts to Potential Jurisdictional Aquatic Resources).
City of Twentynine
Palms, Developer,
Project Biologist,
California Department
of Fish & Wildlife
Prior to issuance of a
grading permit for
projects proposed on
the Residential GPA
site and future road
dedications.
Biological
Resources Less than Significant
BIO-10 Desert Native Plants Removal Permit
Prior to issuance of grading permits or solar decommissioning activities, the Project applicant shall submit an application and applicable fee paid to City of Twentynine Palms for removal of protected native desert plants under the California Desert Native Plants Act. The applicant shall submit a detailed plan consistent with the requirements of the Act. The City shall hire, at the applicant’s expense, a qualified biologist to review the plan and provide conditions of approval for the grading permit. The Project shall comply with any conditions of approval imposed by the City upon issuance of the permit.
City of Twentynine
Palms, Developer,
Project Biologist
Prior to issuance of
grading permits or
solar
decommissioning
activities.
MITIGATION MONITORING & REPORTING PROGRAM
TWENTYNINE PALMS SOLAR 2024021042
92 Impact Heading Level of Impact After
Mitigation Mitigation Measure Responsible Party/Monitoring Party Implementation Stage The permit application shall specify information outlined in the California Desert Native Plant Act Section 80114, which includes but is not limited to, the number and species of native plants to be removed, a description of the real property from which the plants are to be removed, and in the case that relocation is required, the destination of the native plants and the manner in which the plants are to be salvaged. Pursuant to the California Desert Native Plants Act, tags or seals issued by the City of Twentynine Palms must be attached to the native plants at the time of harvesting and before transporting to their permanent relocation site(s) and must remain attached to the plant until transplanted into its ultimate destination. Transport of salvaged plants will occur as prescribed by the City of Twentynine Palms.
If relocation is required by the applicable review authority, the following actions shall also be implemented to ensure successful relocation of desert native plants:
• Salvaged plants shall be transplanted expeditiously to either their final on-site location, or to an approved off-site area. If the plants cannot be expeditiously taken to their permanent relocation area at the time of excavation, they may be
transplanted in a temporary area (stockpiled) prior to being moved to their permanent relocation site(s).
• Plants designated for relocation shall be marked on their north facing side prior to excavation. Transplanted plants shall be planted in the same orientation as they currently occur on the project site, with the marking on the north side of the trees facing north at the relocation site(s).
• Transplanted plants shall be watered prior to and at the time of transplantation. The schedule of watering shall be determined by the qualified desert native plant expert(s) to maintain plant health. Watering of the transplanted plants shall continue under the guidance of qualified desert native plant expert(s) until it has been determined that the transplants have become established in the permanent relocation site(s) and no longer require supplemental watering.
MITIGATION MONITORING & REPORTING PROGRAM
TWENTYNINE PALMS SOLAR 2024021042
93 Impact Heading Level of Impact After
Mitigation Mitigation Measure Responsible Party/Monitoring Party Implementation Stage Cultural
Resources Less than Significant
CUL-1 Cultural Resource Survey – Residential GPA Site
In order to assure that impacts to cultural resources are reduced to less than significant levels, a cultural resource survey, including an analysis of both historic and archaeological resources, shall be conducted prior to the approval of a tentative subdivision map or any other entitlement to allow development on the Residential GPA site. The survey shall include records searches, literature review and field investigations, and shall include mitigation measures as necessary to protect any resources identified on the site.
City of Twentynine
Palms, Project
Archaeologist
Prior to the approval
of a tentative
subdivision map or
any other entitlement
to allow development
on the Residential
GPA site.
Cultural
Resources Less than Significant
CUL-2 Archaeological and/or Tribal Resource Discovery and Documentation
A Cultural Resources Monitoring and Discovery Plan (Plan) shall be prepared and finalized prior to the initiation of Solar Project construction.
The Plan will require that qualified archaeological monitor(s) be present and that tribal monitor(s) representing the Cahuilla Band, the Agua Caliente Band and the Yuhaaviatam be present during all grounddisturbing activities within the Project site, unless Tribe(s) provide the City with written withdrawal from their monitoring request. The applicant/developer shall allow 45 days from initial contact with the above-listed Tribes to enter into a contract with the Tribes for monitoring services. If the applicant/developer can demonstrate to the City they were unable to secure an agreement from the above-referenced Tribe, or if the contracted Tribe fails to fulfill its obligation under the contract terms, then the applicant/developer may retain an alternative qualified tribal monitor approved by the City. Monitoring requirements and locations will be defined in the Plan, along with resource discovery protocols and guidance for reducing or terminating site monitoring in the case that no artifacts are identified. Should an artifact be discovered, all construction activity within 100 feet of the discovery shall stop until a qualified archaeologist in collaboration with Tribal Cultural Monitor(s) can evaluate the significance of the artifact and make a determination whether further study is necessary, and whether or when work may resume. Should the artifact be found to be significant under CEQA, an archaeological treatment plan and further data recovery may be required, as determined by the Project archaeologist and the Tribes.
City of Twentynine
Palms, Project
Archaeologist, Tribal
Monitor(s)
Prior to the initiation of
Solar Project
construction.
Cultural
Resources Less than Significant
CUL-3 Reburial Protocol
Prior to issuance of grading permits: the developer/applicant shall come to an agreement with the consulting tribes indicating an area on-site which will be used, if needed, for reburial of any artifacts that have been City of Twentynine
Palms, Project
Archaeologist, Tribal
Monitor(s)
Prior to the initiation of
Solar Project
construction.
MITIGATION MONITORING & REPORTING PROGRAM
TWENTYNINE PALMS SOLAR 2024021042
94 Impact Heading Level of Impact After
Mitigation Mitigation Measure Responsible Party/Monitoring Party Implementation Stage identified during grading and cannot be avoided. This area will be protected and not disturbed in the future. This is confidential information, and the exact nature of this area will not be called out on the grading plans.
Cultural
Resources Less than Significant
CUL-4 Monitoring and Treatment Plan
A Monitoring and Treatment Plan that is reflective of the project mitigation (“Cultural Resources” and “Tribal Cultural Resources”) shall be completed by the archaeologist and submitted to the Lead Agency for dissemination to the Yuhaaviatam of San Manuel Nation Cultural Resources Management Department (YSMN, also known as San Manuel Band of Mission Indians). The City shall approve the Plan following consultation with the Tribe Any and all findings will be subject to the protocol detailed within the Monitoring and Treatment Plan.
City of Twentynine
Palms, Project
Archaeologist, Tribal
Monitor(s)
Prior to the initiation of
Solar Project
construction.
Cultural
Resources Less than Significant
CUL-5 Archaeological Monitoring
Due to the heightened cultural sensitivity of the proposed project area, an archaeological monitor with at least 3 years of regional experience in archaeology shall be present for all ground-disturbing activities that occur within the proposed project area (which includes, but is not limited to, tree/shrub removal and planting, clearing/grubbing, grading, excavation, trenching, compaction, fence/gate removal and installation, drainage and irrigation removal and installation, hardscape installation [benches, signage, boulders, walls, seat walls, fountains, etc.], and archaeological work). A sufficient number of archaeological monitors shall be present each work day to ensure that simultaneously occurring ground disturbing activities receive thorough levels of monitoring coverage.
City of Twentynine
Palms, Project
Archaeologist, Tribal
Monitor(s)
Prior to the initiation of
Solar Project
construction.
Hazards and
Hazardous
Materials
Less than Significant
HAZ-1 Prior to construction, a Hazardous Material Management Plan shall be prepared by the Applicant and submitted to the City for review and approval, to specify the method for handling and disposing of hazardous material related to the construction process.
City of Twentynine
Palms, Developer
Prior to construction
and the issuance of
permits.
Hazards and
Hazardous
Materials
Less than Significant
HAZ-2 A toxicity characteristic leaching procedural (TCLP) test must be performed to determine the toxicity level of solar panel(s) prior to its being recycled or disposed. If the solar panel waste does not exceed the threshold to be defined as hazardous waste, no further action is required. If the solar panel’s toxicity level exceeds the threshold and is defined as hazardous waste, all federal, state, and local regulations City of Twentynine
Palms, Operations
Manager
Prior to disposal of
solar panels during
operation
MITIGATION MONITORING & REPORTING PROGRAM
TWENTYNINE PALMS SOLAR 2024021042
95 Impact Heading Level of Impact After
Mitigation Mitigation Measure Responsible Party/Monitoring Party Implementation Stage regarding the disposal of hazardous waste will be applied to the solar panel’s disposal, including the use of a qualified hauler, and disposal in a designated landfill.
Hydrology and
Water Quality Less than Significant
HYD-1 Spill Prevention, Control, and Countermeasure Plan (SPCCP) The Applicant shall prepare a Spill Prevention, Control, and Countermeasure Plan (SPCCP) that shall clearly state measures to stop the source of a spill, contain the spill, clean up the spill, dispose of contaminated materials, and train personnel to prevent and control future spills. The SPCCP shall identify sources of oil or hazardous wastes that may be stored or used on site. If oil or hazardous wastes would be stored on site during operations, the SPCCP shall identify the location of storage, anticipated volumes of materials to be stored, method of storage, and countermeasures to address potential spill or accidental release of materials. In addition, the SPCCP shall include step-by-step instructions for the response to spills at a facility. In addition, the spill response plan should:
• Identify individuals responsible for implementing the plan • Define safety measures to be taken with each kind of waste • Specify how to notify appropriate authorities, such as police and fire departments, hospitals, or municipal sewage treatment facilities for assistance
• State procedures for containing, diverting, isolating, and cleaning up the spill
• Describe spill response equipment to be used, including safety and cleanup equipment
The SPCCP shall be submitted to San Bernardino County Public Works – Environmental Management Division for review and approval prior to occupation/operations and shall be maintained over the operational life of the Project.
City of Twentynine
Palms, Project
Operations Manager,
San Bernardino
County Public Works
– Environmental
Management Division
The SPCCP shall be
submitted to San
Bernardino County
Public Works –
Environmental
Management Division
for review and
approval prior to
occupation/operations
and shall be
maintained over the
operational life of the
Project.
Tribal Cultural
Resources Less than Significant
TCR-1
Treatment of Cultural Resources During Project Implementation If a pre-contact cultural resource is discovered during project implementation, ground-disturbing activities shall be suspended 60 feet around the resource(s), and an Environmentally Sensitive Area (ESA) physical demarcation/barrier constructed.
City of Twentynine
Palms, Project
Archaeologist, Tribal
Monitor(s)
Prior to the initiation of
Solar Project
construction.
MITIGATION MONITORING & REPORTING PROGRAM
TWENTYNINE PALMS SOLAR 2024021042
96 Impact Heading Level of Impact After
Mitigation Mitigation Measure Responsible Party/Monitoring Party Implementation Stage The Project Archaeologist shall develop a research design that shall include a plan to evaluate the resource for significance under CEQA criteria. Representatives from YSMN, the Archaeologist, and the Lead Agency shall confer regarding the research design, as well as any testing efforts needed to delineate the resource boundary. Following the completion of evaluation efforts, all parties shall confer regarding the resource's archaeological significance, its potential as a Tribal Cultural Resource (TCR), and avoidance (or other appropriate treatment) of the discovered resource. Removal of any cultural resource(s) shall be conducted with the presence of a Tribal monitor representing the Tribe, unless otherwise decided by YSMN. All plans for analysis shall be reviewed and approved by the applicant and YSMN prior to implementation, and all removed material shall be temporarily curated on-site.
It is the preference of YSMN that removed cultural material be reburied as close to the original find location as possible. However, should reburial within/near the original find location during project implementation not be feasible, then a reburial location for future reburial shall be decided upon by YSMN, the landowner, and the Lead Agency, and all finds shall be reburied within this location.
Additionally, in this case, reburial shall not occur until all grounddisturbing activities associated with the project have been completed, all monitoring has ceased, all cataloguing and basic recordation of cultural resources have been completed, and a final monitoring report has been issued to Lead Agency, CHRIS, and YSMN. All reburials are subject to a reburial agreement that shall be developed between the landowner and YSMN outlining the determined reburial
process/location, and shall include measures and provisions to protect the reburial area from any future impacts.
Should it occur that avoidance, preservation in place, and on-site reburial are not an option for treatment, the landowner shall relinquish all ownership and rights to this material and confer with YSMN to identify an American Association of Museums (AAM)-accredited facility within the County that can accession the materials into their permanent collections and provide for the proper care of these objects in accordance with the 1993 CA Curation Guidelines. A curation agreement with an appropriate qualified repository shall be developed between the landowner and museum that legally and physically
MITIGATION MONITORING & REPORTING PROGRAM
TWENTYNINE PALMS SOLAR 2024021042
97 Impact Heading Level of Impact After
Mitigation Mitigation Measure Responsible Party/Monitoring Party Implementation Stage transfers the collections and associated records to the facility. This agreement shall stipulate the payment of fees necessary for permanent curation of the collections and associated records and the obligation of the Project developer/applicant to pay for those fees.
All draft records/reports containing the significance and treatment findings and data recovery results shall be prepared by the archaeologist and submitted to the Lead Agency and YSMN for their review and comment. After approval from all parties, the final reports and site/isolate records are to be submitted to the local CHRIS Information Center, the Lead Agency, and YSMN.
Tribal Cultural
Resources Less than Significant
TCR-2: Inadvertent Discoveries of Human Remains
If human remains or funerary objects are encountered during any activities associated with the project, work in the immediate vicinity (within a 100-foot buffer of the find) shall cease and the County Coroner shall be contacted pursuant to State Health and Safety Code §7050.5 and that code enforced for the duration of the project.
City of Twentynine
Palms, Project
Archaeologist, Tribal
Monitor(s), County
Coroner
In the event human
remains are
discovered.
061220129 061219109
061220122
061220125
061218101 061218106
061220120
061220115
061220112
061220109 061214127
061220110
061101105 061104112
061220128
061220105 061220101 061219108
061218105 061101109 061101108 061101107 061101106 061104116 061104115 061104114 061104113 061324102 061432128 061429121
061429134 061429109 061429133
061428112
061428111
29 PALMS SOLAR FACILITY
MAY 2023
AS SHOWN
DATE
SCALE PLANS PREPARED BY: 14392
605 Third Street Encinitas, CA 92024
760.942.5147 Fax 760.632.0164
E-GROUP PS LLC
40764 WINCHESTER RD. SUITE 590
TEMECULA, CA 92591
(949) 763-9555
APPLICANT:
PRELIMINARY SITE PLAN
PRELIMINARY SITE PLAN C-1
GRAPHIC SCALE
PLAN
29 PALMS SOLAR FACILITY
MAY 2023
AS SHOWN
DATE
SCALE PLANS PREPARED BY: 14392
605 Third Street Encinitas, CA 92024
760.942.5147 Fax 760.632.0164
E-GROUP PS LLC
40764 WINCHESTER RD. SUITE 590
TEMECULA, CA 92591
(949) 763-9555
APPLICANT:
PRELIMINARY SITE PLAN
ENLARGED PLAN AND DETAILS C-2
GRAPHIC SCALE PLAN
DETAIL 1
DETAIL 2 Page 886 of 1008
29 PALMS SOLAR FACILITY
MAY 2023
AS SHOWN
DATE
SCALE PLANS PREPARED BY: 14392
605 Third Street Encinitas, CA 92024
760.942.5147 Fax 760.632.0164
E-GROUP PS LLC
40764 WINCHESTER RD. SUITE 590
TEMECULA, CA 92591
(949) 763-9555
APPLICANT:
PRELIMINARY SITE PLAN
DETAILS C-3 Page 887 of 1008
MEMO TO PLANNING
COMMISSION
TO: Planning Commission
FROM: Keith Gardner
FOR MEETING: March 3, 2026
SUBJECT: Correspondence Received
Staff has received the following correspondence since the closing of the public review period of the Draft Environmental Impact Report:
1) Document provided by Pat Flanagan dated February 27, 2024 titled “Update to Natural and Working Lands Climate Smart Strategy” (in opposition)
2) Chris Tiffany letter dated December 17, 2025 (in opposition) 3) Document provided by Pat Flanagan dated one dated February 6, 2024 titled “The California Desert’s Role in 30x30: Carbon Sequestration and Biodiversity” (in opposition) 4) Email from Dr. Shanese Risper dated February 17, 2026 with attached letter (in support) 5) Email from Suzanne Lyons dated February 16, 2026 with attached letter (in opposition) 6) Email from Joseph and Ronnie Tiner dated February 17, 2026 (in opposition) 7) Email from 29 Palms Creative Center & Gallery dated February 18, 2026 (in opposition) 8) Email from Gretchen Grunt dated February 19, 2026 (in opposition) 9) Document from Morongo Basin Conservation Association dated January 22, 2026 (in opposition) 10) Letter from Adams Broadwell Joseph & Cardozo dated February 14, 2026 (in opposition)
2 February 27, 2024
Subject: Update to Natural and Working Lands Climate Smart Strategy [email protected]
California Natural Resources Agency
California Environmental Protection Agency
California Air Resources Board
California Department of Food and Agriculture
Dear Agency Members,
This letter is in response to California Natural Resource Agency’s (CNRA’s) request for public input to inform the update to the Natural and Working Lands (NWL) Climate Smart Strategy as mandated by AB 1757. We appreciate the opportunity to provide input and expertise to the state agencies currently engaging in this process and recognize the importance of adhering to the highest standards of scientific practice for the greatest outcome for the NWL Climate Smart Strategy in accordance with the legislation.
