Anderson Dam and Reservoir

Anderson Dam and Reservoir was named for Leroy Anderson, the key founder and first president of the Santa Clara Valley Water Conservation District. It was built in 1950, on a 500-acre dairy and cattle ranch along Coyote Creek purchased from the estate of John Cochran and his wife, Aphelia Farmington. Anderson Reservoir is the largest man-made lake in Santa Clara County. The reservoir can store 90,373 acre-feet of water. Its surface area is 1,271 acres. *

To aid downstream agencies and as required by state law, Valley Water has developed inundation maps that estimate what areas could be flooded in the unlikely event of an uncontrolled release of water from the Anderson Reservoir.

Each map shows an area shaded in dark blue could be inundated in normal weather conditions with normal flows in streams and a full reservoir. Additionally, a lighter shade of blue indicates additional areas that could be flooded if an uncontrolled release were to occur during a major storm, when stream flows downstream and upstream are already very high and the pool in the reservoir is also well above the spillway crest. Technical details about these maps are described on the Cover Page.

See the Cover Page for a legend that shows the areas covered in each of the 10 sheets listed below.

Additionally, the inundation maps are accompanied by a table that shows estimates of the time and depth of a water release depending on the two scenarios noted above, the distance from the reservoir, and how water flows north to San Francisco Bay or south to Monterey Bay.

Anderson Dam drilling underway

Anderson Reservoir FAQ (PDF 773 KB)

Preliminary Seismic Stability Evaluation of Anderson Dam
(PDF 2.7 MB)

Dam Instrumentation Project, neighborhood notice (PDF 3 MB)

*Reservoir storage values have been updated to reflect recent survey results.