A realistic statewide plan, experts say, would tell developers that they could not build if no water was available, and might have restricted some of the enormous growth in the Atlanta area over the last decade. Already, officials have little notion how to provide for a projected doubling of demand over the next 30 years. The ideas that have been floated, including piping in water from Tennessee or desalinating ocean water, would require hundreds of billions of dollars and painful decision making the state has been reluctant to undertake.

Image Low levels this month at Lake Lanier, which supplies water to Atlanta. The Southeast has been slow to respond to its drought. Credit... John Bazemore/Associated Press

“It’s been develop first and ask questions later,” said Gil Rogers, a lawyer with the Southern Environmental Law Center.

Instead, Georgia has engaged in interminable squabbles with neighboring states over dam releases and flow rates. The latest effort at mediation with Alabama fell apart just last month. And Georgia officials insist that Atlanta would have plenty of water were it not for the Army Corps of Engineers, which they say has released more water from its main source of water, Lake Lanier, than is necessary to protect three endangered species downstream. Last week, Mr. Perdue filed for an injunction against the corps to stop the release of water. (Downstream, Alabama officials responded in protest, saying they need the releases.)

“We are not here because we consumed our way into this drought, as some would suggest,” said Carol Couch, Mr. Perdue’s director of environmental protection.

Those making that argument against Georgia include many people in Florida, the only state in the region to have adopted a water plan and home to the downstream end of the basin that includes Lake Lanier. An editorial Friday in the St. Petersburg Times said that the blame lay not with the corps but with “a record drought, unrestrained population growth and poor water-conservation habits.”

Bruce A. Karas, vice president of sustainability for Coca-Cola, said no one from the City of Atlanta or its water planning district had approached company officials to ask them to conserve water. Mr. Karas said the company had worked to reduce consumption on its own since 2004.

“We’re very concerned,” Mr. Karas said. “Water is our main ingredient. As a company, we look at areas where we expect water abundance and water scarcity, and we know water is scarce in the Southwest. It’s very surprising to us that the Southeast is in a water shortage.”