A federal judge has ruled the city of Atlanta must get Congressional approval in the next three years to continue withdrawing water from it's main supply.

Atlanta currently relies on water from Lake Lanier, a resevior northeast of the city. Friday, a U.S. District Court Judge ruled Atlanta's withdraws from the lake are illegal. The decision has surpised many Georgia officials. There has been ongoing legal dispute between Georgia, Florida and Alabama over using Lake Lanier's water.

Florida and Alabama say the withdraws hurt regional ecosystems. But Georgia has argued a decades old agreement made with the U.S. Army Corp of Engineers allows metro Atlanta to use the water.

Lake Lanier is maintained by the Army Corp, and being a federal entity, Judge Paul Magnuson ruled any water agreement must be approved by Congress. Georgia's two U.S. Senators issued a joint statement saying they will work to win that approval.

However, Friday's decision is expected to be appealed.

Tags: Georgia, Atlanta, Florida, Congress, Alabama, Lake Lanier, Paul Magnuson, tri-state water war, U.S. District Judge, U.S. Army Corps of Engineers