According to the Colorado Revised Statutes:
"(5.5) "Outfitting services" means providing transportation of individuals, equipment, supplies, or wildlife by means of vehicle, vessel, or pack animal, facilities including but not limited to tents, cabins, camp gear, food, or similar supplies, equipment, or accommodations, and guiding, leading, packing, protecting, supervising, instructing, or training persons or groups of persons in the take or attempted take of wildlife."
(I added the bold.)
So--assuming you actually want to take people to a river for part of their training--what you want to do probably requires an outfitter's license, and whoever actually accompanies the clients is a guide and requires CPR and Basic First Aid certifications. In addition, if you do this on public land, you probably need a permit from the agency that controls it--Forest Service, BLM, etc.
What you need to do is find an outfitter (a shop) who operates on the river you plan to use for this and make a deal to do it under their outfitter's license. You would generate the business and do the guiding. They would get a cut for letting you operate under their outfitter's license, liability insurance, permits, etc.