Laserfiche WebLink
<br />_.'.":'r'~~ <br /> <br /> <br />US <br />GS <br /> <br />Upper CoIoradp Riyer Basin. NAWQA <br />F ACT SHE E T <br /> <br />What Affects Water Quality In the Upper Colorado River Basin? <br /> <br />--l,()ri E. Apodaca. Verlin C. Stephens. and Nancy E. Driver <br /> <br />I'\) <br />t,; The Upper Colorado River Basin is J of 60 study units selected for water-quality assessment by the <br />CJl U.S. Geological Survey as part of the National Water-Quality Assessment program. Understanding the <br />:~~ environmental setting of the Upper Colorado River Basin study unit is important in evaluating water-quality <br />issues in the basin. Information about the environmental setting identifies the basin characteristics and <br />includes natural and human factors that affect the physical, chemical, and biological quality of water in the <br />basin. This information has been used to design surface-water- and ground-water-quality sampling networks <br />in the basin to assess oyerall water quality of the basin. <br /> <br />INTRODUCTION <br /> <br />In 1991. the U.S. Geological Survey (USGS) began to imple- <br />ment the National \Vater-Quality Assessment (NAWQA) program. <br />Goals of the NA WQA program are to (I) describe water-quality <br />conditions for 11 large part of the Nation's freshwater streams, <br />rivers. and aquifers; (2) describe how water qual.ily is changing <br />over time: and (3) improve the understanding of the primary natural <br />and human factors that affect water-quality conditions (Leahy <br />and others. 1990). To complete this program, the USGS plans to <br />investigate 60 river basins and aquifer systems (study units) <br />throughout the United States. Information obtained from these <br />different study units will help Federal, State, and local agencies <br />make needed management, regulatory, and monitoring decisions to <br />better prolect, use, and enhance water resources. This fact sheet. <br />based on Apodaca and others (1996), describes how the environ- <br />mental setting of the Upper Colorado River Basin (UCOL) study <br />unit affects water quality in the basin. Infonnation about the <br />environmental setting, which is based on natural and human <br />factors, was used to design surtace-waler- and ground-water-quality <br />sampling networks for the study unit. <br />The UeOL study unit, located in western Colorado, has a drain- <br />age area of about 17.800 square miles (fig. 1). The primary river <br />within the basin, the Colorado River, originates in the mountains <br />of central Colorado and nows about 230 miles southwest into Utah. <br />Major tributaries to the Colorado River are the Blue, Eagle, Roar- <br />ing Fork, and Gunnison Rivers. In 1990. population in the basin <br />was about 234,000 (Bureau of Census, 1990). The largest popula- <br />tion center in tile basin is the area around Grand Junction, Colo. <br /> <br />ENVIRONMENTAL SETTING <br /> <br />The environmental setting of the VeOL study unit provides a <br />framework for understanding the basin characteristics, which are <br /> <br />important in the design of an integrated study of the surface <br />water and ground water of the basin. Natural factors that affect <br />background water-quality conditions in the VeOL basin are <br />physiography, climate, geology, and soils. Human factors that <br />affect water-quality conditions are water management and use <br />and land use in the basin. <br /> <br /> <br />UPPER COLORADO RIVER <br />BASIN STUDY UNIT <br /> <br />UTAH[.:. .... ...H..'....,...I.. .....\ COLO. RAD,.O <br /> <br />. .~,. "'.;., ;,. ",' ,'. ... ,," . <br />-. .i)' <br /> <br />EXPLANATION <br /> <br />'ii 1Q:~MIl.tS <br />>' 1'1:'; 'j' <br />0' 10 4O.;iLouii'EfIS <br />" <br /> <br />- -.-. - Physiographic Provin.ce.{iou(1dary <br />Stu1v Unit Boundary <br />... Surtace.-Water~SarnPling Site <br /> <br />..-,,~ <br /> <br />.,. ...,~~~ ~ :..:;:~ H' <br /> <br />Figure 1. Location of the Upper Colorado River Basin study unit. <br />