In the foreground is O'Neill Forebay, and in the background is B. F. Sisk Dam (also known as San Luis Dam), a major earth-filled dam in Merced County, California, which forms San Luis Reservoir, the largest off-stream reservoir in the United States. 
SACRAMENTO, Calif. – The Bureau of Reclamation and the California Department of Water Resources are conducting exploratory work, including clearing, excavation and controlled blasting of rock material in the Basalt Hill area near B.F. Sisk Dam, located between Los Banos and Gilroy, between 6 a.m. to 8 p.m. during April and May.
The exploratory findings on Reclamation lands will help identify size and quality of granular material for the planned construction of a Safety of Dams Modification project.
The joint project between Reclamation and DWR will add stability berms and other physical features to the existing 3.5-mile-long earthen B.F. Sisk Dam to reduce risks associated with a large seismic event.
The public may hear the controlled blasting when it occurs, but it is not expected to impact the public or the environment. Controlled blasting is a commonly used practice at dam construction sites throughout the United States. Public roads will remain open during the controlled blasts; check recreation area updates on San Luis Reservoir and B.F. Sisk Dam websites before visiting in April.
Construction on the multi-year project is planned for summer of 2021. An environmental impact statement/environmental impact report was completed in September 2019, with the Record of Decision/Notice of Determination signed on December 3, 2019.
For questions, contact Mynul Chowdhury with Reclamation at 916-978-5335 or mchowdhury@usbr.gov or Sara Paiva-Lowry with DWR at 916-653-9342 or Sara.Paiva-Lowry@water.ca.gov.
For project updates, visit https://www.usbr.gov/mp/sod/projects/sisk/.
Contact: Mary Lee Knecht, 916-978-5100, mknecht@usbr.gov
Maggie Macias, 916-653-8743, mmacias@water.ca.gov
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The Bureau of Reclamation is a federal agency under the U.S. Department of the Interior and is the nation's largest wholesale water supplier and second largest producer of hydroelectric power. Its facilities also provide substantial flood control, recreation opportunities, and environmental benefits. Visit our website at www.usbr.gov and follow us on Twitter @USBR and @ReclamationCVP.
The California Department of Water Resources operates and maintains the State Water Project, which supplies water to more than 27 million people and 750,000 acres of farmland. The SWP also provides flood control, hydroelectric power generation, recreational opportunities, and fish and wildlife habitat restoration. Visit our website at water.ca.gov.