Most of California’s water supply is managed through two major projects: the Central Valley Project (CVP) and the State Water Project (SWP). These systems rely on an intricate network of rivers, dams, reservoirs and pumps to store and distribute water across the state. Understanding how these systems work is key to navigating California’s ongoing water challenges.
The CVP is operated by the U.S. Bureau of Reclamation (BOR) and governed by the U.S. Fish and Wildlife Agency, Endangered Species Act, Biological Opinions, State Water Resources Control Board and the California Department of Fish and Wildlife. It delivers federally managed water from Northern California’s Shasta and Folsom Lakes, primarily for agricultural use.
The SWP is managed by the California Department of Water Resources and governed by the State Water Resources Control Board (State Board), with input from the Department of Fish and Wildlife (DFW), the Endangered Species Act and the Biological Opinions. It supplies water from Lake Oroville to cities, farms and wetlands.
Both projects coordinate water movement through the Sacramento-San Joaquin Delta and the San Luis Reservoir, a crucial storage site shared by state and federal water users.
In the Central Valley is the Friant Dam, located on the upper San Joaquin River in the Sierra Nevada foothills of Fresno County, which forms Millerton Lake. Friant Water Authority manages delivery of San Joaquin River water supplies via the Friant-Kern Canal on behalf of Friant Division Contractors of the federal CVP. These deliveries are subject to the Bureau of Reclamation’s ability to satisfy the senior water rights of the San Joaquin River Exchange Contractors through supplies delivered from the Delta and other sources. Both the San Joaquin River and the Sacramento River flow into the Delta and out to the San Francisco Bay.
The crash of fish species in the Delta and sequent development of the Biological Opinions have severely limited the amount of water the two large pumps are allowed to divert into San Luis Reservoir, which can hold 2,027,840 acre-feet of water of which 1,062,180 acre-feet is the state’s share and 965,660 acre-feet is the federal share for the CVP. According to the BOR, 95 percent of water collected in the Delta was flushed out to sea during the 2024 water year. On Feb. 12, 2025, the total Delta inflow was 177,996 cubic feet per second, or 352,808 acre-feet per day. Only 5.5 percent over a 14-day average was diverted into the San Luis Reservoir. As of mid-February 2025, the Reservoir had 1,601,000 acre-feet (78 percent total capacity) of which 668,000 acre-feet is for CVP contractors.
The two lakes in recent news articles regarding President Donald J. Trump’s Executive Order, Lake Success and Lake Kaweah, are operated by the BOR and are primarily used for flood control. These two lakes, located just south of Fresno, rarely meet full capacity because of the January and February water releases.
When wet weather is predicted for the months of January, February and March, the Army Corps of Engineers will release water, frustrating farmers who use that water in the hot summer months. Both the Kaweah and Success water levels were higher than normal because of early predictions that this will be a dry year and based on our unusually dry January. The unexpected release of 6,700 acre-feet of water from Lake Success and Kaweah was not wasted but used for groundwater storage due to the quick response by farmers. Connecting these systems is the Kern River Intertie, which has been used to move water into the California Aqueduct, which then flows to southern California.
Water rights, water transfers, environmental regulations and state and federal agencies all play a large role in how California manages water. It is our main objective to continue working to move the needle so farmers have a sufficient amount of water to grow the food we eat.