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<br />W <br />-.J <br />N <br />OJ <br /> <br />The Colorado River Compact apportioned 7.5 million acre-feet of the <br />water annually from the Colorado River system to each of the Upper and <br />Lower Basins in perpetuity for exclusive beneficial consumptive use. In <br />addition to the apportionment of 7.5 million acre-feet, the Lower Basin <br />is given the right to increase its beneficial consumptive use of water <br />from the Colorado River system up to 1 million acre-feet annually. The <br />compact further provides that the States of the Upper Basin will not <br />cause the flow of the river at Lee Ferry to be depleted below an <br />aggregate of 75 million acre-feet for any period of 10 consecutive <br />years. The treaty with Mexico, signed in 1944, provided for the annual <br />guaranteed delivery by the United States of 1.5 million acre-feet of <br />Colorado River water to Mexico. <br /> <br />With the water allocated to the Upper Basin by the Colorado River <br />Compact and with the 1944 Mexican Treaty signed, the Upper Basin States <br />began negotiations which resulted in the signing of the Upper Colorado <br />River Basin Compact in 1948. Under the terms of this compact, Arizona <br />is permitted to use 50,000 acre-feet of water annually from the Upper <br />Colorado River system, and the remaining water is apportioned to the <br />other Upper Basin States as follows: <br /> <br />State of Colorado <br />State of New Mexico <br />State of Utah <br />State of Wyoming <br /> <br />2. Topography <br /> <br />The Upper Basin is comprised of highly dissected mountainous plateaus <br />typified by deep canyons, mesas, river valleys, and rolling hills. <br />The Basin is bounded by mountains studded with high, rugged peaks with <br />elevations ranging from 3100 feet at Lee Ferry to more than 14,000 feet <br />at some of the higher mountain peaks. The landscape has been scoured <br />and eroded by rivers and streams, augmented to some extent by glaciation <br />and winds. Stream erosion, as the principal weathering agent, has <br />produced cuts where various rock layers of all ages are exposed. <br /> <br />51. 75 percent <br />11.25 percent <br />23.00 percent <br />14.00 percent <br /> <br />The Lower Basin is composed of a complex of plateaus, mountains, canyons, <br />deserts, and plains with elevations ranging from 75 feet above sea level <br />near Yuma, Arizona, to over 12,600 feet above sea level at Humphreys Peak <br />near Flagstaff, Arizona. <br /> <br />3. Geology <br /> <br />Geologic formations in the Upper Basin range in age from Recent to <br />Precambrian. The dramatic erosional features, together with the bril- <br />liant colors of the formations, have been the basis for designating <br />several national parks and monuments. The southern Rocky Mountains in <br />Colorado are impressive from both a scenic and geologic viewpoint. <br />Regional uplifting and other forces have exposed an assortment of <br />igneous and metamorphic rocks which are among the oldest known. <br /> <br />11-2 <br />