The University of Nebraska-Omaha's Elkhorn Research Station is perfectly placed along the Elkhorn River. It sits just outside of Omaha and is near the end of the Elkhorn's long run through farm and ranch country in the northeast. Alan Kolok of the Nebraska Watershed Network isn't looking for one particular chemical in the water of the Elkhorn - he knows this historically muddy river carries lots of sediment, and that sediment transports a suite of chemicals from upstream. Mimicking river exposures on minnows, they are finding that the chemicals can 'defeminize' the female fishes after 9 days of exposure.