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<br />0[2294 <br /> <br />. <br /> <br />8/6/90 <br /> <br />SALINI1Y CONTROL PROGRAM <br /> <br />The Problem <br /> <br />. <br /> <br />The salinity concentration in the Colorado River fluctuates annually with the overall <br />Basin water supply. At its headwaters in the mountains of north-central Colorado, it has <br />a salinity (total dissolved solids) concentration of only about 50 mg/L (milligrams per <br />liter). The salinity concentration progressively increases as the river flows downstream <br />as a result of water diversion, evaporation from reservoirs, and salt contributions from a <br />variety of sources. Historically salinity levels at Imperial Dam range from an annual <br />average of 826 mg/L in 1982 to 621 mg/L (provisional) in 1987 (when record-high flows <br />flushed and filled the major reservoirs, resulting in significantly lower salinity levels at <br />Imperial Dam). Without control measures, however, the concentration is projected to <br />increase, following the overall rising trend, possibly reaching a level of 966 mg/L at <br />Imperial Dam by 2010. A total salt load of about 9 million tons annually entering Lake <br />Mead in the Lower Colorado River Basin adversely affects more than 18 million people <br />and more than 1 million acres of irrigated farmland in the United States. The salt load <br />results in approximately $311 million of damage annually to Basin water users. The <br />losses associated with municipal and industrial use sector occur primarily from increased <br />water treatment costs, accelerated pipe deterioration and appliance wear, automotive <br />radiators, increased soap and detergent needs, and decreased water palatability. <br />According to the Environmental Protection Agency (EP A), the recommended secondary' <br />standard for public drinking water should contain no more than 500 mg/L of IDS. <br /> <br />For irrigators, the higher salinity concentrations cause lower crop yields, altered crop <br />patterns, higher leaching and drainage requirements, and higher management costs. . <br />Agricultural losses (either through lower yields or higher production/manageineut.costs) <br />begin when salinity levels of applied irrigation water reach 700 to 850 mg/L, depending <br />upon soil conditions and type of crop grown.;, <br /> <br />In the late 1960's and early 1970's, leaders at the regional and national levels began to <br />recognize the total problem and to seek comprehensive solutions. ' ' <br /> <br />'" ..... <br /> <br />The Solution <br /> <br />. <br /> <br />In 1972, an amendment to the Federal Watet Pollution Control Act, Public LawJ2-500' , <br />(now known commonly as the Clean Water Act), sets forth a public policy~embracing' ~. ' <br />the restoration and maintenance of water quality, pollution effluent discharge', Ii~tation, <br />and eventual zero pollution discharge. EPA interpreted the Act to require'w~ter.quality _ <br />standards, including beneficial use designations, numeric salinity criteria, and:aplan of <br />implementation for the Colorado River. Numeric criteria. were subseq~ently established ~. -. <br />at three stations by the Coloratlo River Basin, Salinity Control Forum (Forum):. The <br />criteria and a plan of implementation were adopted by each of the Bas.UF'State~ aqd <br />.~ ~ .<;~::. .- <br />'-'! :' "':'" ~. f :~. <br /> <br />1 <br /> <br />\ <br />