The Pebble gold mine in Alaska is being dealt a potentially lethal blow with the U.S. Army Corps of Engineers set to reject a permit for the project Wednesday.

The proposed mine in southwestern Alaska, which would tap one of the world’s largest undeveloped copper and gold deposits, has been dogged by protests for years, as conservationists warn industrial mining operations near Bristol Bay threaten a flourishing sockeye salmon fishery.

Army Corps of Engineers spokesman John Budnick confirmed the agency would issue a formal record of decision rejecting the project.

In August, the Army Corps concluded the mining plan from Northern Dynasty Minerals Ltd. “would likely result in significant degradation of the environment,” and the agency demanded a mitigation plan to offset the project’s effects on nearby wetlands. Northern Dynasty’s subsidiary Pebble Limited Partnership submitted the mitigation plan earlier this month, though the details weren’t released to the public.

Pebble is in a remote area in southwestern Alaska that drains into Bristol Bay. Conservationists, local activists and fishing operations have fought the project for years, citing potential impacts on the environment and native cultures in the region. More recently, Pebble has drawn opposition from prominent Republicans including Donald Trump Jr. and skepticism from some prominent local politicians.

Northern Dynasty’s U.S. shares plunged 11 per cent as of 12:54 p.m. in New York, after rising as much as 8.5 per cent earlier Wednesday.

“How many other projects are strongly opposed by both Alaskan senators, by 80% of the people that live in the region, by commercial fishermen, by recreational fishermen, by Donald Trump Jr., and by Jane Fonda?” said Joel Reynolds, a senior attorney with the Natural Resources Defense Council. “It’s astonishing the range of opposition, and that, I think, puts it in a unique category. This project really has no friends, other than a Canadian company and its shareholders.”

The fate of the project took a further public-relations blow in September after the release of covertly taped comments revealed a top mining executive boasting of his ties to state and federal leaders. The so-called Pebble Tapes incensed the project’s critics and led to the resignation of Pebble head Tom Collier.

Developers may still have a limited opportunity to pursue the decision administratively; they also can challenge the rejection in federal court.

Regardless of the Army Corps’ verdict, conservationists are pressing the Environmental Protection Agency to even more definitively kill the proposed mine, by wielding its broad authority under the Clean Water Act to veto projects involving the discharge of dredged material. President-elect Joe Biden has promised to block the project, calling the area “no place for a mine” and noting the government reached the same conclusion while he was vice president.