National Water Quality Assessment Program: Eastern Iowa Basins

Pesticides In Ground-water Of The Iowa River Corridor; An Area Of Changing Land Use

by E.M. Sadorf

Program abstract of the 109th Session of the Iowa Academy of Science meeting, April 27, 1997, Dubuque, Iowa

Twenty-three monitoring wells, ranging in depth from 9 feet to 40 feet, were sampled in the summer of 1996 as part of a U.S. Geological Survey investigation of the effects of changing land use on ground water quality in the Iowa River alluvial aquifer. Approximately thirty percent of the crop land on the Iowa River Corridor , a region bounded by bluffs along the Iowa River between Tama and Amana, is being taken out of production as part of the Iowa River Corridor Project.

Atrazine, metolachlor, cyanazine, acetochlor, and metribuzin were detected at or above the method detection limit. Atrazine was detected in 11 of the wells, metolachlor in 6 ,cyanazine in 3, acetochlor in 2, and metribuzin in 1. Of these five pesticides, metolachlor, cyanazine, acetochlor, and metribuzin decreased in concentration with increased well depth within well nests. There was no general trend for atrazine. None of the pesticides exceeded the USEPA's maximum contaminant levels.

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