State Water Project
The California State Water Project (SWP) is a multi-purpose water storage and delivery system that extends more than 705 miles -- two-thirds the length of California. A collection of canals, pipelines, reservoirs, and hydroelectric power facilities delivers clean water to 27 million Californians, 750,000 acres of farmland, and businesses throughout our state.
Planned, built, operated and maintained by DWR, the SWP is the nation’s largest state-owned water and power generator and user-financed water system. The project is considered an engineering marvel that has helped fuel California’s population boom and economic prosperity since its initial construction.
The SWP was designed to deliver nearly 4.2 million acre-feet of water per year. Water is received by 29 long-term SWP Water Supply Contractors who distribute it to farms, homes, and industry. Today, about 30 percent of water from the SWP is currently used for irrigation, mostly in the San Joaquin Valley, and about 70 percent is used for residential, municipal and industrial use.
The State Water Project also plays an important role in efforts to combat climate change. Not only does it help California manage its water supply during extremes such as flooding and drought, it is also a major source of hydroelectric power deliveries for the State's power grid.
Benefits of the SWP:
The primary purpose of the SWP is water supply delivery and flood control, but it provides many additional benefits, including:
- Power generation
- Recreation activities
- Environmental stewardship
DWR manages the California State Water Project (SWP) to ensure adequate water supplies are available under various hydrologic and legal conditions while maintaining operational flexibility.
DWR also develops, plans and implements the operation of the SWP in coordination with environmental and regulatory agencies to meet fish, water, and environmental requirements for the Feather River and Sacramento-San Joaquin Delta.
Additionally, the SWP coordinates closely with other water storage and water users that utilize the Sacramento-San Joaquin Delta watershed. The other agency that operates in a similar fashion to move water throughout California is the federal Bureau of Reclamation’s Central Valley Project (CVP).
Learn more about DWR's operations and maintenance.
The SWP is operated in a manner that protects endangered and threatened species under the State and federal endangered species acts.
DWR also conducts water quality monitoring for the SWP. This program is currently managed by the Division of Operations and Maintenance, Environmental Assessment Branch. Initially, this program sought to monitor eutrophication (an increase in chemical nutrients) and salinity in the SWP. Over time, the water quality program expanded to include parameters of concern for drinking water, recreation, and wildlife.
While the majority of the SWP was being constructed in the 1960s, public agencies and local water districts signed long-term water supply contracts with DWR. Today, the 29 public agencies and local water districts are collectively known as the SWP long-term water contractors or simply, SWP water contractors.
The water supply contracts (which expire in 2035) sets forth the maximum amount of SWP water a contractor may request annually (see Table A amounts, below). However, the amount of SWP water available for delivery will vary yearly, based on a number of factors, including:
- Hydrologic conditions
- Current reservoir storage
- Delivery requests from the SWP water contractor
Learn more about State Water Project management.
- California Independent System Operator
- California Public Utilities Commission
- Federal Energy Regulatory Commission
- State Water Contractors Association
- United States Army Corps of Engineers
- U.S. Bureau of Reclamation Central Valley Project
- Western Area Power Administration
- Western Electricity Coordinating Council
- Western Systems Power Pool