Laserfiche WebLink
<br />PROBLEMS AND NEEDS <br /> <br />Problems and Needs Associated With Salt Loading <br /> <br />Agricultural, municipal and industrial water quality problems result <br />from excessive salts contained in the waters of the Colorado River. <br />Water of 500 milligrams-per-1iter (mg/l) total dissolved solids (TDS),' <br />or greater concentration can cause problems. Water in Lake Mead has <br />an average concentration of 680 mg/l. The salt concentration increases <br />downstream in the Colorado River. At Imperial Dam near Yuma, Arizona <br />the average concentration of salts in 1977 was 820 mg/l. Overall, <br />annual U. S. economic damages attributed to salinity are estimated at <br />$499,000 for each mg/l at Imperial Dam, based on 1980 prices)1 Additional <br />agricultural damages occur from use of river water in the Republic <br />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 subsurface <br />and ground water return flows. <br /> <br />Increasing salinity levels affect irrigated agriculture by (1) <br />limiting the kinds of crops that can be grown and (2) reducing crop <br />yields. Increases in the concentration of salinity affects municipali- <br />ties and industries by (1) requiring the use of water softeners and <br />reducing the effective life of water pipes, fixtures and water-using <br />appliances and (2) causing corrosion and scale formations in boilers and <br />cooling systems from calcium and magnesium. <br /> <br />Salts have built up in soils over the years because of inadequate <br />drainage, composition of parent material and inaitu weathering. This <br />results in reduced production on irrigated land in Virgin Valley. <br /> <br />Sources of Salts <br /> <br />Sources of salt are natural and man_induced. The man-induced salinity <br />in the Colorado River system is estimated at 53 percent of the total, <br />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 />Chemical composition of surface and ground water was previously <br />discussed in the Setting section (see Tables 5, 6 and 7). The water has <br />a high concentration of sulfate during low summer flows. The chemical <br />composition is unique within the Colorado River Basin (see Appendix A, <br />page A-12). <br /> <br />1/ <br /> <br />Adjustment to 1980 prices was made using the Consumer Price <br /> <br />000285 <br /> <br />Index. <br /> <br />27 <br />