Lake Mead formed in 1930s following construction on the Hoover Dam along the Colorado River. At maximumcapacity, the reservoir would hold 36 trillion liters (9.3 trillion gallons); water in the vicinity of the dam would have an elevation of about 372 meters (1,220 feet) above sea level. In July 2000, the lake level was relatively high at 366 meters (1,200 feet). By July 2015, however, the level had dropped to 329 meters (1,078 feet).
Read full post at NASA Earth Observatory.