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<br />III. ENVIRONMENTAL CONSEQUENCES <br /> <br />A. Description of the Physical Environment <br /> <br />The Colorado River Basin encompasses a rich array of the most diverse <br />aesthet i c and product i ve resources in the Un ited States. The seven Bas i n <br />States are Wyoming~ Utah~ Colorado~ Nevada~ New Mexico~ Arizona~ and <br />California. However~ the productivity of the Basin's lands is tempered and <br />controlled by its arid and semi arid climate. For all practical purposes, <br />water resources development has dictated the future of the Basin since the <br />turn of the century. A 1979 report by the Comptroller General describes <br />the Basin succinctly. <br /> <br />"The Colorado River originates in the Rocky Mountains of Colorado and <br />Wyoming, flows southwest about 1,400 miles, and empties into the Gulf <br />of California. It drains an area of 242,000 square miles in seven <br />States, which represents one-twelfth of the area of the United States~ <br />excluding Alaska. The basin has climatic extremes of year-round snow <br />cover and heavy precipitat'ion on the high peaks of the Rockies and <br />desert conditions with very low precipitation in southeast California <br />and southwest Arizona. The Colorado River is controlled by several <br />dams and reservoirs. The Glen Canyon Dam and Lake Powell store most <br />of the Upper Bas in I s water and contro 1 releases to the Lower Bas in. <br />The Hoover Dam and Lake Mead store most of the Lower Basin IS suppl y <br />and control the amount of water released to Lower Basin users."[4] <br /> <br />Review of the alternatives by project scientists indicates the San Juan <br />Mountains may be the scientifically desirable location to initiate the <br />Colorado River Basin Augmentation Demonstration proposal. The Upper <br />Colorado Region Comprehensive Framework Study describes the area as <br />fo 11 ows : <br /> <br />"The main tributary of the Colorado River in the subregion is the San <br />Juan River, second largest tributary in the Colorado system. The San <br />Juan heads on the western slope of the Continental Di vi de in south- <br />western Colorado and enters the main stream about 80 miles upstream <br />from Lee Ferry. Three small rivers, Dirty Devil~ Escalante, and <br />Paria, drain the eastern side of the Wasatch Plateau in Utah and join <br />the Colorado from the west. <br /> <br />"The 1 argest towns of the subregi on are Durango and Cortez in <br />Colorado, Monticello and Blanding in Utah, and Farmington in New <br />Mexico. Page at Glen Canyon Dam is the only community of significant <br />size in the Arizona portion of the subregion. Most of the remaining <br />Arizona portion is in the Navajo Indian Reservation. <br /> <br />"The subregion is served by U.S. Highways 84, 89~ 160~ 164~ 550~ and <br />666 and by an extens i ve system of State hi ghways and secondary roads. <br />The subregion has no interstate highways at present, but Interstate <br />70~ when completed~ will traverse the headwaters of the Dirty Devil <br />River. Service by the narrow-gage branch line of the Denver & Rio <br />Grande Western Railroad in the western part of the subregion in <br />Colorado and New Mexico has now been largely discontinued. <br /> <br />7 <br />