This letter has been written by the Science Team within the Inland Deserts Working Group. We are a diverse group of desert scientists, desert experts, and dedicated desert conservationists. Our areas of expertise include carbon sequestration in desert soils, climate change impacts to the desert ecosystem, biological diversity in the desert ecosystem, desert native plants, and large-scale utility projects across desert lands.
Collectively, we have spent well over a century studying and protecting California’s deserts. Our work has been shaped entirely by scientific data and peer-reviewed research.
3 Our first comment concerns conflating deserts with other “Sparsely Vegetated Lands.” This is a scientifically inaccurate miscategorization that acts as a barrier to carrying out the goals of AB 1757, which are intended to promote climate-smart land management and deliver on our state’s climate goals via natural and working lands.
Miscategorizing deserts as simply analogous to other “sparsely vegetated lands” without recognizing California’s desert ecosystem as a category unto itself creates an inaccurate foundation and starting place to fully exploit the carbon sequestration, biodiversity, and cultural values of California’s desert ecosystem. The absence of a distinct ecosystem category only serves to perpetuate the misunderstood narrative that has long surrounded our deserts. Scientific research has turned this narrative around, and it is long overdue for policy efforts to catch up and integrate data-driven research into its work. The starting place for this to take place is to categorize our state’s desert region properly.
Desert lands cover over 25% of our state. They differ significantly from beaches and “rocks and ice” in function, ecosystem services, vegetation types, response to fire, and capacity for restoration, making the grouping of them with these sectors wholly misguided. The distinction of the desert region was recognized by Congress in 1976 when they designated 25-million acres of land in Southern California as the California Desert Conservation Area through the Federal Land Policy and Management Act, or FLPMA (1).
BLM California Desert Conservation Area Boundary
Conservation Biology Institute 2014
https://databasin.org/maps/new/#
4 In addition to the designation and recognition of our state’s desert ecosystem by legislation, the Intergovernmental Panel on Climate Change (IPCC) produced the 2022 CCP3 report titled “Deserts, Semiarid Areas and Desertification”(2). The cross-chapter report outlines projected impacts to desert ecosystems as a result of climate change.
The document notes, “Deserts and semiarid areas are in ‘drylands’, which comprise hyperarid, arid, semiarid and dry sub-humid areas.” The authors note that “Drylands host unique, rich biodiversity…and provide important ecosystem services…” (p. 2199).
Most relevant to the work of AB 1757, the CCP3 Report found that “Semiarid ecosystems have a disproportionately large role in the global carbon cycle, driving trends and interannual variability of the global carbon sink” (p. 2201).
Our second comment concerns the distinction between desert lands and other types of “Sparsely Vegetated Lands”.
Beach vegetation is subject to regular catastrophic events (e.g., inundation by storm surge) that select for relatively short-lived species that can rapidly reestablish themselves via seeds or resprouting. Red Sand Verbena (Abronia maritima) and Beach Saltbush (Atriplex leucophylla) recolonize within weeks of being washed out by a spring tide. These often have extensive, though relatively shallow root systems, which are limited by salt water beneath the fresh water lens (3).
Alpine tundra is the major plant community of high elevation “bare rock and ice”. Most species are deeply rooted, though only in relation to total plant size. Generally small and always low growing, these plants often exist as a mat, a growth habit that protects the plant from freezing winter winds. A dinner-plate sized specimen of Moss Campion (Silene acaulis) might be hundreds of years old, a few centimeters tall, and with a taproot extending a foot or more into the shallow soil (4).
Deserts are very different from either of these ecosystems, with a mix of droughtavoiding (spring) annuals, perennials with roots that reach many meters to deep sources of water, and succulents with extensive shallow roots to take full advantage of infrequent rain.
Designating the “desert” as a separate category is not excessive “splitting” of vegetation types. In a broad sense, there are three separate deserts within the state of California (out of four in North America). All three desert provinces support significantly different vegetation assemblages. All are fundamentally different from assemblages on beaches or in areas of alpine tundra.
Our third comment is related to the second one. At the Natural Working Lands review on February 7, one of the moderators opined in response to our concerns, that a
5 separate “desert” category is unnecessary because the existing model accommodates areas of “chaparral” within the otherwise “sparsely vegetated” desert, implying that creosote bush bajada is functionally equivalent to chaparral. This interpretation can be shown to be incorrect by examining the Net Ecosystem Exchange (NEE) rates of the various vegetation types, listed in a table in Section IV of our report, “AB 1757 Nature Based Solutions: Desert Sector” (5). In this table, one reads that 100-year-old Chaparral sequesters 520 kg Carbon per hectare per year in wet years, and 180 kg/HA/yr in dry years. By comparison, Creosote Bajada scrub sequesters over 1000 kg Carbon/HA/yr, and is less impacted by yearly rainfall, as their deep roots reach groundwater or other deep sources of water.
There are many other differences. For instance, vegetation density varies between both ecosystems: chaparral is not normally sparsely vegetated but is characterized by dense vegetation, unlike desert vegetation. Both chaparral and desert are drought tolerant, but fire adaptation in chaparral is a component of the natural ecosystem process, whereas the desert is poorly adapted to wildfire with low capacity for recovery.
Precipitation patterns between the two ecosystems also differ. Chaparral is dependent upon winter rains, which are more effective than summer rains as a function of evapotranspiration. Deserts are subject to precipitation that is either unpredictable or seasonal with largely summer monsoonal precipitation. Summer monsoons are generally short, high-intensity bursts in patches that run off. The desert’s distinct precipitation pattern results in the widely dispersed nature of desert vegetation and elevates the importance of desert microphyll woodlands. Reliance on precipitation patterns as justification for linking categorization of ecosystems is flawed in that this scheme dismisses significant ecosystem processes and differences. The ecology of the chaparral and desert ecosystem types is radically different. This is evident when considering two regions – Tucson and San Diego - that receive similar levels of precipitation but are represented by very dissimilar ecosystem vegetation types.
Our fourth and final comment is a response to CNRA’s request for comment on the goals listed in “Nature-Based Climate Solutions” and “Cross-Cutting Priorities”. We are only commenting on Climate Solutions goals for “Sparsely Vegetated Lands”.
Deserts comprise over a quarter of the land area of California. (The exact proportion depends on how one defines “desert”). By comparison, beaches and alpine tundra (combined) are significantly less than one percent of the land area of the state (6). So all sections of “Sparsely Vegetated Lands – Priority Nature-Based Climate Solutions” in CNRA’s documentation should be replaced by sections mainly applicable to desert lands. In particular, the current Sections D and E apply only to beaches. (We do not think this is a desirable outcome; it merely illustrates some of the severe limitations of a miscellaneous “Sparsely Vegetated Lands” category.)
Specifically, we agree with Goal A to “protect [lands] from disturbance and conversion to other land types”.
6 We would limit most efforts on Goal B (“restore native plants”) to apply only to riparian areas. As we discussed in our report “AB 1757 Nature Based Solutions: Desert Sector”, restoration of most desert ecosystems – especially replacing carbon lost when the desert is disturbed – is unrealistic in any reasonable time scale. This goal should be replaced by one that provides pathways to preserve intact desert lands.
Goal C (“appropriate use of cultural fire”) has limited applicability in deserts, e.g. palm oases. As we have noted elsewhere, our deserts are not adapted to a chaparral-like fire regime. Efforts in this area should be redirected to reducing fuel loads from invasive grasses that fuel most destructive desert fires.
Goals D and E concern beaches and have nothing whatsoever to do with the desert. In a “Sparsely Vegetated Lands” category, we are fine with the recommendations being applicable to non-desert areas, though fairness suggests that one of them be allocated to “bare rock and ice” (more generally known as alpine tundra).
We have no comments and are satisfied with “Cross-Cutting Priorities for Climate Smart Land Management,” as currently written.
Thank you again for the opportunity to comment.
Sincerely,
Dr. Michael Allen, Ph.D. Distinguished Professor Emeritus. Department of Microbiology and Plant Pathology, University of California, Riverside Susy Boyd, MNR. Master of Natural Resources, Forests and Climate Change. Oregon State University
Pat Flanagan, B.A. Biology. California State University, Long Beach. Director, Morongo Basin Conservation Association
Robin Kobaly, M.S. Biology and Plant Ecology. University of California, Riverside.
Executive Director, The Summertree Institute
Arch McCulloch, M.S. Computer Science. Azusa Pacific University. B.S Geology / Computer Science. California State University, Dominguez Hills. President, Mojave Chapter, California Native Plant Society
Joan Taylor, Governing board of the Coachella Valley Mountains Conservancy, and boards of Friends of the Desert Mountains and The Wildlands Conservancy.
Chairperson, California Conservation Committee and California/Nevada Desert Committee of Sierra Club
7 Steve Bardwell
President
Morongo Basin Conservation Association
Josefina Barrantes
30x30 Coordinator
Environmental Protection Information Center (EPIC)
Sendy Hernández Orellana Barrows
Conservation Program Manager
Consejo de Federaciones Mexicanas (COFEM)
Linda Castro
Assistant Policy Director
CalWild
Nick Jensen, PhD
Conservation Program Director
California Native Plant Society
Arch McCulloch
President and Conservation Chair
Mojave Desert Chapter
California Native Plant Society
Fred Chynoweth
Conservation Chair
Kern County Chapter
California Native Plant Society
Mahtisa Djahangiri
Campaign Strategist
Sierra Club California
Sam Easley
Executive Director
Transition Habitat Conservancy
Robin Kobaly
Executive Director
The SummerTree Institute
8 Pamela Flick
California Program Director
Defenders of Wildlife
Jora Fogg
California Associate Program Director
Conservation Lands Foundation
Frazier Haney
Executive Director
The Wildlands Conservancy
Kelly Herbinson
Executive Director
Mojave Desert Land Trust
Lis Olaerts
30x30 Coordinator
Sierra Nevada Alliance
Susan A. Phillips
Professor of Environmental Analysis, Director
Robert Redford Conservancy for Southern California Sustainability Bettina Rosmarino
Land Acquisition Director
Oswit Land Trust
Dan Silver
Executive Director
Endangered Habitats League
Mason Voehl
Executive Director
Amargosa Conservancy
Ileene Anderson
Senior Scientist/California Desert Director
Center for Biological Diversity
Colin Barrows
Co-Founder
CactusToCloud Institute
9 Kayla Browne
Desert and Renewable Energy Policy Director
Payahuunadü / Eastern Sierra
Friends of the Inyo
Damon Yeh
California Project Manager
Wildlands Network
Dr. Bob Przeklasa
Executive Director
Native American Land Conservancy
Footnotes:
1. Bureau of Land Management California Desert District Office. (n.d.). National Conservation Lands of the California Desert. U.S. Department of The Interior.
Retrieved February 21, 2024, from https://www.blm.gov/programs/nationalconservation-lands/national-conservation-lands-of-the-california-desert
2. Mirzabaev, A., L.C. Stringer, T.A. Benjaminsen, P. Gonzalez, R. Harris, M. Jafari, N. Stevens, C.M. Tirado, and S. Zakieldeen, 2022: Cross-Chapter Paper 3:
Deserts, Semiarid Areas and Desertification. In: Climate Change 2022: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [H.-O.
Pörtner, D.C. Roberts, M. Tignor, E.S. Poloczanska, K. Mintenbeck, A. Alegría, M. Craig, S. Langsdorf, S. Löschke, V. Möller, A. Okem, B. Rama (eds.)].
Cambridge University Press, Cambridge, UK and New York, NY, USA, pp. 2195– 2231, doi:10.1017/9781009325844.020.
10 3. Native Beach Plants | Explore Beaches. (n.d.).
https://explorebeaches.msi.ucsb.edu/sandy-beach-life/native-beach-plants
4. Doak, D. and Morris, W. Life and times of tundra plants: How long do they live, and how they are responding to climate change (U.S. National Park Service). (n.d.). https://www.nps.gov/articles/aps-v12-i1-c3.htm
5. Allen, M., Boyd, S., Flanagan, P., Kobaly, R., McCulloch, A., Taylor, J., Barrows, C., & Barrows, C. (2024, February). The California Desert’s role in 30X30:
Carbon sequestration and biodiversity. Retrieved February 23, 2024, from https://static1.squarespace.com/static/61815979dfa7a7572c721a67/t/65c3fdd84 5022354cdacf1b7/1707343322633/C+Sequestration+Desert+Sector+Report+Re vised+2.7.24+%281%29.pdf.
6. California’s coastline is about 1350 km long. The state’s area is 423,970 sq km. If all coastline is beach and is 1 km wide, this is 0.3 percent of the state. Alpine tundra is more difficult to estimate, but almost certainly covers less area.
1 To: Twentynine Palms Planning Commission, City Council, and City Staff Date: February 16, 2026
Subject: Request for 90-Day Continuance – E-Group PS Solar Project Dear Planning Commissioners, City Council Members, and City Staff, Hello to you all who care for our community and have taken up the opportunity and responsibility to protect it. I personally want to express my gratitude to you for taking on the hard work involved.
I also love our community—the land and people. And I too try to protect it, for the sake of generations to come.
Today, I am respectfully requesting that the City not vote on the E-Group project documents package that was distributed Thursday February 12 with the vote announced for Tuesday February 17, 2026. Instead, I request at least a 90-day continuance. The five-day review period, which spans a holiday weekend, has not given enough time for commissioners and the public to review hundreds of pages of complex materials. These materials include the Development Agreement (DA), Conditional Use Permit (CUP), rezoning and general plan changes, and the Responses Document. (That’s the document from Terra Nova intended to address public concerns and demonstrate CEQUA compliance before project approval.)
In recognition of the enormous amount of reading you are doing, I will try to make this letter as brief as I can—just stating main reasons why the 90-day continuance is needed.
1. Careful document review is essential because the Development Agreement includes “vested rights.” Once vested rights are granted, the applicant has extensive rights to develop the project based on the terms stated in the DA and CUP at the time that they are signed. Terms cannot be updated. If new information about the project emerges or realworld impacts prove worse than predicted, the City’s ability to require sensible remediations beyond what is specified in the DA and CUP would be limited.
For example, we know from the DEIR that mass grading (over a half-million cubic yards of earthmoving) would be required to flatten the rolling landscape. In our windy environment, severe dust impacts are foreseeable. Instead of telling us how the company would prevent severe dust effects, the DEIR defers dust-controls to “future studies” and leaves the actual engineering plans unspecified. We are left not knowing exactly how EGroup proposes to deal with dust. Once rights are vested, if E-Group reveals an approach to dust management that we as a community find unsuitable, there is little the City can do beyond what is already required in the approved DA and CUP documents.
2. The Responses Document contains inadequate as well as incorrect information, so CEQA compliance has not been established. The DEIR Responses are a requirement under CEQA. They are meant to show that public objections have been considered and do not pose real risks so the project can move forward.
Decision-makers and the public need adequate time to read the Responses carefully to determine if in fact they are true, fair, and evidence-based. If they are not, the City cannot
2 lawfully rely on the EIR to approve the project under CEQA. I have not yet read all the Responses, but I have found examples of incorrect or missing information as well as Responses that don’t address the commenters’ stated concerns at all. Here is an example.
