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<br />." <br /> <br />? <br /> <br />CHAPTER II <br /> <br />THE COLORADO RIVER BASIN <br />YESTERDAY AND TODAY <br /> <br />The Colorado River drains approximately 242,000 square miles in the southwestern United <br />States. It drains parts of seven states and two countries.17 <br /> <br />Its headwaters arise in the high Rocky Mountains, primarily in Colorado, Wyoming and Utah. <br />The river flows approximately 1,400 miles from the headwaters of the Green River above Pinedale, <br />Wyoming to its mouth in the Gulf of California. It is the second longest river in the Continental <br />United States. <br /> <br />Although considered one of the great rivers of North America, the flow as measured by the <br />natural discharge at its mouth is really quite modest. For example, both the Colorado River and the <br />Columbia River Basin drain an area of approximately 250,000 square miles. The average annual <br />natural discharge18 of the Columbia is 13 times that of the Colorado.19 In fact when compared with <br />other rivers based on natural discharge, the Colorado is slightly larger than the Hudson, but slightly <br />smaller than the Illinois River.20 <br /> <br />The reason is simple. The Colorado River is primarily a desert river. The basin itself averages <br />about 12" per year in precipitation. 21 Most of the runoff originates as snow in the high mountains that <br />rim the Basin, the San Juans, the central Colorado Rockies, the northern Colorado Rockies, the <br />Uintahs, the Wind River and Wyoming ranges. These mountains range in elevation from about <br />10,500' to over 14,000'. <br /> <br />17The total drainage area of the Colorado River Basin is 244,000 square miles. Of this, 242,000 square miles is in the United States <br />and 2,000 is in the Republic of Mexico. Many also believe the Salton Sink, comprised of the Imperial Valley, Salton Sea and <br />CoacheIla Valley is a natural or geologic part of the Colorado River Basin. Ifincluded, it would add another 7,800 square miles to <br />the Basin. See House Document 419, page 3 I. <br /> <br />- IIBy "natural discharge" I mean the flow ifit was unaffected by man. It is also sometimes referred to as a "virgin flow," <br /> <br />19pritz van der Leeden "Water Resources of the World, Selected Statistics," TABLE 5-72. <br /> <br />20 id. <br /> <br />2JHouse Document 419, page III-55. <br /> <br />Page -9- <br />