Assessment of historical surface-water quality data in southwestern Colorado, 1990-2005
Scientific Investigations Report
2012-5255
Prepared in cooperation with the Bureau of Land Management, Bureau of Reclamation, Southwestern Water Conservation District, San Miguel County, and Telluride Power/Water
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Abstract
The spatial and temporal distribution of selected physical and chemical surface-water-quality characteristics were analyzed at stream sites throughout the Dolores and San Juan River Basins in southwestern Colorado using historical data collected from 1990 through 2005 by various local, State, Tribal, and Federal agencies. Overall, streams throughout the study area were well oxygenated. Values of pH generally were near neutral to slightly alkaline throughout most of the study area with the exception of the upper Animas River Basin near Silverton where acidic conditions existed at some sites because of hydrothermal alteration and(or) historical mining. The highest concentrations of dissolved aluminum, total recoverable iron, dissolved lead, and dissolved zinc were measured at sites located in the upper Animas River Basin. Thirty-two sites throughout the study area had at least one measured concentration of total mercury that exceeded the State chronic aquatic-life criterion of 0.01 μg/L. Concentrations of dissolved selenium at some sites exceeded the State chronic water-quality standard of 4.6 μg/L. Total ammonia, nitrate, nitrite, and total phosphorus concentrations generally were low throughout the study area. Overall, results from the trend analyses indicated improvement in water-quality conditions as a result of operation of the Paradox Valley Unit in the Dolores River Basin and irrigation and water-delivery system improvements made in the McElmo Creek Basin (Lower San Juan River Basin) and Mancos River Valley (Upper San Juan River Basin).
Study Area
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | Assessment of historical surface-water quality data in southwestern Colorado, 1990-2005 |
| Series title | Scientific Investigations Report |
| Series number | 2012-5255 |
| DOI | 10.3133/sir20125255 |
| Year Published | 2013 |
| Language | English |
| Publisher | U.S. Geological Survey |
| Publisher location | Reston, VA |
| Contributing office(s) | Colorado Water Science Center |
| Description | vii, 74 p. |
| Time Range Start | 1990-01-01 |
| Time Range End | 2005-12-31 |
| Country | United States |
| State | Colorado |
| Online Only (Y/N) | Y |
| Additional Online Files (Y/N) | N |
| Google Analytic Metrics | Metrics page |