The Dolores River flows for more than 200 miles through southwestern Colorado, starting high in the San Juan Mountains and descending to its confluence with the Colorado River near the Colorado-Utah border. In an average snowpack year, the river is boatable from late April to early June, while in a dry year, there may be no boatable flows at all. The Dolores flows through five major western life zones, from the Alpine Life Zone at its headwaters to the Upper Sonoran Life Zone along much of its lower reach (from 6,400 to 5,000 feet in elevation).
Additional Dolores River information regarding boats and permits Here