A tri-state dispute threatening metro Atlanta's water supply is heading to an appeals court.

A three-judge panel on the 11th U.S. Circuit Court of Appeals in Atlanta plans to hear arguments Wednesday as Georgia seeks to overturn a judge's order that severely restricted the ability of metro Atlanta to withdraw water from Lake Lanier.

U.S. District Court Judge Paul Magnuson ruled in 2009 that Atlanta had little legal right to take water from Lake Lanier because the water body was built for hydroelectric power, not water supply. Magnuson signed an order that would severely restrict water withdrawals from the lake starting July 2012 unless Georgia strikes a political deal with Alabama and Florida.

Communities downstream from Atlanta want assurances they will have enough water for fisheries, farms, industry and towns.