Where Southern California gets its water source

If you’ve ever wondered, “Where the heck does my water come from?”  We’ve got the answers for you! There are many water districts that provide Southern Californians with water, but surprisingly, only a few different water sources where the districts get the water. California uses both surface water (lakes, rivers, streams) and groundwater (water beneath the earth’s surface, also known as aquifers) to supply its customers with water. The Sacramento, San Joaquin, and Colorado Rivers collectively provide all of California with about 80% of its drinking water. 

The State Water Project provides water to many California residents. According to the California Department of Water Resources, “The California State Water Project (SWP) is a water storage and delivery system of reservoirs, aqueducts, power plants and pumping plants extending more than 700 miles—two-thirds the length of California”. Snowpack and rain from the Sierra Nevada Mountain range flows into the Sacramento and San Joaquin Rivers, which end up in the Sacramento-San Joaquin Delta. The water from the Delta goes through the California Aqueduct, and then to the homes of millions of residents in Southern California. 

The Colorado River flows into the Metropolitan Water District’s Colorado River Aqueduct, which provides most of Southern California with its water. The Colorado River Aqueduct is 242 miles long, traveling from Lake Havasu (a reservoir on the Colorado River) to Riverside, California. Each water district in California has its own method of obtaining water from different sources. For example, the Metropolitan Water District wholesales water to their member agencies, one of which is the San Diego County Water Authority.

San Diego County Water will then wholesale that same water to its member agencies, such as the City of Oceanside. They will then provide water to whoever lives in that service area. The districts don’t always obtain water this way; there’s also groundwater, local streams, and reservoirs, private sectors, etc. that can also be the sources for a city’s water.

Because California suffers from severe droughts, there are many underground aquifers that collect water for future use. This groundwater comes in handy when the state is suffering from a lack of surface water. The water can be pumped into local wells/pumps and distributed when necessary. The California Department of Water Resources states, “During dry years, groundwater contributes up to 46 percent (or more) of the statewide annual supply, and serves as a critical buffer against the impacts of drought and climate change. Many municipal, agricultural, and disadvantaged communities rely on groundwater for up to 100 percent of their water supply needs”.

It’s important for us to remember that even though it seems like the supply of water is endless, it is a natural resource and it should be valued. Most of us are lucky enough to have easy access to clean, drinkable water in our homes, but many people are not as fortunate. It’s crucial to be conscious of how much water we use and to limit the amount of water we waste in our homes and our workplaces. Together we can help save billions of gallons of water for our state.