B.F. Sisk Dam (SCCAO)
B.F. Sisk Dam is a 300-foot-high zoned compacted earthfill embankment located on the west side of California's Central Valley approximately 12 miles west of Los Banos, California. The dam is over 3-1/2 miles long and impounds San Luis Reservoir which has a total capacity of over 2 million acre-feet.
The dam was built between 1963 and 1967 to provide supplemental irrigation water storage for the Federal Central Valley Project and municipal and industrial water for the California State Water Project. Water is lifted into the reservoir for storage by the Gianelli Pumping – Generating Plant from the California Aqueduct and from the Delta-Mendota Canal via O’Neill Forebay.
B.F. Sisk Dam (also known as San Luis Dam) is owned by the Bureau of Reclamation (Reclamation) and operated by the California Department of Water Resources (DWR). Reservoir storage space is allotted 55 percent State and 45 percent Federal.Safety of Dams Investigations Background
A series of studies and analyses culminating in the seismic risk analysis that was completed in 2006 determined that there is justification to take action to reduce risk to the downstream public. Consequently, Reclamation, with collaboration from DWR, initiated a Corrective Action Study to investigate and determine a course of action to mitigate risk. This decision was a result of the following developments:
- Increases in the estimates of both the severity of ground shaking due to nearby earthquake faults, primarily the Ortigalita fault, which crosses San Luis Reservoir and the probability of a large event on this fault.
- New understanding of the properties of the dam’s foundation materials and their ability to resist deformation when subjected to severe shaking.
- Advances in computer-based analysis methods, which allow better assessment of the behavior of the dam under seismic loading.
Geology: Reclamation and DWR have completed several geologic investigations to better understand:
- The foundation materials beneath the dam
- As-built placement of embankment zoning
- Borrow area locations and materials
Engineering: Appraisal level designs have been completed and development of feasibility level designs are underway. All structural alternatives would include raising the dam to increase available freeboard and at least one downstream berm to stabilize the embankment if exposed to earthquake shaking. Each alternative would also include new zoning in the downstream side of the crest to protect against cracking. A structural alternative with a lower construction cost which would require a reservoir restriction is also under consideration.
Economics: An economic analysis to compare life cycle cost of each alternative is underway. The analysis is being performed using the Common Assumptions Workgroup that includes, Reclamation, DWR, and water user representatives.
Environmental: Reclamation has issued a solicitation for environmental and cultural resources compliance services. DWR and Reclamation are participating in this task which will be in compliance with state and federal guidance.
Corrective Action Study: This phase of the Safety of Dams project is referred to as a Corrective Action Study (CAS). It will result in feasibility level designs, development of alternatives, and selection of the preferred alternative. Completion of the CAS is expected in May 2017.
Final Design Phase: Once the CAS phase is complete the Final Design Phase will be initiated. The Final Design Phase tasks will include perform analyses and design; prepare drawings and specifications for the preferred alternative; prepare environmental documentation; prepare a Modification Report to the federal Office of Management and Budget and to Congress. Congressional acceptance of the Modification Report allows funding for construction.
- Project Timeline (PDF - 228 KB)
- Factsheet (PDF - 150 KB)
- Project Status Updates for Water Users: Bureau of Reclamation and the California Department of Water Resources (DWR) have been providing periodic project status updates (joint briefings) to Central Valley Project (CVP) and State Water Project (SWP) customers. The first of these joint briefings was held on April 15, 2009 at DWR’s downtown office. The last briefing was provided by Mynul Chowdhury on June 21 via conference call from Reclamation’s Regional office. He sent out PowerPoint Presentation prior to the briefing. He updated on current status of the project including deformation analyses, CAS Alternatives and CRB recommendations. He also briefed on overall schedule, budge and cost including final design and construction phase of the project. Both SWP and CVP water contractors agreed to have next briefing in June 2017, after completion of the CAS.
Reclamation and DWR intend to notify water users of upcoming briefings via email. Email notifications for next briefing would probably go out by May 30 , 2017. If your organization is not already on the notification list, please contact: SWP: David Panec, or CVP: Mynul Chowdhury.
- Geologic and Geotechnical Investigations (PDF - 43 KB)
- Facilities Data Information
- Letter to CVP, Environmental Scoping Meeting, September 2009 (PDF - 1.9 MB)
- Environmental Scoping Meeting, September 2009:
- Press Release (PDF - 67 KB)
- Notification Card (PDF - 214 KB)
- Comment Card (PDF - 194 KB)
- Local Species That May Be Affected (PDF - 5.6 MB)
- What is Scoping (PDF - 234 KB)
- Recreation Concerns (PDF - 1.9 MB)
- Project Area Map (PDF - 171 KB)
- B.F. Sisk History (PDF - 108 KB)
- Alternatives Under Consideration (PDF - 7.2 MB)
- What is an EIS/EIR? (PDF - 221 KB)
For additional information, please contact MP Region Safety of Dams or call 916-978-5328.Note: Documents in Portable Document Format (PDF) require Adobe Acrobat Reader 5.0 or higher to view, download Adobe Acrobat Reader