Our Primary Water Sources
The water that flows from your tap originated from a number of sources including snowpack, rainfall and underground aquifers.
Imported Surface Water
More than three-quarters of our water supply originates high in the Sierra Nevada mountains as snowmelt. The water flows downstream where it is pulled into infrastructure created by the State Water Project (SWP) that allows it to distribute or convey the water throughout the entire state.
The SWP conveys the water through the California Delta, its first major stop where the water is divided between two major aqueducts. The majority of the water that comes to Zone 7 is conveyed via the South Bay Aqueduct to the Tri-Valley area. We purchase this water from the SWP, and invest in the infrastructure that helps bring the water to our community.
Local Surface Water
A small portion of our water supply comes from local rain runoff which is stored in Del Valle Reservoir. This amount fluctuates each year depending on how much rain we receive. During rainy years, local surface water helps offset the amount we purchase from the SWP. During dry years, we have less local surface water available and need to rely more on imported surface water.