In a California desert where a giant solar-and-battery project is currently under construction, some pieces of history have only recently been documented. Before construction began, archaeologists identified several previously unrecorded cultural resource sites near Hinkley in San Bernardino County.
As part of the environmental studies required before construction could begin, archaeologists surveyed hundreds of acres of the project site. Rather than uncovering a major archaeological site, they documented smaller traces of past human activity.
Several of those sites had not appeared in previous archaeological records. One item they found was a single stone flake.
The discoveries were made during environmental reviews required before the project could move forward.
Six sites appeared where no records existed before
The Overnight Solar Project will be constructed on approximately 596 acres of an 825-acre parcel in an unincorporated area of San Bernardino County. The project will consist of a 150-megawatt solar panel installation, a battery storage installation, an on-site substation, and transmission lines connecting the project to existing electrical distribution systems.
Before construction could begin, the developers were required to complete environmental studies under the California Environmental Quality Act (“CEQA”). In addition to reviewing impacts upon wildlife, those studies also examined historical and culturally sensitive locations within the project area.
To meet those requirements, archaeologists conducted cultural resource surveys throughout the site. During their survey, archaeologists documented 13 cultural resources within the site, six of which were newly identified.
Some of the sites were previously unknown
Several of these sites had not previously been listed in any archaeological reports.
Large-scale development projects do not always produce major discoveries. Many produce only small traces of past human activity.
An example of this type of find occurred when archaeologists documented a single isolated stone flake discarded by prehistoric peoples long before European settlers arrived in the region.
Why a desert tortoise had to be carefully considered
Protecting wildlife was another major part of the environmental review process. Specifically, plans included measures to mitigate potential impacts to Mojave Desert Tortoise habitats.
Examples of these measures include specialized tortoise-proofing around work areas using exclusion fencing. The project will also include tortoise relocation efforts overseen by both the California Department of Fish and Wildlife and the U.S. Fish and Wildlife Service.
Additional details about those mitigation measures are outlined in the project’s environmental review documents published by LUS.
The environmental review also evaluated how potential impacts could be identified, measured and mitigated. Mitigation monitoring requirements were later adopted as part of the approval process, according to the California Environmental Quality Act.
Those mitigation measures and monitoring requirements were incorporated into the conditions of approving the Overnight Solar Project.
Approval required changing some of the existing rules
The developers were also required to obtain several land-use permits before beginning construction on the Overnight Solar Project.
First, the county had to amend the Rural Living designation for the property to Resource Land Management. Next, the San Bernardino County Planning Department amended the zoning classification for the property from Rural Living to Resource Conservation.
Finally, San Bernardino County issued a conditional use permit allowing for the generation of commercial electricity at the site.
Construction could finally move forward
San Bernardino County Land Use Services oversaw the environmental review process. On August 19th, 2025, a Notice of Determination (“NOD”) was filed indicating that an Environmental Impact Report (“EIR”) had been completed and that mitigation monitoring requirements had been implemented as part of the project’s approval.
The Overnight Solar Project will be connected directly to an existing Southern California Edison transmission line called the Kramer-Coolwater Transmission Line.
Before electricity begins flowing into the grid, the environmental review process has already documented 13 cultural resource sites (including six newly identified locations) across hundreds of acres of the Mojave Desert.
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