During the spring of 1998, water levels were measured in 656 wells completed in the Mississippi River Valley alluvial aquifer in eastern Arkansas. Water samples were collected during the summer of 1998 from about 140 wells completed in the alluvial aquifer and measured for specific conductance, and samples from 119 wells were analyzed for dissolved chloride concentrations.
The regional direction of ground-water flow in the alluvial aquifer is generally to the south and east except where water levels are affected by ground-water withdrawals. A large depression in the potentiometric surface is located in Arkansas, Lonoke, and Prairie Counties. Shallower depressions are located in Poinsett, Lee, St. Francis, and Woodruff Counties. Potentiometric depressions in the alluvial aquifer generally are a result of long-term pumping and probably are affected by variations in aquifer characteristics. Water-level data from 22 wells with 26 or more years of record indicate long-term water levels in the alluvial aquifer declined an average of about 0.38 foot per year.
Specific conductance measurements made on water samples collected during the study ranged from 199 microsiemens per centimeter at 25 degrees Celsius at a well in Drew County to 3,800 microsiemens per centimeter at 25 degrees Celsius at a well in Chicot County. Dissolved chloride concentrations ranged from 2.1 milligrams per liter at a well in Mississippi and St. Francis Counties to 820 milligrams per liter at a well in Chicot County. The high chloride concentrations occurred in the same area of Chicot County as the high specific conductance.
Additional publication details
USGS Numbered Series
Status of water levels and selected water-quality conditions in the Mississippi River valley alluvial aquifer in eastern Arkansas, 1998
Water-Resources Investigations Report
U.S. Dept. of the Interior, U.S. Geological Survey ;
U.S. Geological Survey, Branch of Information Services [distributor],