Laserfiche WebLink
<br />. <br /> <br />l'\:) <br />l'\:) <br />o <br />ol:>. <br /> <br />and hardness, and, in general, high TDS would require treatment to <br />be used in most industrial processes, The ground water is unfit for <br />most irrigation applications, <br /> <br />UPPER MAIN STEM, COLORADO RIVER (WAU 140100) <br /> <br />Most of the Upper Main Stem Basin (Fig. D.3) is a major zone <br />of aquifer recharge. ~wst recharge is mountain snowmelt but further <br />down the Colorado River, nearer to Grand Junction, significant <br />recharge cccurs from streams and irrigation canals (Lohman, 1965). <br />Ground water is discharged by stream seepage, evapotranspiration, <br />and well withdrawals. <br /> <br />. <br /> <br />Ground water resources along the headwaters of the Colorado <br />River are meager. Most rocks in the region are impermeable to <br />water (granite, shale, schist, and gneiss) and only where fractured <br />signtficantly can they yield water to wells. Most wells in such <br />rock structures yield only 1 to 5 gpm and only rarely do they yield <br />more than 10 gpm (Boettcher, 1972; Voegeli, 1965). Other potential <br />aquifers, such as terrace deposits, have been drained or their <br />resources (Voegeli, 1965). The only aquifers that yield moderate <br />amcunts are areas underlain by Dakota Sandstone and Tertiary sedi- <br />ments (e.g., North and Middle Park formations) near Granby, Colorado. <br />Most wells in Dakota Sandstone obtain less than 50 gpm (Boettcher, <br />1972). <br /> <br />Most wells now are tapped into alluvial deposits along the <br />Colorado, 31ue, and Fraser rivers. Yields are as high as 400 gpm <br />from Blue River alluvia near Dillon, Colorado, but wells more com- <br />monly give between 5 and 100 gpm (Boettcher, 1972; Voegeli, 1965). <br /> <br />Water quality from both bedrock and alluvial aquifers is <br />excellent, except that some glacial deposits have excessive iron <br />content for domestic use (Voegeli, 1965). <br /> <br />Seventy-five miles downscream from the headwaters of the Colo- <br />rado River a particularly prodigious Pennsylvanian carbonate rock <br />group, plus some Pennsylvanian Leadville Limestone and the Dyer <br />Formation, appears near McCoy. Colorado. In a 17 square-mile <br />region these aquifers hold between 8,600 and 86,000 AF (with an <br />average of 43,000 AF) of recoverable water (Hampton, 1974). Wells <br />drilled to depths of 3,000 feet yield 2,000 gpm or more. One well <br />has a measured flow of 3,200 gpm (Hampton, 1974; Boettcher, 1972). <br />These measured yields are among the highest in Colorado. The water <br />is under artesian pressure at several points~ . <br /> <br />. <br /> <br />D-17 <br />