The Green River flows 730 miles from Wyoming's Wind River Range through Utah and into Colorado, ultimately joining the Colorado River. This major tributary carves through diverse landscapes including high mountain valleys, dramatic canyons, and desert terrain across multiple counties in three states. The river's character changes dramatically along its course, from cold mountain freestone waters in Wyoming's Sublette County near Pinedale to the tailwater fishery below Flaming Gorge Dam in Daggett County, Utah, and finally to warmer, slower waters as it meanders through Utah's Emery, Grand, San Juan, and Wayne Counties before entering Colorado. The stretch below Flaming Gorge Dam has earned international recognition as a world-class trout fishery, with reports suggesting densities of 8,000 to 14,000 fish per mile in prime sections. The river supports both coldwater trout fisheries in upstream reaches and warmwater species downstream, offering diverse angling opportunities from Wyoming's high country through Utah's red rock canyons and into Colorado's Dinosaur National Monument.