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Physical Characteristics of the Colorado River:

The Colorado River rises in the mountains of Colorado and flows in a southwesterly direction for approximately 1,400 miles until it empties into the Gulf of California in Mexico. It falls some 12,000 feet in its course which provides its potential for power generation. The river flows through Colorado, Utah, and Arizona and along the Arizona-Nevada and Arizona-California boundaries and in the "limitrophe section"; i.e., the boundary between Arizona and Mexico. Significant amounts of water are added by tributaries, which originate in the State of Wyoming, Colorado, Utah, New Mexico, Nevada and Arizona but not in California. In the late 1800's and early 1900's, there was commercial navigation on the river.

The river and its tributaries drain portions of seven States: Wyoming, Colorado, Utah, New Mexico, Arizona, California and Nevada, or a vast area of approximately 242,000 square miles, about one-twelfth the area of the continental United States, excluding the States of Alaska and Hawaii. This large basin is approximately 900 miles long and 300 miles wide in the northern part and 500 miles wide in the southern part. Most of it is so arid that the viability of numerous communities in it is largely dependent upon the controlled and managed use of the Colorado River System and the availability of its water to make it productive and inhabitable. The upper portion is one of high elevations, narrow valleys, and a short growing season. The lower portion has lower elevations, wide basins and deserts, and a long growing season. While not a part of the natural drainage area, an additional area of 7,500 square miles, which includes the Imperial and Coachella Valleys in southern California, is considered to be a part of the Lower Colorado River Basin. Population within the drainage area is approximately 4 million but through water exports from the river and tributaries nearly 16 million people receive a supplemental water supply from the river.

A canyon section in northern Arizona and southern Utah permits a convenient division of the Colorado River Basin. As described in Article II of the Colorado River Compact of 1922, the Colorado River Basin is divided into the Upper Basin, where waters naturally drain into the Colorado River above Lee Ferry, and the Lower Basin, where waters drain into the Colorado River below Lee Ferry. Lee Ferry, the boundary between the Upper and Lower Basins, is in northern Arizona approximately 1 mile downstream from the Paria River or 17 miles below the Glen Canyon Dam.


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