Loper discovered his love of river running while placer mining on the San Juan River. In 1907 and using three boats, Loper, along with Charles Russell and Edwin Monett attempted to boat from Green River, Utah through the Grand Canyon. Loper left Russell and Monett in Glen Canyon on November 1, 1907, to repair a camera, and was to rejoin the two other men at Lees Ferry not later than December 1. The two men waited for Loper at the Ferry until December 13, 1907, then proceeded into Marble Canyon without Loper. Russell and Monett completed their river cruise through the Grand Canyon and arrived at Needles, California, on February 8, 1908, with one boat.Marston, Otis R., (2014). "From Powell To Power; A Recounting of the First One Hundred River Runners Through the Grand Canyon. Flagstaff, Arizona: Vishnu Temple Press, pp. 203–209