DEIR public comment 39 states:
“The DEIR concedes permanent, unmitigable aesthetic impacts but fails to fully contextualize these impacts within the City’s gateway setting, tourism economy, and established residential character.”
The Response to this comment states:
“Aesthetic impacts are addressed in DEIR Section 2.3, which concludes that the project is not visible from most public viewpoints, including Two Mile Road, and would not significantly impact scenic vistas. Because the project would not significantly impact scenic vistas or be visible from most publicly utilized roadways, it is not anticipated to impact tourism.”
Three points about this Response: First, my house is about 1400 feet to the east of the site. We absolutely could see the huge site from our property as could other homes in the area. It would destroy the scenic vista we enjoy. The Response does not address how the “established residential character” of our neighborhood would be affected by the site at all. Secondly, DEIR Section 2.3 contradicts the Responder, saying that “…the Solar Project would be visible…” from Two Mile Road. (The photo below from EGroup’s marketing site shows several photos of the visible panels from Two Mile Road.) Thirdly, the Reponses Doc goes on to reduce impacts on tourism to just its visual impacts, then waves these away by relying on the claim that the site would not be visible from 2 Mile Road--even though it is! Tourist impacts occur due to dust, loss of an open area that many people hike and drive recreational vehicles through, and other factors too.
The Responses overlook all of this. How many other valid public concerns does the Responses doc dismiss without adequate consideration? The doc needs careful scrutiny. https://genevasolarproject.com/minimizing-impacts/
One more issue I have looked into regarding the Responses Document concerns AB 205.
In no way does it lessen the point that community members have been making about the E-Group plant having a generating capacity of less than the AB-205 threshold of 50 MW AC. E-Group has referred to the plant’s “generating capacity” as “50 MW” in many instances. However, the Response now shows that the plant only meets this threshold if
3 you define “generating capacity” in a less common way--as dc nameplate. I have written a letter to the CEC asking whether they would have accepted a project with a DC nameplate value of 51 MW but a generating capacity of only 38 MW AC. I expect to hear back soon. Regardless, environmental impacts including desert tortoise occupancy and dust, it is doubtful that the E-Group project would have breezed through AB 205 approval. E-Group should not have presented the project as such. A continuance will allow us to wait for a response from the CEC. That will clarify whether the 50 MW DC claim would have cleared the approval process. Until then, we do not know.
3. E-Group’s Business Structure In evaluating whether the Project’s claimed benefits justify adoption of a Statement of Overriding Considerations, the City must also consider the nature and capacity of the applicant. E-Group is a small firm based in Slovakia with fewer than 20 employees worldwide, no verified record of completing projects in the United States, and a primary business focus in renewable-energy finance rather than engineering, construction, or long-term plant operations. These facts raise legitimate concerns regarding technical capacity, long-term accountability, and whether the company intends to build and operate the facility itself or instead obtain entitlements and later transfer the project to another entity. Given the permanent land use changes and long operational life proposed, binding commitments and independent technical review are essential before concluding that the promised public benefits are reliable and sufficient.
Before vested rights are granted, E-Group should disclose whether it is structured as a “Special Purpose Vehicle” (SPV). SPV’s are thinly capitalized and may not have enough financial reserves to cover emergency situations. The DA and CUP require special protections if E-Group is an SPV, so this must be determined before a vote is taken.
Please see the attached letter I wrote to the City last June about the need for more transparency about E-Group’s business structure. Unfortunately, my letter was never acknowledged by City recipients, and the concerns remain.
4. Community benefits are inadequate. The Development Agreement’s “Community Benefit Payment” schedule is $105,000/year during construction, then $120,000/year, then $135,000/year, and ultimately $150,000/year (CPI-adjusted) for most of operations.
The Responses defend the amount by emphasizing that it reaches $150,000 annually and saying it was supported at a prior workshop. However, at that workshop commenter Susan Pepelow stated that the yearly payment of $100,000-$150,000 is about the cost of just one week of the City’s Sheriff contract, so does little for the City’s funding needs.
Also, the payment looks favorable relative to payments some large plants receive when expressed as dollars per acre. However, using the metric dollars per MW, the payment is just moderate or modest. In addition, comparison to other plants inflates the payment for our city because other plants do not have nearby substations; E-Group admits proximity to the Carodean substation is a major value-add to the plant within our city limits.
Community groups were completely left out of the benefits negotiation process in our case, and there is no compensation set aside for them as AB 205 would have provided.
Further, residents most affected by the plants’ negative impacts (including nearby neighbors exposed to maximum noise, dust, visual blight, and property value loss)
4 receive no particular compensation. AB-205 style community benefit packages center consideration of these residents on the basis of fairness and equity. By contrast, the Responses document addresses fairness in comment 14 when it says “The CEQA process does not take into consideration equity, fairness, or economic impacts associated with a given community project.” An AB-205 style community benefits package may leave the City out of negotiations, but such a package would be vastly preferable to what many of us residents receive from the E-Group process—which is no benefits at all.
Finally, the E-Group plant introduces significant financial risk to the City for reasons discussed previously and in this letter. The documents up for a vote on Tuesday frame the payment in a way that favors the applicant but it obscures the questions that residents care about: How would residents and the City benefit from the project relative to its burdens and risks? And the co-equal question: What would be the lasting impact of this project on our natural environment and future of our city? For all of these reasons, I respectfully request that the Planning Commission continue the February 17 hearing for at least 90 days.
Once again, I thank you for your time.
Sincerely,
Suzanne Lyons
Twentynine Palms, CA
(530) 264-6223
enc
Chris Tiffany
7054 Sherman Road
29 Palms, CA 92277
December 17, 2025
Twentynine Palms City Council
6136 Adobe Road
Twentynine Palms, CA 92277
Re: E-Group PS Solar Project
Please enter this letter into the Pubic Comments for the above named project.
I stand in opposition to this solar field project.**. Forward to all members of the Planning Commission, as my first email could to be opened.
1. The extensive grading and ripping up of these undisturbed 184 acres of native vegetation exposes our area to dust and fine particulate that is contrary to the motivation that has brought generations of residents to the high desert expressly for our healthy air quality. It is common knowledge that the veneer that holds our desert soils is fragile and once disturbed take hundreds of years to heal. This acreage is habitat for a variety of species large, small and microscopic. Do we really want our view shed ruined, our climate altered by a project like this one? Drive to Desert Center on a windy day and see the destruction of pristine desert at the Desert Sunlight Solar Farm and witness the dust storms this indiscriminate grading up of native vegetation has created there.
2. The City should be a leader in the High Desert and an outspoken advocate for placing solar panels on existing buildings and homes and on all new construction. This simply makes sense over large solar fields.
3. Also, approving another Zoning Change is a mistake. The Development Code does not allow solar farms. Chipping away at the General Plan is not a good idea. The vision was written into the Plan to safeguard the future of our beloved desert home.
4. A final question: This Terra Nova Planning and Research group is the same company that advocated for a Negative Declaration for the Ofland project, avoiding the rules of CEQA that require a full environmental impact study for developments of this magnitude. This company is based in Palm Desert where the entire region no longer holds any evidence of the dunes once covered with sand verbena that I hold in my own memory. I don’t think anyone who lives in 29 Palms wants a paved over community or acres of industrial developments like this solar farm represents.
I thank you for your consideration of these thoughts. My personal ties and love of this desertscape were forged over 70 years ago.
** revised 2-16-26: Please read my public comments at tomorrow’s Planning Commission meeting, February 17, 2026 and on March 3rd.. I am truly flabbergasted that Staff has recommended approval of this destructive project. Are they even residents dedicated to the future health and well being of 29 Palms?
The California Desert’s Role in 30X30:
Carbon Sequestration and Biodiversity
February 6, 2024
Dr. Michael Allen, Ph.D. Distinguished Professor Emeritus. Department of Microbiology and Plant Pathology, University of California, Riverside
Dr. Cameron Barrows, Ph.D. Conservation Ecologist, Emeritus. Center for Conservation Biology, University of California, Riverside
Colin Barrows, Co-founder, Cactus to Cloud Institute
Susy Boyd, MNR. Master of Natural Resources, Forests and Climate Change. Oregon State University Pat Flanagan, B.A. Biology. California State University, Long Beach Robin Kobaly, M.S. Biology and Plant Ecology. University of California, Riverside Arch McCulloch, M.S. Computer Science. Azusa Pacific University. B.S Geology / Computer Science. California State University, Dominguez Hills
Joan Taylor, Governing board of the Coachella Valley Mountains Conservancy, and boards of Friends of the Desert Mountains and The Wildlands Conservancy. Chairperson, California Conservation Committee and California/Nevada Desert Committee of Sierra Club
1 Author Biography
Dr. Michael Allen. Dr. Michael Allen has a Bachelor of Science in Biology from Southwestern College in Kansas, a Master of Science in Botany from the University of Wyoming, and a Ph.D. in Botany from the University of Wyoming, and is currently a Distinguished Professor Emeritus in Microbiology and Plant Pathology at the University of California, Riverside. He has worked on carbon flux and mycorrhizae since his dissertation, served as a program officer at the National Science Foundation where he managed Long-Term Projects, Ecosystems, and Conservation and Restoration Biology. During his tenure, he led discussions for the initiation of the National Ecological Observatory Network (NEON), served as an original member of various NEON boards, led the Biodiversity workshop, led the California bioregion discussions, and designed the soil sensor network that was adopted by NEON to measure soil carbon flux.
Dr. Cameron Barrows. Dr. Cameron Barrows worked for The Nature Conservancy (TNC) with his wife Kate, managing the last remaining old growth redwood forest in Mendocino County, CA, and conducting research on Spotted Owls (1980-1986). Dr. Barrows continued working for TNC and other NGO conservation organizations to implement the first-in-the-nation Habitat Conservation Plan in the Coachella Valley and expanding that plan to encompass the full breadth of biodiversity within that valley (1986-2005). Research focused on the Coachella Valley fringe-toed lizard and flat-tailed horned lizard. He worked with the Research Faculty at the University of California Riverside’s (UCR) Center for Conservation Biology (2005-2022). Research focused on the response and resilience of desert species to modern climate change. Emeritus Research Faculty at UCR (2022-Retired). Still doing research and still married to Kate (44 years and counting). Their son Colin is carrying the desert conservation torch into the coming decades.
Colin Barrows. Colin is a Coachella Valley naturalist and desert advocate who works to promote conservation of natural open spaces and native species. He works with local agencies to advance habitat conservation, recreational trails planning, and education about desert ecosystems. He also serves on the board of the Mt. San Jacinto Natural History Association. Colin currently serves as co-founder of the Cactus to Cloud Institute.
Susy Boyd. Susy Boyd completed her MNR [Master of Natural Resources] degree at Oregon State University with an emphasis in Forests and Climate Change. Her research project developed climate change predictions and impacts on Seasonally Dry Tropical Forests in Mexico’s Yucatan region. Prior to her studies with OSU, she received a Master of Arts degree in Rhetoric and Communication at UC Davis where she also served as lecturer. She currently works with Mojave Desert Land Trust as Public Policy Coordinator.
Pat Flanagan. Pat Flanagan is a naturalist - educator with a BA degree in biology from CSU Long Beach. She was the director of education at the Tijuana River National Estuarine Research Reserve for 10 years. She developed the first bilingual coastal wetland curriculum for bi-national distribution and training. This curriculum was later adapted to the Colorado Desert for the Desert Protective Council. She was a founding member of the Mojave Desert Land Trust where she held various positions. She is on the board of the Morongo Basin Conservation Association (20 years) for whom she has studied and commented extensively on Utility Scale Solar projects in the Mojave Desert. She is an advisor to the Mojave Desert Resource Conservation District and the naturalist at the historic 29 Palms Inn Oasis of Mara.
Robin Kobaly. Robin Kobaly holds both BS and MS degrees in Biology and Plant Ecology from the University of California, Riverside. She served as a botanist for the U.S. Bureau of Land Management for 21 years, working on regional conservation plans, habitat management plans, management plans for Areas of Critical Environmental Concern (ACEC), and environmental impact statements. Kobaly served on the Independent Science Panel providing science-based input to the planning process for the Desert Renewable Energy Conservation Plan (DRECP). She currently serves as Executive Director of The SummerTree Institute, an environmental education non-profit.
Arch McCulloch. Arch McCulloch has Bachelor of Science degrees in Computer Science and in Geology from California State University at Dominguez Hills, and a Master of Science degree in Computer Science from Azusa Pacific University. He spent 35 years as a software and information assurance engineer in the defense industry. He is currently on the boards of Morongo Basin Conservation Association (MBCA) and the Mojave Desert Chapter of California Native Plant Society (CNPS).
Joan Taylor. Joan Taylor has been conserving the California desert for over five decades, including eight years as an appointed stakeholder to DRECP, where she co-authored the joint environmental NGO comments on the CEC energy-acreage calculator. Joan has received numerous awards and acknowledgements for her life-long leadership
2 in desert conservation. Currently, she serves on the governing board of the Coachella Valley Mountains Conservancy, The Wildlands Conservancy, and Friends of the Desert Mountains. Joan also chairs the Sierra Club’s California Conservation Committee and its California/Nevada Desert Committee.
Contact information:
Dr. Michael Allen
[email protected]
Dr. Cameron Barrows
[email protected]
Susy Boyd
[email protected]
Pat Flanagan
[email protected]
Robin Kobaly
[email protected]
Arch McCulloch
[email protected]
3 The California Desert Conservation Area
Executive Summary
Our state’s southeast desert region is unlike any other locale of the state. California’s desert ecosystem comprises a staggering 25% of state land (approx.26 million acres) and is locally accessible to approximately half of our state’s population. The unique beauty of the desert ecosystem has driven visitation to the region, with Joshua Tree National Park recognized as the 8 th most visited national park in
the country in 2022.
In spite of its rapidly rising popularity, the California desert as an ecosystem remains poorly understood, underfunded, and misperceived. One of the most persistent mischaracterizations is that the California desert is a barren wasteland with low biodiversity and limited capacity for carbon storage. Scientific data refutes these inaccuracies, and this report will demonstrate that the California desert has extremely high biodiversity and is a significant carbon sink with tremendous opportunity to sequester carbon and help our state meet its atmospheric carbon reduction goals.
There are 2 key takeaway messages from this report:
1. The desert’s carbon storage process differs significantly from more widely understood sectors such as forests, grasslands, chaparral, and wetlands.
2. Because of the distinct carbon storage process found in the desert ecosystem, there is one recommended strategy to maximize the desert sector’s contribution to carbon emission reduction: intact desert lands need to be left undisturbed.
4 REPORT OVERVIEW
Executive Summary…3
I. Introduction…5
II. Maximizing Carbon Sequestration and Biodiversity Protections…5 Characterizing disturbed lands…6
Why restoration is not an effective means to maximize carbon sequestration…9 III. The Critical Relationship Between Undisturbed California Desert Lands and Carbon Sequestration…10
IV. Overview of Carbon Sequestration Process in Desert Ecosystems…11 V. Quantification of Carbon Sequestration…14
VI. Modeling Carbon Sequestration in Our Deserts…21
VII. Mapping and Identifying Prioritized Areas of our Desert…21 Microphyll woodlands/Creosote bajada scrub…21
VIII. Additional benefits…23
Biodiversity in our deserts…23
Economic benefits to disadvantaged communities…25
Biocrusts in the desert…26
Health benefits…27
IX. Transition to Clean Energy: Meeting our Clean Energy Goals and Minimizing Disturbance to our Desert Ecosystem…28
Utility Scale Solar and Avoidance of Desert Disturbance…28 X. Policy Strategies and Tools to Maximize Carbon Sequestration and Conservation Values…30
XI. Conclusion…33
5 I. Introduction. California’s goal of carbon neutrality seeks to balance the net flux of greenhouse gas emissions (GHG) from all sources and sinks.
California’s non-forest habitats play an unappreciated but critical role [in carbon sequestration] …. As with forests, non-forest habitats can store carbon by keeping it from being released and sequester it by removing it from the atmosphere. Habitats in arid and semi-arid regions — including shrublands, grasslands, and deserts — have been found to store significant amounts of carbon while being resilient to drought and increased atmospheric carbon (Yap et al., 2023).
