The Central Valley is a broad, elongated, flat valley that dominates the interior of California. It is 40–60 mi (60–100 km) wide and runs approximately 450 mi (720 km) from north-northwest to south-southeast, inland from and parallel to the Pacific coast of the state. It covers approximately 18,000 sq mi (47,000 km2), about 11% of California's land area. The valley is bounded by the Coast Ranges to the west and the Sierra Nevada to the east.
The Central Valley Project (CVP) is a federal power and water management project in the U.S. state of California under the supervision of the United States Bureau of Reclamation (USBR). It was devised in 1933 in order to provide irrigation and municipal water to much of California's Central Valley—by regulating and storing water in reservoirs in the northern half of the state, and transporting it to the water-poor San Joaquin Valley and its surroundings by means of a series of canals, aqueducts and pump plants, some shared with the California State Water Project (SWP). Many CVP water users are represented by the Central Valley Project Water Association.
The Governor Edmund G. Brown California Aqueduct is a system of canals, tunnels, and pipelines that conveys water collected from the Sierra Nevada Mountains and valleys of Northern and Central California to Southern California. Named after California Governor Edmund Gerald "Pat" Brown Sr., the over 400-mile (640 km) aqueduct is the principal feature of the California State Water Project.
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 Joaquin rivers and lies just east of where the rivers enter Suisun Bay, which flows into San Francisco Bay, then the Pacific Ocean via San Pablo Bay. The Delta is recognized for protection by the California Bays and Estuaries Policy. Sacramento–San Joaquin Delta was designated a National Heritage Area on March 12, 2019. The city of Stockton is located on the San Joaquin River at the eastern edge of the delta. The total area of the Delta, including both land and water, is about 1,100 square miles (2,800 km2). Its population is around 500,000.
Oroville Dam is an earthfill embankment dam on the Feather River east of the city of Oroville, California, in the Sierra Nevada foothills east of the Sacramento Valley. At 770 feet (235 m) high, it is the tallest dam in the U.S. and serves mainly for water supply, hydroelectricity generation, and flood control. The dam impounds Lake Oroville, the second-largest reservoir in California, capable of storing more than 3.5 million acre-feet (1.1×10^12 US gal; 4.3×109 m3).
Lake Oroville is a reservoir formed by the Oroville Dam impounding the Feather River, located in Butte County, northern California. The lake is situated 5 miles (8 km) northeast of the city of Oroville, within the Lake Oroville State Recreation Area, in the western foothills of the Sierra Nevada. Known as the second-largest reservoir in California, Lake Oroville is treated as a keystone facility within the California State Water Project by storing water, providing flood control, recreation, freshwater releases to assist in controlling the salinity intrusion into the Sacramento-San Joaquin Delta and protecting fish and wildlife.
San Luis Dam, also known as B.F. Sisk Dam, is a major earth-filled dam in Merced County, California, which forms San Luis Reservoir, the largest off-stream reservoir in the United States. The dam and reservoir are located in the Diablo Range to the east of Pacheco Pass and about 10 miles (16 km) west of Los Banos. San Luis Dam, a jointly-owned state and federal facility, stores more than 2 million acre feet (2.5 km3) of water for the California State Water Project and the federal Central Valley Project. Although the dam is located in the valley of San Luis Creek, the majority of its water comes from man-made aqueducts which are supplied from other rivers in Northern California.
The California State Water Project, commonly known as the SWP, is a state water management project in the U.S. state of California under the supervision of the California Department of Water Resources. The SWP is one of the largest public water and power utilities in the world, providing drinking water for more than 27 million people and generating an average of 6,500 GWh of hydroelectricity annually. However, as it is the largest single consumer of power in the state itself, it has a net usage of 5,100 GWh.
The North Bay Aqueduct (NBA) is part of the California State Water Project that was built in two phases, Phase I (1967-1968) and Phase II (1985-1988). The aqueduct is 27.4 miles (44.1 km) long all in pipelines and serves Napa and Solano counties, California. The aqueduct provides water to about 500,000 residents in Solano and Napa.
