U.S. Geological Survey Toxic Substances Hydrology Program--Proceedings of the Technical Meeting Charleston South Carolina March 8-12,1999--Volume 2 of 3--Contamination of Hydrologic Systems and Related Ecosystems, Water-Resources Investigation Report 99-4018B

Changes in Herbicide Concentrations in Midwestern Streams in Relation to Changes in Use, 1989-98

By Elisabeth A. Scribner, William A. Battaglin and Donald A. Goolsby, and E.M. Thurman

This report is available in pdf format: Scribner.pdf

ABSTRACT

Water samples were collected from Midwestern streams in 1994-95 and 1998 as part of a study to help determine if changes in herbicide use resulted in changes in herbicide concentrations since a previous reconnaissance study in 1989-90. Sites were sampled during the first significant runoff period after the application of preemergent herbicides in 1989-90, 1994-95, and 1998. Samples were analyzed for selected herbicides, two atrazine metabolites, three cyanazine metabolites, and one alachlor metabolite. In the Midwestern United States, alachlor use was much greater in 1989 than in 1995, whereas acetochlor was not used in 1989 but was commonly used in 1995. The use of atrazine, cyanazine, and metolachlor was about the same in 1989 and 1995. The median concentrations of atrazine, alachlor, cyanazine, and metolachlor were substantially higher in 1989-90 than in 1994-95 or 1998. The median acetochlor concentration was higher in 1998 than in 1994 or 1995.