Many people know the Rio Grande as a recreational river--a place for float trips through the canyons of Big Bend; for fishing at Lakes Amistad and Falcon; for archaeological study of ancient pictographs at the river's confluence with the Pecos; or for hiking the river in New Mexico and Colorado. Yet these pleasant interludes on the Rio Grande in its more scenic stretches are only part of its story. The other parts include controversies over water...