If there's a ground zero for the epic drought that's tightening its grip on the South, it's once-mighty Lake Lanier, the Atlanta water source that's now a relative puddle surrounded by acres of dusty red clay.

Tall measuring sticks once covered by a dozen feet of water stand bone dry. "No Diving" signs rise from rocks 25 feet from the water. Crowds of boaters have been replaced by men with metal detectors searching the arid lake bed for lost treasure.

Lake Lanier's the primary source of drinking water for more than 4 million people, reports CBS News correspondent Mark Strassmann. But levels have plunged to eight feet below normal. And without rain in another month, levels could drop another five feet, passing the record low.

"This lake is a survivor," Jeff "Buddha" Powell told a worried customer at his bait shop along the barren banks.

"If you panic, you don't help Mother Nature," he added. "It's going to rain when it rains."

But this is a once-a-century drought, reports Strassmann. In the best estimate, without rain, metro-Atlanta has 120 days left of usable drinking water.

That dire prediction has some towns considering more drastic measures than mere lawn-watering bans, including mandatory rationing that would penalize homeowners and businesses if they don't reduce water usage.

"We're way beyond limiting outdoor water use. We're talking about indoor water use," said Jeff Knight, an environmental engineer for the college town of Athens, 60 miles northeast of Atlanta, which is preparing a last-ditch rationing program as its reservoir dries up.

 Source : CBS News