

A worker with the Pebble Mine project test drills in the Bristol Bay region of Alaska. (Al Grillo/Associated Press)

The Environmental Protection Agency announced Friday it will examine whether to block a massive gold and copper mine proposed in Alaska -- a major win for environmentalists, native tribes and commercial fishing companies that have been seeking to kill the project for more than three years.

“Extensive scientific study has given us ample reason to believe that the Pebble Mine would likely have significant and irreversible negative impacts on the Bristol Bay watershed and its abundant salmon fisheries,” said EPA Administrator Gina McCarthy in a statement.

“It’s why EPA is taking this step forward in our effort to ensure protection for the world’s most productive salmon fishery from the risks it faces from what could be one of the largest open pit mines on earth. This process is not something the agency does very often, but Bristol Bay is an extraordinary and unique resource.”

While the announcement does not mean the Obama administration has made a final decision to prohibit Northern Dynasty Minerals Ltd., a Canadian-based firm, from starting construction on the Pebble Mine project, it will delay it for months and make it much harder for the controversial project to move ahead at all.

White House press secretary Jay Carney framed the move as part of President Obama's broader effort to protect public lands and waters.

"The White House strongly supports that decision by the EPA," Carney told reporters Friday. "The step is consistent with the president’s commitment to protect pristine American places for future generations.”

During the course of the EPA review the U.S. Army Corps of Engineers cannot issue a federal discharge permit. which Northern Dynasty would need in order to dump waste into the surrounding Bristol Bay watershed.

EPA is invoking its authority under the Clean Water Act to determine whether it should permanently bar the Army Corps of Engineers from issuing the discharge permit for the mine.

The mine, which has also attracted investment from global mining giant Rio Tinto PLC, has become a major issue for the conservation community, which considers it one of the most important environmental decisions President Obama can make in his second term.

“It’s difficult to imagine a more significant conservation achievement than protecting Bristol Bay,” said Chris Wood, president of the advocacy group Trout Unlimited. “This is one of the few places left on earth where nature works as it should, and it’s a breadbasket for the world, supplying literally hundred thousands of people with wild salmon.”

Bristol Bay is home to a critical fishery that supports nearly half the world’s sockeye salmon, and EPA issued a scientific assessment last month that concluded up to 94 miles “of salmon-supporting streams and 1,300 to 5,350 acres of wetlands, ponds, and lakes” would be eliminated by the footprint of a mining pit, depending on its size. The fishery not only supports a vibrant commercial fishery, but several native Alaskan tribes that have lived there for centuries.

EPA has invoked its 404(c) authority under the Clean Water Act only 13 times in its history. In starting the months-long process, the agency is sending a letter to the Army Corps of Engineers, the state of Alaska and the mine's sponsor to ask why they believe the operation would not damage the pristine watershed. These groups have 15 days to respond, though the agency can extend that deadline.

After that point EPA's regional administrator in the Pacific Northwest will issue a "proposed determination" that would lay out whether the company can discharge waste into the area, and if so, where and how much. The public will have an opportunity to comment on the proposal, after which point the regional administrator will send a recommendation to EPA headquarters to be finalized.

EPA has already conducted two peer-reviewed scientific assessments of the project, though proponents of the mine questioned whether the reviews were adequate. Michael Conathan, who directs ocean policy at the liberal think tank Center for American Progress, said in a statement the agency's decision "reflects the conclusions amassed over years of scientific and economic analysis."