The Sparta aquifer supplies the majority of water for industrial, municipal, and agricultural uses in Union County, Arkansas, and the surrounding area. In Union County, the Sparta aquifer has been used increasingly since development began in the early 1920s, resulting in water-level declines of more than 360 feet (ft) in some areas. In addition, water quality of the Sparta aquifer has degraded in some areas as usage has increased. In response to the declining water levels and degraded water quality, the Arkansas Natural Resources Commission designated the Sparta aquifer as a Critical Ground-Water Area in five counties of southern Arkansas in 1996. Ground-water flow models developed by the U.S. Geological Survey (USGS) indicate that withdrawals from the Sparta aquifer in Union County must be reduced to 28 percent of 1997 withdrawals (about 6 million gallons per day (Mgal/d)) to maintain water levels at or above the top of the Sparta Sand (Hays, 2000).