HYDROGEOLOGY AND WATER-QUALITY OF THE BUFFALO RIVER AND BIG CREEK IN NEWTON COUNTY, AR: A PRELIMINARY INVESTIGATION OF HYDROGEOLOGY AND WATER-QUALITY NEAR A MAJOR CONFINED-ANIMAL FEEDING OPERATION

A swine confined-animal feeding operation (CAFO) in Newton County, AR near the Buffalo River was approved and permitted without essential scientific data addressing the hydrogeology of the region. The CAFO is adjacent to Big Creek, which is a major tributary to the Buffalo River. The region has karst geology, providing for rapid recharge to groundwater with little attenuation of contaminants. Contamination mechanisms of concern to the Buffalo River and Big Creek include leakage from waste lagoons, runoff from the lagoons during large storm-events, and groundwater contamination. Preliminary biogeochemical data was collected from the Big Creek basin and the Buffalo River during the months of July and August. Water samples were collected from 17 springs, 4 streams, 1 shallow well, and 3 deep wells. Geochemical analyses of water samples indicated calcium-bicarbonate type water was predominate in the study area. Calcium concentrations ranged from 36.0 mg/L – 117.8 mg/L, and alkalinity ranged from 44.0 mg/L – 300.0 mg/L. Calcium-bicarbonate type water is indicative of dissolution of limestone from the Boone Formation, which outcrops in the study area. Specific conductivity measurements ranged from 191 µS/cm – 813 µS/cm, which also indicated the occurrence of limestone dissolution. Specific conductivity and temperature measurements suggested groundwater flow is heavily influenced by recharge during storm-events. Deeper groundwater was found to be calcium-bicarbonate-chloride type, which is indicative of longer subsurface hydraulic residence time. Deeper groundwater had elevated magnesium levels ranging from 3.82 mg/L – 19.0 mg/L indicating dissolution of deeper dolomitic intervals within the Everton Formation, elevated chloride concentrations of 11.7 mg/L – 40.9 mg/L and elevated sodium concentrations of 2.4 mg/L – 13.3 mg/L. Both indicate increased subsurface hydraulic residence time. Biological data show E.coli and fecal coliform concentrations varied from <1.0 – 980.4 MPN/100mL and from <1.0 - 241,900 MPN/100mL, respectively. The wide range of E.coli and fecal coliform concentrations may result from widespread livestock feeding operations and recreational use of sampled water; however more data is necessary to elucidate sources of bacterial constituents in groundwater and surface-water.