As reported by Yap et al., globally, scientists estimate that deserts store 999 – 1,899 petagrams [Pg] of carbon. In the United States, southwest deserts sequester 50 teragrams [Tg] of carbon annually (equal to
0.05 Pg). And in California’s northern Mojave Desert, field experiments demonstrated that CO2 exchange plays a larger role in global carbon cycling than what scientists and policy makers have long assumed.
The desert ecosystem, unlike other sectors, is largely unmanaged with the exception of some restoration projects. Additionally, the desert’s recovery from alterations of any kind takes place on a time scale at a much slower rate relative to other ecosystem types, up to thousands of years.
The desert’s function as a significant global carbon sink is an emerging and exciting scientific territory that merits a central place in any endeavor to meet climate change goals.
Center for Biological Diversity, Yap, T., Prabhala, A., & Anderson, I. (2023). Hidden in Plain Sight:
California’s Native Habitats are Valuable Carbon Sinks (W. Leung, Ed.).
II. Maximizing Carbon Sequestration and Biodiversity Protections Maximizing carbon sequestration and concurrent protection of high biodiversity in the California desert ecosystem is achieved by conserving 100% of undisturbed public lands.
Arch McCulloch, MS
Board Member, Morongo Basin Conservation Association / Mojave Desert Chapter of CNPS It is axiomatic that disturbances in the desert take a long time to heal. Scars in terrain altered by General Patton’s World War II training exercises remain visible today, and areas grazed by cattle still, over 60 years later, support vegetation assemblages that indicate a history of grazing and associated fires (Sawyer et al. 2009). Deliberate disturbances, such as the desert intaglios near Blythe, can last for many centuries.
Many desert perennials are long-lived: Joshua trees (Yucca brevifolia) can live over 100 years and Mojave yuccas (Yucca schidigera) can live over 1,000 years; desert ironwood (Olneya tesota) may live a thousand or more (Rymer 2023). Creosote bush (Larrea tridentata) clonal rings over 10,000 years old are still living in parts of the Mojave Desert (Porter 2012). Blackbrush (Coleogyne ramosissima) may take over 60 years to re-establish on sites where it has been removed (Anderson 2001). Obviously, restoration of disturbed sites is complicated by these time scales.
In desert soils, restoration is even more complicated due to very deep and expansive root systems and to the complex soil biota that has co-evolved with plants on particular sites over millennia. After removal of perennial plants, the re-establishment of this deep soil biota, even more than the extremely slow growth rates of desert perennials, means there is no practical way to restore lands where this relationship has been disrupted.
6 Photovoltaic solar (PV) is rightly seen as a core energy resource to reduce our carbon footprint. The issue is where to place it to best attain this goal. There is great risk of unintended consequences when Southern California deserts are narrowly assumed to be the primary locale for utility scale solar, as we discuss in the following sections. Photovoltaic efficiency is highest on cool, sunny days, which maximizes the electric potential of the solar cell. Since cloud cover and high ambient temperatures both reduce PV efficiency, cooler areas with higher cloud covers will have PV efficiency comparable to hot areas with lower cloud cover. Locating solar panels as close as practicable to load will reduce resistance losses. The success of PV generation in Germany shows that acceptable efficiency is achievable with these strategies.
Given the ability of undisturbed desert land to bind and hold carbon on a scale of millennia, and the difficulty of restoring disturbed desert lands to anything approaching this capability, we believe that any solar project proposed for the desert should be sited on the vast areas that have already been disturbed by urban, agricultural, and industrial installations (and by the ruins, both physical and biological, of former installations).
In sum, any calculation of equivalent carbon savings by a desert solar installation must, if it is honest, subtract carbon no longer sequestered by the destroyed vegetation, as well as carbon being released to the atmosphere by soil now exposed to weathering. It must also account for replacing an ecosystem service (that, if undisturbed, would continue to operate independently and indefinitely), with an industrial service requiring near-constant maintenance and complete equipment replacement every few decades.
References
Anderson, M.D. 2001. Coleogyne ramosissima in Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. https://www.fs.usda.gov/database/feis/plants/shrub/colram/all.html [2023, July 13].
Porter, D.M. 2012. Zygophyllaceae. Pages 1279-1280 in Baldwin, B.G., D.H. Goldman, D.J. Keil, R.
Patterson, T.J. Rosatti, and D.H. Wilken, editors. The Jepson Manual: Vascular Plants of California, University of California Press.
Rymer, C. 2023. The Ironwood: Stately Sanctuary in the Sonoran Desert in Cooperative Extension Master Gardener Journal. The University of Arizona, College of Agriculture and Life Sciences. https://cals.arizona.edu/maricopa/garden/html/pubs/0803/ironwood.html. [2023, July 13].
Sawyer, J.O., T. Keeler-Wolf, and J.M. Evens. 2009. A Manual of California Vegetation, 2nd Edition. Page 343. California Native Plant Society.
Characterizing Disturbed Lands
Susy Boyd, MNR. Master of Natural Resources, Forests and Climate Change, Oregon State University Public Policy Coordinator, Mojave Desert Land Trust
Disturbed lands are those areas where infrastructure development has been or may be encouraged. The state of California as a whole has much to offer in terms of disturbed lands suitable for utility infrastructure as we transition to clean energy and meet our state’s impressive climate change mitigation goals.
Landscape-scale disturbance falls across a continuum. A pristine desert ecosystem characterizes one end of the spectrum, and worst-case scenario characterized by loss of ecosystem function represents the other end of the spectrum (C. Barrows Ph.D., personal communication, September 14, 2023). A functioning desert ecosystem provides ecosystem services beyond carbon sequestration including habitat for desert organisms. So long as perennial woody vegetation remains intact, the landscape can be considered a functioning ecosystem, even with presence of non-native grasses and mustard that have
7 ephemeral impacts based on water availability. Other examples of undisturbed lands subject to minor impacts include areas with light or well-managed grazing, lands affected by wildfire (with root zone left undisturbed), and lands impacted by flooding with no expected continuing disturbance.
Examples of landscapes that have lost most of their functionality would be abandoned building sites, fallow agricultural lands, and large-scale mining operations; degraded OHV playgrounds; parking lots; and rights-of-way for transmission lines and canals. Residential and commercial developments are also regions where ecosystem function has been reduced to nonfunctional status.
In 2023, the California Energy Commission [CEC] released a staff report entitled, “Land-Use Screens for Electric System Planning.” Land use screens are high level land use evaluation tools that identify favorable sitings for renewable energy after considering technical and economic criteria; legal restrictions; and planning considerations for biodiversity, crop production, climate resilience, and landscape intactness. The 2023 report provides descriptors for landscape intactness:
Terrestrial landscape intactness: A measure of landscape condition based on the extent to which human impacts such as agriculture, urban development, natural resource extraction, and invasive species have disrupted the landscape across California. The Conservation Biology Institute (CBI) has created a multicriteria evaluation model using more than 30 data layers, or variables…. The CEC staff partitions this dataset at the mean to create two categories: areas that are already disturbed and have degraded ecosystem function and areas where development would impair the landscape and cause new disturbance. In this analysis, areas of low landscape intactness are most suited for exploration of renewable resource potential, whereas areas of high intactness are better suited for conservation. Therefore, the higher category of landscape intactness values is used to remove technical resource potential from the state.
Lands with degraded ecosystem function are shown in blue (below the mean) in the following map and areas with high intactness value (above the mean) are displayed in orange. Areas with high landscape intactness (orange) indicate areas with low priority for infrastructure development in order to preserve ecosystem function, biodiversity, and carbon sequestration capacity. Intact landscape characterizes much of the California desert region, though large tracts of disturbed land across the state remain highly viable options for renewable energy development. More thorough analysis of disturbed desert lands is needed for planning purposes. Future industrial scale solar projects should be sited on disturbed lands that already exhibit low intactness.
8 Source: Hossainzadeh, S. et al. 2023.
Landscape Intactness as calculated by CBI is partitioned into high and low categories based on the mean.
Orange = High intactness [Undisturbed]
Blue = Low intactness [Disturbed]
Reference
Hossainzadeh, Saffia, Erica Brand, Travis David, and Gabriel Blossom. 2023. Land-Use Screens for Electric System Planning: Using Geographic Information Systems to Model Opportunities and Constraints for Renewable Resource Technical Potential in California.
California Energy Commission. Publication Number: CEC-700-2022-006-F.
9 Why desert restoration is not an effective means to achieve atmospheric carbon reduction goals Robin Kobaly, M.S. Biology and Plant Ecology, University of California, Riverside Executive Director, The Summertree Institute
The rate and success of restoration efforts or recovery of disturbed ecosystems is largely dependent upon water availability. When an impacted ecosystem has ample water available for seed germination, root establishment, and growth of new foliage, recovery can be fairly rapid, ushering back the community of insects, reptiles, birds, mammals, and microbes that depend upon plants in the ecosystem. However, if a disturbed ecosystem has limited rainfall and low soil nutrient content, recovery either naturally or through restoration efforts takes much longer and may not always succeed. Recovery from disturbance by temperate ecosystems is much faster than in arid ecosystems, with both infrequent, unpredictable precipitation and low soil nutrients contributing to the slower recovery of arid ecosystems such as those in the California deserts.
Recovery and restoration in forest ecosystems requires about 40 years, but recovery and restoration in desert ecosystems can take centuries longer. Research suggests that removal of desert vegetation and disturbance of the topsoil requires about 30 years before the pre-existing plant community begins to grow back, over two centuries before even partial recovery of species composition occurs, 50 – 300 years for recovery of plants to pre-disturbance cover and biomass, and up to 3,000 years before the disturbed area returns to the ecosystem function it had before disturbance. Disturbance is defined here as a physical force (e.g., road building, plowing for agriculture, construction of industrial-scale solar fields, etc.) that removes most or all the plant biomass.
Research indicates that the older the plant community, the longer the recovery time. Desert ecosystems are known for the longevity of their perennial plant community, with many shrubs living hundreds (blackbrush, Mormon tea, galleta grass, pinyon, etc.) to thousands of years (creosote, Mojave yucca, California juniper, nolina, desert ironwood, etc.). Data show that protecting deserts from disturbance is critical for sustaining old communities, valuable for their generational contributions to ecosystem stability.
The desert’s ancient plants sustain their community through centuries of drought episodes, excessive heat waves, frosts that kill younger plants, and attacks by diseases and pests that compromise younger plants struggling to become established.
Some scientists have hypothesized that if disturbed, the oldest communities may not actually recover, even with restoration efforts, and they could be replaced by an alternative community. The reasoning is that climate and other conditions (e.g., invasion by exotic species, climate extremes, anthropogenic nitrogen deposition) have changed so much since the communities developed hundreds to thousands of years ago, restoration attempts may not be successful in recreating the original ecosystem, and a different community may become established instead of the original community.
Active revegetation in southwestern deserts has generally been confined to small areas because of its expense, the unpredictable weather that makes restoration effectiveness uncertain, and logistical challenges associated with implementing treatments across large desert areas.
Since disturbances can leave scars in the desert visible for multiple human generations and because restoration is so difficult, costly, and not guaranteed, great care should be exercised before disturbing the desert, not simply for ecosystem health, but also to preserve visual aesthetics, air quality, human health, ecotourism viability, biodiversity, and carbon sequestration capacity. For these reasons, conservation of intact desert lands should be prioritized over restoration of land not already scheduled for disturbance by infrastructure projects.
10 References
Abella SR, Newton AC. Fernandez-Bernal A, De La Rosa MA. Arid Environments and Wind Erosion. Nova Science Publishers Inc.; Hauppauge, NY, USA: 2009. A systematic review of species performance and treatment effectiveness for revegetation in the Mojave Desert, USA; pp. 45–74.
Bowers, J. E., Webb, R. H., & Rondeau, R. J. 1995. Longevity, recruitment and mortality of desert plants in Grand Canyon, Arizona, USA. J. Veg. Sci. 6: 551-564.
Lovich JE, Bainbridge D. Anthropogenic degradation of the southern California desert ecosystem and prospects for natural recovery and restoration. Environmental Management 1999; 24:309–326.
Webb RH, Steiger JW, Newman EB. US Geological Survey Bulletin 1793. US Government Printing Office; Washington, DC, USA: 1988. The response of vegetation to disturbance in Death Valley National Monument, California.
III. The Critical Relationship Between Undisturbed California Desert Lands and Carbon Sequestration
Michael F. Allen, Ph.D.
Distinguished Professor Emeritus, Department of Microbiology and Plant Pathology, University of California, Riverside.
A microphyll woodland that was later denuded for a utility-scale solar energy facility. While individual trees and shrubs are small aboveground, belowground their roots expand horizontally and vertically, filling the interspaces and reaching to depths of tens of meters. These deep-rooted plants are also very long-lived, sequestering carbon for hundreds to thousands of years. One clonal creosote shrub was measured as 22 by 8 meters across, and was over 11 thousand years old. • Carbon fixation and allocation in microphyll woodlands and creosote shrubland is relatively insensitive to local precipitation due to the access that these vegetation types have to two alternate sources of water: moisture from large rain events even miles away that saturate the soil,
11 and access to groundwater by deep roots. These factors allow plants in microphyll woodlands and creosote bajadas to photosynthesize and sequester carbon throughout the seasons even without local precipitation. Although highly variable annually, measurements of net ecosystem exchange [NEE] in mesquite stands through a growing season can exceed 200 kilograms of carbon per hectare per year (kgC/ha/y) and net ecosystem exchange of creosote bajada scrub can exceed 1,000 kgC/ha/y. Our back-of-the-envelope conservative estimates suggest that these two vegetation types could sequester an average of 1.5 million tons of C per year. [By comparison, NEE during a wet year in Baja California was 520 kgC/ha/y with a sky island coniferous forest above southern California desert at 300 kgC/ha/y, a 100-year-old chaparral during a wet year of 520 kgC/ha/y, and drought year of 180 kgC/ha/y, the La Selva tropical rainforest of 1,000 kgC/ha/y (dry year)/3,000 kgC/ha/y (average)/5,000 kgC/ha/y (wet year), and a boreal forest 780 kgC/ha/y]. In deserts, the organic carbon of the ecosystem turns over on an average of 38 years, with soil and sediments turning over on a 200-year average. This contrasts with a temperate forest of 25 and 55 years, respectively; a cropland turnover of 22 and 40 years, respectively; and a perennial grassland turnover of 36 and 100 years, respectively. Desert organic carbon once fixed stays in the system longer than in other ecosystems, releasing back to the atmosphere slowly.
However, unlike the large storage of organic C in most ecosystems, much of the desert total carbon is stored as calcites, generated by respiration.
• Calcites, layered into caliche, form from autotrophic respiration from deep roots and symbiotic microbes, and from heterotrophic respiration of the transferred organic matter. If buried and undisturbed, this carbon can remain sequestered for millennia. We estimate that more than 262 million tons of C could be stored in California deserts as calcites. • Importantly, buried calcites are dissolved upon exposure to air and water. Upon exposure, the CO2 in calcium carbonates can be released from disturbed soils up to 2.4 gC/m2/day, or 24 kgC/ha/day following a precipitation event.
• We suggest a new C sequestration modeling approach to validate and close the desert carbon budgets using an ecohydrology approach, incorporating deeper water use and using normalized difference vegetative index {NDVI} rather than precipitation as a driver of CO2 fixation, and linking the NEE to deep C sequestration.
Conclusion
• Large-scale disturbance of deserts, particularly within critical ecosystems such as creosote bajadas and microphyll woodlands, has the potential to reduce not only California's biodiversity, but also a source of long-term carbon sequestration, releasing calcite carbon stored for millennia.
IV. Overview of Carbon Sequestration Process in Desert Ecosystems Robin Kobaly, M.S. Biology and Plant Ecology, University of California, Riverside Executive Director, The Summertree Institute
What drives carbon capture and storage in deserts?
The combination of a hot, dry climate, and dynamic plant adaptations to that extreme climate has created a unique pathway for the capture and storage of carbon (carbon sequestration) in deserts. Sparse rainfall has resulted in desert soils that are abundant in minerals such as calcium, but low in nutrients like nitrogen necessary for plant growth. That sparse rainfall, combined with hot, dry surface soils, has enticed many desert plants to grow exceptionally long roots to reach deep soils that still hold moisture from rain
12 events from years past and possibly from miles away, or even deep enough to reach down to groundwater.
