| Calero Reservoir | |
|---|---|
 May 2009 | |
  Calero Reservoir  Calero Reservoir | |
| Location | Santa Clara County, California |
| Coordinates | 37°11′08″N121°46′39″W / 37.18556°N 121.77750°W /37.18556; -121.77750[1] |
| Type | Reservoir |
| Primary inflows | Cherry Canyon,[2] Pine Tree Canyon[3] |
| Primary outflows | Arroyo Calero[4] |
| Catchment area | 7.14 sq mi (18.5 km2) |
| Basin countries | United States |
| Managing agency | Santa Clara Valley Water District |
| Max. length | 2.2 miles (3.5 km) |
| Surface area | 349 acres (141 ha) |
| Water volume | 9,934 acre-feet (12,253,000 m3) |
| Surface elevation | 476 feet (145 m) |
| References | [5][1][2][3][4][6] |
Calero Reservoir, also calledCalero Lake, is areservoir inSan Jose, California, located in theCalero neighborhood ofAlmaden Valley inSouth San Jose. It is the site ofCalero County Park, which also includes a large area covering the lake and hundreds of acres of hills around it.
The reservoir was formed by the Calero Dam,[7] built in 1935 (90 years ago) (1935) acrossArroyo Calero, which is also known asCalero Creek.
Calero Dam is an earthen dam 90 feet (27 m) high and 840 feet (260 m) long containing 550,000 cubic yards (420,000 m3) of material. Its crest is 490 feet (150 m) above sea level.[6] The reservoir receives flows from the southwest via Cherry Canyon[8] which has its origin at Fern Peak[9] in the southeastern part of theSanta Cruz Mountains. It also receives minor inputs from the southeast via the ephemeral flows down Pine Tree Canyon[10]
Calero Reservoir is the fourth largest reservoir owned by theSanta Clara Valley Water District.[6] After capturing winter runoff from the nearby foothills and from water transferred, via a canal, from nearbyAlmaden Reservoir, reservoir water recharges groundwater basins and is also provided directly to water treatment plants, via the Almaden Valley Pipeline, to be treated and distributed to county residents.[7] Calero Reservoir also can receive flows fromAnderson Reservoir andSan Luis Reservoir, via the recently restored Cross Valley and Calero pipelines which stretch 10.6 miles (17.1 km), starting from the Coyote Pump Plant inMorgan Hill, extending through parts of unincorporated Santa Clara County, and ending at the Calero Reservoir in South San Jose.[11]
Because alluvium deposits were found beneath the dam in a 2012 independent engineering study, and these could liquify in an earthquake, reservoir levels are currently maintained 19 feet below the spillway. Retrofit construction of the dam may begin only after the retrofit onAnderson Reservoir is complete in 2031.[12] This restriction limits Calero Reservoir to 45% of capacity or about 4,414 acre-feet. When the Calero Dam retrofit is completed, the capacity of Calero Reservoir could be restored to 9,738 acre-feet and increase the outlet capacity from 50 cfs to up to 100 cfs.
Water from Calero Reservoir is carried downstream by Arroyo Calero, a tributary toAlamitos Creek, which is in turn tributary to theGuadalupe River and thence to southSan Francisco Bay.
TheCalifornia Office of Environmental Health Hazard Assessment released a "Do Not Eat" warning regarding eating any fish caught from this reservoir based on the elevated mercury level.[13] The primary fish caught in Calero Reservoir are non-native, includinglargemouth bass (Micropterus salmoides), Eurasiancommon carp (Cyprinus carpio), andblack crappie (Pomoxis nigromaculatus).[14]
A 4,471-acre (1,809 ha) county park surrounds the reservoir[15] and provides limited fishing[16] ("catch-and-release"), picnicking, hiking, and horseback riding activities. Although swimming is prohibited,[17] boating, water-skiing and jet-skiing are permitted in the reservoir.[18]
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 nearbyAlmaden Reservoir watershed and accepts imported water.
Mercury has been found to accumulate in Almaden, Calero, Guadalupe, Anderson and Stevens Creek Reservoirs at levels that make the fish unsafe to eat.
Swimming at Almaden, Coyote, Anderson and Calero reservoirs is prohibited by the state Department of Health to protect the drinking water supply from potential bacteriological contamination.
Boating is permitted from 8am to ½ hour before sunset in the following reservoirs: Calero,Coyote Lake,Anderson,Stevens Creek andLexington.
