In 1869, John Wesley Powell led a small party down the Green and Colorado Rivers in a bold attempt to explore the Grand Canyon for the first time. After their monumental expedition, they told of raging rapids, constant danger, and breathtaking natural beauty of the American landscape at its most pristine. Jon Waterman combines sheer adventure and environmental calamity in this trailblazing cautionary account of his 2008 trip down the overtaxed, drying Colorado. Dammed and tunneled, forced into countless canals, trapped in reservoirs and harnessed for electricity, what once was untamed and free is now humbled, parched, and so yoked to human purposes that in most years it trickles away 100 miles from its oceanic destination. Waterman writes with informal immediacy in this eye-witness account of the many demands on the Colorado, from irrigating 3.5 million acres of farmland to watering the lawns of Los Angeles. He shows how our profligacy and inexorable climate change spark political conflict, and how we can avert this onrushing ecological crisis. As he follows Powell afloat and afoot, Waterman reaches out both to adventure travelers and to scientists, conservationists, environmentalists, and anyone interested in the fragile interplay between nature and humans.