California water 101

July/August 2023 California Bountiful magazine

California's water is captured and stored in reservoirs, in snowpack and in underground aquifers before being transported to farms and cities. Shasta Dam, pictured, is a keystone of the Central Valley Project.

How precipitation is stored and moved for growing food

Story by Ching Lee

California would not be one of the world’s leading agricultural producers without its complex water system.

Thanks to the Golden State’s dry Mediterranean climate, farmers here enjoy an almost year-round growing season, allowing them to grow more than 400 crops. Farmers owe much of this productivity to their ability to control when and how much water is applied to their crops.

In addition to using water pumped from the ground, California farms irrigate, on average, more than 9 million acres of cropland with water from rivers, lakes and reservoirs, according to the California Department of Water Resources.

During the rainy season, the state captures and saves some precipitation in reservoirs, or man-made lakes. Rain is also stored in the form of snowpack. As it melts, the runoff enters California streams and rivers, supplying water during the summer months.

This surface water is transported through a sophisticated system of aqueducts, canals and pipelines. Three major engineering feats allow the precious resource to move to California farms and cities:

Central Valley Project

This is a network of 20 dams and reservoirs, 500 miles of canals, conduits and tunnels, and hydroelectric power plants and other facilities. Built in the 1930s, the federal CVP transports water from Lake Shasta near Redding in Northern California through the Central Valley, delivering enough supply for a third of the state’s farmland and close to 1 million households each year, according to the U.S. Bureau of Reclamation, which owns and operates the project.

State Water Project

Constructed in the 1960s and 1970s, this collection of 34 reservoirs, five hydroelectric facilities and more than 700 miles of canals and pipelines extends about two-thirds the length of the state. It includes the California Aqueduct, the nation’s largest state-built water distribution system. The facility supplies water to 750,000 acres of farmland and 27 million Californians, according to DWR, which operates the system. The project has been credited with helping to fuel the state’s population boom and economic prosperity.

Colorado River Aqueduct

Completed in 1941 by the Metropolitan Water District of Southern California, this 242-mile system of canals, tunnels and siphons carries millions of gallons of water a day from the Colorado River across the desert to Southern California. Farms in Imperial and Riverside counties, which grow most of the nation’s winter vegetables, rely on water from the Colorado River. The 1,450-mile-long river supplies 4.4 million acre-feet of water to the state each year.

Ching Lee

Learn more: The California Bountiful Foundation, the science and research arm of the California Farm Bureau, has analyzed agricultural water use. See it here.