Light rainfall and low groundwater fed the "exceptional" drought - the government's worst category - as it swelled like an angry ink blot throughout the northeast corner of the state, state climatologist David Stooksbury said Thursday.

Some 12 percent of Georgia is now classified as "exceptional," compared with just 1 percent last week. About 60 percent of the state is classified in moderate drought or worse, an improvement from three months ago when nearly the entire state was locked in those conditions.

Georgia officials are particularly concerned the drought has steadily sapped Lake Lanier, Atlanta's main water supply, and other key reservoirs scattered across north Georgia.

The lakes may not fully recover this winter even with normal rain levels, Stooksbury said.

Yet normal precipitation is far from certain - there's no indication the winter will be abnormally wet or dry, but Stooksbury noted the last 15 years has trended toward dry winters.

"That just means that next summer we'll already be behind when the high moisture demands of the late spring and summer begin," he said.

The historic drought creeped across the Southeast last year and forced state and local officials to order the sweeping water restrictions to save dwindling resources. Landscaping companies went under, cars stayed dirty and some towns worried about running dry.

Georgia banned virtually all outdoor watering throughout the northern part of the state. The legal battle over federal water rights among Georgia, Florida and Alabama intensified. Legislators in Tennessee and Georgia sparred over rights to the Tennessee River.

Stooksbury encouraged residents to continue water conservation measures that helped some communities avoid water shortages during the height of the drought last year.

"The prudent thing is to conserve, and Georgians have done an outstanding job over the last year conserving," he said. "The word is: Keep doing what you've been doing - keep conserving."