Sparta Aquifer Recovery Study

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Union County Water Conservation Board

Sparta Aquifer Information and Study Background

The Sparta aquifer is an important source of groundwater for southeastern Arkansas and northern Louisiana. It is the only viable aquifer in Union County, Arkansas. Seven cities, 29 rural water associations, and 11 major industries in Union County use the Sparta as a raw water source.

The Sparta underlying Union County is a confined aquifer consisting of a sequence of unconsolidated sand units that are contained within the Tertiary-age Sparta Sand formation. Over the past 50 years the Sparta has been declining beneath the major pumping centers located in El Dorado and Magnolia, Arkansas; and Hodge and Monroe, Louisiana as the rate of discharge exceeds the aquifer's natural recharge rate. The cone-shaped groundwater depression underlying Union County and the cone of depression underlying Ouachita Parish have to some degree merged into a trough of depression connecting southern Arkansas and northern Louisiana. In some areas the overdraft is causing upwelling and lateral migration of high salinity water, which may lead to costly water treatment options for many communities.

A hydrogeologic model of the Sparta aquifer in Union County, developed in 1999 by the U.S. Geological Survey (USGS) estimated that in order to restore aquifer levels to the top of the Sparta Sand, groundwater usage in Union County must be reduced to about 28 percent of 1997 rates. This represents a reduction from about 21 million gallons per day (MGD) to about 6 MGD. Model details can be found in Sustainable-Yield Estimation for the Sparta aquifer in Union County, Arkansas, available from the USGS in Little Rock, Arkansas.

 

In response to declining water levels, the Arkansas Soil and Water Conservation Commission (ASWCC) in 1996 declared five counties in Arkansas "critical groundwater areas." Critical groundwater designations encourage local interests to develop a plan of action to address problems. In 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 in south central Arkansas, bordering Louisiana. This historic accomplishment was made possible by the unselfish dedication of the County's industries, elected officials, and citizens to saving their most precious resource, the Sparta aquifer.

The Union County Water Conservation Board has 11 elected members, all of whom are volunteers, representing 11 separate political subdivisions within the county. Following its formation in 1999, the Board began the process of regulating groundwater use in Union County. The Board's actions included implementation of a usage fee for groundwater users. The usage fee provides revenues needed to fund improvements to save the Sparta. Specifically, the Board, with the assistance of engineering consultants Burns & McDonnell, developed a Water System Master Plan to determine how to best serve the long-term water supply needs of the County. Several alternatives were identified and evaluated in the master plan. The quickest and most cost-effective alternative was to supply raw water from the Ouachita River to area industries and thereby eliminate the need for those industries to use groundwater.

The Ouachita River is a controlled-release waterway (by means of U.S. Army Corps of Engineers locks and dams) that supports barge traffic. A 65-MGD river intake and pump station, settling facilities and 5 miles of 48-inch pipeline were completed in several contracts in Phase I. Phase II is now underway with construction of a 3-million gallon storage tank, a booster pump station, and service lines and connections to three area industries (El Dorado Chemical, Great Lakes Chemical Corporation - Central Plant, and Lion Oil) and is expected to be completed by the end of 2003.

In 2002, the Board received a grant from the U.S. Environmental Protection Agency to study the recovery of the Sparta aquifer as these industries and other users reduced their reliance on groundwater. The Board is conducting the Sparta Aquifer Recovery Study with the assistance of the Union County Conservation District, the U.S. Geological Survey, and Burns & McDonnell. During the Study, selected wells in Union County and adjacent counties and parishes will be monitored for water quality and water levels as the aquifer recovers.  The well locations are shown on the map below.  Water quality monitoring wells are sampled twice annually by the USGS and analyzed for chloride.  Water level monitoring wells (real-time wells operated by USGS and automated data logger wells operated by the Union County Conservation District) are continuously monitored to observe changes in Sparta aquifer levels.  Data from the USGS real-time wells are automatically uploaded every 6 hours to the USGS web site at http://waterdata.usgs.gov/ar/nwis/current/?type=gw.  Data from the UCCD automated data logger wells are manually downloaded as often as is practical.  The UCCD strives to download this data monthly and post it to the Sparta Aquifer Recovery Study web site. Semi-annual progress reports are submitted twice annually to EPA (click here for access to these reports).  

The data will be used to determine if Phase 2 of the alternative water supply project, and other conservation efforts will be sufficient to save the Sparta aquifer or if it will be necessary to implement Phase 3, which would provide surface water to more industries currently withdrawing water from the Sparta aquifer.