Extent of gray limestone aquifer (interpreted to be unconfined), southwestern Florida, USGS WRIR 99-4213, figure 29

Leakance, which is the vertical hydraulic conductivity of the confining unit divided by its thickness, can be used to provide an indication of the degree of confinement of the aquifer. For purposes of this discussion, an aquifer is considered to be well confined, or have 'good confinement', if leakance was less than 1.0 x 10-3 1/d. Sites where leakance was determined by aquifer testing to be less than 1.0 x 10-3 1/d or the behavior of the aquifer was described as confined or well confined (tables 8 and 9) are shown in figure 29. These sites are located in southern Hendry County, western Broward County, and central Miami-Dade County and are in areas where the thickness of the confining unit approaches or is more than 50 ft. However, confining bed thickness did not necessarily prove to be a determinant of confinement. The map shows the extent of the gray limestone aquifer in southwestern Florida. Results from 35 new test coreholes and aquifer-test, water-level, and water quality data were combined with existing hydrogeologic data to define the extent, thickness, hydraulic properties, and degree of confinement of the gray limestone aquifer in Southern Florida. The western boundary is not mapped and is set to the western boundary of the study area.

The purpose of this report is to evaluate the hydrogeologic framework, hydraulic properties, and ground-water flow of the gray limestone aquifer in southern Florida. The report also emphasizes the geologic framework (stratigraphy and structure) and the hydrogeologic framework (aquifers and confining and semiconfining units) above and below the gray limestone aquifer.