thumb|200px|The Delta-Mendota Canal
200px|thumb|Canal [[siphon under a smaller stream, north of Patterson, California]]
thumb|Map of [[Central Valley Project. Delta Mendota Canal, in blue, runs northwest to southeast, in the central part of the map.]]
The Delta–Mendota Canal is a aqueduct in central California, United States. The canal was designed and completed in 1951 by the U.S. Bureau of Reclamation as part of the Central Valley Project. It carries freshwater to replace San Joaquin River water which is diverted into the Madera Canal and Friant-Kern Canal at Friant Dam.
The canal begins at the C.W. Bill Jones Pumping Plant (also known as the Tracy Pumping Plant). Water is lifted from the Sacramento-San Joaquin Delta at the Clifton Court Forebay. The canal runs southward along the western edge of the San Joaquin Valley, parallel to the California Aqueduct, and diverges to the east after passing the San Luis Reservoir, receiving more water and eventually emptying into the San Joaquin River near the city of Mendota. The canal travels through six California counties: Alameda, San Joaquin, Stanislaus, Merced, and Fresno counties.
History
After years of drought, the state of California highlighted the importance of a large-scale water project, thus creating the California State Water Plan, but eventually being taken over by the U.S. Bureau of Reclamation in 1931 due to the Great Depression. In 1937 the Central Valley Project was approved by Congress to deliver freshwater throughout the San Joaquin Valley. The Friant-Kern Canal east of Fresno was built to distribute water through the eastern parts of the Central Valley, however, altered the natural flows of the San Joaquin River between the Friant Dam and confluence of the Merced River. The Delta–Mendota Canal was approved for the exchange of water rights in the downstream portion of the San Joaquin River. With the use of the Tracy Pumping Plant, water from the Sacramento River would be diverted into the Delta–Mendota Canal. The United States Bureau of Reclamation and the San Luis Delta Mendota Water Authority are responsible for maintaining the water quality that is discharged at the south end of the canal. The Delta–Mendota Canal is also a key feature to the Delta Division Project which is managed by the Bureau of Reclamation, to minimize salt intrusion from the San Francisco Bay.
Due to the length of the canal, it required several contracts to complete the construction. The first contracts given by the Bureau of Reclamation were awarded on June 14, 1946, to Hubert H. Everist for station 686+00-1365+00, and workers went on strike against the subcontractor Fred J. Maurer and Son. The next series of contracts were awarded on October 24, 1946 to the Morrison Knudsen Company, Inc., and the M.H. Hasler Construction Company, who worked on the stations 185+00-231+00 and 243+00-774+00. The pumping station is 60 miles (96 km) to the southeast from the City of San Francisco, in the rural community of Byron, California, near the city of Tracy.
Water is extracted from the southern portion of the San Joaquin Delta, and pumped to contractors in the San Joaquin Valley, San Benito and Santa Clara counties to meet urban and agricultural demands. With the use of two 15 foot diameter pipes, six 22,500-horsepower motors, roughly 8,500 Acre-feet (AF) of water from the Delta can be transported southward daily, after being lifted nearly 200 feet. A series of two 108 inch diameter pipes of 500 feet in length connect the state managed California Aqueduct and the federally managed Delta–Mendota Canal. The pipes have a capacity to pump 467 cubit feet of water per second from the California Aqueduct to the Delta–Mendota Canal. This amount of water restores 35,000 acre feet of water annually to the Central Valley Project. The four pumping units are from Cascade Pump Company from Santa Fe Springs, California, Pump Model 48MF with a 48-inch diameter discharge, with the capability to pump 55,125 gallons per minute.
Protecting fish species
Another key feature is the Tracy Fish Collection Facility. In order to protect threatened and endangered species, a series of sloughs, channels, and tanks, help capture the fish and safely reintroduce them into the Delta waterways. Constructed in the 1950s, its objective is to protect aquatic fauna from being injured or killed by the pumps that facilitate water to the south of the state. The facility is roughly 1 km east from the Pumping Plant, and became operational 1957.
Land subsidence
Land subsidence is prevalent throughout the San Joaquin Valley, but was unrecognized prior to the construction of the canal. After construction, discrepancies in elevation were believed to be caused by earthquake. Post construction years, the southern 30–40 miles of the canal exceeded subsidence of 6 feet. Many use the gravel road adjacent to the canal for biking and walking. No water-contact activities aside from fishing are allowed.
- United States Bureau of Reclamation
- USGS annual flow data