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<br />. <br /> <br />. <br /> <br />. <br /> <br />o <br />~"- <br />CJ1 <br />-J <br /> <br />The largest source of selenium contamination in the areas studied is seepage originating from <br />the Ashley Valley sewage lagoons. Water in the lagoons is free from selenium, but passes <br />through fractured Mancos Shale and discharges to Ashley Creek carring a selenium load in <br />excess of 1 kilogram per day. Seepage from the sewage lagoons also contribute about 9,000 <br />tons per year of salt to Ashley Creek. In 1997, the State of Utah, U.S. EPA, the BOR, and the <br />local sewer district begain the planning and funding process for a new waste-water treatment <br />plant that will remove this source of salt and selenium to AsWey Creek. <br /> <br />NASQAN II <br /> <br />NASQAN II monitors the water quality of large rivers in four of the nation's largest river basins <br />-- the Mississippi, Columbia, Colorado, and Rio Grande. The program objectives are: <br /> <br />to provide an on-going description of the dissolved and particulate fluxes in the basins; <br /> <br />to detennine the regional sources areas for these materials; and <br /> <br />to assess the effect of human influences on measured concentrations and fluxes. <br /> <br />Individual Districts are responsible for data and sample collection, quality control, and initial <br />data review. Sample and data collection strategies in each basin are established by a basin <br />coordinator, who has overall responsibility within the basin. A national interpretive team has <br />been established to produce reports from the data collected and to evaluate the overall program <br />design. <br /> <br />In the Colorado River Basin in FY97, the USGS operated 9 sites under the aegis of the <br />NASQAN II program. Four of the sites were scheduled for 12 samples during the year, with <br />the capacity to collect 3 additional samples in response to flood events. These sites were the <br />Colorado River near Cisco, Utah; the Green River at Green River. Utah; the San Juan River <br />near Bluff, Utah; the Colorado River above Diamond Creek, Arizona. Fifteen samples were <br />collected at the Utah sites, 12 at the Arizona site. Three sites were scheduled for 6 samples in <br />FY97. These were the Colorado River at Lees Ferry, Arizona; below Hoover Dam, <br />Arizona-Nevada; and above Imperial Dam, Arizona-California. To examine the question of <br />chemical stability of water immediately below Glen Canyon Dam, two of the Lees Ferry <br />samples were shifted upriver to just below the dam, resulting in an additional site. The last site <br />was the Colorado River at the Northerly International Boundary above Morelos Dam, near <br />Andrade, California. This site was sampled 7 times. All samples collected were analyzed for <br />suspended sediment concentrations, and concentrations of dissolved and selected total nutrients. <br />dissolved and suspended organic carbon, dissolved and suspended trace elements, and dissolved <br />pesticides and major ions. <br /> <br />9 <br /> <br />,-. <br /> <br />4<~,__-,"._ .-.,..(i,__ ,k_.14i~ <br />