A shapefile was created that shows the approximate inland extent of saltwater intrusion at the base of the Biscayne aquifer in 2022 in Miami-Dade County, Florida. The approximate location of the saltwater interface is represented by the 1,000-mg/L isochlor at the base of the Biscayne aquifer. The term “approximate” is used here because certain areas of the map lack sufficient spatial distribution of monitoring wells to create a precise representation. The approximate location of the 1000-mg/L isochlor was identified using chloride concentrations and specific conductance data from groundwater wells. These data are provided in the child item, "Summary tables for the approximate inland extent of saltwater intrusion at the base of the Biscayne aquifer in 2022, Miami-Dade County, Florida".