The State Water Project is the nation’s largest, state-built water and power development and delivery system, supplying clean, high-quality water to 27 million Californians.

It's one of California's cleanest and most cost-effective water supply sources.

The State Water Project gets us through droughts more efficiently than any other source, augments local water supply sources and recharges groundwater basins.

Some regions rely on the State Water Project for up to 80% of their supply.


How It Works

The vast majority of the state’s water supplies come from the high Sierra Nevada Mountains where rainfall and snowmelt fill rivers and tributaries that travel toward the Sacramento-San Joaquin Delta. The SWP captures and stores a small share of these supplies, which are then delivered through 700 miles of canals and pipelines for use throughout the state.

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Regional Factsheets
The Sacramento-San Joaquin Delta

The Delta is home to more than 700 native species and serves as California's primary freshwater supply hub - the heart of the State Water Project and its federal counterpart, the Central Valley Project, as well as many farms and landowners within the Delta region.

Challenges in the Delta

California must reinvest in its water future. The state's outdated water delivery system tasked with protecting and moving supplies through the Delta is no longer fit for the job.

  • Earthquakes and rising sea levels pose a constant threat to freshwater

  • Crumbling infrastructure coupled with strict environmental restrictions prevent water managers from capturing needed rainfall when it's abundent


Delta Conveyance

We need to modernize our state’s water delivery system, making it more resilient to climate extremes including recurring drought and flooding, protecting against earthquakes, and ensuring a reliable water supply for our homes, farms and businesses. As directed by the Governor and building on work already conducted, the Department of Water Resources is pursuing a new environmental review and planning process for a single-tunnel solution to modernize Delta conveyance and meet these needs:

Water Supply Reliability

Secure California's water supply and provide safe, reliable water throughout the state.

Drought Preparedness

Provide water agencies the flexibility to capture and store more water when supplies are available, enabling the state to better prepare and minimize the impacts of future droughts.

Seismic Security

Built to withstand earthquakes and protect this critical water supply from potential disruptions caused by climate change.

Environmental Restoration

Restore the natural direction of Delta river flows by moving the primary diversion point from the South Delta to the North Delta, benefiting threatened fish species.

Public water agencies that purchase water from the State Water Project and Central Valley Project would fund the construction, ongoing operations and any environmental mitigation associated with the project.

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Built for Our Future

Built in the 1960s, the State Water Project generates and uses hydropower and remains a valuable investment in California's infrastructure. As California's fourth-largest energy producer, it's ahead of every major utility in meeting the state's 2050 carbon goals.