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<br />~ <br />~ <br />(. ;. <br />'r">i <br />c:~ <br />C.-) <br /> <br />Appendix 2. <br /> <br />THE SALINITY PROBLEM <br /> <br />Salt and the River <br /> <br />Nature and man are loading the Colorado River with salt* diminishing <br />the quality of water available for beneficial use. Flowing <br />through a basin which includes parts of seven states, the <br />Colorado River picks up mineral salts dissolved from geologic <br />formations, hot springs, and other sources. Farms, homes, <br />and industries withdraw water for use, increasing salt concentrations <br />in the remaining flow. Each use that takes water from and <br />returns it to the river adds new salts, increasing the salinity <br />problem. When the Colorado reaches Imperial Dam, 20 miles <br />north of the U.S.-Mexico border, its salinity level is 16 <br />times higher than at its source. <br /> <br />The river's total salt load fluctuates annually with the overall <br />basin's annual water supply (about 14 million acre-feet), <br />but an average 9 to 10 million tons of salt reach Hoover Dam <br />each year. Depending on the level of development, by the <br />year 2010, between 2.1 and 2.8 .illion tons of water-borne <br />salt--enough to cover 1 square mile to a depth of 1-1/2 feet--will <br />have to be removed from the river annually to meet Federal <br />water quality standards and protect the integrity of water <br />quality agreements with Mexico. <br /> <br />Currently, salt damage robs Colorado River Basin water users <br />of approximately $110 million yearly, with damages expected <br />to mount, without controls, to nearly $270 million (constant <br />1982 dollars) by 2010. Municipal and industrial water users <br />suffer an estimated 70 percent of the loss, with the remaining <br />30 percent borne by agricultural users. Every milligram per <br />liter (mg/L) increase in salinity at Imperial Dam is expected <br />to cause an additional half million dollars in damage each <br />year when salinity concentrations reach the 875 to 1225 mg/L <br />range. <br /> <br />Not reflected in economic terms are damages in Mexico nor <br />the subtle water changes that may adversely affect human and <br />animal health. <br /> <br />Without effective controls for the Colorado River, salinity <br />will soon reach unacceptable levels, preventing Basin States <br />from putting their water allotments to best use and endangering <br />the integrity of agreements with Mexico. <br /> <br />Legislation and Authority <br /> <br />The need for salinity control for the Colorado River has been <br />rec09nized and addressed in Federal legislation and in agreements <br />made pursuant to the international treaty. <br /> <br />*Total dissolved solids <br /> <br />39 <br />