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08/09/99 MON 17:01 FAX 801 524 5021 USFWS-Utah Field Office -*44 RO-COKANUT 11002 Middle Green River 1998 Collection Report U.S. Fish and Wildlife Service Irrigation drainage studies conducted under the National Irrigation W middle Green River basin, Utah, by the U.S. Fish and Wildlife Servic and Bureau of Reclamation from 1986 to 1989 detected significantly selenium in water, sediment, and biota (Stephens et al., 1988; Peltz ai et al., 1992). Areas with particularly high concentrations were Ouray Ashley Creek, and Stewart Lake Waterfowl Management Area. At Stewart Lake, studies demonstrated that large concentrations of and biota have resulted from selenium laden irrigation drainage enti irrigation drains, J144. Selenium concentrations in water entering been consistently elevated (up to 140 µg/L), while selenium concen outlet ranged from 1 to 12 µg/L during 1986 through 1992. Selenium concentrations in 98% of composite whole-body fish saml during 1986, 1988, and 1989 were substantially elevated above the 7 dry weight (dw) for warmwater fishes (Stephens, et al., 1994, Appen percent of waterbird eggs sampled during the same period exceeded gg/g dw for waterbird eggs. All aquatic invertebrate samples were e Threshold of -3) gg/g dw for dietary items. Elevated concentrations o detected in fish from the Green River, with concentrations ranging fl Selenium concentrations were largest in fish from the Stewart Lake/. areas where 73% of the samples exceeded the Toxicity Threshold (> fish). Monitoring of biota in Stewart Lake and the Green River in 1994 an selenium contamination in Stewart Lake had not improved since the the mean selenium concentration in waterbird eggs was higher than 1 sampling emphasis was on fish, plankton, fall waterfowl and Ameri( Selenium concentrations in fish samples ranged from 15.0 to 40.7 gi gg/g dw and coot livers contained as much as 49.1 gg/g dw and coo During 1997, extensive sampling of fish in Stewart Lake and the G sampling of Green River backwaters was completed. A similar me completed in 1998. During both 1997 and 1998 high Green River Stewart Lake through a newly constructed inlet channel in an attem sediments from the lake. Preliminary results from USGS sediment potential 5% to 25% decrease in selenium concentrations. iter Quality Program in the U.S. Geological Survey, .arge concentrations of Ld Waddell, 1991; Stephens National Wildlife Refuge, lium in water, sediment the lake through lake from the drains have ons in water at the lake -s collected in Stewart Lake ?xicity Threshold of 4 µg/g ix A). Seventy-six (76%) ie Toxicity Threshold of 8 ;vated above the Toxicity selenium have also been m 1.9 to 49 pg/g dw. shley Creek and Jensen E µg/g dw for warmwater 1995 indicated that ;first sampling in 1986, and 11988-89. During 1996 an coots (Fulcia americana). /g dw, plankton 12.3 to 21.9 muscle 18.0 lcg/g dw. n River and opportunistic oring program was also ws were brought into to "flush out" contaminated in 1997 indicated a