The 10 reservoirs operated by Valley Water are highly visible elements of the water supply and flood protection programs for Santa Clara County.
Fast facts:
- Valley Water operates 10 reservoirs in Santa Clara County.
- The reservoirs have a total storage capacity of approximately 170,000 acre-feet (One acre-foot is enough water for two families of five for one year.)
- The reservoirs, which were constructed in the 1930s and 1950s for water conservation (not flood protection) catch storm runoff that otherwise would flow into San Francisco Bay.
- The reservoirs do also provide incidental flood protection by containing runoff early in the rainfall season, serve recreational needs, and benefit the environment by storing water to maintain flow in the creeks.
- Current Reservoir levels
- Reservoir Topographic/Bathymetric Maps (fishing maps)
Valley Water has a number of water rights associated with its reservoirs and stream diversions. Valley Water has created a website to comply with Section 933(b)(4) of California Code of Regulations, Title 23, Division 3., Chapter 2.8, which was an outcome of California Senate Bill No. 88 (SB-88):
Almaden Dam and Reservoir
Almaden Reservoir is one of Santa Clara County's six original reservoirs, built in 1935, and is one of 10 current reservoirs operated by the Santa Clara Valley Water District. Able to store 1,590-acre feet of water, the reservoir, located 12 mile south of San Jose, produces about 4 percent of the district's local water supply and also provides water for groundwater recharge.
Its accompanying earth fill dam stands 110-feet tall with a crest of about 500-feet. Subject to safety regulations by the State Division of Safety and Dams (DSOD), Almaden Dam is currently considered a high-hazard dam due to the number of people who live in the potential flood zone downstream and the extensive amount of damage that a flood could cause in case of a dam breach.
The seismic project
In 2000, the water district launched the Almaden Dam Improvements Project to address sediment accumulation at the dam's intake structure and correct aging outlet works infrastructure. In 2005, a seismic stability evaluation for the dam halted the planning phase and while the findings in 2012 indicated the embankment is stable, the dam will still require work to ensure its long term reliability. The project, currently in design phase, will:
- Modify or construct a new intake structure to meet DSOD regulatory standards.
- Reconfigure the spillway as the result of potential findings from the reservoir's future probable maximum flood investigation.
- Correct ongoing operation and maintenance issues to aging hydraulic lines, valves and energy dissipaters.
In 2016, Valley Water's Board of Directors approved a consultant amendment to perform improvements to the Almaden-Calero Canal in addition to the already approved consultant agreement for improvements at the Almaden Dam. However, project improvements are on hold until Valley Water completes improvements at the Anderson, Calero and Guadalupe dams.
For more information, contact Public Information Representative Tony Mercado at 408-630-2342 or at [email protected].
Inundation maps
Inundation Map of Hypothetical Fair Weather Failure of Almaden Dam (2019) (Weather Failure index map)
Inundation Map of Hypothetical Inflow Design Flood Failure of Almaden Dam (2019) (Flood Failure index map)
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 (Weather Failure index map)
Inundation Map of Hypothetical Inflow Design Flood Failure of Anderson Dam (Flood Failure 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.
Calero Dam and Reservoir
The Santa Clara Valley Water District built the Calero Dam during the Great Depression, completing it in 1935 after acquiring land as the Santa Clara Valley Water Conservation District. The dam and reservoir is one of the six original reservoirs approved for construction by voters in May 1934.
Both dam and reservoir are located on Calero Creek. The 2.2-miles-long reservoir can store 9,934 acre-feet of water. Its surface area is 349 acres.* Calero Reservoir provides water directly to drinking water treatment plants, which treat and test it for safety. The district then distributes the water to water retailers to sell to the county’s 1.8 million residents. Calero also captures and stores winter runoff to recharge groundwater basins, helps store water from the nearby Almaden Reservoir watershed and accepts imported water.
The water district is currently in the midst of a seismic retrofit of the Calero Dam. To learn more about that project, click here.
*Reservoir storage values have been updated to reflect recent survey results.
Inundation Maps
Inundation Map of Hypothetical Fair Weather Failure of Calero Dam (2019) (index map)
Inundation Map of Hypothetical Fair Weather Failure of Calero Auxiliary Dam (2019) (index map)
Inundation Map of Hypothetical Inflow Design Flood Failure of Calero Dam and Calero Auxiliary Dam (2019)
Chesbro Dam and Reservoir
Elmer J. Chesbro was the president of the South Santa Clara Valley Water Conservation District at the time of the construction of Chesbro dam and reservoir in 1955. Chesbro dam and reservoir are located on Llagas Creek three miles west of Morgan Hill. The reservoir can store 7,945 acre-feet of water. Its surface area is 283 acres*.
Projects:
Inundation maps
Inundation Map of Hypothetical Fair Weather Failure of Chesbro Dam (2019) (Weather Failure index map)
Inundation Map of Hypothetical Inflow Design Flood Failure of Chesbro Dam (2019) (Flood Failure index map)
*Reservoir storage values have been updated to reflect recent survey results.
Coyote Dam and Reservoir
Many geographic features in California were named directly or indirectly after the coyote. The Spanish explorer Juan Bautista de Anza named the river Arroyo del Coyote after coyotes seen during his journey. The Coyote Reservoir is located on the former Rancho San Ysidro, a cattle ranch that belonged to Ygnacio Ortega in the early 1800s. Coyote Dam and Reservoir is one of original six reservoirs approved for construction by voters in May 1934. Construction of the dams began in 1934, after the PWA approved a grant for $673,000. Its capacity is 23,244 acre-feet of water. Its surface area is 635 acres*.
