ABSTRACT
This research tests whether a program to install Best Management Practices (BMP’s) will improve ground-water quality in a karst aquifer. The Pleasant Grove Spring Basin, in southern Logan County, Kentucky, was selected for study because it is largely free of non-agricultural pollution sources. Mapping the drainage basin boundary determined its area is approximately 4,167 hectares (10,291 acres). Approximately 92 percent of the watershed is in agricultural production. Ground-water flow in the basin is divided into a diffuse, slow-flow regime and a conduit, fast-flow regime. Nitrate is the most widespread, persistent contaminant in the basin, but concentrations do not exceed MCL’s for drinking water. Atrazine has been consistently detected in low concentrations, and other pesticides occasionally occur. Triazines (including atrazine) have exceeded drinking water MCL’s during spring flooding. Flow-weighted average concentrations for 1992–93 were 4.91 ug/L for atrazine and 5.0 mg/L for nitrate nitrogen. Averages for 1993–94 were 0.97 ug/L and 5.7 mg/L respectively. Bacteria counts typically exceed drinking water limits. The diffuse and conduit flow regimes have a major influence on the timing of contaminant peaks and valleys in storm event chemographs.
