The federal Central Valley Project (CVP) is the state’s largest water supplier and the largest of the Bureau of Reclamation’s seventeen irrigation projects. The CVP delivers 7 million acre-feet of water on average each year to irrigate 3 million acres or about one-third of California’s irrigated lands, as well as supply drinking water for 1 million households. The CVP also provides hydroelectric power, flood protection, recreation, and water quality benefits, and supplies much of water for the state’s wildlife refuges.
Construction of the Central Valley Project
At the turn of the century, California had the fastest growing population and economy; however, the state’s variable climactic swings of droughts and floods required infrastructure beyond the ability of local communities to construct on their own. This drove a focus from local water supply and flood control projects to larger inter-regional projects that could move and manage water over longer distances.
At the same time, the growth of irrigated agriculture in the Central Valley was reducing flows of freshwater into the Delta, causing salt water to intrude inland, affecting croplands, hindering industrial development, and impacting Antioch and Pittsburg’s water supply. By 1926, salinity intrusion forced Antioch and Pittsburg to stop drawing water from Suisun Bay for agricultural and industrial use, a source the cities had used since the mid-nineteenth century.
For decades, sporadic efforts had been made by various local, state and federal agencies to channel water from the mountainous areas to the lower lying areas for agriculture, but it wasn’t until the Marshall Plan was developed in 1919 did the idea of a statewide scheme of reservoirs and canals gain traction. The Marshall Plan became the basis for the 1930 State Water Plan, and in 1933, the state legislature authorized the project and the sale of revenue bonds. However, in the era of the great Depression, there were few buyers. Eventually, the state asked the federal government to step in with President Franklin Roosevelt authorizing the project in December of 1935.
The Rivers and Harbors Act of 1937 reauthorized the project and appropriated funds for its construction. Later that year, construction began on the Contra Costa Canal with water delivered to the East Bay for the first time in 1940. Construction of Shasta Dam began in 1938 and was completed by 1945. Over the next three decades, Congress would pass thirteen separate measures to authorize additional facilities with the final dam, New Melones, completed in 1979.
Central Valley Project Facilities
Today, the CVP consists of 18 dams and reservoirs, 11 power plants, three fish hatcheries, and 500 miles of canals and aqueducts. The Central Valley Project does not consist of contiguous faculties, and is therefore divided into eight divisions, some of which work in conjunction with other divisions, while other divisions operate completely independently. The Central Valley Project delivers irrigation water to an area spanning the length of the Central Valley from Shasta Reservoir to Kern County; Central Valley Project water also serves water for urban uses in the Bay Area and parts of the Central Valley.
Benefits and impacts of the Central Valley Project
The Central Valley Project is not only the state’s largest water project, but also perhaps its most controversial. When the project was authorized during the Great Depression, some of the environmental consequences could be foreseen, yet the decision was made to go ahead anyway, with the belief that creating an abundant supply for the farms and cities would serve the greater good.
Certainly, the benefits of the Central Valley Project to the state and to the nation have been incalculable. The construction of the Central Valley Project helped propel California to the top as the largest agricultural state in the country, providing inexpensive food and fiber to the nation and to the world. California has led the nation in agricultural and dairy production for the last 50 years. The Central Valley and the Delta produce 25% of the nation’s table food on only 1% of the country’s farmland. Fresno County is the most productive county in the nation, growing 350 crops worth more than $1 billion. Six of the state’s top ten agricultural counties are in the San Joaquin Valley.
In addition, the availability of water and power from the Central Valley Project and other water development projects brought manufacturing and commerce to the state and created millions of jobs in the process. Central Valley Project facilities have prevented billions of dollars of damage from floods, and allowed cities and farms to grow and prosper on the valley floor.
Sara Nevis / DWR
However these benefits were not achieved without a heavy price. In Northern California, the filling of Shasta Reservoir inundated traditional Native American lands and the diversion of up to 90% of the flow of the Trinity River water into the Sacramento River basin has decimated salmon and steelhead populations, creating intense conflict between the United States and Native American tribes in the area which continues to this day.
The construction of Shasta, Friant and other dams did not include fish ladders, blocking access to much of the spawning grounds on the upper Sacramento and San Joaquin rivers and tributaries. Attempts to offset the losses through using hatcheries have essentially failed. Further downstream, freshwater wetlands that once provided habitat for a myriad of fish, migratory birds, and terrestrial species were drained and reclaimed for farming.
The San Joaquin River has paid a heavy price when the entire flow of the river was diverted at Friant Dam, leaving an intermittently dry riverbed for 150 miles. Since construction of the dam, the riverbed below Friant Dam has functioned primarily as a regional drain and flood control channel.
In recent decades, efforts have been underway to address the impacts, including the Central Valley Project Improvement Act, the San Joaquin River Restoration Program, and the Trinity River Restoration Program.
For more information on the Central Valley Project
- Central Valley Project Operations Office: Bureau of Reclamation webpage with the latest water operations, reservoir reports, and more.
- Central Valley Project Wikipedia page
This page was updated August 14, 2024.