Projects:
Inundation maps
Inundation Map of Hypothetical Fair Weather Failure of Coyote Dam (Weather Failure index map)
Inundation Map of Hypothetical Inflow Design Flood Failure of Coyote Dam (Flood Failure index map)
*Reservoir storage values have been updated to reflect recent survey results.
Guadalupe Dam and Reservoir
The Santa Clara Valley Water District built the Guadalupe Dam during the Great Depression, completing it in 1935 after acquiring land as the Santa Clara Valley Water Conservation District. The dam and reservoir is one of the six original reservoirs approved for construction by voters in May 1934. The reservoir's surface area is 74 acres. * Both are located along Hicks Creek on Guadalupe Creek, a tributary of the Guadalupe River.
Issues facing the dam and reservoir
Guadalupe Reservoir, which can store about 3,415 acre-feet of water, has a critical problem of extensive mercury contamination. It lies about two miles from the now closed New Almaden Mines, once one of the largest mercury producing mines in the Americas, and still feels the effects of the old work, particularly during large runoff events when mercury containing sediments from mine wastes get into the water from the mining areas. The reservoir is impaired because of its level of toxicity. For more information on how the water district has addressed the problem, click here.
The Guadalupe Dam, meanwhile, will soon be the subject of a seismic upgrade to shore up the dam after a 2011 engineering study found it to be a risk during a large earthquake.
Inundation maps
Inundation Map of Hypothetical Fair Weather Failure of Guadalupe Dam (2019) (Weather Failure index map)
Inundation Map of Hypothetical Inflow Design Flood Failure of Guadalupe Dam (2019) (Flood Failure index map)
Lexington Reservoir and Lenihan Dam
Lexington Reservoir and James J. Lenihan Dam are located on Los Gatos Creek about three miles south of the town of Los Gatos. The dam was constructed in 1952. Initially, the dam was referred to by different names, primarily "Windy Point Dam," because the location of the proposed dam was near an obscure spur known as Windy Point. In 1947, water district directors decided to name the dam and reservoir for Lexington, a small nearby community that was sacrificed when the reservoir was built. In 1996, Lexington Dam was renamed for James J. Lenihan, the Santa Clara Valley Water District's longest-serving director with 37 years of service.
The 2.5-miles-long reservoir is the second-largest water district reservoir. The reservoir capacity is 19,044 acre-feet of water. Its surface area is 412 acres*.
Inundation maps
Inundation Map of Hypothetical Fair Weather Failure of Lenihan Dam (Lenihan Dam index map)
Inundation Map of Hypothetical Fair Weather Failure of Austrian Dam and Lenihan Dam (Austrian & Lenihan Dam index map)
Final SSE2A Reports (December 2012):
Projects and information:
*Reservoir storage values have been updated to reflect recent survey results.
Stevens Creek Dam and Reservoir
Stevens Creek Reservoir is located on Stevens Creek about two miles southwest of Cupertino. Stevens Creek was originally known as Arroyo de San José Cupertino. The stream now bears the name of an early settler, Captain Elishia Stephens, a South Carolinian, who led the first successful passage of wagons over the Sierra Nevada in 1844. Stevens Creek dam and reservoir is one of six original systems approved for construction by voters in 1934. It was completed in 1935. In 1985, an additional 231,000 cubic yards of material was added to the dam, raising it 10 feet. The reservoir capacity is 3,138 acre-feet of water. Its surface area is 92 acres*.
Inundation Maps
Inundation Map of Hypothetical Fair Weather Failure of Stevens Creek Dam (2019) (index map)
Final SSE2A Reports (January 2013)
Projects:
*Reservoir storage values have been updated to reflect recent survey results.
Uvas Dam and Reservoir
Uvas dam and reservoir are located on Uvas Creek about two miles upstream from the intersection of Watsonville and Uvas roads in southern Santa Clara County. The Spanish name for grapes, "uvas," is preserved in a number of place names, all apparently referring to the abundance of wild grapes. Uvas Creek got its name from the land grant Cañada de las Uvas (grape ravine) dated June 14, 1842. Uvas Dam was a part of the South Santa Clara Valley Water Conservation District. It was completed in 1957. The reservoir's capacity is 9,835 acre-feet of water. The surface area is 288 acres*.
*Reservoir storage values have been updated to reflect recent survey results.
Inundation maps
Inundation Map of Hypothetical Fair Weather Failure of Uvas Dam (2019) (Weather Failure index map)
Inundation Map of Hypothetical Inflow Design Flood Failure of Uvas Dam (2019) (Flood Failure index map)
Vasona Dam and Reservoir
Vasona dam and reservoir is located on Los Gatos Creek within the town of Los Gatos. Albert August Vollmer, who came to the area in 1887, named the area after a pony he had as a child. Vasona Lake Dam and Reservoir is one of six original reservoirs approved by the voters in 1934. The reservoir capacity is 495 acre-feet. The surface area is 57 acres. The dam was completed in 1935 and new gates were installed in 1997.
Inundation maps
Inundation Map of Hypothetical Fair Weather Failure of Vasona Dam Spillway Structure (Vasona Dam index map)
Inundation Map of Hypothetical Fair Weather Failure (West Side) of Vasona Dam (Vasona Dam West Side index map)
Inundation Map of Hypothetical Fair Weather Failure (East Side) of Vasona Dam (Vasona Dam East Side index map)
