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Anderson Dam and Reservoir

Aerial view of Anderson Dam

Anderson Dam and Reservoir was built in the 1950s 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 on a 500-acre dairy and cattle ranch along Coyote Creek purchased from the estate of John Cochran and his wife, Aphelia Farmington, provided a suitable site.

The Board submitted plans in 1949 resulting in the scheduling of a bond election for the following summer. The total cost for the land and construction was estimated at $3 million and the reservoir would store an estimated 89,073 acre-feet of water, more than all the other reservoirs combined. The bond was approved and once approval had been given by state engineers and plans and surveys had been evaluated, construction began. The reservoir was completed in record time between the last rains of spring and the first rains of autumn 1950.

Anderson Reservoir is the largest of the 10 water district reservoirs and provides a reliable supply of water to Santa Clara County. It is large enough to fit all the other nine county reservoirs inside its area. Water stored in the reservoirs provides about 25 percent of the county’s water supply and 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).

When will Anderson Reservoir be closed to the public?
It is expected that the reservoir will be available for recreational use until spring 2015. The current plan is to drain the reservoir from spring through fall 2015 (a process that will take approximately nine months), and during this time the reservoir will be closed to recreational activities. The reservoir will likely be empty from early 2016 through 2018 in support of construction activity, and no recreational use will be allowed then. After construction is complete, refilling of the reservoir will be dependent on “Mother Nature,” or how much rainfall the area receives.

Answers to most commonly asked questions about the project can be found in the following links:

Anderson publications

Informational materials:


Anderson Dam Seismic Stability Study completed 
(press release)
In July 2011, the Santa Clara Valley Water District completed a seismic stability evaluation of Anderson Dam. The evaluation found that the dam is subject to significant damage if a large earthquake were to occur close to the dam. 

A storage restriction of 25.5 feet below the spillway has been put in place to protect public safety. The dam’s two regulatory agencies, the California Division of Safety of Dams and the Federal Energy Regulatory Commission approved the restriction. The restriction will allow the dam to fill to 67 percent of its full storage capacity. Staff believes that this will prevent the uncontrolled release of water after a major earthquake.

The water district has initiated a capital project, the Anderson Dam Seismic Retrofit Project, to complete the planning, design and construction of a seismic retrofit by the end of 2018. The operating restriction will remain in place until the project is completed.


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