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<br />to reduce salt discharges to the Colorado River by controlling salinity
<br />and erosJon from the Basin's irrigated lands and contributing water- .
<br />shed areas. The results of the study will be presented in a USDA report
<br />which will interface with U. S. Bureau of Reclamation reports on LaVerkin
<br />Springs, Littlefield Springs, and Las Ve~s Wash.
<br />
<br />III. GENERAL DESCRIPTION OF THE STUDY UNIT
<br />
<br />Physical
<br />
<br />Loca tion
<br />
<br />The Virgin River Unit, a part of the Colorado River Basin, comprises
<br />an area of 19,554 square miles in southwestern Utah, northwestern Arizona,
<br />and southern Nevada. Of the total area, 12,381 square miles lie in Nevada,
<br />2,846 square miles in Utah, and 4,327 square miles in Arizona. The Virgin
<br />River Unit as proposed in this report, consists of the pre-Lake Mead drain-
<br />age and includes Muddy River and its principal tributaries, Meadow Valley
<br />Wash and White River, and a small area immediately above the former con-
<br />fluence of the Virgin with the Colorado River that now drains directly into
<br />Lake Mead, It also inCludes Las Vegas Valley and the Lake Mead-Lower Colo-
<br />radv River Valleys in Nevada, and the north rim of the Grand Canyon in
<br />Arizona. Figure 1 shows the locations of the Subbasins, and Table 1 gives
<br />the areas by State and Subbasin.
<br />
<br />Table 1, Land Area by State and Subbasin, Virgin River Unit, Nevada, Utah
<br />and Arizona
<br />
<br /> Subbasin i Area by State - Square Miles Total I
<br /> , Nevada , Arizona i Utah I
<br />I Virgin River I , i
<br />! 1,834 I 2,002 , 2,846 6,682 i
<br />Muddy River i 1,757 I 0 0 1,757
<br /> ! , ;
<br /> White River 2,769 , 0 ; 0 2 769
<br /> ;
<br />
<br />Meadow Valley Wash I 2,386 0 , 0 2,386
<br />,
<br />Las Vegas Valley I 2,113 i 0 i 0 2,113 I
<br />Grand Canyon I 97 ! 2,325 I 0 2,422 J
<br /> i i I 1
<br />Lake Mead-Lower Colo. 1,425 0 I 0 1,425
<br /> i
<br />Total 12 , 381 4,327 2,846 i 19,554
<br /> I
<br />
<br />The Virgin River proper, draining an area of about 6,682 square miles,
<br />rises in the Pine Valley Mountains and Kolob Plateau in southwestern Utah
<br />at elevations approaching 10,000 feet, flows southwesterly across the
<br />northwestern corner of Arizona and empties into Lake Mead in Clark County,
<br />Nevada, at an elevation of about 1,200 feet.
<br />
<br />Muddy River comprises about 1,757 square miles, wholly within Nevada.
<br />Muddy River proper rises from springs in upper Moapa Valley and flows
<br />
<br />3
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