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<br />PROBLEMS AND NEEDS <br /> <br />Colorado River Water Quality <br /> <br />The Colorado River at its headwaters in the mountains of north- <br /> <br />central Colorado has a salinity (dissolved mineral concentration) of only <br /> <br />about 50 mg/L. The salinity progressively increases downstream as <br /> <br />a result of water diversions and salt contributions from a variety of <br /> <br />sources. In 1979, the salinity averaged about 810 mg/L at Imperial Dam, <br /> <br />the last major diversion point on the Colorado River in the United <br /> <br />States. <br /> <br />The high salt load of 10 million tons annually in the Lower Colorado <br /> <br />River Basin adversely affect more than 17 million people and about 1 <br /> <br />million acres of irrigated farmland in the United States. Municipal and <br /> <br />industrial water users and irrigators experience estimated direct and <br /> <br />indirect annual economic losses of $450,000 (January 1980 prices) for <br /> <br />each increase of 1 mg/L in salinity at Imperial Dam. The salinity also <br /> <br />adversely affects water users in Mexico. <br /> <br />The losses associated with municipal and industrial use occur <br /> <br />primarily from increased water treatment costs, accelerated pipe corro- <br /> <br />sion and appliance wear, increased soap and detergent needs, and <br /> <br />decreased drinking water palatability. The Public Health Service recom- <br /> <br />mends that drinking water contain no more than 500 mg/L of total dis- <br /> <br />solved solids (TDS). For irrigators, high concentrations cause decreased <br /> <br />crop yields, altered crop patterns, increased leaching and drainage <br /> <br />requirements, and increased management costs. Agricultural losses <br /> <br />begin when salinity levels reach 700-850 mg/L, depending upon soil <br /> <br />conditions and the type of crop grown. <br /> <br />"\ ~ c' " <br />l:Ul O~~ <br /> <br />14 <br />