HOME

TheInfoList



OR:

Anderson Lake, also known as Anderson Reservoir, is an
artificial lake A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from t ...
in
Morgan Hill Morgan Hill is a city in Santa Clara County, California, at the southern tip of Silicon Valley in the San Francisco Bay Area. Morgan Hill is an affluent residential community, the seat of several high-tech companies, and a dining and recreation ...
, located in southern
Santa Clara County, California Santa Clara County, officially the County of Santa Clara, is the sixth-most populous county in the U.S. state of California, with a population of 1,936,259 as of the 2020 United States census, 2020 census. Santa Clara County and neighboring Sa ...
. The reservoir is formed by the damming of Coyote Creek just below its confluence with Las Animas Creek. A county park surrounds the reservoir and provides limited fishing ("
catch and release Catch and release is a practice within recreational fishing where after capture the fish is Fish hook, unhooked and returned live to the water. Originally adopted in the United Kingdom by Coarse fishing, coarse fishermen to Overfishing, preser ...
"), picnicking, and hiking activities. Although swimming is prohibited, boating, water-skiing, and jet-skiing are permitted in the reservoir. The
California Office of Environmental Health Hazard Assessment The Office of Environmental Health Hazard Assessment, commonly referred to as OEHHA (pronounced oh-EEE-ha), is a specialized department within the cabinet-level California Environmental Protection Agency (CalEPA) with responsibility for evaluati ...
has issued a safet
advisory
for any fish caught in Anderson Lake due to elevated levels of mercury and PCBs.


History

The reservoir was created in by the construction of the Anderson Dam across Coyote Creek in the foothills of the Diablo Mountains east of
Morgan Hill Morgan Hill is a city in Santa Clara County, California, at the southern tip of Silicon Valley in the San Francisco Bay Area. Morgan Hill is an affluent residential community, the seat of several high-tech companies, and a dining and recreation ...
. The reservoir and dam were named after Leroy Anderson, a key founder and first president of the
Santa Clara Valley Water District The Santa Clara Valley Water District (also known as Valley Water) provides stream stewardship, wholesale water supply and flood protection for Santa Clara County, California, in the southern San Francisco Bay Area. The district encompasses all ...
(not to be confused with the music composer of the same name). It is the largest reservoir owned by the district.


Risk of dam failure

In January 2009, a preliminary routine seismic study suggested a small chance that a large-
magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...
earthquake (6.6 with the dam at the
epicenter The epicenter (), epicentre, or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter or focus, the point where an earthquake or an underground explosion originates. Determination The primary purpose of a ...
, or 7.2 up to a mile away) could result in flooding in Morgan Hill and as far away as San Jose. In response, the
Santa Clara Valley Water District The Santa Clara Valley Water District (also known as Valley Water) provides stream stewardship, wholesale water supply and flood protection for Santa Clara County, California, in the southern San Francisco Bay Area. The district encompasses all ...
(SCVWD) lowered the water level to 74 percent of capacity and announced a further analysis of the situation, which could possibly result in retrofitting the dam if necessary. Updated findings in October, 2010 indicated that the dam could fail if a magnitude 7.25 earthquake occurred within of the dam, potentially releasing a wall of water high into downtown Morgan Hill in 14 minutes, and deep into San Jose within three hours. In response SCVWD has lowered the water to 54% full, which is feet below the dam crest. In July 2011, SCVWD issued a report stating that the seismic stability study on Anderson Dam was completed. The storage restriction that has been in place since October 2010 was adjusted, allowing 12 additional feet of storage, which measures 68 percent of the dam's capacity, up from 57 percent. The water district initiated a capital project for a seismic retrofit by the end of 2018. The operating restriction was to remain in place until the project was complete. Remediation of the problem was expected to cost as much as
US$ The United States dollar (Currency symbol, symbol: Dollar sign, $; ISO 4217, currency code: USD) is the official currency of the United States and International use of the U.S. dollar, several other countries. The Coinage Act of 1792 introdu ...
100 million. In December 2016, SCVWD reported that further geotechnical analysis indicated that considerably more work would need to be performed on the dam, essentially removing it and rebuilding it. The existing dam had been built on alluvial deposits which could liquefy during an earthquake. Accordingly, the estimated cost rose to US$400 million and the start of work was rescheduled to 2020, with completion planned for 2023–2024. After years of additional studies and interim actions, the
Federal Energy Regulatory Commission The Federal Energy Regulatory Commission (FERC) is an independent agency of the United States government that regulates the interstate transmission and wholesale sale of electricity and natural gas and regulates the prices of interstate transport ...
dismissed the Water District's plans as insufficient to address the risk of catastrophic failure and ordered on February 20, 2020, that lowering of the reservoir to deadpool storage begin no later than October 1. The letter noted that the district's "actions to date do not demonstrate an appropriate sense of urgency" regarding the risk of catastrophic failure in the case of an earthquake. In 2020, the reservoir was drained, to 3% of its capacity. This will enable the water district to disassemble and rebuild the dam. It had the effect of increasing San Jose's reliance on imported water.


