California solar project threatens Mojave wildlife corridor, scientists say

- The state of California has approved a solar project in the Mojave Desert on land that serves as a migration corridor for desert bighorn sheep and habitat for the desert tortoise. - Scientists and conservation advocates say the approval threatens one of the last intact desert ecosystems in California, but the California Energy Commission says ecological mitigation will reduce the impacts on wildlife and that the project will bring more renewable energy to the state. - The Mojave is already fragmented by Interstate 15, and solar projects add further threats; the ability to move between mountains is what keeps the bighorn sheep population from collapsing. The Mojave Desert may look like a flat, brown stretch of nothing between Los Angeles and Las Vegas. But threading through its rocky mountain ranges is an intricate network of wildlife movement that has sustained desert species for thousands of years. Now, scientists and advocates say a solar project approved by the state of California threatens to sever it. In April, the California Energy Commission, the state agency that oversees energy infrastructure, voted 4-0 to approve a $700 million, 1,080-hectare (2,670-acre) solar facility proposed by New Jersey-based developer VC Renewables on federal land adjacent to the Mojave National Preserve. The preserve, spanning more than 1.6 million acres, is one of the largest in the U.S. National Park System and is located in Southern California. The project, known as Soda Mountain Solar, sits in the migration corridor that desert bighorn sheep (Ovis canadensis nelsoni) use to move between mountain ranges. This large solar array would also obstruct desert tortoise (Gopherus agassizii) habitat, which has already undergone significant loss due to climate change and land developments. The energy commission’s environmental review found the project would cause significant and unavoidable harm to wildlife. Scientists and conservation advocates say the approval threatens one of the last intact desert ecosystems in California. But the commission’s final order memo states that ecological mitigation incorporated into the solar project would reduce the impacts on desert wildlife to “less than significant” and that the commission expects the project will bring more renewable energy to the state. Scientists and conservationists say the impact would be severe, pointing out the commission did not adopt the mitigation measures they had proposed. VC Renewables, which is also a subsidiary of European fossil fuel trader Vitol, did not respond to Mongabay’s request for comment on the solar project’s impact on desert species and their corridor. Web of wildlife movement California’s Mojave National Preserve is less visited than nearby Joshua Tree or Death Valley, which provide a quintessential desert experience for tourists. “Mojave National Preserve is pretty wild and affords the American public a true desert experience of connecting with the land without other people around you or without a lot of infrastructure,” said Chance Wilcox, California desert associate director for the National Parks Conservation Association. But it has other, irreplaceable value for ecologists, which is the connectivity corridor. The preserve is a stretch of desert that allows species to move across a landscape, where creosote bush flats give way to rocky foothills and dry washes. This allows species, including the endangered desert tortoise, to move across terrain that is fragmented by roads, development and climate change. The preserve shelters mule deer (Odocoileus Hemionus), bobcats (Lynx rufus), mountain lions (Puma concolor), desert horned lizards (Phrynosoma platyrhinos), checkerboard lizards (Trogonophis wiegmanni) and rare plant species found nowhere else in California. It’s also one of the largest habitats in the state for the desert tortoise (Gopherus agassizii), a federally listed threatened species, which depends on the flat valleys of the Mojave Desert, which is the terrain the solar project would pave over. “That’s some of the highest habitat suitability across the Mojave Desert tortoise’s range,” said Kristina Drake, director of conservation ecology at the Mojave Desert Land Trust. “I see that area as the number-one major lifeline for that species in the future.” To conservationists, the Mojave is already straining. Interstate 15 has fragmented wildlife habitat, cutting populations off from each other. Desert solar projects add another threat, by leveling the desert surface, which permanently changes how water moves across the landscape, impacting the desert ecosystem. Drake said most utility-scale solar projects in Mojave, which are not connected to Soda Mountain, already have changed the contour of the landscape. These alterations include removing vegetation and grading and flattening the land, which transforms the water surface flows. “It completely changes the water dynamics in these regions. You can end up with flooding in some areas, and you can end up with other areas that no longer receive any water.” Islands in the desert And then there are the bighorn sheep, which have come at the center of debates surrounding the solar project. Desert bighorn live in the steep, rocky terrain of ranges like the nearby Cady and the Soda mountains, where they can watch for predators