Lake Mead, above the Hoover Dam, is at its lowest level since it was first filled in 1937, and it has reached this record low two years in a row. Given that its lowest level generally occurs during late June or July, the lake level will likely continue dropping.
The following images show the lake at its full capacity (May 1984) and at its new low (May 2016). At present, Lake Mead is ~37% full due to ongoing drought in the southwest.
For more, included an image comparison, visit NASA’s Earth Observatory site.
May 1984 – Lake Mead at full capacity
May 2016 – Lake Mead at present low level