Document Type


Publication Date

January 1978


Rivers draining arid basins increase in salinity content in the downstream area to the point where water users are often significantly damaged. The problem in some cases can be ameliorated by altering upstream water and land use practices. An economic trade off exists between the cost of such upstream efforts and the downstream benefits achieved. This report examines options for salinity management in the Colorado River Basin. The study sought to provide additional information to estimate 1) economic damages caused by various salt concentrations to agricultural and municipal water users and 2) economic costs of salinity control measures by upstream water users. Damages were estimated for high salinity levels to provide guidelines to project future conditions. Control costs were estimated with a physical model developed to predict the response of soil, water, and crop factors. Input-output models were used to estimate indirect economic impacts. Agricultural damages for each milligram per liter of salt concentration at Imperial Dam in the 900 to 1400 range were estimated to be #33,100 annually. Of the total, $28,200 are in the Imperial Valley and decreasing g amounts occur respectively in the Palo Verde, Yuma, Colorado River Indian Reservation, Sand Diego, Coachella, and Central Arizona and $11,400 for the $112,000 per mg/1. Comparable estimates were $11,200 for Central Arizona and $11,400 for the Las Vegas area. As for controlled costs, 80 percent of the initial salt load could theoretically be at an incremental cost of less than $2.20 per ton. The comparison of the reduction measures showed on-farm practices to be the last expensive alternative for reducing salinity. Based on an approximation that 1 mg/1 at Imperial Dam is equivalent to 10,000 tons of salt, the above estimated benefits of salinity reduction would be about $17 per ton. Salinity control projects at Paradox Valley and acreage retirements in the Grand and Uncompaghre Valleys were found to be economically justified but lining the Grand Valley Canal was not. The above estimates are approximations obtained from available data and can be improved by further studies to cover additional cost and benefit effects or by more comprehensive data the effects covered.