Ground-water resources of the upper White River basin in Arkansas

Abstract

The upper White River basin in Arkansas lies almost entirely within the Ozark Plateaus physiographic province, which consists of deeply dissected plateaus underlain by limestone, shale, and dolomite. Significant water-yielding units within the upper White River basin include the Eminence and Potosi Dolomites, the Roubidou Formation, the Gasconade Dolomite and the Van Buren Formation, outcrops of undifferentiated Paleozoic rocks, the Nacatoch Sand, and quaternary deposits. Water in the Quaternary deposits is the most heavily used, but areally, other units are significant sources of groundwater for domestic and rural use. The quality of groundwater withdrawn from the various units generally is suitable for most uses, although groundwater in the study area is typically very hard. Iron concentrations commonly exceed allowable limits. Yields from the different water-yielding units are highly variable. The Eminence and Potosi Dolomites are known to yield as much as 230 gal/min. Nearer the surface, the Gunter Sandstone Member of the Van Buren Formation yields as much as 500 gal/min. Above the Gunter Sandstone, the Roubidoux Formation yields as much as 450 gal/min to wells. In contrast to the high yields from these deeper units , the outcrops of Paleozoic rocks commonly yield less than 10 gal/min. The Quaternary deposits yield as much as 2,500 gal/min of very hard water. Elevated nitrate concentrations that exceed U.S. Environmental Protection Agency primary drinking-water standards occur in Marion County. In addition, saline water is present in the Quaternary deposits near Bald Knob and Cord, Arkansas. (USGS)