This map report presents the configuration of the top of the highly permeable dolomite zone of the Floridan aquifer in the Southwest Florida Water Management District. The top of the highly permeable dolomite generally corresponds to the top of a thick bed of massive, hard, dark brown dolomite occurring in the Avon Park Limestone of Eocene age. The altitude of the top of the permeable dolomite varies from about 100 feet below the National Geodetic Vertical Datum of 1929 in the north to about 1 ,600 feet below the datum in the south. (Kosco-USGS)