LOS BANOS, Calif. – The Bureau of Reclamation is awarding a major construction contract for Phase 2 of the B.F. Sisk Safety of Dams Modification Project. The $255 million award to NW Construction marks a significant milestone in the continued effort to improve public safety and water supply reliability in California.
“Reclamation is committed to ensuring the safety and integrity of our water infrastructure,” said Reclamation 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.”
B.F. Sisk Dam was originally constructed in 1967 and is a key feature of the Central Valley Project and State Water Project. The dam, located on the west side of the San Joaquin Valley, impounds San Luis Reservoir, the largest offstream reservoir in the nation, and plays a critical role in delivering water for prime farmland, California communities, and wildlife refuges.
The 382-foot-tall dam is situated within a seismic zone associated with the Ortigalita Fault. Reclamation’s Dam Safety Program evaluates risks and implements actions such as the project at B.F. Sisk Dam.
The dam safety project, Reclamation’s largest under the 1978 Safety of Dams Act, will construct stability berms and shear keys, and raise the crest of the existing 3.5-mile-long earthen dam. The combination of these features will improve downstream public safety concerns by reducing the likelihood of overtopping if slumping were to occur during a seismic event.
Phase 1 of the dam safety modifications, which included construction of stability berms and foundation preparation, began in 2021 and was successfully completed in 2024. Phase 2 will construct a large stability berm along the central portion of the dam that requires placing about 15 million cubic yards of earthen material. The last phase will raise the dam 10 feet for safety. The strategic placement of these engineered earthen materials will bolster the dam so that a seismic event does not cause the dam to slump below the reservoir leading to dam failure.
To learn more about the B.F. Sisk Safety of Dams Modification Project, visit www.usbr.gov/mp/sod/projects/sisk/index.html.
