Twitchell Reservoir is a

reservoir A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including contr ...

in southern

San Luis Obispo County San Luis Obispo County (), officially the County of San Luis Obispo, is a county on the Central Coast of California. As of the 2020 census, the population was 282,424. The county seat is San Luis Obispo. Junípero Serra founded the Mis ...

and northern

Santa Barbara County Santa Barbara County, California, officially the County of Santa Barbara, is located in Southern California. As of the 2020 census, the population was 448,229. The county seat is Santa Barbara, and the largest city is Santa Maria. Santa Barba ...

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

. The reservoir has a capacity of and is formed by Twitchell Dam on the

Cuyama River The Cuyama River (Chumash: ''Kuyam'', meaning "Clam") is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed March 15, 2011 river in southern San Luis Obispo County, northern Santa Barbar ...

about from its headwaters in the Chumash Wilderness Area and about from its confluence with the Sisquoc River, where they form the Santa Maria River. Twitchell Dam was built by the

United States 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 ...

between 1956 and 1958. The original names were Vacquero Dam and Vacquero Reservoir, but they were changed to honor T. A. Twitchell of Santa Maria, a proponent of the project. The dam and reservoir provide

flood A flood is an overflow of water ( or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are an area of study of the discipline hydrol ...

control and

water conservation Water conservation includes all the policies, strategies and activities to sustainably manage the natural resource of fresh water, to protect the hydrosphere, and to meet the current and future human demand (thus avoiding water scarcity). Popula ...

. The

Central Coast of California The Central Coast is an area of California, roughly spanning the coastal region between Point Mugu and Monterey Bay. It lies northwest of Los Angeles County and south of San Mateo and Santa Clara counties, and includes the rugged, undevelop ...

only receives significant amounts of rainfall during the winter, this area averaging per year. The water is stored in the reservoir during big winter storms and released as quickly as possible while still allowing it to percolate into the soil and recharge the

groundwater Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit ...

. This means that the reservoir is usually far from full. It is estimated that the project increases recharge by annually. Sedimentation is a problem for the reservoir, as the reservoir is being filled 70 percent faster than expected. This reduces its capacity and blocks the water inlet to the control gates. Some

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand ...

has been removed by flushing it out during releases, but much of it is simply deposited immediately downstream, interfering with flows. There is no public access to the dam or reservoir.From U.S. Government Bureau of Reclamation web site.
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Notes

References

United States Bureau of Reclamation - Santa Maria Project
* {{authority control Reservoirs in San Luis Obispo County, California Reservoirs in Santa Barbara County, California Dams in California United States Bureau of Reclamation dams Dams completed in 1958 Reservoirs in California Reservoirs in Southern California

See also

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References