Leslie “Les” Allen Jones started running the Green with his cousin, Bus Hatch, in the late 1940s. He helped out with the huge Sierra Club trips that Hatch ran during the Echo Park Dam controversy, but finding those too crowded he started going solo in boats of his own design. A civil engineer by training, Les constructed a variety of aluminum kayaks and canoe/kayak hybrids.  With these he ran the Green, the Colorado in Cataract Canyon, and the Grand Canyon solo, or with one other companion such as Ulrich Martin and Walter Kirshbaum, champion German kayakers. Les was also one of the founding members of the Western River Guides Association, an early river runners organization that included boaters from all over Utah and the surrounding states. They held raucous meetings once a year, usually in Salt Lake City, and Les, who was a devout member of the LDS Church, finally quit the association because there was too much drinking and swearing. In 1955, Les joined the Eggert-Hatch film expedition, specifically chosen by Don Hatch as a boatman for his strength and experience. 

What Les is most famous for, though, were his scroll maps. Up to this time, in the mid-1950s, there were no river guides or waterproof maps; the only way you could tell where you were on the river was by using the USGS quadrangle maps. One of Les’s jobs had been creating highway and other maps for the Utah Highway Department, and he wanted a better way of keeping track of where he was on his solo river adventures. So he put his drafting skills to work and created a map that depicted the entire course of the river on a scroll. Compact and easy to use, the boater could just keep rolling the map to follow his course. As he gained experience, Les started adding more and more information; names of rapids, historical notes, interesting features, and even conservation messages and prayers.  His first maps were only of the Green and Colorado rivers and their tributaries, but Jones soon branched out to rivers all over the west. He also started printing them on vinyl, like the material used for blueprints, so they could more easily be used on the river. Les, along with Otis ”Dock” Marston, came up with the 1-10 rapid rating scale used in the Grand Canyon; when asked why he used his own scale instead of the American Whitewater 1-6 scale, Les replied “Because you and I have ten fingers.”