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<br />PROBLEMS AND NEEDS <br /> <br />Problems and Needs Associated With Salt Loading <br /> <br />Agricultural, municipal and industrial problems result from excessive <br />salts contained in the waters of the Colorado River System. Water of <br />500 milligrams per liter (mgjl) total dissolved solids (TDS), or greater. <br />con(entration can cause problems. Water in Lake Mead has an average <br />concentration of 680 mgj1. The salt concentration increases downstream. <br />in 1 :'fl Colorado River. At Imperial Dam near Yuma, Arizona the average <br />conc(jltration of salts in 1977 was 820 mgjl. Overall, annual economic <br />dal1K;;es attributed to salinity are estimated at $499,000 for each mg/l <br />at !~,lperia1 Dam, based on 1980 prices. Additional agricultural and other <br />dal1K\jes occur in the Republic of Mexico below Imperial Dam. <br /> <br />Irrigation in the Colorado River Basin increases the rate at which <br />soluble salts are removed from soil and underlying aquifer by surface and <br />ground water flows. <br /> <br />Salinity affects irrigated agriculture by (1) limiting the types <br />of crops grown and (2) reducing crop yields. Salinity affects municipali- <br />ties and industries by (1) requiring the use of water softeners and reducing <br />the effective life of water pipes, fixtures and water-using appliances and <br />(2) causing corrosion and scale formations in boilers and cooling systems <br />from calcium and magnesium. <br /> <br />Agricultural production in Moapa Valley that has either been eliminated <br />or significantly reduced by excessive accumulation of salts is estimated <br />to exceed five percent of the total irrigated cropland. Salts have built <br />up in sons over the years because of inadequate drainage, composition of <br />parent material and insitu weathering. <br /> <br />Sources and Kinds of Salts <br /> <br />.Sources of salt are natural and man-induced. The man-induced <br />salinity in the Colorado River system is estimated at 53 percent of <br />the total, distributed as follows: <br /> <br />37% Irrigation <br />12% Reservoir evaporation <br />3% Exports <br />1% Municipal and industrial <br />53% Total man-induced salinity <br /> <br />About 33 percent of the salt load of Muddy River is man-induced. <br />This is distributed as follows: <br /> <br />31% Irrigation and evaporation from <br />reservoirs and distribution systems <br />2% Man accelerated erosion <br />33% Total man-induced salt load <br /> <br />0027'J4 <br /> <br />24 <br /> <br />... <br />