AN INVESTIGATION OF IRRIGATION-RELATED CONTAMINANTS IN WATER, BOTTOM SEDIMENT, AND BIOTA FROM GOSHEN COUNTY, WYOMING.

We conducted a comprehensive evaluation of trace element concentrations in water, sediment, aquatic vegetation, aquatic invertebrates, waterbird eggs, and fish resulting from irrigation drainwater during 1995 in Goshen County, Wyoming. We also analyzed waterbird eggs and fish from this area for organochlorine residues and attempted to determine the nesting success of various waterbirds. Boron concentrations were elevated (\u3e300 ug/g dry weight) in aquatic vegetation above concentrations shown to adversely affect sensitive waterfowl; however, these concentrations are similar to those found in aquatic vegetation sampled in other areas throughout Wyoming. Mercury concentrations in aquatic vegetation, aquatic invertebrates, and fish were slightly elevated above the recommended concentration of mercury (\u3e0.1 ug/g wet weight) in food items for the protection of sensitive avian species. However, mercury presently does not appear to be bioaccumulating in birds to concentrations expected to cause adverse affects. Cadmium was slightly elevated in aquatic invertebrates (\u3e1.2 ug/g dw) from two sites but neither fish or bird tissue had elevated cadmium concentrations. Chromium was slightly elevated in aquatic vegetation from two sites; but, the significance of these residues is unclear. Chromium was not found in waterbird eggs or fish in concentrations (\u3e4.4 ug/g dry weight) that suggest chromium contamination is present. Dieldrin was detectable in one avocet egg and DDE was detected in all avian eggs and fish. However, the concentrations of cadmium, chromium, and organochlorine pesticides were not at concentrations that cause adverse effects to fish and wildlife resources