BOULDER CITY, Nev. (NBC News) -- The latest report from the National Drought Mitigation center finds that California is now at the "exceptional drought" stage, the worst in history. Neighboring states are in similar shape.
Lake Mead is supposed to be the nation's largest man-made reservoir, but after years of drought it's disappearing and taking with it the water supply for 40-million people across seven states.
"Water managers in California, in January were saying we have about 18-24 months of water supply, and then after that they will readily admit they don't know," says NASA water cycle scientist Jay Famiglietti. "If it doesn't rain they don't know what is going to happen."
The lake is at its lowest level since 1937 when it was created with the completion of the Hoover Dam, 139 feet below capacity.
Parched, cracked earth, waterside docks now 500 feet or more from the shoreline and a visible ring along the rocks mark where the water is supposed to be.
And that's just what we can see.
"While everyone is focused on the surface water, the ground water is quietly disappearing," Famiglietti notes.
Data from a new study on the problem shows underground water sources are drying up at a disturbing rate, six to seven times the rate of decline in lake mead.
"I think that we're past the point of recovering. We're really at the point of managing our way through the future," Famiglietti predicts.
-- Jay Gray reports