The Justice Department recently recommended that the high court not take up the case, maintaining in a brief filed last week that Georgia's arguments are flawed and that the issue is not significant enough to merit Supreme Court attention.
Georgia asked the Supreme Court in August to overturn a lower court decision that invalidated an agreement between Georgia and the Army Corps of Engineers for water withdrawals from Lake Lanier, a massive federal reservoir that provides most of Atlanta's water.
Lanier is at the heart of a nearly two-decade water feud among Georgia, Florida and Alabama.
To meet growing needs over the coming decades, Georgia and the corps agreed in 2003 to allow the state's withdrawals to jump from about 13 percent of the lake's capacity to about 22 percent.
Florida and Alabama contested the agreement, arguing that the lake was initially built for hydropower and that providing water to Georgia was not an authorized use.
A federal district court sided with Georgia. But in February, the U.S. Court of Appeals in Washington overturned that decision, saying the agreement between Georgia and the corps amounted to a major operational change at the reservoir that required congressional approval.
"The federal government has accepted the appellate court's ruling that the secret agreement between Georgia and the Corps of Engineers was illegal, and it's about time for Georgia to accept it as well," said Alabama Governor Bob Riley.