Seawater intrusion is a concern for many coastal communities in California, particularly for those who rely on groundwater.
Seawater intrusion happens when ocean water moves into freshwater aquifers, which are underground layers of water-soaked rocks and sand. These aquifers are a critical source of fresh water, especially in coastal areas.
Groundwater pumping has lowered groundwater elevations to a point that allows seawater to flow inland from the Monterey Bay. When too much fresh water is drawn from aquifers for uses like irrigation, drinking, and industrial processes, the balance between coastal fresh groundwater aquifersand the ocean is disturbed. This imbalance allows seawater to flow into the aquifers, where fresh water is being overdrafted.