SAVANNAH, Ga. (AP) — A federal agency delivered a big setback Friday to a company's controversial plan to mine near the edge of the Okefenokee Swamp and its vast wildlife refuge.

A government memo said the Army Corps of Engineers is reasserting jurisdiction over Twin Pines Minerals' proposal to mine minerals just outside the Okefenokee, home to the largest U.S. wildlife refuge east of the Mississippi River.

Scientists have warned that mining close to the swamp's bowl-like rim could damage its ability to hold water. They urged the Army Corps of Engineers to deny the project a permit. But the agency declared in 2020 it no longer had that authority after regulatory rollbacks under then-President Donald Trump narrowed the types of waterways qualifying for protection under the Clean Water Act.

Trump's rollbacks were later scrapped by federal courts. President Joe Biden's administration has sought to restore federal oversight of development projects that under Trump had been allowed to sidestep regulations to prevent pollution of streams or draining of wetlands.

Michael Connor, the assistant Army secretary for civil works, said in the Friday memo that prior decisions waiving the Army Corps' jurisdiction over the Georgia mining plan and another proposed mine outside Tucson, Arizona, had been reversed.

Connor wrote that both projects would have to start over with new applications for federal permits. He said the prior decisions allowing them to bypass federal regulators “are not valid” because tribal governments with ancestral ties to the proposed mining sites had not been consulted.

The Twin Pines project in Georgia will require consultation with the Muscogee Creek Nation before it can move forward, the memo said.

“We have said from the day we announced our plans that we would follow the regulations before us at any given time,” Steve Ingle, president of Twin Pines, said in a statement. He added: “We intend to move forward with our application and fulfill all requirements."

U.S. Sen. Jon Ossoff, a Georgia Democrat who has fought the proposed mine outside the Okefenokee since he took office last year, called the decision a major victory.

“I am pleased to announce the restoration of protection for this wildlife refuge and its surrounding wetlands,” Ossoff said in a statement late Friday. "The Okefenokee is a natural wonder and one of Georgia’s most precious lands. I will continue fighting to protect it for future generations.”

Alabama-based Twin Pines had been awaiting a permitting decision by Georgia's Environmental Protection Division, the sole regulator with oversight over the project before the federal government's Friday decision, which restores the Army Corps regulatory authority over 556 acres (225 hectares) of wetlands in the proposed mining area.

The Okefenokee National Wildlife Refuge covers nearly 630 square miles (1,630 square kilometers) in southeast Georgia and is home to alligators, bald eagles and other protected species. The swamp’s wildlife, cypress forests and flooded prairies draw roughly 600,000 visitors each year, according to the U.S. Fish and Wildlife Service, which manages the refuge.

Two decades ago, chemical giant DuPont retreated from plans to mine outside the Okefenokee after meeting fierce resistance. Twin Pines wants permits to mine a small fraction of the acreage DuPont pursued. Ingle has insisted his company can mine the site without harming the swamp.

Government scientists have been skeptical. In February 2019, the Fish and Wildlife Service wrote that the proposed mine could pose “substantial risks” to the swamp, including its ability to hold water. Some impacts, it said, “may not be able to be reversed, repaired, or mitigated for.”

Conservation groups cheered the federal government's decision.

“Mining on the doorstep of a rare ecological treasure like Georgia’s Okefenokee Swamp defies common sense," Kelly Moser, an attorney for the Southern Environmental Law Center who specializes in clean water issues, said in a statement. "And we are thrilled that this announcement removes the threat to hundreds of acres of critically important wetlands.”

Russ Bynum, The Associated Press