Root partners like fungi and bacteria living on or within those deep-rooted desert plants absorb and share resources with their plant host, helping their plant partners overcome the minimal presence of water and nutrients. These pressures, adaptations, and partnerships all work together to create an unexpected mechanism for extremely long-term carbon storage – and carbon capture that can continue even when we least expect it: when rainfall is just a memory across the desert.
How does the desert capture and store carbon?
While desert plants do capture and store carbon aboveground in foliage and woody tissue, they store much of their captured carbon deep underground in a massive network of connected roots and fungal root-partners, unlike forests which store most of their carbon aboveground or near the soil surface. Some of this carbon is stored in the tiny but numerous filaments of root-partnering fungi, called mycorrhizal fungi, that live in partnership with plant roots. The filaments, or mycelia, of one large group of these mycorrhizal fungi are coated with a “sealant” called glomalin made from carbon that was captured aboveground by the plant host. Because there can be so many miles of fungal hyphae (covered with glomalin) in each cubic foot of desert soil, glomalin is attributed with storing one-third of the world’s soil organic carbon.
Much of the carbon these plants capture aboveground from the air and convert into sugar is eventually turned into inorganic carbon underground. When the long roots breathe out (respire) carbon dioxide deep into dark moist soil, this carbon dioxide combines with the abundant calcium in our arid soils to create mineralized deposits called calcite (calcium carbonate), or “caliche” when it forms into layers. These deposits start as tiny crystals but eventually grow to large crystals, then chunks, and into layers of caliche that can start at the soil surface or form at various depths underground. These calcite/caliche deposits can store captured carbon in this inorganic form for hundreds, to thousands, to even hundreds of thousands of years…if not disturbed.
Where does carbon sequestration occur in deserts?
Historically, much of the desert’s “soil organic carbon” has been missed by soil scientists, because many soil studies conclude at “plow-line depth,” or between 6 and 12 inches. These studies aren’t of much relevance in the desert because most of the carbon that desert plants capture is stored extremely deep in the soil. Roots of most (non-succulent) desert plants grow incredibly deep, up to ten times longer than the plant is tall in their critical quest to find soil moisture, and the subterranean biomass of this network of deep roots is filled with organic carbon. A veritable inverted “forest” of root mass holds carbon deep underground in desert soils. These deep roots and their connected fungal root partners continuously breathe out carbon dioxide from just below the soil surface down to as much as 150 feet (over 40 meters), or down to groundwater. That exhaled carbon, in contact with calcium and moisture, is eventually converted underground into calcium carbonate (calcite) crystals which can form into layers of caliche, capable of storing that carbon for millennia.
When does carbon sequestration happen in deserts?
Carbon is captured wherever desert plants grow, but the level and timing of that capture varies with the types and distribution of those plants across the landscape. Desert grasslands and areas with shallowrooted shrubs and cacti capture carbon in response to rain events; in these habitats, carbon accumulation after precipitation can be as high as in wetter ecosystems. Habitats with deep-rooted plants, such as
13 microphyll woodlands (dry washes with small-leaved trees like palo verde, mesquite, and ironwood), as well as creosote bajada scrub (broad alluvial slopes with creosote bushes) can continue to photosynthesize and capture carbon long after rain events. Because of their long roots that reach to deep, percolated water from previous rain events (possibly occurring miles away), or even reaching down to groundwater, these stands of desert plants can extend their carbon fixation long into drought cycles.
These factors allow plants in microphyll woodlands and creosote bajadas to photosynthesize and sequester carbon throughout the seasons even without local precipitation.
How much carbon is captured and stored in the desert?
Scientists are currently working on ways to measure deeply buried carbon across vast landscapes like the California Desert that are highly diverse in topography, soils, climate, and vegetation. Carbon-storing calcite/caliche deposits are distributed in patches in some places and in vast layers in others. Also, these deposits are distributed at varying soil levels depending upon rainfall and the depth of desert plant roots that can deposit carbon all the way down to groundwater. Arriving at a total value for stored underground carbon in a diverse desert is much more challenging than for other more homogeneous landscape types.
However, we do have data that measures how much carbon is accumulated by plants in some specific desert habitats, and can compare capture rates to other ecosystems around the planet.
The primary gauge of an ecosystem’s carbon sink potential is the net exchange of carbon between the ecosystem and the atmosphere, i.e., the carbon balance of the land, or how much carbon comes in versus how much carbon goes out. This measurement is called “net ecosystem exchange,” or NEE. By comparing the carbon balance of diverse ecosystems, we can get an idea of the relative strength of each ecosystem’s carbon sink capacity. Dr. Michael Allen has summarized NEE measured within various ecosystems worldwide. He compared them to those measured across two vegetation types thought to sequester significant amounts of carbon in the California desert (microphyll woodlands, which can contain mesquite, and creosote bajada scrub). As shown in the table below, the carbon sink capacity of creosote bajada scrub rivals that of a tropical rainforest or boreal forest. Even microphyll woodlands are in the range of coniferous forests in southern California. The combined two desert vegetation types, microphyll woodland and creosote bajada scrub (just two of many vegetation types in the California desert), could sequester an average of 1.5 million tons of carbon per year.
Net Ecosystem Exchange Rate kilograms Carbon per
hectare per year
Sky island coniferous forest in southern California desert 300 100-year-old chaparral during a wet year 520
100-year-old chaparral during a drought year 180
La Selva tropical rainforest (wet year) 5000
La Selva tropical rainforest (dry year) 1000
Boreal forest 780
Mesquite stands (microphyll woodland) in California desert 200+ Creosote bajada scrub in California desert 1000+
14 What happens to stored carbon if we disturb desert soils? Despite its long-term storage capacity, caliche releases its sequestered carbon when vegetation is removed and soils are disturbed and exposed to erosion. As caliche degrades in disturbed soils, its calcium and carbon molecules are uncoupled, releasing the carbon to reenter the atmosphere as carbon dioxide.
Why care?
We risk losing massive accumulations of carbon stored underground as calcite/caliche if the desert soil surface is disturbed. This carbon capture and storage system is functioning now and will continue to capture and store carbon if soils are not disturbed. Most of the caliche in our desert soils was actually formed during the Pleistocene when the climate supported more dense and productive vegetation. In fact, Dr. Michael Allen at the UCR Center for Conservation Biology commented on the desert’s capacity to store large amounts of carbon dioxide as caliche, noting that, “The amount of carbon in caliche, when accounted globally, may be equal to the entire amount of carbon as carbon dioxide in the atmosphere.”
Removal of carbon from our atmosphere is now being considered an important component of fighting climate change. The synthetic conversion of excess atmospheric carbon dioxide to calcite and storing it underground is gaining much attention and funding (although with major technical difficulties). Our deserts are performing this conversion every day, automatically, without any input from humans, and it will continue that unaided sequestration and long-term storage if simply left undisturbed.
V. Quantification of Carbon Sequestration in the Desert Carbon and California Deserts: June 2023.
Michael F. Allen, Ph.D.
Distinguished Professor Emeritus, Department of Microbiology and Plant Pathology, University of California, Riverside.
Arid lands worldwide have sequestered carbon (C) for millennia. Human–caused perturbations of deserts alter this balance and risk releasing significant amounts of CO2 to the atmosphere, exacerbating global warming. Although the net primary production in California Desert Ecosystems is generally low, there remains a net positive carbon sequestration in wildland ecosystems, particularly across desert bajadas and microphyll woodlands.
There remains a view that, because of low precipitation, high temperatures, and sparse vegetation, hot deserts of southern California are of limited value to carbon sequestration.
However, our deserts contain a very large carbon sink. Laid down over thousands of years, desert C is more dynamic and sensitive to disturbance than is often acknowledged. As Martin and colleagues (Martin et al. 2021) noted:
"Although equilibrium is often assumed between soil carbon dioxide and groundwater, disequilibrium may result from heterogeneous distributions of recharge, flow paths, and respiration often seen in the carbonate critical zone. Understanding the controls of this disequilibrium, which drives carbon dioxide dissolution or evasion and alters pH, weathering reactions, and carbonate mineral dissolution or precipitation, is critical in linking the carbonate critical zone to the global climate system."
15 Below, I outline the basis for our concerns with the loss in natural wildland deserts because of its importance in the global atmospheric carbon budget as well as the associated loss of biodiversity (Hernandez et al. 2015).
CO2 fixation. Due to the low leaf area, one assumption made by large-scale ecosystem models is that deserts fix carbon at relatively low rates. But when water is available, leaves of desert plants photosynthesize at the same rates as in other ecosystems, and leaves can grow rapidly with soil moisture. Broadly, and especially during drought, rates of flux, net ecosystem exchange (NEE), across scales measured by techniques such as eddy flux, are often low but highly variable. At Deep Canyon during a series of dry years, our NEE was slightly positive. Alternatively, from the desert free air CO2 enrichment (FACE) research project, under ambient CO2 conditions, NEE was estimated up to 1.27 metric tons of carbon per hectare per year (MTC/ha/y) (Jasoni et al. 2005). The standing crop mass was 11 kg of carbon per hectare (kgC/ha), 80% of which was soil organic carbon (SOC) and sensitive to atmospheric CO2 levels, largely deposited as soil C (Evans et al. 2014). For the Sonoran desert ecosystem, NEE was estimated as ranging from 120 kg.of carbon per hectare during a dry season to 360 kg.of carbon per hectare during a wet season (Huxman et al. 2004). [By comparison, NEE for a wet year in a desert in Baja California was up to 520 kgC/ha/y, a sky island above southern California desert at 200 to 300 kgC/ha/y, a 100 year old Chaparral of 520 kgC/ha/y, and drought year of 180 kgC/ha/y, the La Selva tropical rainforest of 1,000 kgC/ha/y (dry year)/3,000 kgC/ha/y (average)/5,000 kgC/ha/y (wet year), and a boreal forest 780 kgC/ha/y].
From these desert NEE measurements, where is the additional carbon in deserts? Likely deep in the profile (see discussion in C sequestration). Desert grasslands and areas with shallow-rooted shrubs and cacti are coupled to precipitation and carbon accumulation depending on local precipitation. However, large pulses in precipitation provide groundwater that extends the length of active photosynthesis of deeply-rooted shrubs (greater than 50m) such as creosote and mesquite (Prosopis) (Huxman et al. 2004) and utilization of deep groundwater from storms generated far upstream can extend the carbon fixation of stands into drought cycles in deserts (Scott et al. 2006) and in the uplands such as the montane sky islands (Kitajima et al. 2013). Plants with shallow roots in deeper pools and in groundwater can access many sources of water in which to undertake photosynthesis and carbon accumulation (Querejeta et al. 2007, Querejeta et al. 2009). Reynolds and colleagues (Reynolds et al. 2004) challenged the simple "pulse-reserve" complex showing that in deserts, sequences of pulses are more important than individual events, and Weiss and colleagues (Weiss et al. 2004) found that Normalized Difference Vegetation Index (NDVI), using satellite imagery that visualizes greenness, showed that water from distant sources (groundwater) can extend photosynthetic activity (Bisigato et al. 2013, Rohde et al. 2021).
What is clear is that simple precipitation models are inadequate for assessing carbon sequestration in arid lands, riparian corridors, or any areas that have underground sources of water. Understanding and modeling Carbon requires a complex approach that integrates ecohydrology and plant morphologies (Gutiérrez-Jurado et al. 2006).
Where does the fixed CO2 go? Groundwater originates at higher elevations in complex terrain, traveling in subsurface flows to lower bajadas, providing moisture to creosote and microphyll woodlands. At these lower elevations, plants have very deep rooting systems from several meters down at least to 53m [174’] in the case of honey mesquite, Prosopis juliflora, (Canadell et al. 1996) and down into the caliche layer in the case of creosote, Larrea tridentata (Barbour 1969), sometimes growing through cracks and extending below the caliche layers and affecting water fluxes and soil development (Gutiérrez-Jurado et al. 2006).
Because they can utilize the deep groundwater, shrub photosynthesis extends beyond the local precipitation season (Ávila-Lovera et al. 2017). Isotopic signature data from my group at Deep Canyon showed that the deep-rooted shrubs acquired between 69% and 87% of their water for photosynthesis from groundwater (M. Allen unpublished data). Others (Ogle et al. 2004) have shown that the water through the stem could well be used to model water uptake profiles, and thereby provide estimates of stored soil water use, and thereby assess the SOC buried deep in the profile.
16 This deeper C is the reason for some of the slow turnover of SOC and for the formation of calcites (discussed below).
C sequestration. In terrestrial ecosystems, there are three forms of sequestered C to be considered. The first is easier to estimate and model, and that is aboveground herbaceous and woody tissue, with some estimates providing belowground tissue C as well. At the global scale, current aboveground biomass is 349 Pg, belowground 92 Pg, totaling 441 Pg C (Walker et al. 2022). The second is the soil organic carbon (SOC), globally equaling 3,037 Pg C, or more than 8 times the estimated aboveground carbon, and nearly 7 times the total standing crop biomass.
If we use a NEE figure of 200 kgC/h/y (see CO2 fixation section) for creosote and for microphyll woodlands, we can begin to estimate at least the C accumulation for desert ecosystems. There are 2.47 acres per ha. Using the CA 4th Climate Change Assessment for the Inland Desert Area, there are 489,423 acres of microphyll woodland and 17,466,886 of creosote. Using this estimate, that would amount to an average of 1.5 million tons of carbon accumulated by these two vegetation types annually.
Using the EPA Level III Ecoregions map, that would amount to 1.88 million tons of carbon. These estimates are in the range for coniferous forests or oak woodlands in southern California.
There are large gaps, such as between the NEE of Jasoni and Huxman. If 80% of the carbon (C) is allocated belowground to a meter in depth (Evans et al. 2014), and a large fraction is transported deep, then the overall carbon accumulation will be underestimated. In isotopic studies, soil calcite values show evidence of C recycling in soil (Schlesinger 1985, Allen et al. 2013) above the caliche layers, suggesting extensive C recycling. C is transferred downward via roots deep into the profile (sometimes more than 50m). Respiration of roots and symbiotic microbes (autotrophic respiration) and decomposers (heterotrophic respiration) produces CO2. Add water (ground water or surface precipitation) and calcium (Ca)-derived upslope from basalts, limestone, marble or dolomite -- and some of that CO2 is bound into calcites, the most stable of which is CaCO3. Because the process is a dynamic equilibrium, add water again, and exposed calcite can be re-solubilized. Some of the CO2 is volatilized back to the atmosphere and the Ca moves downward with the water. That Ca rebinds with newly respired CO2 in the deeper layer, again forming calcite. The deeper the process occurs, the higher the CO2 concentration. The process continually repeats itself to the maximum depth that water travels (forming a caliche layer), or to groundwater. Surface measurements, such as from eddy covariance techniques, are highly variable as the environmental conditions are fickle even within the footprint of the sensors, and for sensitivity to assumptions regarding fetch and topography. Most comprehensive soil carbon measurements (from soil cores) to date are constrained to the top meter of the soil.
Further, to understand sequestration, we must also incorporate carbon turnover. For example, despite enormous production, tropical rainforests have fast rates of decomposition resulting in a rapid turnover, thereby returning the fixed carbon back to the atmosphere. In wet tropics, the average turnover for vegetation is 15 years, and soil organic carbon (SOC) 27 years. Temperate forests vegetation turns over on average every 25 years, and the SOC in 55 years (Reichle 2020). Desert vegetation turns over every 38 years, but the SOC turns over on a 200-year span. Moreover, carbonates, when buried, can remain for millennia, but upon exposure, will volatilize releasing CO2 to the atmosphere.
The soil carbon component is complex, but there are indicators that deserts may sequester SOC in many complex forms. As an initial example, in the Mojave Desert under Creosote (Larrea tridentata) canopy, the arbuscular mycorrhizal fungal standing crop was 423 kgC/ha (and 635 kgC/ha under elevated CO2). It is very challenging to determine the hyphal lifespan, critical to estimating C sequestration, as literature values range from 5 days (Staddon et al. 2003) to 145 days (Treseder et al. 2010). Currently other efforts to estimate turnover are being undertaken by Allen from image data already collected. Much of the variation is probably due to responsiveness of fungal hyphae to individual precipitation events at daily to seasonal scales (Hernandez and Allen 2013). An example is glomalin, a glycoprotein complex produced largely by arbuscular mycorrhizal fungi, that has a long retention span (Rillig et al. 1999, Allen 2022).
