COMMITTEE AGENDA MEMORANDUM
Capital Improvement Program Committee
Government Code § 84308 Applies: Yes ? No ?
(If “YES” Complete Attachment A – Gov. Code § 84308)
SUBJECT: title
Receive Information on the Coyote Dam Seismic Stability Project.
End
RECOMMENDATION: Recommendation
Receive information on the conceptual analysis for the Coyote Dam Seismic Stability Project.
Body
SUMMARY:
Valley Water owns and operates 12 jurisdictional dams and 10 reservoirs in Santa Clara County. Dam safety regulatory requirements, Board policies, and obligations associated with dam ownership set the direction for the Dam Safety Program (Program). On January 26, 2026, the CIP Committee (Committee) requested that staff provide an update on the planning-level conceptual analysis for the Coyote Dam Seismic Stability Project (Project). On April 20, 2026, staff stated that a Project update would be presented at the October 2026 Committee Meeting.
Background
Coyote Dam is an earthfill dam constructed in 1936 and is one of only a handful of dams in the world built on an active fault. Coyote Reservoir stores watershed runoff and is located approximately three miles upstream of Anderson Reservoir on Coyote Creek, in which both reservoirs are operated as a system.
Since 1992, Valley Water and the California Division of Safety of Dams (DSOD) have been aware that a major earthquake could damage Coyote Dam, resulting in releases to Anderson Reservoir. Therefore, Coyote Dam has operated at a restricted water level approximately 19 feet below the spillway crest, which reduces the reservoir’s allowable storage to 53% of total capacity, or approximately 22,541 acre-feet.
A 2015 study identified several potential failure modes at Coyote Dam, including embankment overtopping during a Probable Maximum Flood (PMF) due to inadequate spillway capacity and rupture of the Calaveras fault beneath the dam. Fault rupture could potentially result in internal erosion of the core into the do...
Click here for full text