Occurrence of saltwater in the alluvial aquifer in the Boeuf-Tensas Basin, Arkansas

The occurrence of saline water in the alluvial aquifer in the Boeuf-Tensas basin in southeastern Arkansas has been of increasing concern. A band of saline water containing chloride concentrations of greater than 50 milligrams per liter extends through the entire length of the basin. The most severely affected area is located in the southern part of the basin where chloride concentrations are as high as 1,360 milligrams per liter. The origin of the saline water in the alluvial aquifer is not definitely known, but can probably be attributed at least in part, to both upward movement from the Arkansas River. Upward instrusion of saline ground water has probably occurred through one or more of the following: 1) leakage where the Jackson confining unit is thinned or absent, 2) leakage along a fault, and 3) movement through abandoned oil and gas test holes. (USGS)