R.E. Krause Reggina Garza 1992 <p><span>Long-term pumping from the Upper Floridan aquifer in the Savannah, Georgia, area has lowered </span><span>ground-water levels, resulting in increased salinity of ground water by seawater encroachment at Hilton Head </span><span>Island, S.C., and by saltwater intrusion at Brunswick, Ga. Increased pumpage could cause further salinization </span><span>of the ground-water resources. </span></p><p><span>The Savannah and Ogeechee Rivers can be considered potential water-supply sources for the Savannah, Ga., area, on the basis of historic stream flow records and water-quality constituents and properties examined. Analyses of stream-discharge data indicate that the minimum average discharges for 7 consecutive days for a 10-year recurrence interval (7010), was 5,460 cubic feet per second (ft3/s) at Savannah River near Clyo, Ga., and 192 ft3/s at Ogeechee River near Eden, Ga. For example, 90 percent of the time, flows in excess of the 7010 discharges are about 900 and 200 ft3/s, respectively. However, Georgia Department of Natural Resources, Environmental Protection Division, imposes a non-depletable flow criterion; thus, the actual quantity of water available for withdrawal probably would be less than flows in excess of minimum flow criteria, such as the 7Q10.</span></p><div class="page" data-page-number="11" data-loaded="true"><div class="textLayer"><span>A ground-water flow model was developed and used in conjunction with other previously calibrated </span><span>models in the coastal area to simulate the effects of additional pumping on water levels near sites of seawater </span><span>encroachment at Hilton Head Island and saltwater intrusion at Brunswick. Based on model simulations and the </span><span>constraint of preventing water-level declines at locations of encroachment and intrusion, the potential of the </span><span>Upper Floridan aquifer to supply additional water in the Savannah area is limited under present (1985) </span><span>hydrologic conditions. The water-supply potential ranges from less than 1 million gallons per day (Mgal/d) in </span><span>Liberty, McIntosh, most of Bryan, and southern Chatham Counties, Ga., and in southern Beaufort County, S.C., </span><span>to more than 5 Mgal/d in northern Jasper and northern Beaufort Counties, S.C. Because of the limited water-</span><span>supply potential, hypothetical alternatives involving redistributions, redistributions and small increases, and </span><span>decreases in pumpage were simulated to determine the effects on water levels. These simulations indicate that </span><span>reductions and redistributions of pumping would not adversely affect water levels at locations of encroachment </span><span>and intrusion. Increased pumping would cause water-level declines, which might increase salinization of the </span><span>fresh-water aquifer.</span>.&nbsp;<br></div></div> application/pdf 10.3133/ofr92629 en U.S. Geological Survey Water-supply potential of major streams and the upper Floridan Aquifer in the vicinity of Savannah, Georgia reports