What is saltwater intrusion?

Saltwater intrusion refers to the movement of saltwater into freshwater aquifers, which can contaminate drinking water sources. This intrusion occurs when the natural balance between freshwater and saltwater is disrupted, usually due to excessive groundwater extraction or sea-level rise.

An excessive number of wells in an area can contribute to saltwater intrusion. When water is pumped out from aquifers at a faster rate than it can be naturally replenished, it creates a pressure gradient that can allow saltwater to intrude into the freshwater aquifers. This is especially a concern in coastal areas where saltwater is present. The increased pumping of water from multiple wells can lower the pressure head, as seen in Figure 1, and increase the likelihood of saltwater intrusion. It is important to manage the number and rate of well pumping to prevent or minimize saltwater intrusion in freshwater aquifers.

Climate change can exacerbate saltwater intrusion by causing sea levels to rise, which increases the pressure on coastal aquifers and allows saltwater to infiltrate freshwater sources. As sea levels rise, the interface between freshwater and saltwater is pushed further inland, leading to the contamination of wells and other freshwater sources with saltwater. This can have significant consequences for communities that rely on freshwater for drinking, agriculture, and other purposes, as it can render the water unusable without treatment. It is important to monitor and manage saltwater intrusion to ensure the availability of safe freshwater resources in coastal areas.

Saltwater Intrusion | U.S. Geological Survey (usgs.gov): Comprehensive information on saltwater intrusion, its causes, and management strategies.

Climate Adaptation and Saltwater Intrusion | US EPA: Insights into climate-related impacts on freshwater resources, including saltwater intrusion.

SELA-Ready-Saltwater-Intrusion-Private-Water-Wells-FAQ.pdf. 2023. Louisiana Department of Health.