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Show APPENDIX XII 1203 REGIONAL PROBLEMS AND ISSUES XII-25 There are a number of critical problems and issues in the 11 Western States that, while not Westwide in scope, do involve two or more States or a major river basin. These have been classified as regional problems, of which nine have been identified. Four of these are centered in the Colorado River Basin and involve Colorado River salinity, Colorado River water supply, lower Colorado River management, and oil shale development in the Upper Colorado River Basin. Four occur in the Columbia River Basin and involve total water management of the Columbia River system, the Columbia River estuary, the Middle Snake River Canyon controversy, and erosion in the Palouse area. The ninth regional problem pertains to anadromous fisheries in the Pacific Northwest. Colorado River Salinity.-As the waters of the Colorado River are put to consumptive use, the remaining waters are becoming progressively more saline, particularly in the lower reaches of the river. The concentrations of dissolved solids in the lower mainstream are already approaching the threshold limits for some uses. The primary agricultural impacts of increasing salinity will be in the Imperial, Coach-ella, Gila, and Yuma Valleys where a wide diversity of crops is produced. Adverse effects will also be experienced in Mexico. The primary impacts on municipal and industrial water supply will affect the Metropolitan Water District of southern California, the Las Vegas service area, and upon completion of the Central Arizona project the Phoenix and Tucson metropolitan areas. The adverse effects of increasing salinity are primarily economic in character and confined to the consumptive uses of water. Instream uses of water for hydroelectric power production, for recreation, for fish and wildlife, and for overall environmental purposes will not be significantly affected. Recent studies by the Bureau of Reclamation estimated total annual direct and indirect economic losses of about $230,000 for each part per million of future increase in salinity of the Colorado River at Imperial Dam. Taking as a base the acceptable salinity levels of 500 p/m for municipal and industrial supplies and 750 p/m for agricultural use, the total damages attributable to salinity in the Colorado River system for 1973 were about $53 million. By the year 2000 these damages to the total regional economy are expected to reach $124 million per year if no control measures are applied. The 1972 Joint Federal-State Enforcement Conference on the matter of pollution of the interstate water of the Colorado River and its tributaries initiated new efforts to establish an overall salinity control policy for the river. The seven basin State conferees and Federal representatives concluded that such a policy should have as its objective the maintenance of salinity concentration at or below levels found in the lower main stem while the upper basin continues to develop its compact apportioned water. The 1972 Federal Water Pollution Control Act Amendments have been interpreted by the Environmental Protection Agency to require the establishment of numerical salinity standards on the Colorado River. Another related matter that highlights the need for basinwide salinity controls is a recently executed agreement with Mexico to resolve the international salinity problem with Mexico. Under that agreement, water delivered to Mexico shall have an average annual salinity of no more than 115 p/m (plus or minus 30 p/m) over the average annual salinity of waters arriving at Imperial Dam. Adequate studies have not been completed to identify accurately the quantitative contribution of salinity concentrations from various sources in the basin, but the order of magnitude is (1) natural sources, (2) irrigation sources, (3) reservoir evaporation, (4) out-of-basin export, and (5) municipal and industrial sources. Solutions to the salinity problems on the Colorado River will result from the cooperative efforts of all involved Federal, State, and local agencies and organizations. The primary study effort under way at this 35 |