Lake Lanier on Monday night dropped to its lowest point since the reservoir was constructed in the 1950s.

The lake hit 1,052.64 feet above sea level, about 11 feet below average.

The old record of 1,052.66 was set in December 1981, also during a severe drought. The next year, an El Nino weather pattern pumped monsoon-like rains into the metro region and refilled the lake within six months.

That's unlikely to happen this time. The opposite weather pattern is in effect, La Nina, which typically creates a warmer, drier winter here.

Since spring 2006, Lanier has been depleted by the relentless drought and by releases of its water downstream to keep power plants operating and federally protected mussels alive.

Federal biologists on Friday agreed to let the U.S. Army Corps of Engineers keep more water in Lanier. That will buy some time for more than 3 million metro Atlantans who rely on the lake for drinking water. But it won't fill the lake; that could take three years of normal rainfall.

Right now, Lanier is holding only 42 percent of its stored water capacity. Twenty-two percent of the lake's surface water has disappeared. That's clearly evident in aerial photos showing wide stretches of beach and bank never visible before.

Most docks are dry. Only one of the corps' 104 boat ramps is still usable.

Yet Lanier contains more water than two other, smaller federal reservoirs downstream. The corps, which operates the lake, increasingly has relied on Lanier to help meet downstream needs.