LAKE MEAD, NRA, AZ – JULY 17: The Arizona Intake Towers at the Hoover Dam are shown on July 17, 2014 in the Lake Mead National Recreation Area, Arizona. Last week, North America’s largest man-made reservoir dropped below 1,082 feet above sea level, the lowest it’s been since the Hoover Dam was built in the 1930s. A 14-year drought in the Southwestern United States and a dwindling supply of water from the Colorado River, in part due to cuts in the reservoir’s annual allocation of water from Lake Powell, has left a white “bathtub ring” of mineral deposits left by higher water levels on the rocks around the lake as high as 130 feet. The National Park Service has been forced to close or extend boat launch ramps, and move entire marinas to try to keep up with the receding water levels. (Photo by Ethan Miller/Getty Images)