The Environmental Protection Agency announced Tuesday a move to protect one of the world’s largest salmon runs—in Alaska’s Bristol Bay—by vetoing a controversial plan for a copper and gold mine in the region. 

The decision prohibits disposal of mining waste in streams that support the Bristol Bay fishery and aims to prevent “unacceptable adverse effects” from the proposed mine, called the Pebble project, the EPA said in an executive summary of its decision. The agency’s action effectively quashes the mine proposal. 

Mining interests have long had their eyes on the remote tundra of Southwest Alaska, which is home to a massive copper, gold and molybdenum deposit about 200 miles from Anchorage. But fishermen, Alaska Native communities and environmental groups for years have voiced opposition to the project. 

A 2020 mine proposal outlines plans for a mile-wide open pit, roads, a gas pipeline, a power plant, waste ponds and other infrastructure that could damage about 100 miles of streams and 2,000 acres of wetlands, according to the EPA. 

“It’s so hard to even put into words what today means to us,” said Katherine Carscallen, a third-generation Bristol Bay fisherman and executive director of Commercial Fishermen for Bristol Bay. “I think today’s decision clears the cloud that we’ve had over our heads for so long. Pebble Mine has been an existential threat.” 

The Biden administration’s decision​ finalizes a December recommendation from the EPA and caps a process that started more than a decade ago, when Bristol Bay tribes petitioned the federal government to halt the Pebble project. 

The agency’s decision relies on a seldom-used provision of the 1972 Clean Water Act. Before Tuesday, the EPA had used its so-called “veto authority” to block a project or permit only 13 times in 50 years. It came a week after the Biden administration banned logging and road construction in Alaska’s Tongass National Forest. Both the Pebble mine veto and the Tongass ban reversed previous actions by the Trump administration. 

“The Bristol Bay watershed is a vital economic driver, providing jobs, sustenance, and significant ecological and cultural value to the region,” EPA administrator Michael Regan said in a press release. “With this action, EPA is advancing its commitment to help protect this one-of-a-kind ecosystem, safeguard an essential Alaskan industry, and preserve the way of life for more than two dozen Alaska Native villages.”

Tribal leaders and environmental groups were quick to laud the decision. But mining industry representatives and some of Alaska’s political leaders criticized it as federal overreach and questioned its legality. 

“EPA’s veto sets a dangerous precedent,” Alaska Gov. Mike Dunleavy said in a statement. “Alarmingly, it lays the foundation to stop any development project, mining or non-mining, in any area of Alaska with wetlands and fish-bearing streams.” In December, Dunleavy threatened to sue if the EPA vetoed the project. 

John Shively, chief executive of the company advancing the mine, Pebble Limited Partnership, called the EPA’s action “unlawful and unprecedented” and said in a statement that the agency “continues to ignore fair and due process in favor of politics.” He said his company planned to take legal action against the decision. Pebble has maintained its mine wouldn’t harm the fishery.

The National Mining Association issued a statement Tuesday, in response to the EPA’s announcement, saying the U.S. won’t be able to achieve its electrification and energy priorities “if U.S. government authorities continue on this adversarial path with domestic mining projects.” 

The current owners of the Pebble project have been working to develop a mine in the Bristol Bay region for about two decades, and their project has had a tumultuous run. The Obama administration proposed blocking it in 2014, but the EPA reversed course under President Trump. 

Then, in 2020, the U.S. Army Corps of Engineers denied the project a critical permit, finding the proposed mine would significantly damage the environment. And in December, Pebble suffered another blow when a local Alaska Native corporation set aside 44,000 acres of land as a conservation easement, protecting it from mining-related activities. 

In addition to sustaining the world’s most abundant sockeye salmon run and a commercial fishery that generates about $2 billion a year, Bristol Bay is vital to Yup’ik, Dena’ina and Alutiiq peoples whose livelihoods depend on healthy land and water. 

“The folks that live in the region rely on subsistence. And the most important part of that is salmon,” said Daniel Cheyette, Bristol Bay Native Corporation senior vice president for lands and resources. “It’s just a very important part of who everyone is.” 

While the EPA’s decision marked a potentially fatal setback for the mining project, the Bristol Bay fishery shows no signs of letting up. About 80 million sockeye salmon returned to the region last summer, the largest run on record. 

“Our runs have been getting just steadier, bigger, and last year was just off the charts,” said Mark Niver, who has fished in Bristol Bay for more than 40 years. “The reason why it produces salmon so well is it’s untouched. The water is perfectly made for raising salmon.”