2003 - Laserfiche WebLink

Home Browse Search

PART III CAUSES AND IMPACTS OF SALINITY e fisheries and warm water endemic or endangered species naturally are in conflict. [2] In addition to downstream effects, the depth of withdrawal in reservoirs has become a significant issue concerning the productivity of reservoir fisheries, eutrophication, nutrient retention, salinity routing, esthetics, and evaporation.[3] At present, there are concerns about evaporation, temperature, and nutrient processes in Fontenelle and Flaming Gorge Reservoirs, Lake Powell, and Lake Mead. 2. Economic , In the Lower Basin, present peak TDS concentrations are ap- proaching critical levels for some salt sensitive crops. While the water is suitable for irrigating most crops, TDS concentrations are high enough that special irrigation practices are used in some cases. At the present time, TDS concentrations are being maintained below the stand- ards. Complete development of apportioned water by the States will result in increases in TDS that would be more detrimental to agriculture without salinity control measures. e A consortium of water resources centers in the States of Arizona, California, Colorado, and Utah cooperated in a study funded by the Office of Water Research and Technology and the Bureau of Reclamation to assess the economic damages caused by various salt concentrations to agricultural and municipal water users. This study is documented in a report, Salinity Management Options for the Colorado River, Water Re- sources Planning Series Report P-78-003, June 1978.[4] Based upon the findings of that report, Reclamation has pub- lished a summary working document entitled, Colorado River Salinity-- Economic Impacts on Agricultural, Municipal, and Industrial Users. [5] The estimated future annual damages to the Lower Basin water users in 1976 dollars were $343,000 for each 1 mg/L increase in TDS at Imperial Dam when concentrations reach the range of 875 mg/L to 1,225 mg/L. The damage figure is approximately $561,000 per mg/L in 1984 dollars. These annual damages were calculated using the 1972 salinity standard of 879 mg/L (approved by EPA in 1975) and a projected full development salinity concentration of 1,225 mg/L at Imperial Dam. The annual municipal damages are divided as follows: Metro- politan Water District, 54 percent; Central Arizona Project, 8 percent; and lower main stem users, 8 percent. Total agriculture annual damages are 30 percent. Industrial impairments and Upper Basin damages were not evaluated. e 15