Green River Basin

Green River
Seeds-kee-dee-Agie
River
The Green River near Canyonlands National Park
Country	United States
States	Wyoming, Colorado, Utah
Border of drainage basin	W: Great Basin Divide E: Continental Divide of the Americas
Tributaries
- left	New Fork River, Blacks Fork
- right	Yampa River, White River
Cities	Green River, Wyoming, Green River, Utah
Source	Wind River Mountains
- coordinates	43°09′13″N 109°40′18″W / 43.15361°N 109.67167°W / 43.15361; -109.67167
Mouth	Colorado River
- location	Canyonlands National Park, San Juan County, Utah
- coordinates	38°11′21″N 109°53′07″W / 38.18917°N 109.88528°W / 38.18917; -109.88528Coordinates: 38°11′21″N 109°53′07″W / 38.18917°N 109.88528°W / 38.18917; -109.88528
Length	730 mi (1,175 km)
Basin	48,100 sq mi (124,578 km2)
Discharge	for Green River, Utah
- average	6,121 cu ft/s (173 m3/s)
- max	68,100 cu ft/s (1,928 m3/s)
- min	380 cu ft/s (11 m3/s)
Green River watershed

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 730 miles (1,170 km) long, beginning in the Wind River Mountains of Wyoming and flowing through Wyoming and Utah for most of its course, except for 40 miles (64 km) 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 6,121 cubic feet (173.3 m³) 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, although the Grand carried a higher volume of water at its confluence with the Green.