California’s biggest lake, about 350 square miles, is dying. It’s not the first time. The Salton Sea, straddling the Imperial and Coachella Valleys, is the latest incarnation of a body of water that has been drying and refilling over eons with water from the Colorado River. Native Americans once fished and camped on Lake Cahuilla, a prehistoric and larger version. The Salton Sea was born in the early 1900s after a canal burst sent water from the Colorado flooding into the valley over a period of two years.