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California State Water Project Today

A picture of Oroville Dam
Oroville Dam

The California State Water Project is the nation's largest state-built water and power development and conveyance system. It includes facilities—pumping and power plants; reservoirs, lakes, and storage tanks; and canals, tunnels, and pipelines—that capture, store, and convey water to 29 water agencies.

The SWP’s watershed encompasses the mountains and waterways around the Feather River. Rain and melting snow run off mountainsides and into waterways that lead into Lake Oroville. The lake in Butte County is the State Water Project’s official start and a part of a complex that includes three power plants, a forebay, and an afterbay. One of the power plants, Hyatt Powerplant, is the largest and was built in the bedrock under the lake.

A picture of Antelope Lake
One of the many vistas that can be found in the vicinity of Antelope Lake.

There are three smaller lakes above Oroville in Plumas County—Antelope Lake, Frenchman Lake, and Lake Davis—which are mainly used for recreation and downstream releases for fisheries. Lake Davis also provides water to the nearby community of Portola.

A picture of the Sacramento and Feather River Confluence
Confluence of two important Northern California
water resources: the Sacramento and Feather rivers.

When water is needed, Lake Oroville releases water into the Feather River. It travels down the river to where the river converges with the Sacramento River, the state’s largest waterway. Water flows down the Sacramento River into the Sacramento-San Joaquin Delta. Some of the water is pumped into the North Bay Aqueduct, which serves Napa and Solano counties.

A picture of Clifton Court Forebay
Aerial of Clifton Court Forebay

The remaining water travels further south in the Delta, where it is pumped by Banks Pumping Plant into the 444-mile-long California Aqueduct. Water then enters Bethany Reservoir, where the South Bay Aqueduct begins. It serves Alameda and San Jose counties.

A picture of San Luis Reservior
San Luis Reservior

Water in the mainstem of the California Aqueduct flows south by gravity into the San Luis Joint-Use Complex, which was designed and constructed by the federal government and is operated and maintained by the Department of Water Resources. Within the complex are O’Neill Forebay, Sisk Dam and San Luis Reservoir, the nation’s largest offstream reservoir (it has no natural watershed), the Gianelli Pumping-Generating Plant, Dos Amigos Pumping Plant, and the San Luis Canal. This section of the California Aqueduct serves both the SWP and the federal Central Valley Project.

After leaving the Joint-Use Complex, water travels through the central San Joaquin Valley and splits near Kettleman City into the Coastal Branch Aqueduct, completed in 1997, to serve San Luis Obispo and Santa Barbara counties.

A picture of Edmonston Pumping Plant
Edmonston Pumping Plant

The water in the mainstem is pumped up California’s hilly terrain by three pumping plants—Buena Vista, Teerink, and Chrisman— until it reaches Edmonston Pumping Plant, the SWP’s largest. Its huge motor-pump units, each standing about 65 feet tall and weighing more than 400 tons, lift water nearly 2,000 feet up and over the Tehachapi Mountains through 10 miles of tunnels.

A picture of Pyramid Lake
Pyramid Lake

As the water reaches the bottom of the mountain, it bifurcates (splits) into two branches: the West Branch and the East Branch (the mainstem). Water in the West Branch is pumped by Oso Pumping Plant into Quail Lake. From there, it enters a pipeline leading into Warne Powerplant to generate power. Water is then discharged into Pyramid Lake, travels through Angeles Tunnel, and into Castaic Powerplant (the latter two are joint developments by DWR and the Los Angeles Department of Water and Power, their owner). At the end of the West Branch is Castaic Lake and Castaic Lagoon, a popular Southern California recreation spot.

A picture of Silverwood Lake
Silverwood Lake

Water flowing down the East Branch generates power at Alamo Powerplant then is pumped uphill by Pearblossom Pumping Plant. The plant lifts the water 540 feet. From there, it flows downhill through an open aqueduct, linked at its end to four underground pipelines which carry the water into the Mojave Siphon Powerplant, which discharges the water into Lake Silverwood. When water is needed, it is discharged into Devil Canyon Powerplant and its two afterbays. The 28-mile-long Santa Ana Pipeline then takes it underground to Lake Perris, the southernmost SWP facility and one of Southern California's most popular recreation spots.

A picture of East Branch Construction
East Branch Extension construction

The SWP's most recently constructed facility, the East Branch Extension delivers water from Devil Canyon Powerplant's Afterbay to Yucaipa Valley and the San Gorgonio Pass area in San Bernardino and Riverside counties. The project— consisting of 13 miles of buried pipeline, three pump stations, and a 90 acre-foot regulatory reservoir—will meet the region's water needs for the next 40 years. SWP water will be used to recharge overdrafted groundwater basins and allow more flexibility for local water systems.

The extension, completed in 2003, is a cooperative project between DWR, the San Bernardino Valley Municipal Water District, and the San Gorgonio Pass Water Agency. The two contractors will pay for the project's construction costs by repaying the principal and interest of revenue bonds sold to finance the project.

Many SWP facilities were renamed to recognize individuals who made valuable contributions to the Project, the water industry, and environment.

State Water Project Facts and Figures
Number of storage Facilities 33
Lakes/Reservoirs (primary) 21
Total Reservoir Storage 5.8 million acre-feet = 7.2 cubic kilometers
Largest Reservoir Capacity 3.5 million acre-feet = 4.3 cubic kilometers
Largest Reservoir Surface Area 15,810 acres
Longest Reservoir Shoreline 167 miles
Highest Dam Structure 770 feet = 235 meters
Largest Dam Structure 80 million cubic yards = 61 million cubic meters
Longest Dam Crest 42,000 feet = 12,802 meters
Highest Dam Crest Elevation 5,785 feet - 1,763 meters
Length of Canals and Pipelines 701 miles = 1,128.15 kilometers

Hydroelectric Power Generation-(1983-2002)
Largest Annual Energy Output 8.57 Billion kWh (2002)
Average Total Energy Generated Annually 6.5 Billion KWh
Average Annual Energy Available 8.6 Billion KWh
Average Net Use 5.1 Billion kWh

California Aqueduct
Starting Maximum Pumping/Canal Volumes 10,670 cfs /10,300 CFS
Largest Pumping Capacity 15,450 cfs
Largest Canal Capacity 13,100 cfs
Widest Part of Canal 110 feet
Deepest Part of Canal 32.8 feet
Highest Pump Lift/Volume 1,926 feet = 587 meters/4,480 CFS

Financing of the SWP

By the end of 2001, about $5.2 billion had been spent to construct SWP facilities.

Future projects focus primarily on maintenance and repair projects.

SWP financing of capital expenditures has come from various sources, the major source being the sale of general obligation and revenue bonds, all repaid by the SWP contractors, 29 public agencies that have contracts for water deliveries from the Project. Other capital funding sources have included tideland oil revenues, investment earnings, funds advanced by the contractors, recreation appropriations, and federal flood control payments.