Current Water Supply

The Five Cities communities currently get their water from a combination of surface water (water that collects surface streams, lakes, and reservoirs) and groundwater (water found in underground aquifers). The surface water sources are the State Water Project and the Lopez Lake Reservoir and the groundwater source is the Santa Maria Groundwater Basin (SMGB). During times of drought, less water is available from both surface water and groundwater sources.

 

Surface Water

The Five Cities communities get their surface water from a combination of the State Water Project and Lake Lopez reservoir.

State Water Project water comes from a combination of snowpack, runoff, reservoir storage, pumping capacity from the Delta, and legal environmental constraints on project operations. Statewide the State Water Project deliveries range from 1.4 to 4.0 million acre-feet per year.

Lopez Lake is a reservoir formed by the Lopez Dam on the Arroyo Grande Creek. The reservoir provides water for the Five Cities communities as well as Avila Beach. Lopez Lake Reservoir has reached historic lows as a result of the recent drought.

Groundwater

The Five Cities communities work together to monitor the health of the groundwater basin using a series of groundwater monitoring wells, including several wells along the coast that measure the elevation and quality of groundwater. In 2009, the water quality tests in these coastal monitoring wells showed results consistent with seawater intrusion, which represents a significant threat to the local groundwater supply. The local water agencies quickly shifted to other supplies to allow the water levels to recover and to mitigate this threat. However, even though municipal groundwater pumping has been reduced, the groundwater elevations have continued to decline in recent years. This not only reduces the supply available to the community, it puts the basin at a renewed risk for seawater intrusion. The RGSP will help to recharge the basin and raise the groundwater levels so that the community can continue to responsibly use the groundwater supply without depleting the basin or putting it at risk of seawater intrusion.