The Mokelumne Aqueduct is a water conveyance system in central

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

, United States. The aqueduct is supplied by the

Mokelumne River The Mokelumne River ( or ; ''Mokelumne'', Miwok for "People of the Fish Net") is a -long river in northern California in the United States. The river flows west from a rugged portion of the central Sierra Nevada (U.S.), Sierra Nevada into the Ce ...

and provides water to 35 municipalities in the East Bay in the

San Francisco Bay Area The San Francisco Bay Area, often referred to as simply the Bay Area, is a populous region surrounding the San Francisco, San Pablo, and Suisun Bay estuaries in Northern California. The Bay Area is defined by the Association of Bay Area Go ...

. The aqueduct and the associated dams, pipelines, treatment plants and hydroelectric system are owned and operated by the

East Bay Municipal Utility District East Bay Municipal Utility District (EBMUD), colloquially referred to as "East Bay Mud", is a public utility district which provides water and sewage treatment services for an area of approximately in the eastern side of the San Francisco Bay.S ...

(EBMUD) and provide over 90 percent of the water used by the agency. The aqueduct is the sole water supply for about 1.4 million people in the East Bay. Under present water rights agreements, EBMUD can withdraw up to 325 million gallons (1,230,000 m³) per day, or per year, from the Mokelumne River. In addition, up to 98 million gallons (371,000 m³) per day or per year can be supplied via a branch from the

Sacramento River The Sacramento River ( es, Río Sacramento) is the principal river of Northern California in the United States and is the largest river in California. Rising in the Klamath Mountains, the river flows south for before reaching the Sacramento–S ...

. However, this supply is expected only to be used in the driest 35% of years.

History

In the early 20th century, due to a lack of reliable local water, Bay Area cities began to look to rivers in the

Sierra Nevada The Sierra Nevada () is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primarily ...

, about east, as a potential new source. Although the city of

San Francisco San Francisco (; Spanish language, Spanish for "Francis of Assisi, Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the List of Ca ...

was already extending an aqueduct to the Tuolumne River, East Bay communities wanted to build an independent water system, fearing future " hegemony" of the water system by San Francisco. In 1923, the EBMUD was organized and in 1924 acquired water rights to the Mokelumne River, a major tributary in the San Joaquin River system. On November 4, 1924, residents approved $39 million in bonds to finance the project. Construction began in 1926 and by 1929, the high, concrete arch

Pardee Dam Pardee Dam is a -high structure across the Mokelumne River which marks the boundary between Amador and Calaveras Counties, located in the foothills of the Sierra Nevada approximately northeast of Stockton. History Construction of the Pardee ...

and the First Mokelumne Aqueduct, consisting of a single pipeline, were completed. The first deliveries to the Bay Area were made on June 23, 1929. At the time of completion, Pardee Dam was the tallest in the world (this record was surpassed one year later by

Diablo Dam Diablo Dam is one of three dams along the upper Skagit River in Whatcom County, Washington and part of the Skagit River Hydroelectric Project that supplies Seattle with some of its power needs. The dam was built in Diablo Canyon, a gorge of solid g ...

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered on ...

State). In 1949, a second pipeline was built and in 1963 the third pipeline was constructed, bringing the aqueduct to its present capacity. In 1964, the second major dam of the project, Camanche Dam, was completed below Pardee. In 1970, EBMUD signed a contract with the

U.S. Bureau of Reclamation The Bureau of Reclamation, and formerly the United States Reclamation Service, is a federal agency under the U.S. Department of the Interior, which oversees water resource management, specifically as it applies to the oversight and opera ...

(USBR) for supplemental water from the

Folsom South Canal The Folsom South Canal is an aqueduct in Northern California in the United States. The canal diverts water from the American River at Nimbus Dam in Sacramento County and travels about in a southerly direction, terminating near Clay, about northe ...

, which draws water from the American River near

Sacramento ) , image_map = Sacramento County California Incorporated and Unincorporated areas Sacramento Highlighted.svg , mapsize = 250x200px , map_caption = Location within Sacramento ...

. The USBR supply was delayed for nearly 40 years in part due to minimum flow requirements in the American River to protect

salmon Salmon () is the common name for several list of commercially important fish species, commercially important species of euryhaline ray-finned fish from the family (biology), family Salmonidae, which are native to tributary, tributaries of the ...

and steelhead populations. The Folsom South Canal Connection (FSCC), which links the two waterways, was finally completed in 2009.

