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<br />o <br />("0.1 <br />W <br />..... <br />. <br />N <br /> <br />Grand Jun~tion, Montrose, and <br />Glenwood Spri;ngs are the principal <br />towns in Colotado. Moab is the only <br />major community in Utah. <br />Mineral production is the predomi- <br />nant industry. This area is the <br />Nation's chief .source of molybdenum and <br />is a major sour:ce of vanadium, uranium, <br />lead, zinc, coal, and gilsonite. <br />In the Upper Main Stem reporting <br />area, as in that of the Green River, <br />agriculture centers around production <br />of livestock which feeds on irrigated <br />lands to complement the large areas of <br />rangeland. There is somewhat more <br />diversification of crops in the Upper <br />Main Stem, however, with some major <br />land areas devoted to corn; beans, <br />potatoes, table vegetables, and <br />fruit. This diversification is made <br />possible by climatic and topographic <br />conditions which create favorable air <br />drainage and .inimizefrost damage. <br />Irrigation cbnsumptive use accnuhts <br />for .over half' the wat'er use in the <br />Upper Main Stem. reporting area.' In an <br />average year 'a~out 550,000 acres of <br />land are irrigated. A considerable <br />amount (almost one-third of the total <br />basin use) of 'water is eKported to <br />serve agricultu~al and municipal needs <br />on the eastern s:lope of .the Continental <br />Divide in 'Colorado. <br /> <br />San Juan-Colo{ado: The San Juan <br />reporting area is drained by the <br />Colorauo River and its tributaries <br />below the mouth of the Green River and <br />above Lee Ferry,' Arizona.. The largest <br />of the tributary streams is the San <br />Juan River which heads on the western <br />slope of the Continental Divide in <br />southwestern Colorado. Principal <br />tributaries of the San Juan. River <br />are the Navajo, Los Pinos, Animas, and <br />La Pla'ta Rivers. The other main <br />tributaries in the basin are the <br />Dirty Devil, Kscalante, and Pari.a <br />Rivers which drain a portion of the <br />eastern slope of the Wasatch Plateau <br />in Utah. The reporting area includes <br />about 38,600 square miles in portions <br />of Utah, New Mexico, Arizona, and <br />Colorado. <br /> <br />The largest towns are Durango and <br />Cortez in Colorado; Monticello and <br />Blanding in Utah; and Farmington in New <br />Mexico. Page, near Glen Canyon Dam, is <br />the only community of significant size <br />in Arizona. Most of the remaining <br />Arizona portion is in the Navajo Indian <br />Reservation. <br />Mining and agriculture form the <br />economic base .for .the San Juan-Colorado <br />reporting area. The agricultural <br />development is similar to that of the <br />UPperMa~n Stem with most of the <br />cropland devoted to livestock feeds but <br />with production of diversified market <br />crops on lands with favorable air <br />drainage. The main market crops are <br />fruit, vegetables, and dry beans. <br />Oil, natural gas, .and coal are the <br />most important minerals produced. <br />Thermal elecric power production is <br />increasingly important to the economy <br />of the area. <br />Irrigation accounts for the largest <br />use of water, nearly 80 percent of the <br />San Juan reporting area use. About <br />250,000 acres of land are irrigated in <br />an average year. <br /> <br />Lower ColoradO River Basin <br /> <br />Mainstream below Lee Ferry, Arizona- <br />California-Nevada: The Colorado River <br />has a length of over 700 miles and a <br />drainage area of l32, 300 square miles <br />within 'the Lower Colorado River system <br />in the United States. The river flows <br />from Lee .Ferry to the headwaters of <br />Lake Mead through the spectacular <br />canyons of northern Arizona, including <br />the Grand Canyon. Diversions are made <br />at Lake Mead to the rapid ly expanding <br />North Las Vegas-LaS Vegas-Henderson- <br />Boulder City area for municipal and <br />industrial purposes. The river below <br />Lake Mead courses through canyons and <br />broad alluvial valleys interspersed <br />with bordering groups of moun~ains. <br />Lakes Mohave and Havasu provide flood <br />control and 'regulatory storage below <br />Lake Mead. Lake Havasu also provides a <br />.forebay for pumped export to the <br />Metropolitan Water District of Southern <br /> <br />6 <br />