On its surface, floating solar appears to conserve water while generating carbon-free electricity. River managers are cautious, but some say the West can’t afford to wait.By Jake BolsterGILA RIVER INDIAN RESERVATION, Ariz.—About 33 miles south of Phoenix, Interstate 10 bisects a line of solar panels traversing the desert like an iridescent snake. The solar farm’s shape follows the path of a canal, with panels serving as awnings to shade the gently flowing water from the unforgiving heat and wind of the Sonoran Desert.