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<br />Study Reporting Areas
<br />
<br />o The estimated drainage area of the
<br />,') Colorado River System in the United
<br />~ States is about 242,000 square miles.
<br />. The river orig,inates in the Rocky
<br />'""" Mountains of Colorado and Wyoming,
<br />flows southwest about 1 ,400 miles, and
<br />terminates in the Gul f 0 f Cali fornia.
<br />The system consists of portions of
<br />seven States: Arizona, Cal i fornia,
<br />Colorado, New Mexico, Nevada, Utah, and
<br />Wyoming. The drainage area was divided
<br />into ten sub-basins for the purpose of
<br />this report.
<br />The major tributary streams selected
<br />as reporting are,as in the Upper Colo-
<br />rado River Basin are: Green River
<br />(Wyoming, Utah, Colorado); Upper Main
<br />Stem (Colorado, Utah); and San Juan-
<br />Colorado (Colorado, New Mexico, Utah,
<br />Arizona) .
<br />Six tributary areas in addition
<br />to the mainstream were selected in
<br />the Lower Colorado River Basin: Little
<br />Colorado River (Arizona, New Mexico);
<br />Virgin River (Utah, Arizona); Muddy
<br />River (Nevada); Bill Williams River
<br />(Arizona); Gila River (Arizona, New
<br />Mexico); and remaining areas in
<br />Arizona, Nevada and Utah.
<br />The outflow point and drainage area
<br />for each is sho.ro in Table C-l. The
<br />boundaries of the reporting areas are
<br />sho.ro on the frontispiece map. A brief
<br />description of each reporting area
<br />follows.
<br />
<br />Upper Colorado River Basin
<br />
<br />Green River W.omin -Colorado-Utah:
<br />T e Green R1ver report1ng area com-
<br />prises about 44',800 square miles in
<br />southwestern Wyoming, northwestern
<br />Colorado, and northeastern and east-
<br />central Utah.
<br />Principal tributaries of the Green
<br />River are Blacks Fork, Henry's Fork,
<br />Hams Fork, and Big Sandy Creek in
<br />southwestern Wyoming; Yampa and White
<br />
<br />Rivers on the western slope of the
<br />Continental Divide in northwestern
<br />Colorado; and the Price, Duchesne, and
<br />San Rafael Rivers in eastern Utah.
<br />These st reams are fed by numerous
<br />headwater lakes.
<br />The largest towns in the reporting
<br />area are Rock Springs and Green River
<br />in Wyoming; Vernal and Price in Utah;
<br />and Craig, Steamboat Springs, and
<br />Meeker in Colorado.
<br />Mineral production is the major
<br />industry. oil and natural gas are of
<br />primary importance, as are coal,
<br />gilsonite, asphalt, and trona (soda
<br />ash). Thermal electric power produc-
<br />tion is becoming an increasingly
<br />important industry.
<br />Agriculture ranks near mineral
<br />production in importance to the local
<br />economy. Agricul tural development is
<br />centered around livestock production,
<br />primarily beef cattle and sheep.
<br />Because of a short growing season,
<br />crop production is limited, largely to
<br />small grain, hay, and pasture. These
<br />crops are used as winter livestock
<br />feed and complement the vast areas of
<br />public grazing lands.
<br />Irrigation consumptive use accounts
<br />for about 75 percent of the total
<br />water use in the Green River reporting
<br />area. Nearly 670,000 acres of land
<br />are irrigated in an average year.
<br />Large exports of water are made 'to the
<br />Great Basin in Utah.
<br />
<br />Upper Main Stem, Colorado-Utah: The
<br />Upper Main Stem reporting area is
<br />drained by the Colorado River and its
<br />tributaries above the mouth of the
<br />Green River. Principal tributaries
<br />are the Roaring Fork, Gunnison, and
<br />the Dolores ~ivers. The Upper Main
<br />Stem reporting area consists of 26,200
<br />square miles, with about 85 percent of
<br />the area in Colorado and the remainder
<br />in Utah.
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