In slightly longer than a decade, Nevada's Lake Mead — which sits down river from Lake Powell on the Colorado River — has seen its total volume drop by more than 60 percent. Persistent drought and increased demand have wreaked havoc on water levels, sometimes draining three feet of depth in a month. Now, the lake is listed at about 1,100 feet above sea level, a foot below the previous all-time low set in 1937. With demand not letting up and climate change warming things up, it doesn't look good for Lake Mead. Water managers have the option of releasing water from Lake Powell to raise Lake Mead, but that doesn't solve the problem of not having enough water in the system in the first place.
This gallery was originally published in July 2011 and has been updated with new information.