Glomalin is known to accumulate due to a slow turnover, (measured using immunoreactive soil protein
17 (IRSP), and can be as much as 40 µg/g soil (Clark et al. 2009). Using a 2m rooting depth, this means that there may be 2 metric tons of glomalin protein per ha across the extensive creosote shrubland soils, representing a significant pool of SOC.
Calcites/Caliche Carbon. Carbonates may be relatively unimportant to the global C cycle over a time scale of millions of years, as precipitation and dissolution is continuous. However, at time scales of decades to centuries, the inorganic carbon (Ci), is often in disequilibrium and can dramatically impact the carbon cycle (Martin 2017). At a global scale, as much as 940 Pg Ci is sequestered as soil calcium carbonate (or calcite) with as much as 1404 Pg C as bicarbonate in groundwater, more than all the soil organic C (1530 Pg C), and well more than the 594 Pg C of standing plant biomass (Monger et al. 2015).
Chuckwalla, Gunsight and Cherioni soils contain extensive layering of calcites, and even Carsitas soils have carbonate coatings on the surface of rocks. In the Chuckwalla Valley, for example, estimates ranged from 36 metric tons of carbon/hectare to 82 metric tons of carbon/hectare. Using the smaller figure, and assuming that calcites underlie much of the creosote and microphyll woodlands (14.6 tons of carbon/acre), then a conservative estimate is that there could be as much as 262 million tons of carbon stored deep in desert soils.
Moreover, produced at approximately 4 kgC/ha/y, the buried calcite-C becomes relatively stable.
Schlesinger (1985) estimated that the CaCO3 in the Chuckwalla Valley was formed during the Pleistocene, between 15,000 and 20,000 years ago, and an 85,000-year residence time appears to be relatively accurate. However, upon disturbance, loss rate appears to be significant over annual to decadal time scales, as much as 10 kgC/ha/wet day (Swanson 2017).
The conversion of CO2 to calcite is considered important enough that considerable effort is being undertaken to synthetically convert atmospheric CO2 to calcite (Pogge von Strandmann et al. 2019), the process that desert plants undertake every day.
The Mechanism in deserts. Both roots and microorganisms respire CO2: then CO2 and H2O (water) combine to form HCO3
- and an H+ ion, acidifying the soil. Upon encountering Ca2+ dissolved in soil water, HCO3
- binds to the Ca to form CaCO3, a large fraction of which precipitates to form calcite (limestone, CaCO3), or upon layering, caliche.
Accessing groundwater acquired by deep roots of specialized desert plants. Roots can go down tens of meters to acquire water (Canadell et al. 1996, Jackson et al. 1999). At the interface of the water table, microbial activity may dramatically increase. Just above the water table, arbuscular mycorrhizae search for phosphorus and other nutrients, in part to sustain dinitrogen fixation (with high respiration rates) occurring in the groundwater (anaerobic) by associated bacteria that provides the nitrogen for these ecosystems (Virginia et al. 1986). Mycorrhizae increase respiration of CO2 (Knight et al. 1989) as well as sequestering organic C (Rillig et al. 1999).
Groundwater in western deserts is notorious for being hard, that is, having high concentrations of CaCO3.
As it is pumped up for use, CaCO3 dissociates, releasing CO2 (Wood and Hyndman 2017). They estimated that groundwater depletion could account for a measurable fraction of annual CO2 emission. As caliche is exposed to the atmosphere, caliche degrades releasing CO2 (Hirmas and Allen 2007). One assumption is that because Ca2+ remains in the soil, re-association with HCO3 - will occur (Mills et al.
2020). This certainly will be the case in a closed system (such as a laboratory beaker). But in an open ecosystem, equilibrium remains an open question and is in need of further examination (Leij et al. 1999, Martin 2017, Gallagher and Breecker 2020, Martin et al. 2021). On the surface, CaCO3 equilibrates with CO2 at ~400 ppm, the current atmospheric CO2 level (Hirmas et al. 2010), but soil CO2 where most exchange occurs can range up to 3,000 ppm (Allen et al. 2013), likely accounting for deposition of caliche beds (Schlesinger 1985). Rhizosphere CO2 levels (in the soil rooting zone) can exceed 3,000 ppm in undisturbed soil, but drop in devegetated lands, only increasing CO2 loss from CaCO3 dissolution (Allen et al. 2013). Deep in groundwater, CO2 bound as CaCO3 can exceed 190 mg/L (DeSimone et al. 2009), degassing as it is pumped out (Wood and Hyndman 2017). Surface isotopic values of caliche show that
18 there is a fractionation in the caliche C, indicating that exchange (losses or gains in caliche C) is occurring (Allen et al. 2013, Mills et al. 2020). The conversion of land to agriculture and tree production is resulting in a shallowing of rooting depths nationwide along with a loss of deep root functioning (Billings et al. 2018).
Summary: Concerns.
Adding the dynamics of calcites to the slow SOC turnover demonstrates why the overall C cycling becomes extremely challenging to quantify, especially across long time scales and an area as diverse and large as the California desert. Loss of NEE from California deserts would amount to a significant loss of carbon in addition to loss in California's biodiversity.
But our largest concern is the risk of losing massive accumulations of carbon, stored underground as calcite-C. This C capture and storage system is functioning now and will continue to capture and store C for long time periods if soils are not disturbed. In the Chuckwalla Valley of the California deserts, C as CaCO3 was 8 kgC/m2, within the top 1.35 m of soil (Schlesinger 1985) in one profile and 3.5 kgC/m2in a second. CaCO3 can be found across the valley. Assuming an average of 6 kgC/m2, there could be 60 metric tons of C per ha of microphyll woodland/creosote bush in the surface soils. A large fraction of the Chuckwalla Valley creosote bush and microphyll woodland has already been stripped of vegetation for a single solar development.
It is always challenging to extrapolate beyond the actual locations of measurements. However, existing datasets support this concern. Schlesinger (1985) raised the issue that disturbance of desert caliche C was of concern to C budgets. When we examine soils maps, the bajadas and microphyll woodlands have high concentrations of soil CaCO3, across Chuckwalla, Gunsight and Cherioni soils. These soils are alluvial soils, often with a calcic horizon ranging from 25 cm to more than a meter deep, and often with creosote scrub vegetation fingering into microphyll woodlands. These soils extend from almost every mountain range in the California deserts. So, this is our best estimate.
Cherioni (105)
Denure (67)
Tecopa (83)
Rositas (71) Rositas (69)
Carsitas (100)
Rositas (92)
Cherioni (17) Gunsight (96)
Ligurta (115)
Tecopa (37)
Gunsight (14)
Rositas (15)
Myoma (117) Aco (34)
Tecopa (13)
Tecopa (88)
Lithic Torriorthents (80)
Tecopa (18)
Water (133) Gunsight (131)
Tecopa (56)
Tecopa (19)
Tecopa (40)
Gunsight (36)
Gunsight (48)
Chuckawalla (124)
Arrastre (84)
Rositas (72)
Gunsight (41)
Lithic Torriorthents (1)
Cherioni (7)
Gunsight (68)
Tecopa (53)
Gunsight (4)
Rositas (93)
Niland (134)
Gunsight (5)
Laposa (3)
Gunsight (54) Cherioni (136)
Rositas (104)
Tecopa (31) Calvista (26)
Greenfield (77)
Gunsight (22)
Carsitas (130)
Tecopa (23)
Gunsight (6)
Laposa (8)
Lithic Torriorthents (86)
Tecopa (29)
Bryman (90)
Hyder (55)
Gunsight (12)
Nickel (85)
Cajon variant (106)
Cherioni (102)
Lithic Torriorthents (95) Calvista (99)
Rock outcrop (118)
Badland (51)
Chuckawalla (107)
Gunsight (24)
Lithic Torriorthents (30)
Badland (43)
Calvista (25)
Tecopa (28)
Chuckawalla (119)
Dune land (70)
Rositas (45)
Rositas (16)
Tecopa (50)
Badland (59)
Hyder (63)
Lithic Torriorthents (38)
Tecopa (2)
Chuckawalla (60)
Gunsight (114)
Cherioni (21)
Gunsight (44)
Laposa (10)
Upspring (52)
Rositas (112)
St. Thomas (20)
Tecopa (11)
Playas (27)
Tecopa (87)
Gunsight (42)
Upspring (62)
Cajon (109)
Gunsight (46)
Tecopa (9)
Calvista (0)
Badland (61)
Rositas (49)
Tecopa (76)
Rositas (32)
Gunsight (35)
Upspring (66)
Playas (39)
Tecopa (81)
Carsitas (125)
Playas (33)
Bryman (79)
Gunsight (108)
Nickel (94)
Bryman (78)
Schenco (97) Gunsight (98)
Tecopa (73)
Lithic Torriorthents (89)
Aco (58) Cajon variant (135)
0 10 20 30 40 50 Miles
0 10 20 30 40 50 60 70 80 Kilometers
US Soil Map for East Riverside County
compname id# caco3_l caco3_r caco3_h
Rositas 15 - - -
Cherioni 17 0 3 5 Gunsight 36 4 6 8 Gunsight 96 4 6 8
Cherioni 105 0 3 5 Quantity of Carbonate (CO3) in the soil expressed as CaCO3. Weight percentage of the less than 2 mm size fraction
19 Other maps, such as the SSURGO Soil data for Coachella Valley show high calcite concentrations in the bajadas and in the desert washes north of the Salton Sea, but south of the Salton Sea, where agriculture predominates, that calcite is largely gone, except for some upper edges.
Our final concern is that with increasing disturbance of desert soils by utility-scale solar energy [USSE] there will be a loss of the high biodiversity of California's deserts. We are especially concerned with a direct loss in microphyll woodlands and desert bajadas, and in a potential for the decrease in the linkages between these vegetation types and the uplands where Ca and water inputs occur. Both biodiversity and regulation of carbon cycling will be impacted, to date with unpredictable consequences. The more we learn and apply understanding of the soil carbonate dynamics (Martin et al. 2021) to managing for biodiversity and carbon cycling, the better we will be able to manage desert lands to reduce greenhouse gas production and sustain our biodiversity (Allen and Mishler 2022).
References
Allen, M. F. 2022. Mycorrhizal Dynamics in Ecological Systems. Cambridge University Press, Cambridge.
Allen, M. F., G. D. Jenerette, and L. S. Santiago. 2013. Carbon balance in California Deserts: Impacts of widespread solar power generation., California Energy Commission Publication Number CEC500-2013-063.
Allen, M. F., and B. D. Mishler. 2022. A Phylogenetic Approach to Conservation: Biodiversity and Ecosystem Functioning for a Changing Globe. Pages 155-177 in B. Swartz and B. D. Mishler, editors. Speciesism in Biology and Culture: How Human Exceptionalism is Pushing Planetary Boundaries. Springer International Publishing, Cham.
Ávila-Lovera, E., A. J. Zerpa, and L. S. Santiago. 2017. Stem photosynthesis and hydraulics are coordinated in desert plant species. New Phytologist 216:1119-1129.
Barbour, M. G. 1969. Age and space distribution of the desert shrub Larrea Div Aricata. Ecology 50:679- 685.
Billings, S. A., D. Hirmas, P. L. Sullivan, C. A. Lehmeier, S. Bagchi, K. Min, Z. Brecheisen, E. Hauser, R.
Stair, R. Flournoy, and D. D. Richter. 2018. Loss of deep roots limits biogenic agents of soil development that are only partially restored by decades of forest regeneration. Elementa-Science of the Anthropocene 6.
Canadell, J., R. B. Jackson, J. R. Ehleringer, H. A. Mooney, O. E. Sala, and E.-D. Schulze. 1996.
Maximum rooting depth of vegetation types at the global scale. Oecologia 108:583-595.
Clark, N. M., M. C. Rillig, and R. S. Nowak. 2009. Arbuscular mycorrhizal fungal abundance in the Mojave Desert: Seasonal dynamics and impacts of elevated CO2. Journal of Arid Environments 73:834- 843.
DeSimone, L. A., P. A. Hamilton, and R. J. Gilliom. 2009. The quality of our nation’s waters- Quality of water from domestic wells in principal aquifers of the United States, 1991-2004- Overview of major findings.
Evans, R. D., A. Koyama, D. L. Sonderegger, T. N. Charlet, B. A. Newingham, L. F. Fenstermaker, B.
Harlow, V. L. Jin, K. Ogle, S. D. Smith, and R. S. Nowak. 2014. Greater ecosystem carbon in the Mojave Desert after ten years exposure to elevated CO2. Nature Climate Change 4:394-397.
Gallagher, T. M., and D. O. Breecker. 2020. The Obscuring Effects of Calcite Dissolution and Formation on Quantifying Soil Respiration. Global Biogeochemical Cycles 34.
Gutiérrez-Jurado, H. A., E. R. Vivoni, J. B. J. Harrison, and H. Guan. 2006. Ecohydrology of root zone water fluxes and soil development in complex semiarid rangelands. Hydrological Processes 20:3289-3316.
Hernandez, R. R., and M. F. Allen. 2013. Diurnal patterns of productivity of arbuscular mycorrhizal fungi revealed with the Soil Ecosystem Observatory. New Phytologist 200:547-557.
Hernandez, R. R., M. K. Hoffacker, M. L. Murphy-Mariscal, G. C. Wu, and M. F. Allen. 2015. Solar energy development impacts on land cover change and protected areas. Proceedings of the National Academy of Sciences of the United States of America 112:13579-13584.
Hirmas, D. R., and B. L. Allen. 2007. Degradation of pedogenic calcretcs in West Texas. Soil Science Society of America Journal 71:1878-1888.
20 Hirmas, D. R., C. Amrhein, and R. C. Graham. 2010. Spatial and process-based modeling of soil inorganic carbon storage in an arid piedmont. Geoderma 154:486-494.
Huxman, T. E., K. A. Snyder, D. Tissue, A. J. Leffler, K. Ogle, W. T. Pockman, D. R. Sandquist, D. L.
Potts, and S. Schwinning. 2004. Precipitation pulses and carbon fluxes in semiarid and arid ecosystems. Oecologia 141:254-268.
Jackson, R. B., L. A. Moore, W. A. Hoffmann, W. T. Pockman, and C. R. Linder. 1999. Ecosystem rooting depth determined with caves and DNA. Proceedings of the National Academy of Sciences 96:11387-11392.
Jasoni, R. L., S. D. Smith, and J. A. I. Arnone. 2005. Net ecosystem CO2 exchange in Mojave Desert shrublands during the eigth year of exposure to elevated CO2. Global Change Biology 11:749- 756.
Kitajima, K., M. F. Allen, and M. L. Goulden. 2013. Contribution of hydraulically lifted deep moisture to the water budget in a Southern California mixed forest. Journal of Geophysical ResearchBiogeosciences 118:1561-1572.
Knight, W. G., M. F. Allen, J. J. Jurinak, and L. M. Dudley. 1989. Elevated carbon-dioxide and solution phosphorus in soil with vesicular-arbuscular mycorrhizalwestern wheatgrass. Soil Science Society of America Journal 53:1075-1082.
Leij, F. J., J. Šimůnek, D. L. Suarez, and M. T. van Genuchten. 1999. Nonequilibrium and Multicomponent Transport Models. Pages 405-430 Agricultural Drainage.
Martin, J. B. 2017. Carbonate minerals in the global carbon cycle. Chemical Geology 449:58-72.
Martin, J. B., P. C. De Grammont, M. D. Covington, and L. Toran. 2021. A new focus on the neglected carbonate critical zone. Eos 102.
Mills, J., L. Lammers, and R. Amundson. 2020. Carbon balance with renewable energy: Effects of solar installations on desert soil carbon cycle., California Emergy Commission Publication Number:
CEC-500-2020-075.
Monger, H. C., R. A. Kraimer, S. Khresat, D. R. Cole, X. J. Wang, and J. P. Wang. 2015. Sequestration of inorganic carbon in soil and groundwater. Geology 43:375-378.
Ogle, K., R. L. Wolpert, and J. F. Reynolds. 2004. Reconstructing plant root area and water uptake profiles. Ecology 85:1967-1978.
Pogge von Strandmann, P. A. E., K. W. Burton, S. O. Snæbjörnsdóttir, B. Sigfússon, E. S. Aradóttir, I.
