Learn about Projects for California Department of Water Resources Water System Revenue Bonds, including State Water Project  and The Delta.

State Water Project 

The California State Water Project (SWP) is a water storage and delivery system of reservoirs, aqueducts, power plants and pumping plants extending more than 700 miles—two-thirds the length of California.

Planned, constructed, and operated by the Department of Water Resources, the SWP is the nation’s largest state-built, multi-purpose, user-financed water project. It supplies water to more than 26 million people in northern California, the Bay Area, the San Joaquin Valley, the Central Coast and southern California. SWP water also irrigates about 750,000 acres of farmland, mainly in the San Joaquin Valley.

The primary purpose of the SWP is water supply. 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. Water supply depends on rainfall, snowpack, runoff, water in storage facilities, and pumping capacity from the Delta, as well as operational constraints for fish and wildlife protection, water quality, and environmental and legal restrictions.


The SWP was designed to provide many additional benefits:

  • Flood control – The flood of 1955, which submerged Yuba City, was the impetus for the construction of Lake Oroville.
  • Power generation – The SWP produces hydroelectric power to operate pumping facilities required to move water from Northern to Southern California. The SWP sells power when it generates a surplus of electricity.
  • Recreation – SWP lakes and reservoirs provide opportunities to swim, picnic, waterski, boat, fish, hike, bike, camp, and horseback ride. Visitors are also welcome at three visitors centers located at Lake Oroville, San Luis Reservoir, and Lake Pyramid.
  • Fish and wildlife habitat –The SWP is operated to protect fish and wildlife with fish hatcheries, fish screens and passages, mitigation agreements, fish surveys and monitoring, a fish salvage facility, habitat restoration, and restricted pumping schedules.
Environmental Roles

The SWP operates to balance the needs of water delivery and environmental protection.  The sustainability of California’s water resources depends on the environmental health of the Sacramento-San Joaquin Delta. In cooperation with the federal Central Valley Project, we operate the SWP to limit salinity intrusion into the Sacramento-San Joaquin Delta and Suisun Marsh by supplementing freshwater outflows to the ocean and limiting water exports from the Delta during certain times of the year.

We work cooperatively with regulatory agencies to develop interim and long-term operations solutions that are responsive to federal and State endangered species acts. We participate in habitat restoration projects that preserve and protect special status species impacted by SWP operations. We assess, evaluate, and propose solutions to improve system water management performance through improved operational agreements, economic analyses, and other methods.

Climate change presents an additional challenge to SWP operations. We are studying climate change to understand its impacts on water delivery and the environment, to ensure a sustainable water supply.

The Delta

The picturesque Sacramento-San Joaquin Delta is the hub of California’s water supply, supplying fresh water to two-thirds of the state’s population and millions of acres of farmland. Saltwater from the San Francisco Bay mixes with fresh water from the Sacramento, San Joaquin, and other rivers to create the largest estuary on the West Coast. This estuary provides habitat critical to the survival of many fish and wildlife species. It is also a rich agricultural area, a recreational wonderland, and a complex ecosystem that is home to a dazzling variety of wildlife.

The conveyance of water from north to south relies on the movement of that water through the Delta and its maze of levees and islands and maintaining the right balance of saltwater and fresh water. Careful operations of the State Water Project (SWP) and federal Central Valley Project (CVP) are critical to keeping the balance, especially in the face of new and ongoing water management challenges.

 Challenges Facing the Delta

The long-term sustainability of the Delta and our fresh water supply is threatened by floods, rising sea levels, earthquake damage, aging levees, invasive species, and contaminants. The Delta ecosystem is also facing threats that impact native plants, animals, migratory waterfowl, and fish. Iconic Delta smelt, indicators of the estuary’s health, are on State and federal agencies’ threatened and endangered lists. Equally iconic Chinook salmon and other native fish species also are in trouble as a result of engineered stream flows and disturbances caused by the pumps of the SWP and CVP.

California WaterFix

The California WaterFix addresses California’s concerns about long-term water supply reliability and Delta ecosystem health.

Working through a collaboration of State and federal partners, WaterFix will isolate fish from the effects of water pumping operations while restoring Delta habitat for all wildlife. The benefit to humans is that export pumping will not be frequently curtailed to protect sensitive fish species. Water quality also will be improved by moving export intakes upstream to less saline waters of the Sacramento River just south of the City of Sacramento. 

Despite stresses, the Delta remains one of California’s jewels, a scenic panorama of islands, waterways, wildlife, farmland, ports, marinas, and diverse communities –ranging from quaint small towns to bustling cities. We are committed to working to preserve this important water hub and outdoor treasure.