Where in the World does our Water Come From?


The water that flows from your tap originated from a number of sources including snowpack, rainfall and underground aquifers. The majority of the Tri-Valley’s water supply is imported from outside the region.

On average 70% of our water comes from the Northern Sierra Nevada Mountains as rainfall and snowmelt. Water from the Feather River Watershed is captured in Oroville Reservoir and flows downstream where it is delivered by infrastructure created and maintained by the California Department Water Resources as part of the State Water Project (SWP) system.

During dry years, the water available from the SWP may be limited, which is why we plan to ensure we can sustain short cycles of drought by having water stored in underground aquifers or groundwater basins and surface water reservoirs.

The Livermore Valley Groundwater Basin is critical for the Tri-Valley in providing water in normal years and weathering short-term droughts, providing locally stored water when imported water is unavailable or limited.

Zone 7 serves as the sustainable groundwater manager for the basin — recharging it in normal and wet years and carefully monitoring it during dry years to ensure it does not become overdrawn.

We also receive water in the form of rainfall runoff stored in our local reservoir, Lake Del Valle.