WSP01995

• File Number: 8272.300.50
• Description: Colorado River Basin Salinity Control Advisory Council
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 10/1/1998
• Author: USDA
• Title: Colorado River Salinity Control Program - Federal Accomplishments Report for Fiscal Year 1998
• Water Supply Pro - Doc Type: Report/Study

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UTAH

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Irrigation Drainage and Seleniwn -- Middle Green River Basin

Detailed study of wildlife areas in the middle Green River Basin of Utah during 1986-1990 has
shown that the concentrations of selenium in water and biologic tissues were hannfull to wildlife
at the Stewart Lake Waterfowl Management Area, lower Ashley Creek, and the Ouray National
Wildlife R\:fuge. The sources of selenium at Stewart Lake is irrigation drainage from the Bureau
of Reclamation Jensen Unit, which drains sedimentary deposits of marine and nomnarine origin.
An Environmental Assessment prepared for Stewart lake in 1997 outlined a multi-phase
remediation for selenium at the lake: deepen drainage channels to facilitate drying the lake bed;
route the t).ve ground-water drain directly to the Green River for discharge; and construct an
inlet fromlthe Green River to capture seasonal high flows. These features were constructed
during 1997-1998 and initial monitoring of selenium in the lake sediment indicates the drying
(oxidation) and wetting (mobilization of dissolved selenium) cycles have measureably reduced
selenium by moving it into the Green River during high flows.

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A significljnt linear relation (R2 of 0.65) exists between concentrations of dissolved selenium
discharges to Ashley Creek and concentrations of dissolved solids, but no relation (R2<0.01)
exists bet~een loads of selenium and loads of dissolved solids. This indicates that salinity
controls tllat are chosen only to treat large sources of salt may fail to control loads of selenium.

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The largest source of selenium contamination in the areas studied is seepage originating from
the AshleY, Valley sewage lagoons. Water in the lagoons is free from selenium, but passes
through fr~ctured Mancos Shale and discharges to Ashley Creek carrying a selenium load in
excess of i kilogram per day. Seepage from the sewage lagoons also contribute about 9,000
tons per y~ar of salt to Ashley Creek. In 1997, the State of Utah, U.S. EPA, the BOR, and the
local sewer district began the planning and funding process for a new waste-water treahnent
plant that will remove this source of salt and selenium to Ashley Creek.

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NASQAN II

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NASQAN,n monitors the water quality of large rivers in four of the nation's largest river basins
-- the Mississippi, Columbia, Colorado, and Rio Grande. The program objectives are: to
provide an on-going description of the dissolved and particulate fluxes in the basins; to
detennine Ihe regional sources areas for these materials; and to assess the effect of human
influences 'on measured concentrations and fluxes.

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Individual Districts are responsible for data and sample collection, quality control, and initial
data review. Sample and data collection strategies in each basin are established by a basin
coordinat~r, who has overall responsibility within the basin. A national interpretive team has
been established to produce reports from the data collected and to evaluate the overall program
design.

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In the Colorado River Basin in FY98. the USGS collected water samples at 8 sites for the
NASQANJI program. These sites were (1) Colorado River near Cisco, Utah, (2) the Green
River at Green River, Utah (3) the San Juan River near Bluff, Utah, (4) the Colorado River at

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