ORIGIN AND TRANSPORT OF DISSOLVED CHEMICALS IN A KARST WATERSHED, SOUTHWESTERN ILLINOIS

In the Fountain Creek watershed, which is a karst watershed in Monroe County, southwestern Illinois, relationships between human activities and water quality were explored using detailed land-use maps and by monitoring trends in contaminant mass loads in the stream system, in groundwater discharged from springs with defined recharge areas, and in effluent from the local wastewater-treatment plant. At two selected springs, water quality, discharge, and oxygen isotopes were monitored intensively. The study was conducted between October 2000 and November 2001. The resulting data are tabulated, showing that agricultural land use was the dominant control on water quality and that the agricultural chemicals could be segregated into two groups: those moving rapidly by runoff and conduit flow from agricultural fields to springheads, and those moving slowly to the springheads under diffuse flow. The local wastewater-treatment plant was also a source of several water-quality constituents, including some agricultural chemicals.