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10 Chapter 3-Colorado River Water Quality Assessment Middle Green River Basin, Utah The middle Green River basin efforts were concentrated on the Stewart Lake Waterfowl Management Area and the Ouray National Wildlife Refuge. Other areas studied included Ashley Creek, Pariette Draw, Uinta Basin, and Desert Lake. The problems found in the middle Green River were sufficient for the Task Group to initiate detailed studies in 1988. The detailed study report will be published'in early 1991. Elevated levels of selenium, a naturally occurring element in the soils of the area, have been found in water, sediment, and some birds, fish, and plants at the Stewart Lake Waterfowl Management Area and the Ouray National Wildlife Refuge near Vernal, Utah. Selenium in the soil is leached from the soil by irrigation water. Irrigation drains collect the water and convey it to Stewart Lake. The drainage water from irrigation is used in the wildlife area where selenium is concentrated by evaporation. Selenium has reached levels that cause abnormalities in waterfowl and possibly fish. The Utah Department of Health issued a Public Health Advisory suggesting restricted human consumption offish and waterfowl at Stewart Lake. At Stewart Lake, selenium in water from four irrigation drains ranged from 14 to 140 parts per billion (ppb). Concentrations of selenium in the livers of coots from the lake ranged from 4.9 to 26 parts per million (ppm) dry weight. Carp collected from the lake contained selenium concentrations as high as 31 ppm dry weight. The concentration of selenium in water of the North Roadside Pond at the Ouray National Wildlife Refuge was as great as 93 ppb. Liver tissue from coots contained an average selenium concentration of 32 ppm dry weight. Five bird eggs collected from the North and South Roadside Ponds contained selenium concentrations of as much as 120 ppm. Several deformed coot embryos were discovered in this area and resulted in the closure of a portion of the refuge to public access in 1987. The reconnaissance phase of the study was completed and a report published entitled "Reconnaissance Investigation of Water Quality, Bottom Sediment, and Biota Associated with Irrigation Drainage in the Middle Green River Basin, Utah, 1986-87." See U.S. Geological Survey Water Resources Investigations Report 88-4011. Remediation studies are currently being initiated for Stewart Lake and the Roadside Pond in Ouray National Wildlife Refuge. A future decision will determine ifInterior has further remediation responsibilities in Ashley Creek where seepage from wastewater treatment lagoons flowing through seleniferous soils, may be the major source of selenium and salinity. Lower Colorado and Gila River Valleys The annual flow of the Lower Colorado River is vital to the economic well-being of millions of people in Arizona, California, and northern Mexico. The hydrologic environment of the river has been altered greatly by water resource development. Demands for water include municipal, irrigation, electrical power generation, navigation, recreation, and wildlife habitat needs. /1 / / ! The Department of the Interior has four important functions as a land and water steward in the Lower Colorado and Gila River valleys: (1) the Bureau of Reclamation manages Colorado River diversions to private irrigation districts which irrigate hundreds of thousands of acres of intensively farmed agricultural areas in,' Arizona and California; (2) the Bureau of Indian Affairs manages agricultural areas irrigated by Colorado River diversions within the Colorado River Indian Reservation; (3) the Bureau of Land Management manages extensive lands on the San Pedro and San Simon tributaries of the Gila as well as Fred J. Weiler Green Belt on the main stem of the Gila. The Bureau of Land Management also leases 26 irrigated agricultural land parcels and manages other nonirrigated lands along the Colorado, Bill