The Peripheral Canal was a series of proposals starting in the 1940s to divert water from California's Sacramento River, around the periphery of the San Joaquin-Sacramento River Delta, to uses farther south. The canal would have attempted to resolve a problem with the quality of water pumped south. Pumps create such a powerful suction that the boundary between freshwater to saltwater has shifted inland, negatively affecting the environment. The pumps have increased by 5 to 7 million acre-feet the amount of water exported each year to the Central Valley and Southern California. However, the peripheral canal as proposed would have reduced the overall freshwater flow into the Delta and move the freshwater-saltwater interface further inland, causing damage to Delta agriculture and ecosystems.
The Oroville–Thermalito Complex is a group of reservoirs, structures, and facilities located in and around the city of Oroville in Butte County, California. The complex serves not only as a regional water conveyance and storage system, but is the headwaters for, and therefore perhaps is the most vital part of, the California Department of Water Resources' State Water Project, as one of the largest publicly built and operated water and power development and conveyance systems.
California's interconnected water system serves almost 40 million people and irrigates over 5,680,000 acres (2,300,000 ha) of farmland. As the world's largest, most productive, and potentially most controversial water system, it manages over 40 million acre-feet (49 km3) of water per year. Use of available water averages 50% environmental, 40% agricultural and 10% urban, though this varies considerably by region and between wet and dry years. In wet years, "environmental" water averages 61%, while in dry years it averages 41%, and can be even lower in critically dry years.
The California State Water Resources Control Board (SWRCB) is one of six branches of the California Environmental Protection Agency.
California Reclamation Districts are legal subdivisions within California's Central Valley that are responsible for managing and maintaining the levees, fresh water channels, or sloughs, canals, pumps, and other flood protection structures in the area. Each is run autonomously and is run by an elected board and funded with taxes to property owners in the local area. However, the Central Valley Flood Protection Board has the power to determine that a district is not satisfactorily maintaining the structures and causing the California Department of Water Resources to declare an area as a maintenance area.
The Sites Reservoir is a proposed offstream reservoir project west of Colusa in the Sacramento Valley of northern California, to be built and operated by the Sites Project Authority. The project would divert water from the Sacramento River upstream of the Sacramento–San Joaquin River Delta, through existing canals to a new reservoir 14 miles (23 km) away. Annual yield would depend on precipitation and environmental restrictions.
Delta Conveyance Project, formerly known as California Water Fix and Eco Restore or the Bay Delta Conservation Plan, is a $15 billion plan proposed by Governor Jerry Brown and the California Department of Water Resources to build a 36 foot diameter tunnel to carry fresh water from the Sacramento River southward under the Sacramento-San Joaquin Delta to Bethany Reservoir for use by the State Water Project and the Central Valley Project.
The California Water Plan is the State of California’s long-term strategic plan for managing and developing water resources throughout the state. The Water Plan is mandated by California Water Code Sections 10004–10013, and the California Department of Water Resources (DWR) is required to update the plan every five years. Although the Water Plan does not create mandates, propose specific projects, or authorize funding, Water Code Section 10005 defines the plan and its updates as “the master plan which guides the orderly and coordinated control, protection, conservation, development, management and efficient utilization of the water resources of the state.” Eleven updates to the plan have been prepared since 1957.
The Sustainable Groundwater Management Act (SGMA) is a three-bill package that passed the California state legislature and was signed into California state law by Governor Jerry Brown in September 2014. Its purpose is to ensure better local and regional management of groundwater use and it seeks to have a sustainable groundwater management in California by 2042. It emphasizes local management and formed groundwater sustainability agencies (GSAs) from local and regional authorities who submitted groundwater sustainability plans (GSPs) to the state between 2020 and 2022.
In February 2017, heavy rainfall damaged Oroville Dam's main and emergency spillways, prompting the evacuation of more than 180,000 people living downstream along the Feather River and the relocation of a fish hatchery.
The Central Valley in California subsides when groundwater is pumped faster than underground aquifers can be recharged. The Central Valley has been sinking (subsiding) at differing rates since the 1920s and is estimated to have sunk up to 28 feet. During drought years, the valley is prone to accelerated subsidence due to groundwater extraction. California periodically experiences droughts of varying lengths and severity.
