Report Title: Geohydrology and water quality of the Roubidoux aquifer northeastern Oklahoma
An aquifer test and a digital ground-water flow model were used to estimate aquifer and confining-layer hydraulic characteristics. Using these methods, the transmissivity of the aquifer was estimated to be within a range of 400 to 700 square feet per day. The leakance of the confining layer was determined to be within a range from 0 to 0.13 per day, with a best estimate value in a range from 4.3 x 10-8 to 7.7 x 10-8 per day.
Analyses of water samples collected as part of this study and of water-quality data from earlier work indicate that a large areal change in major-ion chemistry occurs in ground water in the Roubidoux aquifer in northeastern Oklahoma. The ground water in the easternmost part of the study unit has relatively small dissolved-solids concentrations (less than 200 milligrams per liter) with calcium, magnesium, and bicarbonate as the major ions. Ground water in the westernmost part of the study unit has relatively large dissolved-solids concentrations (greater than 800 milligrams per liter) with sodium and chloride as the major ions. A transition zone of intermediate sodium, chloride, and dissolved-solids concentrations exists between the easternmost and westernmost parts of the study unit.
Three water-quality problems are apparent in the Roubidoux aquifer in northeast Oklahoma: (1) Contamination by mine water, (2) large concentrations of sodium and chloride, and (3) large radium-226 concentrations.
Many wells in the mining area have been affected by mine-water contamination. At present (1990), all instances of ground-water contamination by mine water can be explained by faulty seals or leaky casings in wells that pass through the zone of mine workings and down to the Roubidoux aquifer. None of the data available to date demonstrate that mine water has migrated from the Boone Formation through the pores and fractures of the intervening geologic units to the Roubidoux aquifer.
Ground water with large concentrations of sodium and chloride occurs at some depth throughout the study unit. In the eastern part of the study unit, chloride concentrations greater than 250 milligrams per liter are found at depths greater than approximately 1,200 to 1,500 feet. Data are too few to determine the depth to ground water with large concentrations of sodium and chloride in the southern and southwestern parts of the study unit.
Large concentrations of gross-alpha radioactivity in ground water occur near the western edge of the transition zone. Generally, ground water with large concentrations of gross-alpha radioactivity was found to exceed the maximum contaminant level for radium-226.
(available as photostat copy only)