Named by John Wesley Powell during a mapping expedition in the late 1800s, this river and its many tributaries offered an impregnable fortress hideout for Butch Cassidy and other outlaws during the early 1900s. Today backpackers and canyoneering enthusiasts retrace the steps of these early explorers. This area still offers a primitive opportunity where self reliance and pre-planning are required.

River put-in is 4 miles east of State Route 95 on 650 East