The Washoe Indians called it Tah-ve, an unfathomable liquid sapphire set in a 500 square-mile watershed of alpine snow and ice. Too deep and vast to freeze, Lake Tahoe's waters have, over time, reflected pristine forests, barren hillsides littered with slash and sawdust, managed restoration, and the glow of neon casino marquees. Its spectacular natural landscape, shared by both California and Nevada, is more designed than people realize. Humans transformed...