The U.S. Army Corps of Engineers released its environmental report on Northern Dynasty’s proposed Pebble Mine and stated in the report that the mine should not harm the Bristol Bay salmon fishery. This conclusion could help pave the way for federal approval of the mine that has been in the works for two decades.

The formal release of the report helps conclude a process launched more than two years ago, after Pebble applied for a permit from the Corps needed to build the copper, gold and molybdenum mine, the Anchorage Daily News reported.

In a statement announcing the report’s release, the Corps said, “The final EIS is not a permit decision and does not authorize operation of the mine.”

Pebble Limited Partnership CEO Tom Collier called Friday’s release “a critical milestone.”

“The process has been thorough. It has been thoughtful. I have worked in federal permitting for most of my career and can say with certainty the (Corps) has done a very good job,” Collier said in a written statement.

The mine would be built near the headwaters of salmon-producing rivers that support the Bristol Bay fishery, about 200 miles southwest of Anchorage. Major facilities would include a gas pipeline for power, a transportation route to the mine site and a port at Cook Inlet.

It could become one of the largest producers of copper and gold in the U.S., Pebble said in a statement.

The report addresses the project’s environmental impacts and will serve as the baseline document for state and federal agencies considering giving parts of the project the go-ahead.

The Corps, at least 30 days after the report’s release, could use it to issue a permit under the Clean Water Act, allowing damage to wetlands. But the Corps could also reject Pebble’s application, or issue a permit with conditions.

Two other federal permits as well as a number of state permits will be needed for construction to begin on the mine.

The U.S. Coast Guard is weighing a permit for a bridge over the Newhalen River, said Mike Heatwole, a Pebble Limited spokesman.

The Coast Guard will join the Corps in a final decision, said David Hobbie, chief of the Corps’ regulatory division in Alaska.

The Bureau of Safety and Environmental Enforcement must also weigh a right-of-way permit for the subsea natural gas pipeline crossing Cook Inlet.

The three permits, if issued, will conclude the federal permitting process for the project, Heatwole said.

A roughly three-year state permitting process would follow federal approval, he said.

A key state permit will guide construction of the tailings facility that will hold most of the tailings.

The facility will essentially be a “dry-storage” facility, he said. Rain, snowmelt or water used to transport tailings through a pipeline will be allowed to escape into a holding pond, where the water will be managed safely, he said.

Mine opponents have long raised concerns about risks related to a tailings facility failure. Cheyette said the Corps has not required a detailed engineering design of the tailings facility, and instead has punted that decision to the state permitting process.