Occurrence of pesticides in ground water in the White River Basin, Indiana, 1994–95

Pesticides (herbicides and insecticides) are used extensively in the White River Basin. Application of herbicides to corn and soybeans accounts for most of the use. The U.S. Geological Survey collected samples from four networks of monitoring wells in the White River Basin during 1994-95. The most frequently detected compounds in ground water were desethyl atrazine (a breakdown product of atrazine) and the commonly used herbicides, atrazine and metolachlor. Insecticides commonly used in urban and agricultural areas were not found. The highest concentration of any pesticide detected was alachlor at 0.19 micrograms per liter. Most detections of atrazine and desethyl atrazine were in agricultural areas overlying fluvial deposits, which are vulnerable to pesticide contamination, but the concentrations were small (less than 0.1 microgram per liter).