Atrazine in surface water and relation to hydrologic conditions within the Delaware River Basin Pesticide Management Area, Northeast Kansas, July 1992 through December 1994

Since about 1960, atrazine has been used as an effective pre- and postemergent herbicide in the production of corn and grain sorghum. Atrazine is a triazine-class herbicide and was the most frequently detected herbicide in surface water of the lower Kansas River Basin of southeast Nebraska and northeast Kansas (Stamer and Zelt, 1994). Approximately 95 percent of the atrazine applied in the United States is used in corn and grain-sorghum production, predominately in the Mississippi River Basin where about 82 percent of the Nation's corn acreage is planted (CIBA-GEIGY Corp., 1992). Until recent changes in product labeling, atrazine commonly was applied at relatively high rates to control weeds around commercial and industrial areas and along railroad right-of-ways. Crop yields have increased during the last 40 years due in part to the use of herbicides in reducing weed growth and competition for moisture and nutrients. However, concern on the part of water suppliers, health officials, and the public also has increased regarding the safe and responsible use of herbicides. One issue is whether the widespread use of atrazine may pose a potential threat to public-water supplies in areas where the herbicide is used because of its ability to easily dissolve in water and its possible effects on the health of humans and aquatic life.