Ground water occurs in two aquifers in the Temple Terrace area of Hillsborough County, Fla. The lower one is the artesian Floridan aquifer; the upper is the water-table aquifer. The Floridan aquifer is a thick sequence of limestone and dolomite layers which include several permeable zones that generally are treated as a single hydrologic unit. The top of the Tampa Limestone is considered to be the top of the Floridan in the Temple Terrace area. The public supply wells of the city tap the Tampa Limestone and the underlying Suwannee Limestone, in the upper part of the Floridan. The general direction of ground-water movement in the Floridan aquifer is from north to south, but within the city the direction of movement is from northeast to southwest. The quantity of water moving southwest through a 1.8 mile section of the aquifer is about 2.7 million gallons per day. Ample supplies of water in a cavernous limestone, considered to be the most productive water-yielding zone in the aquifer, are available for additional development from the Floridan aquifer. Water-quality data are included also. (Woodard-USGS)