Saltwater intrusion risk low in Santa Clara County

Saltwater intrusion can be a scary thought for those living along the coast. Here in Santa Clara County, groundwater makes up about 40 percent of the water supply, but the possibility of saltwater intrusion is very low because of Valley Water’s groundwater management and the area’s natural geology.

What is saltwater intrusion? It’s when seawater is able to seep into an underground aquifer and move inland. This is possible when groundwater is over-pumped and the groundwater flow direction is reversed, so the salty seawater mixes with the drinkable groundwater. This can contaminate drinking water supplies and render an aquifer unusable.

In many areas along the coast, shallow groundwater may be vulnerable to rising sea levels and saltwater intrusion. However, in Santa Clara County, the aquifers that act as our primary drinking water source are protected by a natural barrier made up of extensive horizontal clay layers. Valley Water does not consider saltwater intrusion to be a significant threat.

Valley Water has managed our groundwater basins for 90 years. We work to safeguard groundwater by replenishing our aquifers with both local and imported water. We are also reducing demands on groundwater through treated surface water deliveries, water conservation, and the growing possibilities of using purified recycled water.

The Silicon Valley Advanced Water Purification Center (SVAWPC) is the largest plant of its kind in Northern California. The highly purified water produced at the SVAWPC is blended with existing recycled water supply to improve its quality. In the future, similar highly purified water can be used in a variety of ways, including expanding Silicon Valley’s future drinking water supplies.

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