Sienna Solar Final Environmental Impact Report

The Sienna Solar and Storage Project is a utility-scale solar photovoltaic and battery energy storage facility proposed for construction on approximately 1,854 acres in San Bernardino County, California, near Haynes Road and east-west of SR-247. The project is designed to generate up to 525 megawatts of solar power with an equal capacity of energy storage using a battery energy storage system, with all generated electricity transmitted to Southern California Edison’s grid via the adjacent Calcite Substation. The project is subject to comprehensive environmental review under the California Environmental Quality Act, with the County of San Bernardino serving as the lead agency, and oversight involving multiple state and federal entities including the Bureau of Land Management, California Department of Fish and Wildlife, Mojave Desert Air Quality Management District, and the California Public Utilities Commission. A Final Environmental Impact Report has been completed, detailing impacts across twelve key areas including air quality, biological resources, cultural resources, hydrology, noise, and greenhouse gas emissions, with mitigation measures required for significant impacts. The project is governed by a detailed set of special contractual and regulatory requirements that include mandatory staffing of qualified personnel such as a Cultural Resources Specialist certified under federal standards and a Qualified Biologist with desert species expertise, who must be present during all ground-disturbing activities with authority to halt work if protected species are disturbed. Pre-construction surveys for desert tortoises and rare plants are required using approved methodologies, with 50-foot buffers mandated around special-status vegetation and compensatory mitigation at a 1:1 ratio for any impact to waters of the U.S. or state. Construction is restricted to 7 a.m. to 7 p.m., Monday through Saturday, with work prohibited on Sundays and federal holidays unless exempted. A Cultural Resources Management Plan and Soil and Groundwater Management Plan must be submitted 60 days prior to construction, alongside a Construction Traffic Management Plan approved by the County Department of Public Works. Public notification must occur at least 15 days prior to ground disturbance, including mail outreach and a dedicated complaint hotline. Environmental compliance is enforced through a Mitigation Monitoring and Reporting Program, with ongoing reporting obligations to county and state agencies, and incidental take permits from U.S. Fish and Wildlife Service and California Department of Fish and Wildlife required if desert tortoises are encountered. No federal procurement structure, contract pricing, acquisition clauses, or payment systems are referenced, as this is an environmental permitting and compliance framework rather than a federal contract award.