Saltwater Intrusion

Saltwater intrusion is the landward migration of seawater into a coastal freshwater aquifer, occurring naturally where denser saline groundwater underlies fresher water near the coast, but greatly accelerated where heavy pumping lowers the freshwater water table and lets the seawater wedge advance inland. Once a coastal well or aquifer is contaminated with salt it can take years of reduced extraction and natural recharge to push the intrusion back, making it one of the more persistent forms of groundwater degradation in densely populated coastal regions. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/