Green River. 1 River, 370 mi (595 km) long, rising in central Ky. and flowing generally NW, through Mammoth Cave National Park, to the Ohio River near Evansville, Ind. Locks and dams make the Green River navigable upstream to the park. 2 River, 730 mi (1,175 km) long, rising near the Continental Divide, W Wyo., and flowing generally S through W Wyo., NW Colo., and E Utah to the Colorado River in Canyonlands National Park, SE Utah; it is the largest tributary of the Colorado. Most of its course flows through deep canyons, including Canyon of the Lodore in Dinosaur National Monument (see National Parks and Monuments, table). The White, Yampa, and San Rafael rivers are its main tributaries. The Colorado River storage project of the U.S. Bureau of Reclamation has extensively developed the Green River basin for irrigation, mining, and hydroelectric power; Flaming Gorge Dam, NE Utah, is the major unit in this project.