The Bureau of Reclamation has awarded a $255 million federal contract to advance seismic safety improvements at B.F. Sisk Dam in Los Banos, a significant infrastructure investment aimed at strengthening the region’s water supply and protecting communities from potential earthquake damage.
The contract marks the next step in an extensive, multi-phase effort to modernize one of California’s key water facilities, ensuring it remains stable and reliable for decades to come.
The dam, originally built between 1963 and 1967, impounds San Luis Reservoir, which is the largest offstream reservoir in the nation. Holding more than 2 million acre-feet of water, it plays a crucial role in supporting farms, communities, and wildlife refuges across California’s Central Valley and beyond. The facility is vital to both the federal Central Valley Project and the State Water Project, making its structural integrity a priority for water security in the state.
Congressman Gray praised the investment, describing it as a vital step toward ensuring reliable water access for farmers and families who depend on it. He emphasized that the Central Valley produces more food for the country than any other region, yet securing adequate water supply has often been a battle. He credited the Bureau of Reclamation’s financial commitment as a positive step toward addressing longstanding concerns about water distribution. Gray also expressed confidence that more federal funding will be secured to support additional water infrastructure improvements in the future.
One of the key motivations for modifying B.F. Sisk Dam is its location near an active seismic zone. The dam sits in an area with high earthquake potential, particularly near the Ortigalita Fault, which crosses the reservoir. Previous investigations indicated that sections of the dam are built on liquefiable and soft soils, raising concerns that a significant earthquake could cause parts of the embankment to slump or crack. In an extreme event, these vulnerabilities could compromise the dam’s ability to safely retain water, creating risks for downstream communities.
Congress enacted the Safety of Dams Act in 1978 to provide federal authorization for addressing structural risks at existing reclamation dams. Under the act, the Secretary of the Interior is empowered to initiate safety modifications to prevent catastrophic failures and protect public welfare. The B.F. Sisk project is the largest dam improvement effort funded under the act, with a total estimated cost of $1.1 billion.
A substantial portion of funding for the safety modifications has come from the Bipartisan Infrastructure Law, which allocated $100 million in 2022 to support dam safety improvements. Work on the project has already included the addition of stability berms and other reinforcements designed to enhance the dam’s structural reliability. One of the most significant changes will be raising the dam’s crest by 10 feet, a measure intended to reduce the likelihood of overtopping in the event of embankment movement during an earthquake.
The project is divided into three phases, with Phase 1 beginning in the summer of 2022. The newly announced funding for Phase 2 will accelerate ongoing structural reinforcements, while the final phase is expected to conclude by 2032.
As California continues to grapple with water supply challenges and the need for resilient infrastructure, the upgrades to B.F. Sisk Dam are expected to provide long-term benefits for agriculture, local communities, and wildlife. Ensuring the stability of San Luis Reservoir is a priority not only for Central Valley residents but for the broader network of water users who depend on the facility to sustain their livelihoods.
