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:

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Continuous water-level records from 155 wells and more than 800 waterlevel measurements made in Georgia during 1984 provide the basic data for this report. Selected wells illustrate the effects that changes in recharge and pumping have had on the various groundwater resources in the State. Daily mean water levels are shown in hydrographs for 1984. Monthly means are shown for the 10-year period 1975-84. Mean annual water levels ranged from 7 feet lower to 7 feet higher in 1984 than in 1983. Water-quality samples are collected periodically throughout Georgia and analyzed as part of areal and regional groundwater studies. Along the coast, chloride concentrations in the Floridan aquifer system continued to fluctuate. This report continues a series of publications that annually presents both water-level and water-quality data for Georgia. Forty-eight wells have been selected to illustrate the effects that changes in recharge and pumping have had on the various aquifers in the State. Daily mean water levels are shown in hydrographs for 1984. Monthly mean water levels, as well as chloride concentrations in selected areas along the coast, are shown for the 10-year period 1975-84. Because the 1984 hydrographs are plotted from daily mean values, the record low or high water level occurring on a day will be lower or higher than that shown on the hydrograph, which shows the mean for that day. The cooperation and assistance of the following agencies in collecting water-level and water-quality data during 1984 are gratefully acknowledged: Georgia Department of Natural Resources, Georgia Geologic Survey; Chatham County; Glynn County; the cities of Brunswick and Valdosta; and the Albany Water, Gas, and Light Commission. The writers are grateful to the following individuals who contributed significantly to the collection, processing, and tabulation of the data:

Abandoned uranium mines in the Monument Valley and Cameron mining districts that have partially filled with water were studied to define hydrologic and chemical characteristics of mine water and shallow ground water and to evaluate possible chemical interactions of shallow ground water and the mine-spoil material that will be used in mine reclamation. Uranium mines in the Monument Valley area were established predominantly in channel-fill deposits within the Shinarump Member of the Chinle Formation. The Shinarump Member yields ground water to wells and may yield water to the Moonlight and Radium Hill mines. Depth-to-water measurements in the area of the Moonlight and Radium Hill mines indicate that local groundwater flow is from the southeast to the northwest along the trend of Oljeto Wash. In the study area near Cameron, uranium was mined from channel-fill deposits within the Petrified Forest Member of the Chinle Formation. Units of the Petrified Forest Member do not yield ground water to wells in the area, but fractures in the lower part of the Petrified Forest Member are probable pathways for upward flow of ground water from the Shinarump Member. Depth-to-water measurements were not sufficient to determine local groundwater flow directions, although previous investigations determined that regional flow in the area is toward the Little Colorado River. In the Cameron area, water in mines can originate from several sources. Most of the mines receive water from surface inflow of rainfall runoff, but ground water also may be transmitted to open pits and drill holes in the subsurface through fractures or along faults in the Petrified Forest Member. Uranium-238 activities in shallow ground water from mines ranged from 150 to 14,000 picocuries per liter and radium-226 activities ranged from 0.10 to 110 picocuries per liter. Uranium-238 activities in pit water from mines ranged from II to 22 picocuries per liter. Radon-222 activities from three groundwater samples ranged from 590 to 250,000 picocuries per liter. Radionuclide activities in well and spring water generally were less than in shallow ground water and pit water. Water from Clay Well spring, which is about 1.9 miles from the nearest mine, contained a uranium-238 activity of 27 picocuries per liter. Radionuclide activities in well and spring water may result from naturally occurring mineralization in waterbearing rock units. The effects of mining activity could not be determined from chemical analyses of well and spring water. Laboratory-batch tests indicate that radionuclide activities varied in leachate and generally correlated with field gamma measurements. Uranium concentrations in leachate samples ranged from 20 to 7,700 micrograms per liter and radium-226 activities ranged from 0.95 to 34 picocuries per liter. Batch tests were done with material that was 2.00 millimeters and smaller. Particle-size data indicate that spoil material near sampling locations is predominantly gravel and coarser sediments at three of the mines and sand-size sediments at the fo...

In 1982, the San Bernardino National Wildlife Refuge was established in San Bernardino Valley to protect unique wetlands habitat for fish and wildlife and an endangered species of fish the Yaqui topminnow. Black Draw, the main surface-water drainage in the valley, is perennial in a short reach in the refuge near the international boundary with Mexico. Ten wells and at least four springs are connected with the wetlands in the refuge. Wetland restoration was begun in response to habitat damage caused by cattle grazing and land clearing for farming. Interlayered alluvium and basalt flows compose the principal aquifer system in the valley. Ground water flows from recharge areas near mountain fronts toward the basin center and then southward. Discharges from flowing wells and springs contribute water to the wetlands in the refuge. Fluctuations in groundwater levels and discharges of flowing wells reflect variations in climatic conditions. Irrigation in the valley is minimal, and groundwater levels have remained stable since the mid-1950's. Discharges from flowing wells were measured during 1983-88. Annual discharge from the flowing wells totals about 400 acre-feet. The effects of groundwater withdrawals in Mexico on we 11-discharge rates in the refuge are not known, but continued development could affect groundwater conditions. Ground water in the study area is of acceptable chemical quality for most uses and does not contain concentrations of constituents that exceed State of Arizona water-quality standards. Only small quantities of ground water are withdrawn near the refuge.