UT OF AN AUGUST fog came a convoy of five rafts, one kayak, and one stand-up-paddleboard, all of them floating the Chattahoochee River along the Alabama-Georgia line. Rowing the raft I sat in was Rowell Guevarra, a former Army Ranger instructor at Fort Benning, Ga., (part of the base is in Alabama), who now volunteers as lead mentor for the Auburn, Ala., Mayfly Project, a national
