The Delta

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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.

What is Delta Conveyance?

Delta conveyance refers to the State Water Project (SWP) infrastructure in the vast network of waterways comprising the Sacramento-San Joaquin Delta (Delta) that collects and moves fresh, clean and affordable water to homes, farms and businesses throughout major regions of the state from the Bay Area to Southern California. The Department of Water Resources (DWR) is the owner and operator of the SWP and is responsible for all associated upgrades and maintenance, including the proposed Delta Conveyance Project that will modernize this water transport infrastructure in the Delta.

Why is Delta Conveyance important?

The Delta is at the center of California’s vital water distribution system. Two-thirds of California’s water originates in the Sierra Nevada Mountains as snowpack, eventually flowing through the Delta, where, consistent with water rights, including applicable water quality requirements, it is delivered to more than 27 million Californians and 750,000 acres of farmland. The infrastructure that enables conveyance for California’s primary water supply is critical to the health of local communities and the success of our state’s economy.

Why is this project needed?

Because the SWP relies on the Delta’s natural channels to convey water, it is vulnerable to earthquakes and sea level rise. Upgrading SWP infrastructure protects against these threats and secures the longevity of the SWP and the future reliability of SWP water supplies. The purpose of the proposed Delta Conveyance Project is to modernize the aging SWP infrastructure in the Delta to restore and protect the reliability of SWP water deliveries in a cost-effective manner, consistent with the State’s Water Resilience Portfolio. And in doing so, allow DWR to address sea level rise and climate change, minimize water supply disruption due to seismic risk and provide operational flexibility to improve aquatic conditions in the Delta.

For more detail, visit SWP's website.