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Show CHAPTER B - DESCRIPTION OF THE REGION GENERAL The Lower Colorado Region, with a total area of 1^1,137 square miles, embraces 106,982 square miles of Arizona, 13>355 square miles of New Mexico, 17,310 square miles of Nevada, and 3,^90 square miles of Utah. Excluding a portion in southern California, the Region is hydro- logically defined by the drainage area of the Colorado River in the United States below Lee Ferry, near Glen Canyon Dam. In addition, it includes several closed basins in Arizona, New Mexico, and Nevada, and some areas in Arizona and New Mexico that drain into Mexico, Areawise, the Region represents about k,Q percent of the contiguous United States and about 7«1 percent of the area west of the Mississippi River. Three major drainage areas divide the Region into subregions: Subregion 1, Lower Main Stem, 56,55*+ square miles; Subregion 2, Little Colorado, 26,977 square miles; and Subregion 3, Gila, 57,606 square miles. The Region was among the earliest to be explored by Europeans, yet, until around 1900, settlement was slow and did not really gather momentum until the modern technologies for pumping ground water and regulating streamflows were perfected and put to use. Dominant influences on the socio-economic growth of the Region have been the availability of land suitable for many uses, the rich mineral resource, and the very attractive mixture of scenery and cli- mate; the primary limiting influence has been the inadequate and poorly distributed water supply. Early enterprise was principally centered around mining such metals as copper, gold, and silver. Then, with improved water production and. management, irrigated agriculture came into equal prominence. More recently, light industries have grown into major economic importance and presently contribute nearly twice the combined dollar value of the? mining and agriculture sectors. Parts of the Region have become meccas for retirement, recreation., and entertainment which have boosted the regional noncommodity dollar output to more than the combined amount from all other regional economic sectors. |