National Geographic : 2010 Apr
• Steamboats once plied Owens Lake (above), before Los Angeles diverted the Owens River into an aqueduct. Dust from the dry lake bed is now a major source of air pollution. Southern California draws much of its water from the Sacramento-San Joaquin Delta (below), which was diked and divided into farms more than a century ago. Many of the aging levees are at risk of failure.