ST. LOUIS — Summertime, and the floating is easy. Living near the Ozarks and not sampling its crystal-clear, spring-fed rivers and streams would be like living in Florida and never going to the beach.

When thinking about a float trip, folks may imagine settling into the body of a canoe, kayak or inner tube, lathering up in sunscreen, donning a lifejacket and popping open a few cold beverages. A ...