Gunnarsson, H. A. Alfredsson, K. G. Mesfin, E. H. Oelkers, and S. R. Gislason. 2019. Rapid CO2 mineralisation into calcite at the CarbFix storage site quantified using calcium isotopes. Nature Communications 10:1983.
Reichle, D. E. 2020. Chapter 8 - Energy flow in ecosystems. Pages 119-156 in D. E. Reichle, editor. The Global Carbon Cycle and Climate Change. Elsevier.
Rillig, M. C., S. F. Wright, M. F. Allen, and C. B. Field. 1999. Rise in carbon dioxide changes in soil structure. Nature 400:628-628.
Schlesinger, W. H. 1985. The formation of caliche in soils of the Mojave-desert, California. Geochimica Et Cosmochimica Acta 49:57-66.
Scott, R. L., T. E. Huxman, W. L. Cable, and W. E. Emmerich. 2006. Partitioning of evapotranspiration and its relation to carbon dioxide exchange in a Chihuahuan Desert shrubland. Hydrological Processes 20:3227-3243.
Staddon, P., C. Ramsey, N. Ostle, P. Ineson, and A. Fitter. 2003. Rapid turnover of hyphae of mycorrhizal fungi determined by AMS microanalysis of 14C. Science 300:1138-1140.
Swanson, A. C. 2017. Disturbance, restoration, and soil carbon dynamics in desert and tropical ecosystems. University of California-Riverside.
Treseder, K. K., J. P. Schimel, M. O. Garcia, and M. D. Whiteside. 2010. Slow turnover and production of fungal hyphae during a Californian dry season. Soil Biology & Biochemistry 42:1657-1660.
Virginia, R. A., M. B. Jenkins, and W. M. Jarrell. 1986. Depth of root symbiont occurrence in soil. Biology and Fertility of Soils 2:127-130.
Walker, W. S., S. R. Gorelik, S. C. Cook-Patton, A. Baccini, M. K. Farina, K. K. Solvik, P. W. Ellis, J.
Sanderman, R. A. Houghton, S. M. Leavitt, C. R. Schwalm, and B. W. Griscom. 2022. The global potential for increased storage of carbon on land. Proceedings of the National Academy of Sciences of the United States of America 119.
Wood, W. W., and D. W. Hyndman. 2017. Groundwater Depletion: A Significant Unreported Source of Atmospheric Carbon Dioxide. Earth's Future 5:1133-1135.
21 VI. Modeling Carbon Sequestration in Our Deserts
Michael F. Allen, Ph.D.
Distinguished Professor Emeritus, Department of Microbiology and Plant Pathology, University of California, Riverside
Many modeling efforts purporting to describe C sequestration in deserts are problematic. They underestimate C accumulation, as they use precipitation drivers at the location of production. However, desert plants use water over longer terms from single large events, and uplift groundwater precipitated in mountains well away from the locations of primary production. We agree with others who have critiqued the California Air Resources Board [CARB] modeling as dramatically underestimating the C sequestration potential by ignoring large parts of the C cycle (CarbonCycleInstitute 2022). Currently, destruction of large wildland deserts for agriculture, mining, or for Utility-Scale Solar Energy (USSE) development is on-going or proposed for California deserts.
We know that traditional precipitation-based modeling for C sequestration is inadequate. However, is there a more useful approach? We argue that there is a more promising direction based on existing modeling approaches.
First, Normalized Difference Vegetation Index (NDVI) should be used to identify the land areas with photosynthetic activity and the duration of that activity (Rohde et al. 2021), not local precipitation. From the greenness activity, it should be feasible to estimate C fixation, replacing the precipitation driver for wet periods in models such as DAYCENT (Parton et al. 1998).
Second, an ECOHYDROLOGY model (Gutiérrez-Jurado et al. 2006) allows for estimating water transport and coupling soil properties (including calcite horizons) building on HYDRUS (Šimůnek et al. 2005).
HYDRUS can also be used with the equations described by Kitajima and colleagues (Kitajima et al. 2013) to quantify the additional timeframes for C gain using intermediate depth- and ground-water sources.
Third, the SLIC model (Hirmas et al. 2010) evaluates the transitions between Ca + CO2 + H2O <> CaCO3.
Fourth, once the water sources and time frames are identified, NEE measurements coupled with soil respiration measurements could provide spot-checks on modeled values.
This modeling approach can provide a comprehensive overview to help close the carbon cycle in the deserts. It is important that the confirmation measurements are based on a long-term dataset, and that, given CO2 and global temperature changes, two or more longer-term C cycling instrument facilities be deployed. The model as developed by the National Ecological Observatory Network (NEON), could serve as a model, and could be installed at field stations such as the NRS stations at the Granite Mountains and Boyd Deep Canyon, or the CSU Zzyzx station.
References: Please see previous section V.
VII. Mapping and Identifying Prioritized Areas of our Desert to Achieve Carbon Reduction Goals
Microphyll woodlands/Creosote
Colin Barrows. Co-founder, Cactus to Cloud Institute
In sections IV, V and VI above, Kobaly and Allen indicated the importance of two specific desert vegetation types in the desert region’s impressive capacity to store carbon. Kobaly notes the combined
22 carbon sequestration capacity of microphyll woodland and creosote bajada scrub could sequester an average of 1.5 million tons of carbon per year. Allen reports that these two vegetation types create a net positive carbon sequestration value within California’s desert ecosystem.
Section VI discussion around the relationship between groundwater and underground caliche formation (carbon sequestration) plays out across these two vegetation types. With the groundwater originating at higher elevations, it traverses in subsurface flows to lower elevations such as those where the creosote bajadas and microphyll woodlands are found. The vegetation types here have rooting systems that can run over 53m [174’] deep. Root systems of creosote can grow into the caliche layer and beyond to reach groundwater sources.
The dynamics of these two vegetation types are of particular interest in demonstrating high capacity for carbon sequestration, though they are not the only vegetation types nor the only means by which carbon may be sequestered within the desert ecosystem. But microphyll woodlands and creosote are of high interest in discussion of carbon sequestration in the desert, and this section identifies and quantifies which desert regions warrant high prioritization for conservation.
EPAIII CA Deserts boundary (DRECP) [Exterior Boundary]
CA Climate Assessment inland desert boundary (30x30) [Interior Boundary] Shrub/Scrub land cover for both areas in and
Microphyll woodland in
Small areas of lighter green outside the 30x30 area.
23 SUMMARY
Boundary Area Desert Vegetation Type Acres
CA 4th Climate Change
Assessment Inland Desert
Area [30X30] Boundary
Shrub Scrub Land Cover 13,300,107
EPA Level III Ecoregions,
Mojave and Colorado CA
Desert Area
Shrub Scrub Land Cover 18,715,754
Recommended acreage of conserved desert land for vegetation cover types microphyll woodlands and creosote bajadas.
It should be noted that these identified lands represent those areas recognized to be highest conservation priority for carbon sequestration function. These acreages represent only a partial opportunity to maximize carbon sequestration and protect biodiversity.
VIII. Additional benefits
Biodiversity in California’s deserts
Cameron Barrows, PhD. Conservation Ecologist, Emeritus. Center for Conservation Biology, University of California, Riverside
Pat Flanagan, B.A. Biology. California State University, Long Beach Board Member, Morongo Basin Conservation Association
California is by far the most biologically diverse of the United States’ contiguous 48 states, with deserts comprising roughly one third of California’s land surface. And yet California’s deserts, as well as deserts worldwide, tend to be overlooked in discussions of biodiversity. The dictionary definition of “desert” reflects the prevailing bias: “a large area of land that has very little water and very few plants growing on it”. Other descriptors include “wasteland,” “barren,” and “lifeless.” Desert is often used as a euphemism for a place where little or no life, food, or culture exists. Other than being arid, none of these perceptions is accurate.
One can test the hypothesis that California deserts are biologically depauperate. Covering one third of California, if species were randomly distributed, then we would expect about 33% of California’s plant and animal species to live in deserts. Values significantly less than 33% would support a belief that our deserts are, compared to elsewhere in California, lacking living things. On the other hand, if values are greater than 33%, then the assumption of our deserts being a barren wasteland would be categorically false.
While exact numbers will vary with shifting taxonomic classifications, California is the home of almost 2300 native annual herbaceous plants, over 3600 native perennial herbaceous (not woody) plants, over 1300 species of native shrubs, and just under 240 native tree species (using Calflora’s Consortium of Herbaria database).
Combining California’s three main deserts—the Great Basin, the Mojave, and the Colorado— along with the “sky island” mountains that are within or border those deserts, it was found:
24 55% of those native California annual herbaceous plants, 53% of perennial herbaceous plants, 60% species of shrubs, and 53% of those native tree species live in the California deserts.
Of the three deserts,
The Mojave has the highest plant species richness, with 49% of those native annual herbaceous plants, 44% of perennial herbaceous plants, 52% of shrub species, and 45% of those native California tree species.
Since this species richness is well above 33% in each of those plant categories, we can reject the hypothesis that California deserts have low biodiversity.
In the categories of annual herbaceous plants and shrubs, California deserts have more species than any other ecological region in California.
Our desert “wastelands” are not only richer from a vegetation standpoint, but they also appear to be incubators of speciation, with many species occurring nowhere else on earth. A recently published study, Pillay et al. (2022, Frontiers in Ecology and the Environment, vol. 20, issue 1) looked at patterns of vertebrate animal species richness across our planet. As expected, They found that the tropics ranked number one. However, deserts were the next most species-rich biome when it came to mammals, birds, and reptiles, higher than temperate forests, shrublands, and grasslands.
In California, reptile species richness is especially high in our deserts.
California has 40 species of native lizards that call our state home. Ninety percent of those can be found in our deserts, again, well above the expected 33% of lizards that were randomly distributed across California. At least six of those lizards are found nowhere else.
Some areas are especially species rich. Along with colleagues from the U.S. and Mexico, we looked at lizard species richness across North America and found nowhere else that compared to deserts in the number of species that occur together.
The top spot was the Coachella Valley at the edge of the Colorado and Mojave Deserts which has 33 lizard species within a 50 km [31.07 miles] radius circle. Of the 34 species of snakes found in California, 76% are found within desert habitats.
We do not have similar data sets for insects. However:
Native bee pollinators in the Joshua Tree National Park area are estimated to include more than 600 species representing 40 genera in 6 families.
And some insect families, such as darkling beetles (Tenebrionidae), specialize in living in arid habitats.
Darkling beetles are the clean-up crews in deserts. Technically detritivores, they eat dead matter, replacing the job fungi and bacteria do in moist environments. Several years ago, [Dr. C. Barrows] conducted a survey of darkling beetles living on the remaining sand dunes of the Coachella Valley. Across those dune fragments [Dr. C. Barrows] found 34 different darkling beetle species. Try to put that into perspective: Imagine finding a lake with 34 resident species of ducks, or a forest with 34 species of warblers, or a mountain range with 34 species of deer.
Beyond biodiversity, people also put value on superlatives such as the antiquity of individual plants or animals. In the Pacific Northwest, redwood trees can reach the advanced age of 3200 years. In the central Sierra Nevada range, giant sequoias can reach 2700 years of age, and in the White Mountains,
25 bristlecone pines can be up to 4800 years old. That’s impressive. But even more impressive is the oldest creosote bush, the most widely distributed desert shrub:
The King Clone creosote is 11,700 years old, an extreme superlative. There are also desert tortoises who can approach nearly 100 years of age.
Economic benefits
Susy Boyd, MNR, Master of Natural Resources, Oregon State University Public Policy Coordinator, Mojave Desert Land Trust
Land that is set aside for conservation holds potentially high economic value as a driver of tourism and recreation. The good news is that recreational use of public lands allows the land to remain largely undisturbed and continue to sequester carbon, thus fulfilling a dual mission while generating local business and tax revenue.
A 2014 report [ECONorthwest] noted economic contributions of Quiet Recreation Visits within 50 miles of recreation sites on BLM-managed lands within California. Total Direct Spending was $243,938,853. In inflation-adjusted dollars for 2023, that amount today would be $314,392,148.
Visit California’s Economic Impact of Travel report for 2021 indicated Local Tax Revenue of $293,000 for the state’s Desert Region, supporting community benefits such as safety, fire, recreation, and library services.
Courtesy of James M. Andre. Sweeney Granite Mountains Desert Research Center. [email protected]
26 References
The Economic Value of ‘Quiet Recreation’ on BLM Lands. 2017. Pew Charitable Trusts.
Economic Impact of Travel in California 2012-2021. Visit California. 2022. Dean Runyon and Associates.
Biocrusts in the desert
Robin Kobaly, M.S. Biology and Plant Ecology, University of California, Riverside Executive Director, The Summertree Institute
Overview:
~ Microscopic organisms living at and near the surface of arid soils produce glue-like substances that hold undisturbed desert soils together and prevent soil erosion ~ These living soils, called biocrusts, create and store valuable fertilizing nutrients for the surrounding plant community
~ Biocrusts, when kept intact, hold otherwise dangerous PM10 and PM2.5 particles and spores, such as Valley Fever, in the soil and out of the air, protecting people from breathing in these health-impacting pollutants
A thin surface crust forms across arid soils on or within the top few centimeters of the soil surface.
Surprisingly, these crusts are not made up simply of encrusted, excess soil minerals as often thought, but are created by microscopic and somewhat larger macroscopic organisms that live together in an unseen but profound world.
The microbes that make up this living “biocrust” live only near the top few centimeters of the soil because they need sunlight to make their own food. As some of these organisms travel through the soil, their network of mucilaginous, hollow tunnels between soil grains records a history of their movements and leaves a legacy of soil cohesion.
These and other tiny microbes living between desert soil grains create and store scarce, valuable, fertilizing nutrients like phosphorus and nitrogen at and below the surface, and they share these building blocks for life with all the plants in the surrounding community. If not disturbed by vehicle wheels or bulldozer blades, this soil cement and the community that produced it can persist for many thousands of years—or more.
Biological soil crusts keep soils intact and prevent dust storms…unless soils are disturbed. The dried, gluelike threads of microbes in biocrusts form a resistant seal across the soil surface, keeping dust, particulate matter, and harmful fungal spores like valley fever from being blown up into the air wherever the soil has not been disturbed.
These living soil crusts take hundreds of years to develop into effective soil “sealants.” When they are allowed to remain intact, they will hold back wind and water erosion, supply nutrients to neighboring plants, improve water infiltration, prevent particulate matter from entering the air, and help keep our air clean and healthy. When living soil crusts are disturbed, choking dust storms occur. Dust storms blow harmful particulate matter into the air – and we breathe it in. The smaller particulate matter (smaller than 10 microns, or PM 10 particles) when inhaled into our lungs cause health impacts ranging from coughing and wheezing to asthma attacks and bronchitis, as well as high blood pressure, heart attacks, strokes, and premature death in people with heart and lung disease.
Keeping desert biocrusts intact protects the health of people living near the soil disturbance as well as people living many hundreds of miles from the point of disturbance.
27 Health benefits
Michael F. Allen, Ph.D.
Distinguished Professor Emeritus, Department of Microbiology and Plant Pathology, University of California, Riverside
Susy Boyd, MNR. Master of Natural Resources, Forests and Climate Change, Oregon State University Public Policy Coordinator, Mojave Desert Land Trust
Maximizing the desert region’s carbon sequestration potential by conserving undisturbed non-military land provides the additional benefit of bolstering public health. Dust, particularly [Particulate Matter] PM10, is an important outcome of disturbance in desert wildlands (Pointing and Belnap, 2014; Frie et al., 2019).
Desert dust erosion resulting from disturbance of desert soils is a source of significant health issues (Lwin et al., 2023) ranging from respiratory particles to local sources of heavy metals including Aluminum, Arsenic, Selenium, Cadmium, Lead, Uranium and Thorium (Frie et al., 2019). Numerous studies have noted evidence of associations between desert and sandstorm dust, and morbidity/mortality rates.
Particle size is believed to be one of the key factors implicated in health risk. Large-sized particles can cause damage to external organs causing skin, eye, and ear irritation. But small size particles are capable of entering the respiratory tract and causing disorders within that system. The smaller size particles may penetrate the respiratory tract and damage cardiovascular, cerebral, cerebrovascular, blood and immune systems.
