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The Green River, located in the western United States, is the chief tributary of the Colorado River. The watershed of the river, known as the Green River Basin, covers parts of Wyoming, Utah, and Colorado. The Green River is long, beginning in the Wind River Mountains of Wyoming and flowing through Wyoming and Utah for most of its course, except for into western Colorado. Much of the route is through the Colorado Plateau and through some of the most spectacular canyons in the United States. It is only slightly smaller than the Colorado when the two rivers merge, but typically carries a larger load of silt. The average yearly mean flow of the river at Green River, Utah is per second.〔 The status of the Green River as a tributary of the Colorado River came about for mainly political reasons. In earlier nomenclature, the Colorado River began at its confluence with the Green River. Above the confluence the Colorado was called the Grand River. In 1921, Colorado U.S. Representative Edward T. Taylor petitioned the Congressional Committee on Interstate and Foreign Commerce to rename the Grand River as the Colorado River. On July 25, 1921 the name change was made official in House Joint Resolution 460 of the 66th Congress, over the objections of representatives from Wyoming and Utah and the United States Geological Survey which noted that the drainage basin of the Green River was more extensive than that of the Grand River,〔(Many years ago, the Colorado River was just Grand ), retrieved January 5, 2008.〕 although the Grand carried a higher volume of water at its confluence with the Green. ==Description== It rises in western Wyoming, in northern Sublette County, on the western side of the Continental Divide in the Bridger-Teton National Forest in the Wind River Range. It flows south through Sublette County and western Wyoming in an area known as the Upper Green River Valley, then southwest and is joined by the Big Sandy River in western Sweetwater County. At the town of La Barge, it flows into Fontenelle Reservoir, formed by Fontenelle Dam. Below there, it flows through open sage covered rolling prairie where it is crossed by the Oregon, California and Mormon emigration trails and then further south until it flows past the town of Green River and into the Flaming Gorge Reservoir in Southwestern Wyoming, formed by the Flaming Gorge Dam in northeastern Utah. Prior to the creation of the reservoir, the Blacks Fork joined the Green River south of Green River, today the mouth of Blacks Fork is submerged by the reservoir. South of the dam it flows eastward, looping around the eastern tip of the Uinta Mountains going from Utah into northwestern Colorado and through Browns Park before turning west and then south into Dinosaur National Monument where it passes through the Canyon of the Lodore (Otherwise known as the Gates of Lodore) and is joined by the Yampa River at Steamboat Rock. It turns westward back into Utah along the southern edge of the Uintas in Whirlpool Canyon. In Utah it meanders southwest across the Yampa Plateau and through the Uintah and Ouray Indian Reservation and the Ouray National Wildlife Refuge. Two miles south of Ouray, Utah, it is joined by Duchesne River, and three miles (5 km) downstream by the White River. Ten miles farther downstream it is joined by the Willow River. South of the plateau, it is joined by Nine Mile Creek, then enters the Roan Cliffs where it flows south through the back-to-back Desolation and Gray Canyons, with a combined length of 120 mi (192 km). In Gray Canyon, it is joined by the Price River. South of the canyon it passes the town of Green River, Utah and is joined by the San Rafael River in southern Emery County. In eastern Wayne County it meanders through Canyonlands National Park where it joins the Colorado. The Flaming Gorge Dam in Utah is a significant regional source of water for irrigation and mining, as well as for hydroelectric power. Begun in the 1950s and finished in 1963, it was highly controversial and opposed by conservationists. Originally, a dam was to be built in Whirlpool Canyon, but the conservationist movement traded the Flaming Gorge dam for halting that proposal. Apocryphally, the Sierra Club, a not-for-profit environmental organization, lost its tax-exempt status for political action in opposing the proposed dam. The Green is a large, deep, powerful river. It ranges from 100 to 300 feet (30 to 100 m) wide in the upper course to 300 to wide in its lower course and ranges from 3 to 50 feet (1 to 15 m) in depth. It is navigable by small craft throughout its course and by large motorboats upstream to Flaming Gorge Dam. Near the areas where the Oregon Trail crosses, the river is 400 - wide and averages about deep at normal flow. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Green River (Colorado River)」の詳細全文を読む スポンサード リンク
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