Florida failed to prove that limiting water use in Georgia would have any effect on how much water comes to the state, the Atlanta Regional Commission and seven other metro Atlanta cities and counties said in a friend-of-the-court brief filed Monday at the U.S. Supreme Court.

The amicus brief came from Fulton, DeKalb, Gwinnett and Forsyth counties; Atlanta and Gainesville; and the Cobb County-Marietta Water Authority, in addition to the ARC.

The dispute over water from the Chattahoochee and Flint rivers is more complex than one state against another state. (Erica A. Hernandez/AJC)

In the filing, the group supported the finding of Special Master Ralph Lancaster, who in February found that Florida "failed to show that a consumption cap" was necessary in the long-running water wars case.

Lancaster’s finding is not final, and the Supreme Court can choose to reject his conclusion.

The amicus brief said Florida’s request for caps on water use in Georgia should be denied, because the state did not prove “that enough additional water would be produced at the right times to have any material effect on the complex ecological harms Florida has asserted.”

The needs of ecosystems are poorly understood, the brief said, as compared to Georgia's agricultural and economic needs. Florida argues that it needs more water to protect Tupelo trees and oysters in Apalachicola Bay.

"These interests are difficult to quantify and virtually impossible to value and weigh against competing interests in Georgia," it said.

Because Florida bears the burden of proof, the brief said, its request to limit water consumption in Georgia should be denied.

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