ABSTRACT
The Dry Creek Watershed in eastern Iowa is marked by agricultural usage, limited topographical relief, karst terrain, and recent residential expansion into its boundaries. This study implicates karst terrain in compromising the private well-water supply of the Dry Creek Watershed by correlating surface water quality change with well-water quality change. Triazines and nitrate were monitored between June and November of 1993 with bi-weekly samplings. Although triazine concentrations were below the Health Advisory Level of 3 ug/L, the relative temporal triazine concentration change was significantly linked between Dry Creek watershed well-water and surface water. Nitrate relative temporal concentration change was not shown to be significantly linked between the surface water and well- water of the Dry Creek watershed, but throughout the course of the study, nitrate was found in concentrations above the Maximum Contaminant Level of 10 mg/L as nitrogen. Residential expansion into the watershed must be married with either expanded municipality water supplies or best available technologies for the treatment of water at private residences. Also, traditional agricultural best management practices such as limited or no-tillage may serve to compromise groundwater quality, especially in the southern portion of the watershed where karst terrain prevails.
