Sparta Aquifer Hydrogeologic Study

In April 1999, the Arkansas legislature passed Act No. 1050 authorizing the creation of groundwater conservation boards in counties designated as "critical groundwater areas." The first county to form such a board was Union County, which borders Louisiana in south central Arkansas. A U.S. Geological Survey (USGS) monitoring well near the center of the county recorded a static water level in 1942 of 60 feet above sea level. By 1999, the static level in the same well had dropped to 180 feet below sea level. This represents an average depletion of 4.2 feet per year near the center of the county over the 57 years of records.

Burns & McDonnell refined a two-state USGS groundwater model of the Sparta Aquifer to represent the information collected from wells and users in Union County, which covers over 1,000 square miles. All water used in Union County came from the Sparta Aquifer. There are seven cities, 22 rural water associations and 11 major industries using Sparta water. The hydrogeologic computer model of the Sparta Aquifer in Union County was used as a basis to evaluate many alternatives that were considered in the master plan to “Save the Sparta.” The selected alternative was to withdraw water from the Ouachita River with a side stream 65-million-gallon-per-day (MGD) intake. The river water would then be treated with coagulation and sedimentation to provide non-potable water. In Phase 1, the non-potable water would be delivered to serve a new power plant and the largest water-using industries via an extensive non-potable water transmission system. Phase 1 of the master plan was completed and the final industry began taking water in late 2005.

In 2002, the U.S. Environmental Protection Agency (EPA) granted the board $1 million to perform the Sparta Aquifer Recovery Study. Major components of the study, planned for completion in 2007, include installation of three new monitoring wells, automated and manual water level monitoring in existing wells, water quality monitoring, development of a project Web site with public access to project data, and biannual reports to the EPA. Burns & McDonnell was retained to manage the study. USGS will provide support for the project by installing monitoring wells, automated water level monitoring equipment and performing groundwater sampling.

• Hydrogeologic modeling
• Biannual groundwater sampling
• Chloride and TDS analysis
• Automated water level data collection
• Project Web site