This map shows the potentiometric surface of the Upper Floridan aquifer in the St. Johns River Water Management District and vicinity for September 1986. The Upper Floridan aquifer is the principal source of potable water in the area. Water level measurements were made on approximately 1,000 wells and on several springs. The potentiometric surface is shown mostly by 5-ft contour intervals. The potentiometric surface ranged from 129 ft above sea level in Polk County to 88 ft below sea level in Nassau County. The steep cone of depression of the potentiometric surface in the Fernandina Beach area of Nassau County is caused by large withdrawal of groundwater for industrial use. Many water levels in the district were equal to or lower than water levels of September 1985. Declines of as much as 2 ft from September 1985 levels were common throughout the district in response to a decline in rainfall and an increase in pumpage. The largest decline from September 1985 potentiometric surface level was 8 ft, occurring in Indian River County. Levels in many wells approached, and in a few wells exceeded, record lows. (USGS)
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USGS Numbered Series
Potentiometric surface of the upper Floridan aquifer in the St. Johns River Water Management District and vicinity, Florida, September 1986
1 map :photocopy ;103 x 63 cm., on sheet 116 x 73 cm.