Explorers learn from experience, get out and see them for yourself.
Missouri's streams change constantly. Every rain brings changes. The Paddler's guide from when I was a kid in the 80's is pretty obsolete now. Accesses have changed due to ownership of the lands. And, the streams have all lost water for the most part due to alot of reasons. Some channels have switched back and forth.
All I had growing up was printed topo maps from Rolla, 7 minute sections. The Paddlers guide. Mo. Road Maps. The MDC issued an atlas for the first time in the late 80's, it was spiral bound and rode in the truck. Forest Service had maps at the local offices. Some of the Scenic Riverways had maps at the accesses.
The net offers so much more info than we ever had. Weather reports, stream gauges, and aerial views. If you subscribe to some sites, even ownership info and real time aerial photos.