Carla Hyde Fromm Sharon A. Watkins Hugh E. Bevans 1995 Median monthly atrazine concentrations detected in surface-water samples from the Big Blue River basin (1977-86) exceeded the U.S. Environmental Protection Agency health-advisory level (3.0 micrograms per liter) during May through September. Herbicide loads transported from the basin in 1986, expressed in tons and in percentage of amount applied, were alachlor (1.2 tons, 0.23 percent), atrazine (19 tons, 2.2 percent), and metolachlor (2.2 tons, 2.7 percent). application/pdf 10.3133/wsp2419 en U.S. Geological Survey The occurrence and transport of agricultural pesticides in the Tuttle Creek lake-stream system, Kansas and Nebraska reports