About 30 percent of Southern California's water comes from the State Water Project, the largest state-built water and power system in the nation. The project runs from Lake Oroville in Northern California to Southern California, crossing the Sacramento-San Joaquin Delta along the way. The SWP serves a population of nearly 25 million Californians from the Bay Area to San Diego as well as providing irrigation for some of the nation's most productive farmland in the Central Valley. The State Water Project is operated and maintained by the California Department of Water Resources and includes 34 storage facilities, reservoirs and lakes; 20 pumping plants; 4 pumping-generating plants; 5 hydroelectric power plants; and about 700 miles of open canals and pipelines.
Metropolitan is the largest contractor on the State Water Project system, receiving about 50% of the SWP's supplies, roughly 1.2 million acre feet (MAF) in an average year.
Metropolitan's SWP allocation varies depending on water conditions in the Eastern Sierra Mountains and environmental conditions in the Sacramento-San Joaquin Delta, which can restrict water deliveries.
To meet regional demands and ensure reliable supplies for Southern California, Metropolitan has been working with state and federal agencies as well as other water contractors to address environmental conflicts and reduce threats to state water supplies in the Sacramento-San Joaquin Bay Delta. In addition, Metropolitan augments water supplies through collaborative water transfer and groundwater banking agreements with other agencies.
Update on Oroville Facilities
April 2019: First Use of Oroville Dam's Reconstructed Spillway
On April 2, California's Department of Water Resources began releasing flows from the Oroville Dam's main spillway for the first time since its reconstruction. DWR planned the releases at 8,300 cubic feet per second to provide room for flood storage within the reservoir in preparation for forecasted storms and growing snowpack.
DWR was anticipating increasing flows to the Feather River later in the week, and planning for further releases later this spring to continue managing snowmelt and lake elevations.
Oroville's main spillway was reconstructed after it suffered severe damage during the record wet start to the 2017 rain season and the subsequent use of an emergency spillway created erosion concerns that promoted an evacuation of communities downstream.
News release from DWR - https://water.ca.gov/News/News-Releases/2019/April/DWR-Uses-Oroville-Main-Spillway
Article from The Sacramento Bee - https://www.sacbee.com/news/local/article228619034.html
Lake Oroville and Oroville Dam in Butte County are part of the State Water Project and an important source of water for Southern California. The Metropolitan Water District of Southern California is the largest State Water Contractors, importing about 30 percent of the Southland's water supplies from Northern California via the state project.
Oroville's main spillway suffered severe damage in February 2017 when flood control releases from the lake eroded sections of a concrete channel. The subsequent use of an adjacent emergency spillway raised erosion concerns that prompted an evacuation of communities downstream. Recovery efforts included work on both the main flood control spillway and the emergency spillway to accommodate potential flows from winter storms.
DWR collaborates with regulatory agencies and a Board of Consultants on the Oroville Spillway design and construction project. Metropolitan has no direct role in the review or implementation of these projects. However, Metropolitan continues to work with DWR on operational issues and future activities at the Oroville facilities. Click here for more.
California Aqueduct
Water from the State Water Project is delivered through the California Aqueduct, a 444 mile-long canal beginning at the south Delta and ending at Lake Perris in Riverside County. It varies in width from 50 to 110 feet and 19 to 32 feet in depth.
Exchanges & Water Banking
Water transfers, water exchanges and groundwater banks (which store water in underground aquifers) are important water management tools that allow agencies to augment local supplies and utilize external distribution and storage systems. Metropolitan’s water portfolio includes a number of water transfer and groundwater banking agreements with state, federal, public and private water districts and individuals.
Transfers and exchange programs were developed to improve the reliability of State Water Project and Colorado River Aqueduct supplies during dry years.
Current banking/transfer programs that provide supplies for delivery via the California Aqueduct include:
- Semitropic Water Banking and Exchange Program, Wasco
- Arvin-Edison Water Management Program, Arvin
- San Bernardino Valley Municipal Water District Program, San Bernardino
- Kern Delta Water District Water Management Program, Taft
- Desert Water Agency/Coachella Valley Water District Advance Delivery Program, Coachella
- Market Transfer Options, DWR Dry-Year Purchase Program and Sacramento Valley Transfer Agreements