The Colorado River Indian Tribes sued earlier this month after Riverside County supervisors approved the Blythe Mesa Solar Project, which would cover nearly six square miles.
The suit contends officials violated California environmental laws by failing to properly disclose or take into account the project's impact on traditional tribal homelands.
The county declined comment because of the pending litigation.
The developer, Renewable Resources Group, says the project has strong local and environmental support, has undergone exhaustive government review and is on developed land. The company also says it will continue working with the tribes to address their concerns.