Specifications

The aqueduct begins at Pardee Reservoir, which is formed by Pardee Dam on the Mokelumne River. The reservoir has a capacity of , or about a 10-month supply. Camanche Reservoir, located directly below Pardee, has a storage capacity of – twice the size of Pardee – but is not directly linked to the aqueduct. However, Camanche allows for greater diversions into the aqueduct by storing winter floodwaters spilled from Pardee. During the dry season, water is released from Camanche in order to satisfy local water-rights holders, eliminating the need to draw water from Pardee. The aqueduct travels southwest for through the western foothills of the

and then west across the Central Valley along the Calaveras River before crossing the

Sacramento–San Joaquin River Delta The Sacramento–San Joaquin River Delta, or California Delta, is an expansive inland river delta and estuary in Northern California. The Delta is formed at the western edge of the Central Valley by the confluence of the Sacramento and San ...

. Near Lodi, the aqueduct is joined by an extension of the Folsom South Canal, which supplements the Mokelumne River supply. Once the water reaches the

Berkeley Hills The Berkeley Hills are a range of the Pacific Coast Ranges that overlook the northeast side of the valley that encompasses San Francisco Bay. They were previously called the "Contra Costa Range/Hills" (from the original Spanish ''Sierra de la C ...

above the East Bay, it is channeled into a complex distribution system consisting of six terminal reservoirs ( Briones, Chabot, Lafayette, San Pablo and Upper San Leandro) with a combined storage capacity of . The water is treated at the San Pablo, Sobrante and Upper San Leandro Treatment Plants before passing through the Claremont Tunnel, which emerges on the western side of the range between

Berkeley Berkeley most often refers to: *Berkeley, California, a city in the United States **University of California, Berkeley, a public university in Berkeley, California * George Berkeley (1685–1753), Anglo-Irish philosopher Berkeley may also refer ...

and

Oakland Oakland is the largest city and the county seat of Alameda County, California, United States. A major West Coast port, Oakland is the largest city in the East Bay region of the San Francisco Bay Area, the third largest city overall in the Bay A ...

. Water not immediately put into the municipal system is stored in the reservoirs for use in times of low delivery or drought. Most of the aqueduct consists of three separate buried steel pipelines, although there are also some aboveground segments. The pipelines, also known as Aqueducts No. 1, 2 and 3, have diameters of , and , respectively. Aside from the main facilities, the distribution system includes of pipes, 125 pump plants, and 168 local reservoirs/storage tanks.

Issues

The aqueduct is located in a seismically active zone and is considered vulnerable to earthquakes, especially the stretch where it crosses the Sacramento–San Joaquin Delta, where an earthquake or storm-induced

levee A levee (), dike (American English), dyke (English in the Commonwealth of Nations, Commonwealth English), embankment, floodbank, or stop bank is a structure that is usually soil, earthen and that often runs parallel (geometry), parallel to ...

failure could damage the pipelines or any of three major river crossings here. A large earthquake (100 year return period or more) could put the aqueduct out of service from 18 months to three years, depending on the extent of the damage. Levee failures in 1980 and 2004 (not caused by earthquakes) on

Jones Tract The Jones Tract is an island containing Lower Jones Tract and the Upper Jones Tract in the Sacramento-San Joaquin River Delta, fifteen kilometres west of Stockton, California, Stockton. The island is bounded on the north by Empire Cut, on the no ...

have threatened the aqueduct. An aqueduct joint at the crossing of the Middle River also failed in 1992, nearly causing a washout of the levee. The aqueduct was shut down in time before an actual levee breach could occur. Because Pardee Reservoir is relatively small among California reservoirs, EBMUD has pursued to raise Pardee Dam to a height of . This would expand the reservoir surface by . The enlarged reservoir would cover , an increase of 62 percent, and the capacity would be about , a roughly 50 percent increase. It would allow for more water to be provided during the dry season that would otherwise have been spilled over the dam during the winter. This project would have flooded between of the Mokelumne River. Due to environmental concerns, the project was shelved in 2011.

References

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External links

The Mokelumne Aqueduct
– Maven's Notebook Aqueducts in California East Bay Municipal Utility District Interbasin transfer Mokelumne River San Joaquin Valley Infrastructure completed in 1929 1929 establishments in California Buildings and structures in Amador County, California Buildings and structures in Calaveras County, California Transportation in Amador County, California Transportation in Calaveras County, California Transportation buildings and structures in Contra Costa County, California Transportation buildings and structures in San Joaquin County, California Transportation buildings and structures in Alameda County, California

History

Specifications

Issues

See also

References

External links