Forsyth County's permit allowing it to discharge 6 million gallons a day of treated waste water into the Chattahoochee River is illegal, according to a state judge.

The ruling late Tuesday by Administrative Law Judge Kristin Miller is a blow to Forsyth's long-running effort to get a permit to release waste water into the Chattahoochee, and a victory for the Upper Chattahoochee Riverkeeper, which filed a suit last year to stop the permit issued by the Georgia Environmental Protection Division.

In her ruling, Miller said the permitted discharge would violate state and federal laws because it would result in lower water quality in the Chattahoochee. The judge said Forsyth could more thoroughly treat its waste water and discharge less pollution into the river.

Tim Perkins, Forsyth County Water and Sewer Department director, said it would cost the county an additional $121,000 a year to clean the volume of water it now discharges to a higher purity level of .13.

UCR executive director Sally Bethea said the group was “thrilled” by the judge’s decision, calling it a “major victory for clean water for all people who recreate in the river and downstream lakes.”

Perkins declined on Wednesday to comment on the ruling. “This is something our commissioners have to be briefed on and we need time to review and evaluate before we comment,” said Perkins.