The high incidence of childhood asthma surrounding the Salton Sea (at a rate over 20%) is among the highest in California. In on-going studies, mice models found that the dust collected from these disturbed desert areas triggered a significant neutrophil inflammatory response that is distinct from the known immune allergic response, causing "asthma-like symptoms" (Biddle et al., 2023). This tells us that there are unknown new diseases emerging from the increasing disturbances in California's desert.
Desert dust may also cause infectious disease by carrying pathogens. An example is Valley Fever, caused by spores of fungi of species of Coccidiodes, which is present in desert soils and triggered upon inhaling dust when surface soils are disturbed
(https://www.cdc.gov/fungal/diseases/coccidioidomycosis/index.html). Valley fever is endemic in California desert soils and increasing dust with disturbance and global warming is of concern (Cat et al., 2019; Gorris et al., 2019). In new studies from California deserts, local dust emissions are increasing and releasing novel microbial pathogens (Freund et al., 2022) that we are only now beginning to identify.
At the global scale, it is estimated that 1.7% of lung-cancer and cardio-pulmonary disease deaths can be attributed to chronic exposure to desert dust. In latitudes with extensive deserts such as Africa, the middle East and Asia, the percentage jumps to 15 – 50%. Short-term exposure to dust was documented to be the source of respiratory illness among 70% of Afghan and gulf war veterans deployed between 2003- 2004.
Clearly, scientific research demonstrates a concerning link between desert dust and severe public health risk. Disturbance to desert soil is a contributor to desert dust, presenting an additional benefit for leaving desert lands undisturbed.
References
Biddle, T.A., Yisrael, K., Drover, R., Li, Q., Maltz, M.R., Topacio, T.M., et al. (2023). Aerosolized aqueous dust extracts collected near a drying lake trigger acute neutrophilic pulmonary inflammation reminiscent of microbial innate immune ligands. Science of The Total Environment 858, 159882. doi: https://doi.org/10.1016/j.scitotenv.2022.159882.
28 Cat, L.A., Gorris, M., Randerson, J., Riquelme, M., and Treseder, K.K. (2019). Crossing the line: Human disease and climate change across borders. Journal of Environmental Health 81, 14-22.
Freund, H., Maltz, M.R., Swenson, M.P., Topacio, T.M., Montellano, V.A., Porter, W.C., et al. (2022).
Microbiome interactions and their ecological implications at the Salton Sea. California Agriculture 76(1), 16-26. doi: 10.3733/ca.2022a0002.
Frie, A.L., Garrison, A.C., Schaefer, M.V., Bates, S.M., Botthoff, J., Maltz, M., et al. (2019). Dust Sources in the Salton Sea Basin: A Clear Case of an Anthropogenically Impacted Dust Budget.
Environmental Science & Technology 53(16), 9378-9388. doi: 10.1021/acs.est.9b02137.
Gorris, M.E., Treseder, K.K., Zender, C.S., and Randerson, J.T. (2019). Expansion of Coccidioidomycosis Endemic Regions in the United States in Response to Climate Change. GeoHealth 3(10), 308- 327. doi: https://doi.org/10.1029/2019GH000209.
Lwin, K.S., Tobias, A., Chua, P.L., Yuan, L., Thawonmas, R., Ith, S., et al. (2023). Effects of Desert Dust and Sandstorms on Human Health: A Scoping Review. GeoHealth 7(3), e2022GH000728. doi:
https://doi.org/10.1029/2022GH000728.
Pointing, S.B., and Belnap, J. (2014). Disturbance to desert soil ecosystems contributes to dust-mediated impacts at regional scales. Biodiversity and Conservation 23, 1659-1667. doi: DOI
10.1007/s10531-014-0690-x.
IX. Transition to Clean Energy: Meeting our Clean Energy Goals and Minimizing Disturbance to our Desert Ecosystem
Introduction
There is a growing understanding that a tension exists between the need to conserve desert land, which itself functions as a significant nature-based solution to store carbon emissions – and expansive renewable energy projects that disturb desert lands and in doing so, release carbon back into the atmosphere.
This is a solvable problem that requires coordination between renewable energy developers, conservationists, policy makers, and the handful of experts who have carefully analyzed and evaluated desert lands and crafted detailed maps that consider solar industry needs, cost, and conservation all at once. This is the key work that needs to be done if desert lands are to continue their critical function as grand carbon sinks. Experts agree that the means to successfully navigate the nexus of industrial solar and conservation of carbon-storing natural desert lands lies with thoughtful, advanced planning, and integration of a suite of renewable energy options. If desert lands are perceived as a sacrificial ecosystem in the name of renewable energy, we run the risk of undermining the long-term carbon storage function they have performed for thousands of years and backpedaling on meeting carbon sequestration targets.
And unlike other ecosystems, once disturbed, recovery in the desert is so long-term it should be considered as a non-option.
Utility Scale Solar and Avoidance of Desert Disturbance Joan Taylor. Chairperson, California Conservation Committee and California/Nevada Desert Committee of Sierra Club.
CA Senate Bill 100 established a landmark policy requiring renewable energy and zero-carbon resources to supply 100 percent of electric retail sales to end-use customers by 2045. To meet this goal, the California Energy Commission, California Public Utilities Commission, California Air Resources Board SB 100 Joint Agency Report estimated a need for an additional 70,000 megawatts (MW) of utility-scale solar to come online by 2045 in its Core Scenario (CEC 2021). Notably, the Core Scenario assumed high electrification demand but did not factor in any advances in renewable technology or in tools to manage peak load, so this estimate can properly be considered conservative.
29 Based on the most recently approved large utility-scale solar project in California, 5.02 acres are required to develop one megawatt of ground-mount single-axis tracking utility-scale solar with four hours of battery storage, including generation ties and other infrastructure (California Water Boards 2021). This equates to approximately 350,000 acres of land or other surface on which to mount PV panels. Even were one to use the now-outdated number of 7.1 acres per megawatt that was assumed nearly a decade ago by CEC (CEC 2014), the total acreage requirement for utility-scale solar would be less than 500,000 acres. For context, there are over 105 million acres in California.
There are numerous feasible options for developing utility-scale solar in California that can deliver the estimated need for new utility-scale solar and provide increased local jobs and other benefits, without disturbing intact desert. Some of these include:
• Water-deprived agricultural lands in the Central Valley estimated to be a minimum of 500,000 acres (Hanak et al, 2019) or as much as 900,000 acres (Escriva-Bou et al, 2023) • 250,000+ acres of selenium- contaminated land in the Westlands Water District • 200,000+ acres of parking lots in California (USGS 2019) • 11,500 MW of capacity on large commercial/industrial rooftops near substations (RETI 2009) • 4,000 miles of canals and 16,000 miles of highway right of ways • Agrivoltaics (ie, slightly elevated or spaced photovoltaic panels) on a portion of the 40+ million acres of farm and ranch lands throughout the state (CDFA) Examples of appropriate utility-scale solar sites and potential additional renewable capacity Preferred Sites Acres Total potential generation
Water-deprived Ag Lands Central Valley 500,000 – 900,000 100,000 MW – 250,000 MW Selenium contaminated land, Westlands Water District 250,000 50,000 MW Parking Lots in CA 200,000 40,000 MW
Large commercial/industrial rooftops near substations n/a 11,500 MW, min (this 2009 estimate is outdated) 20,000 miles highway & canal right of ways (est 100’ wide) 240,000+ 47,000 MW, min TOTAL 1,190,000 – 1,590,000 248,000 – 398,00 MW
Agrivoltaics on 40+ million acres farm & ranch lands 40,000,000+ Millions of MW While utility-scale solar that is sited remote from load is dependent on high voltage transmission, utilityscale solar that is generated “In Front of the Meter” on large rooftops and parking lots at load centers is not dependent on the larger grid. Urban and peri-urban solar eliminates the capital costs, delay, average 7%- line energy losses, steep monthly ratepayer charges for new transmission capacity and inherent lack of reliability of electric power that relies on long-distance transmission. Moreover, transmission costs are rising faster than the cost of the energy wheeled, while PV prices are falling (CPUC 2021), making solar sited at load more attractive for ratepayers, not to mention the benefits of local jobs and energy reliability. But if the full estimated need for utility-scale solar cannot be met on the distribution grid, the alternative of siting solar on water-deprived or contaminated lands and/or utilizing agrivoltaics on a small fraction of the state’s 40 million acres of farm and ranch lands can easily absorb the balance in a win-win for landowners as well as the environment (DOE 2023).
30 The potential solar capacity of the above options far exceeds the energy agencies’ projected need for an additional 70,000 MW of new utility scale solar to meet the state’s 2045 decarbonization goal. Clearly, the above options are the preferred resources to avoid land-use impacts and societal costs of developing transmission-dependent solar on intact desert lands in the California desert.
References
California Energy Commission. 2021. SB 100 Joint Agency Report March 2021: CEC-200-2021-001.
Final Environmental Impact Report for IP Oberon LLC Renewable Energy Project. 2021. California Water Boards Colorado River-R7, SCH No.2021030426
California Energy Commission. 2014. DRECP Acreage Calculator Hanak E, Lund J, Arnold B, et al. 2017. Water stress and a Changing San Joaquin Valley. San Francisco, California: Public Policy Institute of California.
Alvar Escriva-Bou, Ellen Hanak, Spencer Cole, Josué Medellín-Azuara. 2023. The Future of Agriculture in the San Joaquin Valley: Public Policy Institute of California.
Geological Survey data release. 2019. https://doi.org/10.5066/P9UTMB64 E3 and Black & Veatch. 2009. Summary of PV Potential Assessment in RETI and the 33% Implementation Analysis, CPUC Re-DEC Working Group Meeting, December 9, 2009, p. 24.
California Department of Food and Agriculture. (n.d.). Agricultural land loss and conservation. https://www.cdfa.ca.gov/agvision/docs/agricultural_loss_and_conservation.pdf California Public Utility Commission. 2021. Utility Costs and Affordability of the Grid of the Future.
Department of Energy - Office of Energy Efficiency and Renewable Energy. 2023. Solar and Agriculture Co-Location, https://www.energy.gov/eere/solar/solar-and-agriculture-co-location X. Policy Strategies and Tools to Maximize Carbon Sequestration and Conservation Values
Susy Boyd, MNR. Master of Natural Resources, Forests and Climate Change, Oregon State University Public Policy Coordinator, Mojave Desert Land Trust
The state of California has long been recognized for its leadership in transitioning towards new, clean energy sources to reduce CO2 atmospheric emissions. There are, however, two aspects to emissions reductions work.
The first is “what”. This piece is on track. The state has diligently passed legislation and dedicated millions of dollars towards reducing carbon emissions through technological innovation and utilizing our natural and working lands to reach net zero.
The second aspect of carbon emissions work is “how.” While the state has rolled out dozens of utility scale solar energy projects (USSE’s) at an accelerating pace across desert lands, this has taken place at the expense of disturbance of intact desert lands, which counterproductively serve as significant carbon sinks. The irony is that we are releasing carbon into the atmosphere by disturbing desert lands and their long-term sequestered carbon while building infrastructure intended to reduce atmospheric carbon. On this front, California has not yet realized fully its leadership potential. How these transitions are carried out
31 is based on siting decisions made in advance. For instance, China has directed their energy transition efforts towards utility-scale, ground-mounted PV [photovoltaic] panels, whereas Germany has achieved about 90% of its transition development within a built environment.
Several studies have revealed that regulations and policies in California have deemphasized solar growth and development within the built environment close to final destinations to meet demand, and instead favored development within shrublands and scrublands. Hernandez et al. (2015) note that carbon sequestration, among other ecosystem services including groundwater depletion and movement corridors for wildlife, may be adversely impacted globally by land cover conversion of shrubland and scrubland ecosystems.
Shrublands and scrublands have borne the brunt of land use conversion in our state’s efforts to pursue USSE’s on a massive scale, while developed regions remain largely underutilized.
Hernandez et. al. 2015.
How do we, as policy and decision-makers, carry out the task of addressing the “how” aspect of transition to clean energy so that the desert’s carbon sinks remain undisturbed and intact? There are planning tools currently available that allow decision makers the opportunity to simultaneously develop solar installations on desert lands, while protecting conservation values including carbon sequestration all at once. This is the kind of pioneering work that establishes California as an environmental leader.
One such tool is the Carnegie Energy and Environmental Compatibility [CEEC] model, a multiple criteria model that quantifies each solar installation based on environmental and technical compatibility.
The CEEC model is a decision support tool that develops a spatial environment and technical
32 compatibility index that outputs 3 tiers: Compatible, Potentially Compatible, and Incompatible. The model was designed for use in California and can identify environmentally low-conflict areas based on resource constraints and opportunities.
Hernandez et.al., 2015
A second tool of interest for decision-makers seeking to integrate the advancement of USSE’s with conservation of our desert lands is a framework proposed by a group of researchers led by Dr. Rebecca R. Hernandez of UC Davis. Techno-ecological synergies [TES] engineers the mutually beneficial relationships between technological and ecological systems to bolster the sustainability of solar energy across a suite of environments including land, water, and built-up systems. The intent of applying the TES framework to solar energy technologies is an effort for “sustainable engineering” to minimize unintended consequences on nature as we rapidly advance USSE’s on our natural and working lands.
The authors propose expansion of solar energy engineering principles to include both economic and ecological systems based on a synergistic relationship between technology and the environment. The outcome of TES produces products relevant to the technology end of development (PV module efficiency and grid reliability) as well as support for ecosystem services such as carbon sequestration and storage, water-use efficiency, and wildlife habitat. The research team offers 20 potential TES outcomes and discusses metrics and assessment methods to measure TES flows.
One example of a TES opportunity is optimizing land resources. The most degraded lands sites, for example EPA Superfund sites, could produce about 38% of total US energy consumption (based on 2015 assessment). At the same time, degraded lands function as substitutes, sparing undisturbed land with greater capacity for carbon sequestration. Moreover, the negative effects of land cover change and
33 disturbance such as release of GHG emissions, dust release, and soil-borne pathogens are reduced or eliminated.
Further examples of optimizing land resources include co-location of other renewable energy formats (such as wind turbines) adjacent to solar utility, with benefits compounded when this takes place on already degraded land. The number of potential beneficial outcomes for individual TES’s ranges from 6- 13; that is, there are substantial benefits to be gained by the synergistic framework proposed by this system.
While the commitments to transition to clean energy are moving rapidly, it may be necessary to make good use of policies to embed solar energy TESs into the economics of planning.
References
Hernandez, R. R., Armstrong, A., Burney, J., Ryan, G., Moore-O’Leary, K. A., Diedhiou, I., Grodsky, S.
M., Saul-Gershenz, L. S., Davis, R., Macknick, J., Mulvaney, D., Heath, G., Easter, S. B., Hoffacker, M. K., Allen, M. F., & Kammen, D. M. (2019). Techno–ecological synergies of solar energy for global sustainability. Nature Sustainability, 2(7), 560–568. https://doi.org/10.1038/s41893-019-0309-z
Hernandez, R., Hoffacker, M., Murphy-Mariscal, M. et al., Solar energy development impacts on land cover change and protected areas. (2016). Proceedings of the National Academy of Sciences of the United States of America, 113(12), E1768. https://doi.org/10.1073/pnas.1602975113 Hoffacker, M. K., Allen, M. F., & Hernandez, R. R. (2017). Land-Sparing Opportunities for solar energy development in agricultural landscapes: A case study of the Great Central Valley, CA, United States. Environmental Science & Technology, 51(24), 14472–14482. https://doi.org/10.1021/acs.est.7b05110
Parker, S., Cohen, B. D., & Moore, J. E. (2018). Impact of solar and wind development on conservation values in the Mojave Desert. PLOS ONE, 13(12), e0207678. https://doi.org/10.1371/journal.pone.0207678
XI. Conclusion
To fully realize the value of desert lands as part of our state’s efforts to sequester atmospheric carbon, the desert must be recognized as a significant carbon sink -- and it needs to be left undisturbed. Unlike other ecosystems, it has a unique time scale that would require hundreds to thousands of years to recover from disturbance. The highest capacity regions for desert carbon storage, including microphyll woodlands and desert bajadas, should be identified as the top priority regions for conservation. And the state must also place high importance on the “how” part of transitioning to clean energy by careful preplanning and siting of renewables on already disturbed desert lands and developments. We only get to do this once, so it needs to be done right.