Mapping the Encroachment of Salt Water on Miami's Aquifers

"It’s a gentle intruder, moving stealthily underground, out of sight but not undetected. Salt water continues to move farther inland in Florida’s Miami-Dade County, albeit at a slower rate," writes Brett Walton.

That conclusion evidenced by data collected by newly released maps from the U.S. Geological Survey.

The encroachment of salt water on underground aquifers is especially troubling because of Miami-Dade County's reliance on underground water. "All of Miami-Dade County’s municipal water, which serves several million residents and visitors, comes from groundwater, primarily from a thin lens of fresh water called the Biscayne Aquifer," according to Walton.

The USGS has mapped the boundary between salt and fresh water at the base of the Biscayne Aquifer. "The leading edge of the saltwater layer in the southeastern part of the county, the area of greatest intrusion, moved inland at a pace of 102 meters per year between 2014 and 2018," according to Walton.