and find forage. There are about 5,000-6,000 desert bighorn across all of California. What keeps the bighorn population from collapsing is movement between the mountains. Historically, when a local wildlife population dies from disease or drought, animals from a nearby range can eventually recolonize. The flat desert valleys, which the solar project would partially occupy, are the passages between mountains. “What we can do is protect the quality of the habitat and the ability of the animals to move between those habitat patches. That’s our ticket for helping this species hang on,” said Clinton Epps, a wildlife ecology and conservation genetics professor at Oregon State University who has been studying the region’s bighorn sheep since 1999. Christina Aiello, a postdoctoral researcher in Epps’ lab who led a study on bighorn movement, said the passages bighorn sheep use link the Mojave National Preserve to Death Valley National Park. She said the connection is verified through years of GPS tracking and genetic analysis. There are three wildlife crossings under construction along highway I-15 — which are a partnership between the California Department of Transportation, California Department of Fish and Wildlife and high-speed rail line Brightline West. These crossings are designed to restore connectivity, reuniting sheep on the south side of the four- to six-lane highway with populations to the north, which have been separated for decades. The solar project would be built in the flat valley between their mountain ranges. Scientists are concerned that the solar installation and its panels will reflect sunlight across the flat desert floor, something the sheep have never encountered. Getting the sheep to use the structures requires that they feel safe enough to come down from the mountains. Aiello said the solar project threatens that process. “Adding in this new disturbance with a lot of unknowns could impact their kind of risk tolerance, and whether or not they’re going to come down and explore these lower regions that we need them to explore in order to find and use the crossing structure,” Aiello said. Jacob Overson, a resident of the nearby town of Baker whose family has ranched in the desert for decades, described what would happen if the sheep turn back. “When these bighorn sheep come off the mountain to the flat to cross over the valley to the next mountain, they have to cross right through this footprint,” Overson said. Because bighorn sheep have never encountered a solar field before, it could throw them off. “They’re going to go back in the mountains to their safe zone and never be able to migrate.” After 20 years, expedited approval The solar project faced opposition for nearly 20 years, but through Assembly Bill 205, which is a 2022 California law that shifts permitting authority over qualifying renewable energy projects from local governments to the state through an expedited review process, the project came back. It is only the second project approved this way. The energy commission’s environmental impact assessment acknowledged significant and unavoidable harms to biological resources. Scientists, including Aiello, submitted modeling recommending a buffer of 1-2 kilometers (0.6-1.2 miles) between the solar panels and bighorn habitat, based on GPS data and ecological simulations that account for the range of sheep movement across seasons. The commission minimized these recommendations, and instead settled on 0.4 km (0.25 mi), which is what the developer accepted as economically viable. Drew Bohan, the commission’s executive director, signed off, finding that the project’s benefits provide “a new source of energy storage; contributing to the delivery of renewable generation; contributing to the state’s electrical grid reliability by providing renewable electricity during increased load demand,” which he said outweigh the harms. The approval also bypassed the Desert Renewable Energy Conservation Plan (DRECP), which is a federal framework developed by conservation groups, utilities, local communities and the government to designate where desert solar is — and is not — appropriate. The Soda Mountain site was not zoned for solar development under the plan. “There’s a reason that this small parcel of land adjacent to Mojave National Preserve wasn’t immediately zoned in that first kind of fleshing out of the DRECP,” Wilcox said. “It’s because of its proximity to Mojave, it’s because of its proximity to bighorn sheep population.” What comes next The project still requires the federal Bureau of Land Management’s approval before construction can begin. The agency is reviewing the application but has announced no timeline for a decision. Aiello warned that Soda Mountain may help set a precedent, as the second project approved through the opt-in process, potentially signaling to other developers that sensitive desert land is fair game. If solar is prioritized while environmental impacts are pushed aside, Aiello said, she worries “what kind of precedent that sets for what solar projects are going to go through this process.” Banner image: A desert bighorn sheep (Ovis canadensis nelsoni) in Joshua Tree National Park. Image courtesy of Mojave Land Trust. This story was produced with guidance from Covering Climate Now and USC Annenberg Center, and is part of Berkeley Journalism School’s climate reporting program.