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<br />II. SETTING
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<br />A. Location
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<br />The Colorado River Basin in the southwestern United States covers an area
<br />of 254,000 square miles, about one-twelfth of the continental United
<br />States. The Basin includes parts of seven States: Arizona, California,
<br />Colorado, N~vada, New Mexico, Utah, and Wyoming. The Colorado River
<br />extends 1,400 miles from the Continental Divide in the Rocky Mountains of
<br />north-central Colorado to the Gulf of California.
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<br />The Colorado River Compact of November 1922 divided the Colorado River
<br />Basin within the United States into two parts, the Upper Basin and the
<br />Lower Basin; These basins are separated at a point on the river in
<br />,northern Arizona known as Lee Ferry, 1 river mile below the confluence of
<br />the Paria and the Colorado Rivers and 17 miles downstream from Glen Canyon
<br />Dam. (Lee Ferry is not to be confused with Lees Ferry, the site of the
<br />gaging station just above the Paria River.)
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<br />The Upper B~sin encompasses about 45 percent of the drainage area of the
<br />Colorado River Basin, an area of over 113,000 square miles. The Basin is
<br />on the west side of the Continental Divide and includes parts of Arizona,
<br />Colorado, New Mexico, Utah, and Wyoming. The Basin is bounded on the east
<br />and north by mountains forming the Continental Oivide and on the west by
<br />the Wasatcn,Mountains. On the south, it opens to the Lower Basin at Lee
<br />Ferry in northern Arizona.
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<br />The Lower Basin, with an area of over 141,000 square miles, embraces parts
<br />of Arizona,:New Mexico, Nevada, Utah, and California. It includes several
<br />closed basins in Arizona, New Mexico, and Nevada and some areas in Arizona
<br />and New Mexico that drain into Mexico.
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<br />B. Natural :Environmental Characteristics
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<br />The Colorado River Basin is composed of a complex of rugged mountains, high
<br />plateaus, deep canyons, deserts, and plains. Principal physical character-
<br />istics of the region are its variety of landforms, topography, and geology.
<br />The Colorado River flow begins high on the Continental Divide at elevations
<br />of over 14,QOO feet and flows generally southwestward, leaving the United
<br />States at an elevation of about 75 feet above sea level.
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<br />1. Water Supply
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<br />The Colorado River begins where peaks rise more than 14,000 feet high
<br />in the northwest portion of the Colorado Rocky Mountain National Park,
<br />70 miles ,northwest of Denver. It continues southwest for 640 miles
<br />through the Upper Basin to Lee Ferry. The natural drainage area
<br />of the Colorado River below Lee Ferry and above Imperial Dam is about
<br />75,100 square miles. Southwest of the Gila Basin, the Colorado River
<br />continues through its delta area to the Gulf of California in Mexico.
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