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Anderson Dam and Reservoir

General information about the Anderson Dam and Reservoir. For current project information, see the Anderson Dam Seismic Retrofit project page.

Anderson Reservoir is the largest of the 10 water district reservoirs and provides a reliable supply of water to Santa Clara County. It has a total storage capacity of 89,073 acre-feet (one acre-foot is 325,851 gallons of water, enough to serve two households of five for one year). Anderson Dam was built in 1950 and named after the key founder and first president of the water district, Leroy Anderson. A long, deep natural gorge located three miles east of U.S. 101 in Morgan Hill provided a suitable dam site. 

Findings of the original seismic stability evaluation completed in 2011 on Anderson Dam indicated that the downstream and upstream embankments could become unstable during a very large magnitude earthquake and the rupture of faults underlying the dam may have adverse impact on the outlet pipe and intake structure.

A storage restriction of about 55 feet below the dam crest has been put in place to protect the public, reducing the allowed storage capacity to 52,553 acre-feet. This voluntary restriction exceeds the 45-foot restriction approved by the regulatory agencies (California Division of Safety of Dams and the Federal Energy Regulatory Commission) and was instituted by the District in response to additional findings during the design phase of the Anderson Dam Seismic Retrofit Project (ADSRP). The water district and regulatory agencies believe that this restriction will prevent the uncontrolled release of water in case the dam is structurally damaged after a major earthquake.

Inundation maps 
Inundation Map of Hypothetical Fair Weather Failure of Anderson Dam (index map)
Inundation Map of Hypothetical Inflow Design Flood Failure of Anderson Dam (index map)

For project inquiries, please contact Tony Mercado, Public Information Representative, at 408-630-2342 or [email protected]. You can also use "Access Valley Water" to submit questions, complaints or compliments directly from your computer to a water district staff person who can help you.

Anderson Dam and Reservoir
Anderson Dam and Reservoir