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<br />well sue the few who use 90% of the water. No clear reason yetiappears for <br />any lawsuit to be prosecuted. If the Navy needs all the water of the river <br />it can condemn the outstanding rights and pay for them. <br /> <br />.:*" ~~ ~~ * {~ {(- ;~ ~)} * i(- it- <br /> <br />QUALITY OF COLORADO RIVER WATER <br /> <br />C. S. Howard, Regional Chemist, U.S. Geological Survey <br /> <br />In the Colorado River basin the best quality water is in the headwater <br />areas. Almost all uses of the water increase the dissolved solids content and <br />otherwise affect the quality. The major and prospective uses are for power <br />and irrigation, but new industries may use large volumes of water and return <br />industrial wastes to the river. Records of water quality have been collected <br />for the main stream and principal tributaries, but additional records are <br />needed, to show the concentration and chemical character under existing <br />conditions, and to furnish data for showing changes that may take place as <br />a result of additional developments. The analytical results collected by <br />the Geological Survey pertain to the mineral constituents only. <br /> <br />The concentration of dissolved'solids varies with stream flow, and <br />it is not possible on the basis of a few samples to make statements concern- <br />ing the concentration and character of the river water for a long period of <br />time. Concentrations are usually lowest during periods of high runoff, espe- <br />cially from snow melt. Highest concentrations occur during fall and winter <br />when the flow is largely from ground-water. Reservoirs catching appreciable <br />proportions of the annual runoff permit mixing waters of different concentra- <br />tions, and as a result the outflow from reservoirs is usually quite uniform <br />in concentration and character of dissolved solids. Actual concentration of <br />dissolved solids is of interest and importance, but knowledge of the chemical <br />character of the soluble constituents is of greater importance. For that <br />reason analyses are needed of the chemical character by seasons from year <br />to year. Mineral analyses usually include determinations of silica, iron, <br />calcium, magnesium, sodium, bicarbonate, sulfate, chloride, and nitrate. <br />Boron and fluoride are often determined. <br /> <br />Average annual analyses in 1947-48 for various points are shown in <br />Figure 1. The water at Hot Sulphur Springs had a dissolved solids concentra- <br />tion of 59 parts per million (p.p.m.) consisting chiefly of calcium and bi- <br />carbonate; a normal calcium bicarbonate water. Near Glenwood Springs, above <br />the spring area but below the confluence with Eagle River, concentration was <br />232 p.p.m., sulfate, chloride, calcium, and sodium representing the increase. <br />The average at Cameo, at the head of the Grand Valley proje~t, was 366 p.p.m., <br />and at Cisco, 548 p.p.m. Gunnison and Dolores Rivers and irrigation wastes <br />from the Grand Valley project flow into the river between Cameo and Cisco. <br />River water at Cisco had a much higher sulfate and somewhat higher chloride <br />content than at Glenwood Springs. At Grand Canyon the concentration was 556 <br />p.p.m., slightly higher than at Cisco. Below Hoover Dam, releases from Lake <br />Mead had a concentration of 656 p.p.m. At Yuma the river water had a concen- <br />tration of 690 p.p.m. <br /> <br />-17- <br />