The San Luis Dam

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San Luis Dam is a dam that creates San Luis Reservoir, which serves as an off-stream reservoir for the California State Water Project and the Central Valley Project. It is also known as the B.F. Sisk Dam, after Bernie Sisk. The earth-fill gravity embankment dam is 305 feet  tall and was completed in 1967. It is located between Los Banos, California and Gilroy, California, United States along Pacheco Pass.

San Luis Reservoir is the largest off-stream reservoir in the United States, with a capacity of 2,041,000 acre feet. The dam is over 3½ miles long and impounds San Luis Reservoir which has a total capacity of over 2 million acre-feet. San Luis Creek is a small stream that flows through the area and it is sometimes listed as the dam’s watershed, even though it is an off-stream reservoir.

The dam is owned by the U.S. Bureau of Reclamation, but is operated by the California Department of Water Resources to store water for its State Water Project. San Luis Reservoir and O’Neill Forebay serve as the upper and lower reservoirs for the William R. Gianelli pumped storage hydroelectric plant, which began operating in 1968. The plant’s eight Francis turbines produce a combined 424 MW. The sale of peak electricity lowers the overall cost of operating the State Water Project, particularly the California Aqueduct. A short 230 kV power line heads eastward to deliver this electricity to Northern California’s electricity backbone, Path 15.

The dam was dedicated by President John F. Kennedy on August 18, 1962 when Company founder Harry Morrison met with the President.