The coastal parts of Pasco, Pinellas and Hillsborough are undergoing extensive urban development. The Floridan aquifer is the area 's principal water supply. Potentiometric and water-table maps were prepared in order to determine the effect of groundwater withdrawals in selected well fields in west-central Florida. These maps were prepared in May 1977 to capture the annual low-water-level period. Declines in the potentiometric surface ranged from 3 feet in the Starkey well field to 25 feet in the Sun City well field. (Woodard-USGS)