Title:
Hydrogeology and Water Quality of the Lower Floridan Aquifer, Coastal Georgia, 1999-2000

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Author(s)
Falls, W. Fred
Harrelson, Larry G.
Conlon, Kevin J.
Petkewich, Matthew D.
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Hatcher, Kathryn J.
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Abstract
The Lower Floridan aquifer at Richmond Hill, Brunswick, and St Marys, Ga., has permeable intervals of freshwater to slightly brackish water that could provide water users with an alternative water supply to supplement water use from the Upper Floridan aquifer. Strong similarities in water-level fluctuations for the Upper and Lower Floridan aquifers at Richmond Hill, and similar water-level elevations indicate that both aquifers respond as one saturated unit to regional ground-water withdrawals and recharge. Conversely, at Brunswick and St Marys, abrupt changes in water level and chemistry indicate stronger confinement between permeable zones in the Upper and Lower Floridan aquifers, relative to the Richmond Hill area. At Richmond Hill, water in the Upper Floridan aquifer is fresh with total dissolved solids (TDS) concentration of 172 milligrams per liter (mg/L) and a chloride concentration of 5 mg/L. Water in the Lower Floridan aquifer at Richmond Hill is slightly brackish, with a TDS concentration of 1,630 mg/L and a chloride concentration of 160 mg/L. As a result of decades of ground-water withdrawal in downtown Brunswick, water in the Upper Floridan aquifer is brackish ith TDS concentrations as high as 5,000 mg/L and chloride concentrations varying from 1,500 to 3,000 mg/L. The Lower Floridan aquifer at Brunswick consists of a freshwater zone from 1,230 to 1,664 ft below sea level with concentrations of 289 mg/L for TDS and 26 mg/L for chloride; a brackish-water zone from 1,664 to 2,176 ft below sea level with concentrations of 1,360 to 4,330 mg/L for TDS and 190 to 1,300 mg/L for chloride; a saline-water zone from 2,176 to 2,675 ft below sea level with concentrations of 33,600 mg/L for TDS and 18,000 mg/L for chloride; and a brine zone from 2,675 ft below sea level to the total borehole depth of 2,710 ft below sea level with concentrations of 48,300 mg/L for TDS and 26,000 mg/L for chloride. At St Marys, water in the Upper Floridan aquifer is fresh, with a TDS concentration of 463 mg/L and a chloride concentration of 32 mg/L. Water in the Lower Floridan aquifer at St Marys is also fresh, with a TDS concentration of 623 mg/L and a chloride concentration of 28 mg/L.
Sponsor
Sponsored and Organized by: U.S. Geological Survey, Georgia Department of Natural Resources, Natural Resources Conservation Service, The University of Georgia, Georgia State University, Georgia Institute of Technology
Date Issued
2001-03
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