Waterman combines adventure, history and a strong environmental message in this tale of a 450-mile journey in the wake of John Wesley Powell down the Colorado from its source to the Pacific. Weaving history, adventure and tall tales, he includes snapshots of local farmers, boatmen, park rangers and engineers he met along the way. The book includes an excellent, doublesided pull-out map of the Colorado River Basin by National Geographic.  (USW633, $26.00)