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Continuous water-level records from 152 wells and water-level measurements from an additional 750 wells in Georgia during 1986 provide the basic data for this report. Hydrographs for selected wells illustrate the effects that changes in recharge and discharge have had on the groundwater reservoirs in the State. Daily mean water levels are shown in hydrographs for 1986. Monthly mean water levels are shown for the 10-year period 1977-86. During 1986, a prolonged drought resulted in water-level declines throughout the State. Annual mean water levels were from 2.7 feet higher to 17.3 feet lower than in 1985, and record lows were measured in 33 wells in the summer and fall. The 1986 lows were from 0.02 foot to 29.2 feet lower than the previous record lows. The largest declines were measured in the Clayton aquifer in the southwestern part of the State. The declines can be attributed to reduced recharge and increased pumping that resulted from below-normal precipitation during the first half of the year. Water-quality samples are collected periodically throughout Georgia and analyzed as part of area! and regional groundwater studies. Periodic monitoring of water quality in the Savannah and Brunswick areas indicates that the chloride concentration in the Upper Floridan aquifer there generally has remained stable. This report continues a series of publications that annually presents both groundwater level and groundwater quality data for Georgia. Hydrographs from 59 wells have been selected to illustrate the effects that changes in recharge and discharge have had on the various aquifers in the State. A new chapter on Miocene aquifers and expanded coverage of the crystalline rock, water-table, and Upper Floridan aquifers have been added to this year's report. Daily mean water levels are shown in hydrographs for 1986. Monthly mean water levels, as well as chloride concentrations for selected areas along the coast, are shown for the 10-year period 1977-86. Because the 1986 hydrographs are plotted from daily mean values, a record low or record high water level that occurred on a given day would have been lower or higher than that shown on the hydrograph. The report also includes maps that show the potentiometric surfaces of the Upper Floridan, Claiborne, Clayton, Providence, and Dublin-Midvil1e aquifers. The potentiometric surface of an aquifer is an imaginary surface that represents the altitude to which water would rise in tightly cased wells that penetrate the aquifer. The potentiometric surface is highest in areas of recharge and lowest in areas of discharge, indicating that ground water flows from recharge areas to discharge areas. Where discharge is concentrated and exceeds recharge, the potentiometric surface is lowered, forming a cone of depression. The cooperation and assistance of the following agencies in collecting water-level and water-quality data during 1986 are gratefully acknowledged:

Signal Center and Fort Gordon, investigated the presence and disbursal of trace elements and semi-volatile organic compounds in bed sediments from selected streams and impoundments at the Fort Gordon military installation near Augusta, Georgia. Concentrations of 18 trace elements and total organic carbon, and 66 semi-volatile compounds were determined from analysis of the fine-grained fraction of bed-sediment samples from 29 surface-water deposition sites. Analysis of the bed-sediment data indicates that commercial and industrial land-use areas generally are associated with the highest concentrations of trace elements and semi-volatile organic compounds, and the greatest occurrence and distribution of trace elements and semi-volatile organic compounds in bed sediments at Fort Gordon. Bed sediment collected at sites having drainage areas less than 1.0 square mile and greater than 45 percent commercial and industrial land uses, have the most occurrences and the highest concentrations of trace elements and semi-volatile organic compounds. Sampling sites having less than 2 percent commercial and industrial land uses have the lowest concentrations, regardless of drainage basin size. Relative rankings and evaluation of individual trace element and semi-volatile organic compound concentration data identifies two sites that have substantially higher sediment-quality scores than the other sites. This suggests that these sites have the greatest potential risk for adverse effects on aquatic life. The effects of these elevated trace element and semi-volatile organic compound concentrations on aquatic life in these basins may merit further investigation. Information on the occurrence and distribution of toxic substances in surface water on the base is needed to develop an INRMP at Fort Gordon. Toxic substances, when transported from source areas and deposited in streams may adversely affect aquatic life and stream ecosystems. In May 1998, the U.S. Geological Survey (USGS), in cooperation with the Environmental and Natural Resources Management Office of the U.S. Army Signal Center and Fort Gordon, conducted a spatial survey of streams and impoundments to identify trace elements and semi-volatile organic compounds (SVOCs) associated with bed sediment in surface water at Fort Gordon. Trace elements and SVOCs (a class of industrially derived organic compounds) have low solubility in natural waters and tend to accumulate on silt-and clay-sized particles and organic matter. Point and nonpoint anthropogenic sources of trace elements include atmospheric deposition, urban and industrial wastes, urban runoff, storm sewers, landfills, vehicle maintenance areas, and agricultural and silvicultural activities. Although SVOCs may have similar sources as trace elements, specific sources of SVOCs are industrial areas, which use solvents, lubricants, oil additives, and combustion residues that enter surface water primarily in industrial and municipal wastewater effluent and in nonpoint-source runoff (Scudder and others, 1997). The majority of ...