The Bureau of Reclamation has awarded a $255 million construction contract to NW Construction for Phase 2 of the B.F. Sisk Safety of Dams Modification Project—marking a major milestone in efforts to enhance public safety and water supply reliability in California.
“Reclamation is committed to ensuring the safety and integrity of our water infrastructure,” said Acting Regional Director Adam Nickels. “This project represents a major investment in the future of California’s water supply and the communities and ecosystems that depend on it.”
Originally constructed in 1967, the B.F. Sisk Dam is a key component of both the Central Valley Project and the State Water Project. Located on the western side of the San Joaquin Valley, it impounds the San Luis Reservoir—the nation’s largest offstream reservoir—and plays a vital role in delivering water to California’s farmland, cities, and wildlife refuges.
Situated in a known seismic zone near the Ortigalita Fault, the 382-foot-tall dam has undergone comprehensive evaluation through Reclamation’s Dam Safety Program. The current project—Reclamation’s largest under the 1978 Safety of Dams Act—will implement critical structural modifications to mitigate seismic risks.
Phase 2 of the project involves constructing a massive stability berm along the central portion of the dam, requiring approximately 15 million cubic yards of engineered earthen material. This phase follows the successful completion of Phase 1 (2021–2024), which focused on foundation preparation and initial berm construction. A final phase will raise the dam crest by 10 feet to further enhance safety.
The modifications—including berms, shear keys, and elevation adjustments—are designed to prevent slumping and potential overtopping in the event of a significant earthquake, thereby reducing the risk of dam failure and ensuring continued water delivery for generations to come.