San Jose flooding

On February 21, 2017, during the 2017 California floods, the reservoir reached as high as 104% of capacity, creating a large flow over the spillway into Coyote Creek, which overflowed and flooded the Rock Springs/Summerside, Olinder, Naglee Park, Roosevelt, Wooster-Tripp and Berryessa neighborhoods of San Jose along
US Highway 101 U.S. Route 101, or U.S. Highway 101 (US 101), is a major north–south highway that traverses the states of California, Oregon, and Washington on the West Coast of the United States. It is part of the United States Numbered Highway Syst ...
between the reservoir and the south
San Francisco Bay San Francisco Bay (Chochenyo language, Chochenyo: 'ommu) is a large tidal estuary in the United States, U.S. state of California, and gives its name to the San Francisco Bay Area. It is dominated by the cities of San Francisco, California, San ...
.


Anderson Dam

The earthen dam measures long by wide and sits along the Coyote Creek Fault on Coyote Road, east of Morgan Hill. The reservoir itself is situated parallel to the
Calaveras Fault The Calaveras Fault is a major branch of the San Andreas Fault System that is located in northern California in the San Francisco Bay Area. Activity on the different segments of the fault includes moderate and large earthquakes as well as aseis ...
, which runs from Hollister to
Milpitas Milpitas (Spanish for or little cornfields) is a city in Santa Clara County, California, part of Silicon Valley and the broader San Francisco Bay Area. Located on the eastern shore of San Francisco Bay, it is bordered by San Jose to the south, ...
. It holds over of water when full, more than the other nine reservoirs in the county combined.


Anderson Lake County Park

The Anderson Lake County Park is managed by the Santa Clara County Parks and Recreation Department. In addition to the county's largest reservoir is the Coyote Creek Parkway multiple-use trails, the Jackson Ranch historic park site, the Moses L. Rosendin Park, the Burnett Park area, and Anderson Lake Visitors Center. Coyote Creek Parkway, a paved trail along Coyote Creek that heads north to
Hellyer County Park Hellyer County Park is one of 28 Santa Clara County Parks. The park is located just off of Highway 101 in San Jose, California, United States. The park is home to Hellyer Park Velodrome and Cottonwood Lake. Other recreational opportunities at th ...
, is used for hiking, jogging, bicycling, horseback riding, and skating.


See also

*
List of lakes in California There are more than 3,000 named lakes, reservoirs, and dry lakes in the U.S. state of California. Largest lakes In terms of area covered, the largest lake in California is the Salton Sea, a lake formed in 1905 which is now saline. It occup ...
*
List of lakes in the San Francisco Bay Area This list of lakes in the San Francisco Bay Area groups lakes, ponds, and reservoirs by county. Numbers in parentheses are Geographic Names Information System feature ids. Alameda County, California, Alameda County * Almond Reservoir () * Berr ...
*
List of dams and reservoirs in California Following is a list of dams and reservoirs in California in a sortable table. There are over 1,400 named dams and 1,300 named reservoirs in the state of California. Dams in service :''Please add to this list from the below sources.'' Former ...


References


External links


Detailed plan to drain lake1995, 1982, 1983 Anderson Dam spillover videoWaterfall
during the 2017 California floods {{Authority control Morgan Hill, California Reservoirs in Santa Clara County, California Reservoirs in California Reservoirs in Northern California