Pesticides in surface waters of the upper Colorado River basin, Colorado, 1996-98

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Title Pesticides in surface waters of the upper Colorado River basin, Colorado, 1996-98
Creator Bauch, Nancy J.; Spahr, Norman E.
Subject Water quality; Pesticides; Water quality bioassay
Spatial Coverage Colorado River (Wyo.-Utah); Colorado; Utah; Wyoming
Description Forty-four river, stream, and drain sites in the Upper Colorado River Basin in Colorado were sampled during 1996-98 to determine the occurrence and distribution of pesticides in the basin. In a fixed-station study, 57 surface-water samples were collected from October 1996 through January 1998 at four sites. Each site was sampled approximately monthly for up to a year, with more frequent sampling during the spring and summer growing season. In a synoptic study, surface-water samples were collected at 43 sites in the agricultural areas of the Grand Valley and the Uncompahgre River Valley in May 1998. Each site was sampled once. Pesticide concentrations generally were low and varied seasonally and across land uses. Thirty-five pesticides were detected at least once in the two studies, and 11 pesticides accounted for almost 82 percent of the detections. Herbicides were more commonly detected than insecticides, and only the herbicides alachlor and atrazine were detected in more than 50 percent of the samples. Carbofuran was the most commonly detected insecticide and was detected in 19 percent of the samples. Pesticide detections increased and were measured at higher concentrations in the summer months and at the agriculture sites. All pesticide concentrations were less than drinking-water standards, and most complied with human-health advisories and criteria for the protection of freshwater aquatic life. Pesticides in the Upper Colorado River Basin in Colorado were detected slightly less frequently and generally at lower concentrations than in 20 National Water-Quality Assessment Program study-unit basins that collected water-quality data from 1992 through 1996. Results from surface-water sampling conducted during 1996-98 in the Upper Colorado River Basin in Colorado indicate that beneficial uses of water were not being impaired by the presence of pesticides in surface waters in the basin.
Publisher U.S. Geological Survey
Date 2000
Type Text
Format application/pdf
Digitization Specifications pdf file copied from USGS website (http://water.usgs.gov/pubs/wri/wri00-4005/). Uploaded into CONTENTdm version 3.7.
Identifier http://water.usgs.gov/pubs/wri/wri00-4005/
Source Bauch, Nancy J.; Spahr, Norman E., Pesticides in surface waters of the upper Colorado River basin, Colorado, 1996-98, Denver, Colorado: U.S. Geological Survey Water-Resources Investigations Report 00-4005, 46 p.
Language eng
Rights Management Public Domain, Courtesy of the USGS
Holding Institution University of Utah
Metadata Cataloger Kristin Willmore
ARK ark:/87278/s6qj7g74
Setname wwdl_er
Date Created 2005-08-10
Date Modified 2005-08-10
ID 1145893
Reference URL https://collections.lib.utah.edu/ark:/87278/s6qj7g74
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