Even from 38,000 feet in a jet, Hoover Dam is a remarkable achievement. The giant plug in the Colorado River about 30 miles outside Las Vegas, the cause of the swathes of blue in the tan desert landscape, stands as a testament to 20^th century American ingenuity, stubbornness, and political will. From the crest of the dam, the achievement looks more flawed. Lake Mead has dropped 130 feet since 2000, when it was full. It’s now at 37 percent of capacity and declining rapidly enough to capture the full attention of water managers from Los Angeles to Denver.