ABSTRACT

The U.S. Geological Survey collects ground-water data and conducts studies to monitor hydrologic conditions, better define ground-water resources, and address problems related to water supply, water use, and water quality. Water levels were monitored continuously, in Georgia, in a network of 184 wells during 2006 and 182 wells during 2007. Because of missing data or the short period of record (less than 3 years) for several of these wells, a total of 166 wells from the network are discussed in this report. These wells include 18 in the surficial aquifer system, 21 in the Brunswick aquifer system and equivalent sediments, 67 in the Upper Floridan aquifer, 15 in the Lower Floridan aquifer and underlying units, 10 in the Claiborne aquifer, 1 in the Gordon aquifer, 11 in the Clayton aquifer, 12 in the Cretaceous aquifer system, 2 in Paleozoic-rock aquifers, and 9 in crystalline-rock aquifers. Data from the network indicate that water levels generally declined from 2005 levels, with water levels in 99 wells below normal, 52 wells in the normal range, 12 wells above normal, and 3 wells with insufficient data for comparison of 5-year trends and period of record statistics.

In addition to continuous water-level data, periodic synoptic water-level measurements were collected and used to construct potentiometric-surface maps for the Upper Floridan aquifer in Camden, Charlton, and Ware Counties, Georgia, and adjacent counties in Florida during September 2006 and 2007, in the Brunswick area during July 2006 and August 2007, and in the City of Albany–Dougherty County area during October 2006 and October 2007. In general, the configuration of the potentiometric surfaces showed little change during 2006–2007 in each of the areas.

Ground-water quality in the Upper Floridan aquifer is monitored in the Albany, Savannah, and Brunswick areas and in Camden County; and water quality in the Lower Floridan aquifer is monitored in the Savannah and Brunswick areas and in Camden County. In the Albany area, nitrate concentrations generally have increased since the end of the drought during 2002. During 2006, water from two wells had nitrate as N concentrations above the U.S. Environmental Protection Agency's (USEPA) 10-milligram-per-liter (mg/L) drinking-water standard. During 2007, only one well had concentrations above the drinking-water standard.

In the Savannah area, measurement of fluid conductivity and chloride concentration in water samples from discrete depths in three wells completed in the Upper Floridan aquifer and one well in the Lower Floridan aquifer were used to assess changes in water quality in the Savannah area. At Tybee Island, chloride concentrations in samples from the Lower Floridan aquifer decreased during 2006–2007 but were still above the 250-mg/L USEPA drinking-water standard. At Skidaway Island, water in the Upper Floridan aquifer is fresh, and chloride concentrations did not appreciably change during 2006–2007. However, chloride concentrations in samples collected from the Lower Floridan aquifer during 2006–2007 showed disparate changes; whereby, chloride concentration increased in the shallowest sampled interval (900 feet) and decreased slightly in a deeper sampled interval (1,070 feet). At Fort Pulaski, water samples collected from the Upper Floridan aquifer were fresh and did not appreciably change during 2006–2007.

In the Brunswick area, maps showing the chloride concentration of water in the Upper Floridan aquifer were constructed by using data collected from 29 wells during July 2006 and from 26 wells during August 2007. Analyses indicate that concentrations remained above the USEPA drinking-water standard in an approximate 2-square-mile area. During 2006–2007, chloride concentrations increased in only three of the wells sampled and ranged from 4.0 to 20 mg/L chloride.

In the Camden County area, chloride concentration during 2006–2007 was analyzed in water samples collected from eight wells, six completed in the Upper Floridan aquifer and two in the Lower Floridan aquifer. In most of the wells sampled during this period, chloride concentrations did not appreciably change; however, since the closure of the Durango Paper Mill in October 2002, chloride concentrations in the Upper Floridan aquifer near the mill decreased from a high of 184 mg/L in May 2002 to 42 mg/L in September 2007.

Ground-water studies during 2006–2007 include

• Evaluation of ground-water flow, water quality, and water-level monitoring in the Augusta–Richmond County area;
• Evaluation of geohydrology of fractured crystalline rock of northern Georgia;
• Evaluation of ground-water flow and water quality, and water-level monitoring in the city of Albany–Dougherty County area;
• Evaluation of saltwater intrusion, water-level, and water-quality monitoring in the city of Brunswick–Glynn County area;
• Evaluation of saltwater intrusion and alternative water sources as part of the Coastal Sound Science Initiative;
• Evaluation of hydrogeology and effects of pumping on shallow water-bearing zones and the Upper Floridan aquifer, south-central Georgia;
• Evaluation of geohydrology and effects of climate and pumpage change on water resources of the Aucilla–Suwannee–Ochlockonee River Basin, south-central Georgia and adjacent areas of Florida;
• Collection of ground-water data in and adjacent to the State of Georgia;
• Simulation and particle-tracking analysis of selected ground-water pumping scenarios at Vogtle Electric Generation Plant, Burke County, Georgia;
• Assessment of the sustainability of ground-water resources in the City of Lawrenceville area; and
• Participation in the U.S. Air Force Plant 6 remediation assistance program.

First posted April 27, 2009