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Show XII-52 UPDATING THE HOOVER DAM DOCUMENTS 109,600 square miles are above Lee Ferry. The river rises in the Rocky Mountains of Colorado and Wyoming, flows southwest about 1,400 miles, and terminates in the Gulf of California. The system consists of portions of seven States: California, Colorado, New Mexico, Nevada, Utah, Wyoming, and nearly all of Arizona. The drainage area was divided into ten reporting areas: three above Lee Ferry; the Lower Colorado River mainstream; and six tributary areas draining to the mainstream below Lee Ferry (see general location map). A brief description of the reporting areas follows. UPPER COLORADO RIVER Green River: The Green River reporting area comprises about 44,800 square miles in southwestern Wyoming, northwestern Colorado, and northeastern and east-central Utah. Principal tributaries of the Green River are Blacks Fork, Henry's Fork, Hams Fork and Big Sandy Creek in southwestern Wyoming; Yampa and White Rivers on the western slope of the Continental Divide in northwestern Colorado; and the Price, Duchesne, and San Rafael Rivers in eastern Utah. These streams are fed by numerous headwater lakes. The largest towns in the reporting area are Rock Springs and Green River in Wyoming; Vernal and Price in Utah; and Craig, Steamboat Springs, and Meeker in Colorado. Mineral production is the major industry. Oil and natural gas are of primary importance, as are coal, gilsonite, asphalt, and trona (soda ash). Thermal electric power production is becoming an increasingly important industry. Agriculture ranks near mineral production in importance to the local economy. Agricultural development is centered around livestock production, primarily beef cattle and sheep. Because of a short growing season, crop production is limited largely to small grain, hay, and pasture. These crops are used as winter livestock feed and complement the vast areas of public grazing lands. Irrigation consumptive use accounts for nearly 80 percent of the total water use in the Green River reporting area. Nearly 690,000 acres of land are irrigated in an average year. Large exports of water are made to the Great Basin in Utah. Upper Main Stem: The Upper Main Stem reporting area is drained by the Colorado River and its tributaries above the mouth of the Green River. Principal tributaries are the Roaring Fork, Gunnison, and Dolores Rivers. The Upper Main Stem reporting area consists of 26,200 square miles, with about 85 percent of the area in Colorado and the remainder m Utah. Grand Junction, Montrose, and Glenwood Springs are the principal towns in Colorado. Moab is the only major community in Utah. Mineral production is the predominant industry. This area is the Nation's chief source of molybdenum and is a major source of vanadium, uranium, lead, zinc, coal, and gilsonite. In the Upper Main Stem reporting area, as in that of the Green River, agriculture centers around production of livestock which feeds on irrigated lands to complement the large areas of rangeland. There is somewhat more diversification of crops in the Upper Main Stem, however, wfth some major land areas devoted to sugar beets, beans, potatoes, table vegetables, and fruit. This diversification is made possible by climatic and topographic conditions which create favorable air drainage and minimize frost damage. Irrigation consumptive use accounts for over half the water use in the Upper Main Stem reporting area. In an average year nearly 550,000 acres of land are irrigated. A considerable amount (almost one-third of the total basin use) of water is exported to serve agricultural and municipal needs on the eastern slope of the Continental Divide in Colorado. San Juan-Colorado: The San Juan-Colorado reporting area is drained by the Colorado River and its tributaries below the mouth of the Green River and above Lee Ferry, Arizona. The largest of the tributary streams is the San Juan River which heads on the western slope of the Continental Divide in southwestern Colorado. Principal tributaries of the San |