Imported Water

Imported Water

State Water Project

The California State Water Project (SWP) is a multi-purpose water storage and delivery system that includes a collection of canals, pipelines, reservoirs, and hydroelectric power facilities. It delivers clean water to 27 million Californians, 750,000 acres of farmland, and businesses throughout our state.

During an average water year, about half of the SCV’s water is imported, primarily through the State Water Project, which extends for more than 705 miles from north to south, terminating at Castaic Lake.

Water is first stored in Lake Oroville, located northeast of Sacramento. It then travels through various reservoirs, dams, power plants and rivers before reaching the Sacramento-San Joaquin Delta, a complex network of natural and man-made channels.

From the Delta, the water makes its way to the Harvey O. Banks Pumping Plant where it begins a 300 mile journey in the California Aqueduct. Then at the A.D. Edmonston Pumping Plant, the water is lifted 1,926 feet and enters more than eight miles of tunnels to cross the Tehachapi Mountains. From this point the water continues south through the West Branch of the California Aqueduct through Quail Lake, Pyramid Lake and finally into Castaic Lake.

Water is withdrawn from Castaic Lake and flows through large underground pipelines to supply the Agency’s treatment plants, the Earl Schmidt Filtration Plant and the Rio Vista Water Treatment Plant.

This water supply depends on several factors, including rainfall, snowpack, runoff, water in storage facilities, and pumping capacity from the Delta. The amount of water available for distribution is also influenced by the need to protect fish and wildlife, water quality, and environmental and legal restrictions. These factors determine how much the State Water Project is able to release to each of the contract agencies, such as SCV Water, each year. Sometimes we may get as much as 60% of our allotment, but during drought that could be 5%, or even zero.

Visit the California Department of Water Resources website to learn more about the State Water Project.

Delta Conveyance

Delta conveyance refers to State Water Project (SWP) infrastructure in the vast network of waterways comprising the Sacramento-San Joaquin Delta (Delta) that collects and moves high-quality, clean, safe 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.

View this Story Map for more information on several key aspects of the Delta Conveyance Project. 


About the Project

The proposed Delta Conveyance Project would modernize the state’s water infrastructure in the Delta to help protect the reliability of this important water supply for 27 million Californians and 750,000 acres of farmland from earthquakes and climate-driven weather extremes. DWR has prepared new informational materials about the need for the proposed project related to the risks to State Water Project water supplies from climate change and seismic activity.


Animation: Climate Change Vulnerabilities

This animation explains how the proposed Delta Conveyance Project will help California adapt to a hotter future with more unpredictable precipitation and seasonal flow patterns due to climate change. Modernizing the State Water Project infrastructure in Delta will allow us to capture, move and store water during extreme rain events for use when it is needed most, providing flexibility to better manage California’s changing weather patterns. Watch the animation here.


Video: Seismic Quick Question

The next installment in the Quick Questions video series examines why Delta levees are vulnerable to failure during an earthquake and how the proposed project would protect continued operation of the State Water Project in the event of major seismic activity. The recent earthquakes in the Delta underscore this real and serious threat and potentially devastating impact on statewide water supplies. Watch the video here.



Fact Sheet

Delta Conveyance Authority - SCV Water - Agency Overview - November 2023


Click on the link below to read more:


For more information about the project, please visit the Delta Conveyance project page on the CA DWR website.