Lake Mead plummets to unprecedented low, exposing original 1971 water intake valve

The West is in the grips of a climate change-fueled megadrought, and Lake Mead -- the largest manmade reservoir in the country and a source of water for millions of people -- has fallen to an unprecedented low.

The lake's plummeting water level has exposed one of the reservoir's original water intake valves for the first time, officials say.