Organonitrogen Herbicides in the Lower Kansas River Basin

To help managers, planners, and regulators determine when and where surface waters are likely to be adversely affected by organonitrogen herbicides, the authors analyzed various data on the distribution of these compounds in the lower Kansas River basin. They found that atrazine was the most frequently detected herbicide, was found in the highest concentrations, and was most likely to exceed the maximum contaminant level. The highest atrazine concentrations in the water were measured where the largest amounts of atrazine had been applied to the land, and median concentrations were higher in spring and summer than in fall and winter. Atrazine and chemically similar herbicides are not effectively removed by traditional water treatment. The Kansas State Board of Agriculture has established a pesticide management area to decrease the amount of atrazine that enters surface water.