WSP10254 - Laserfiche WebLink

Home Browse Search

(C) ,.:') ~ ,;' ..~ ~ , '. . c: AQUATRAIN April 1983 Section 4. THE SALINITY PROBLEM Salt and the River Nature and man are loading the Colorado River with salt* du-inishing the quantity and quality of vater available for beneficial use. Flowing through a basin which includes parts of seven states, the Colorado River picks up mineral salts dissolved from geologic formations, hot springs, and other sources. Farms, homes, and industries withdraw water for use which increases salt concentrations in the remaining flow. Each water use that takes water from and returns it to the river adds to the salinity problem. When the Colorado reaches Imperial Darn, 20 miles north of the U.S.-Mexico border, its salinity level is 16 times higher than at its source. The river's total salt load fluctuates annually with the overall basin's annual water supply (about 14 million acre-feet), but an average 9 to 10 million tons of salt reach Hoover Darn each year. By the year 2010, between 2.1 and 2.8 Ilillion tons of vater-borne salt -- enough to cover 1 square mile to a depth of 1-1/2 feet -- will have to be removed from the river annually to meet Federal water quality standards und protect water quality agreements with Mexico. Currently, salt damage robs Colorado River Basin water users of approxi- mately $110 Ilillion yearly, with damages expected to mount, without controls, to nearly $270 million (constant 1982 dollars) by 2010. Municipal and industrial water users suffer an estimated 70 percent of the loss, with the remaining 30 percent borne by agricultural users. Every milligram per liter (rng/L) increase in salinity at Imperial Darn causes an additional half million dollars in damage each year. Not reflected in economic terms are damages in Mexico nor the significant losses to the environment and society as salinity harms valuable fish and wildlife habitats and may adversely affect human health. Without effective controls for the Colorado River, salinity will soon reach unacceptable levels, preventing Basin States from putting their water allotments to best use and endangering the integrity of agreements with Mexico. Legislation and Authority The need for salinity control for the Colorado River has been recognized and addressed in Federal legislation and in agreements made pursuant to the international treaty. The AQUATRAIN Project takes its objective of controlling salinity from the 1974 Colorado River Basin Salinity Control Act (Public Law 93-320). *Total dissolved solids 13