Effect of Surface Water and Ground Water Interaction on Atrazine Transport to Pumping Wells

High concentrations of agricultural chemicals in flood waters have been reported in many Midwestern rivers and streams. The public water supply wells of a number of riparian communities are located in alluvial aquifers along the banks of these rivers and streams. A study was initiated along a stretch of the Illinois River to examine the impact of floods on the pumped water quality of selected municipal wells. A sampling event covering a period of nearly two months took place starting late May, 1995 in response to a record flood in the upper reaches of the Illinois River. In early and late Fall of 1995, water samples were col lected to study the baseline chemical concentrations of the river water and the pumped ground water. Another round of sampling is planned for the Spring/Summer of 1996. In the second year, intensive monitoring will be carried out at one site and a detailed surface and ground-water modeling will be conducted.