The U.S. Department of Interior’s Bureau of Reclamation has evaluated the potential environmental impacts of various alternatives to reduce seismic risks at B.F. Sisk Dam in California and says the recommended action will address potential seismic-induced destabilization of the dam, reduce safety concerns and maintain water supply deliveries to state and federal water contractors.
“The safety and welfare of those living downstream of this dam is our priority,” said Reclamation’s Mid-Pacific Regional Director Ernest Conant. “The project will also ensure we protect this vital water supply resource.”
Reclamation co-owns and operates B.F. Sisk Dam (also known as San Luis Dam) with the California Department of Water Resources, along with the off-stream San Luis Reservoir, to provide more than 2 million acre-feet of supplemental storage capacity for the Central Valley Project and State Water Project. The reservoir provides many benefits, including water for irrigation, municipal and industrial use, recreation and hydroelectric power.
The dam is 382 feet tall and impounds water for the 424-MW William R. Gianelli pump-generating plant. The 18,600-foot-long earth-filled gravity embankment dam is in a seismically active area and close to the Ortigalita Fault that underlies the reservoir.
Reclamation has implemented additional risk reduction measures as it works to put a more permanent dam safety project in place. These measures include heightened earthquake monitoring, real-time seismic monitoring, dam safety tabletop exercises with local responders, increased seismic inspection criteria and an update to the dam’s emergency management plan.
Reclamation and DWR expect to begin implementing seismic modifications of the dam at the end of 2020.
The final environmental impact statement/environmental impact report considers and addresses all comments received during the public review period on the draft EIS/EIR. Reclamation anticipates signing a Record of Decision in October 2019.