The Gateway to Dewey Bridge Colorado River river run on the Dolores River in Utah is a scenic and challenging float through red rock canyons. The river has several obstacles, including tight turns, rocky rapids, and low bridges. The difficulty of the run varies depending on the water level, but it is generally considered a Class III-IV+ run. The best time to float this section of water is in the late spring or early summer when the water levels are high enough to avoid scraping against the rocks. The recommended flow for this section is between 600-1500 cfs. It is important to have experience and proper equipment for this river run.