Green River

The Green River is a 730-mile waterway flowing through Wyoming, Utah, and Colorado, and is the chief tributary of the Colorado River. It rises in the Wind River Range of western Wyoming, traverses the arid Colorado Plateau, and joins the Colorado at the Confluence within Canyonlands National Park, Utah. The Green's watershed encompasses approximately 48,100 square miles, with an average yearly mean flow of 6,121 cu ft/s (173.3 m3/s) at Green River, Utah. Along its course the Green cuts a sequence of spectacular canyons, including Flaming Gorge — now impounded by Flaming Gorge Dam, completed in 1963 — followed downstream by Desolation Canyon and Gray Canyon, which together extend roughly 120 mi (192 km) through the Tavaputs Plateau. The river varies widely in character, from 30–100 ft (9–30 m) wide in its upper course to 300–1,500 ft (91–457 m) wide in its lower reaches. Flaming Gorge Dam, in addition to creating Flaming Gorge Reservoir, supplies irrigation, mining, and hydroelectric infrastructure for the region. The dam's cold-water releases sustain the Green's tailwater trout fishery in northeastern Utah, while downstream of the Yampa confluence the river is critical habitat for four endangered native Colorado River fish (Colorado pikeminnow, humpback chub, bonytail, and razorback sucker).