Our Water Sources

State water map

These days you hear a lot about water conservation; messages are everywhere. Why is this relevant to you? It often helps to know the context of where our resources come from so that you can see how your act of conserving water impacts the larger system. For example, did you know that a large portion of the water we use in Southern California travels over 400 miles through the California Aqueduct? The water doesn’t just come from the tap, it comes all the way from the Sacramento-San Joaquin Delta in Northern California. Conserving water in Southern California helps reduce our dependency on imported water, it saves the energy used to transport the water, and numerous other benefits.

Keep reading to learn more about where your water comes from. Our Waterwise Community Center lobby also has a helpful exhibit detailing this important topic.


Lots of water is stored in the ground right below you in the Chino Groundwater Basin (CGB), a very large aquifer. The CGB is important for our local water supply and storage system as it allows us to store our own water and reduce dependency on imported water. In normal years, about 30% of California’s annual water supply comes from groundwater; that figure goes up to 60% in dry years when California’s rivers have less to offer.

You can learn more about what CBWCD does to help recharge groundwater: Learn about our percolation basins here.


Rain is an infrequent but necessary event here in our area. Our storms can be fast and heavy, sending a lot of water down all at once. The water that does not immediately soak into the ground rushes through gutters, down streets, and through rivers and streams. The district and other organizations work to capture as much water as we can by utilizing percolation basins and spreading grounds. This recharges our aquifer naturally so we can be more self-sufficient with our water supplies.

Sacramento-San Joaquin River Delta

The Sacramento-San Joaquin River Delta (the delta) is the hub of our state’s water delivery system and home to one of California’s most important ecosystems. The delta is located where the San Joaquin and Sacramento rivers converge just east of the San Francisco Bay. The water that moves through the delta helps to sustain the largest ecosystem on the West Coast, as well as help drive our state’s economy by supporting agricultural industry and businesses.

Colorado River

The Colorado River supplies water to more than 30 million people and more than 2 million acres of farmland. Its water serves several American Indian tribes and seven states: Arizona, California, Colorado, New Mexico, Nevada, Utah, and Wyoming. While the Colorado River is an important water source for California, the Chino Basin area does not use any of this water.

State Water Project

The State Water Project (SWP) is a network of reservoirs, power plants, pumping plants, tunnels, pipes, aqueducts, and canals spanning 700 miles through the state. The system depends primarily upon rain and snow melt coming from the Sierra Nevada Mountains into the Sacramento River and Sacramento-San Joaquin Delta. The water supplies available to public agencies and customers vary from year to year depending on this rain and snow melt. It serves over 25 million people (two out of threeCalifornians), businesses, and farms. Learn more about the SWP.