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Show XII-54 UPDATING THE HOOVER DAM DOCUMENTS the area. Agriculture is concentrated along the mainstream in the upper reaches of the river, on Silver Creek-a southern tributary-and on the Zuni River in New Mexico. Current irrigated acreage is estimated to be about 32,000; however, it is subject to variation because of frequent water shortages and inadequate storage facilities. Population is predominantly rural with a relatively large Indian segment. Principal cities include Flagstaff, Winslow, and Holbrook in Arizona, and Gallup and Zuni Pueblo in New Mexico. Leading industries include tourism, recreation, manufacturing, mining, and forest products. Virgin River, Arizona-Utah: The Virgin River rises in western Kane County, Utah; flows southwesterly through the northwestern corner of Arizona; and empties into the northern extremity of the Overton Arm of Lake Mead in Virginia. The selected outflow point, the long-term Geological Survey gaging station at Littlefield, Ariz., is about 36 miles upstream from Lake Mead and about 10 miles above the Arizona-Nevada State line. The river is fed chiefly from tributaries heading in the southern high plateaus and mountains in Utah. Several springs contribute water to the river at a relatively uniform rate. The most significant of these springs are located near LaVerkin, Utah, and Littlefield, Ariz. Both springs are highly saline. Agricultural and municipal developments in Nevada below the selected outflow point are included in "remaining areas," as shown on the frontispiece map. Ground water has been developed to a limited degree. The major irrigated areas are located in the LaVerkin-Hurricane-Santa Clara areas of Washington County, Utah, and in the Littlefield area of Mohave County, Ariz. There are small irrigated areas scattered throughout. Present irrigated area is estimated to be about 28,000 acres. Population is predominantly rural. St. George, Utah, is the principal city in the basin. Zion National Park, located near Springdale, Utah, attracts many visitors each year. Muddy River, Nevada: The Muddy River, formerly a tributary of the Virgin River prior to the existence of Lake Mead, rises in the warm springs area of Clark County, Nev., about 10 miles northwest of Glendaie. The river flows southeasterly for about 30 miles, and terminates at the northern extremity of the Over-ton Arm of Lake Mead. Meadow Valley Wash, the major tributary of Muddy River, rises in northeastern Lincoln County and flows south to join the parent stream at Glendaie. The Geological Survey gaging station near Glendaie is about 2.4 miles downstream from Meadow Valley Wash. Outflow varies little from year to year. Meadow Valley Wash, although perennial in the vicinity of Caliente, is normally dry in the last 50-mile reach above Glendaie. Estimated irrigated acreage is about 8,900 acres located in the springs area and scattered throughout the upper reaches of Meadow Valley Wash. The entire basin is sparsely populated. Bill Williams River, Arizona: The Bill Williams River is formed by the mergence of the Big Sandy and Santa Maria Rivers about 7.5 miles above existing Alamp Dam. The river above Alamo Dam drains an area of about 4,700 square miles from small, rough mountain ranges and intervening valleys in parts of Mohave, Yuma, and Yavapai Counties. Alamo Dam and Reservoir, a flood control structure completed in 1968, was built to protect downstream development along the Colorado River. A minimum pool is maintained for recreation and game management purposes. Releases from Alamo Dam and runoff from the intervening area flow westerly and join the Colorado River at the lower end of Lake Havasu. Estimated irrigated acreage is about 4,500 acres with most crops grown to supplement feed for livestock. The limited development in the basin is dominated by copper mining at the unincorporated town of Bagdad, present population about 2,000. A large portion of the water supply in the basin is obtained from ground-water pumpage. Releases from Alamo Dam during the 1971-75 period varied from 1,500 acre-feet in 1975 to 162,500 acre-feet in 1973. Gila River, Arizona-New Mexico: The Gila River is the largest tributary to the Colorado River in the Lower Colorado River system. The drainage 8 |
