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Reconnaissance investigation of water quality, bottom sediment, and biota associated with irrigation drainage in the Dolores Project area, southwestern Colorado and southeastern Utah, 1990-91

Water-Resources Investigations Report 94-4041

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Abstract

Water, bottom-sediment, and biota samples were collected in 1990-91 to identify water-quality problems associated with irrigation drainage in the Dolores Project area. Concentrations of cadmium, mercury, and selenium in some water samples exceeded aquatic-life criteria. Selenium was associated with irrigaton drainage from the Dolores Project, but other trace elements may be transported into the area in the irrigation water supply. Selenium concentrations exceeded the chronic aquatic-life criterion in water samples from lower McElmo Creek and Navajo Wash, which drain the Montezuma Valley, from newly irrigated areas, and from the Mancos River. The maximum selenium con- centration in water was 88 micrograms per liter from Navajo Wash. Concentrations of herbicides in water were less than concentrations harmful to aquatic life. Selenium concentrations in four bottom-sediment samples exceeded the baseline concentrations for soils in the Western United States. The largest selenium concentrations in biota were in samples from Navajo Wash, from newly irrigated areas north of the Montezuma Valley, and from the Mancos River basin. Selenium concentrations in aquatic-invertebrate samples from the newly irrigated areas exceeded a guideline for food items consumed by fish and wildlife. Selenium concen- trations in whole-body suckers were larger in the San Juan River downstream from the Dolores Project than upstream from the project at Four Corners. Selenium concentrations in fathead minnow samples from two sites were at adverse-effect levels. Mercury concentrations in warm-water game fish in reservoirs in the study area may be of concern to human health. Some concentrations of other trace elements exceeded background concentrations, but the concentrations were not toxicologically significant or the toxicologic significance is not known.

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Reconnaissance investigation of water quality, bottom sediment, and biota associated with irrigation drainage in the Dolores Project area, southwestern Colorado and southeastern Utah, 1990-91
Series title:
Water-Resources Investigations Report
Series number:
94-4041
Edition:
-
Year Published:
1995
Language:
ENGLISH
Publisher:
U.S. Geological Survey : USGS Earth Science Information Center, Open-File Reports Section [distributor],
Description:
ix, 126 p. :ill., maps ;28 cm.