Alaska Pebble Mine

FILE - In this July 13, 2007 file photo, workers with the Pebble Mine project test drill in the Bristol Bay region of Alaska near the village of Iliamma. The Trump administration settled a lawsuit Friday, May 12, 2017, over the proposed development of a massive gold and copper mine at the headwaters of one of Alaska's premier salmon fisheries. The Environmental Protection Agency settled the long-running case with the Pebble Limited Partnership, agreeing to allow the Canadian-owned company to seek a federal permit to build its mine near Bristol Bay. (AP Photo/Al Grillo, File)

The U.S. Army Corps of Engineers issued a final environmental report last month stating that the controversial Pebble Mine project "would not be expected to have a measurable effect on fish numbers" in Bristol Bay, the world's largest natural salmon fishery.

Now, the same Trump administration agency has put a halt to the permitting process, saying the current project proposal presents too many environmental risks and "lacks adequate compensatory mitigation."

The mining project, about 200 miles southwest of Anchorage and 60 miles west of Cook Inlet, near Lake Iliamna, would sit at the headwaters that feed Bristol Bay. According to the project description by Pebble Limited Partnership, the mine would produce an annual average of 318 million pounds of copper, 362,000 ounces of gold, 14 million pounds of molybdenum and 1.8 million ounces of silver during its 20 years of production.

The Monday statement from the Corps, while not a veto of the project, instructs Pebble Limited Partnership to come up with a detailed mitigation plan to offset environmental risk before a permit can be issued.

Between the Corps' report in July and Monday's announcement, at least three significant Republican figures have come out against the project and urged President Donald Trump to reject it. This included Fox News host Tucker Carlson, who questioned the project in a show earlier this month; Nick Ayers, another well-known conservative and former chief staff to Vice President Mike Pence; and the president's own son, Donald Trump Jr., who criticized the proposed project in a post to his Twitter account earlier this month.

The Monday announcement marked a win for environmental groups that have been fighting the project since its inception years ago.

The project has long been opposed by the Bristol Bay Native Corp., the regional investment corporation representing the interests of the Indigenous population in the area.

“Today’s action indicates the Army Corps of Engineers, President Trump and Alaska’s senators have listened to science, local voices, and common sense,” said Jason Metrokin, president and CEO of Bristol Bay Native Corp. “We are grateful they are reaching the same conclusion as the many voices across the ideological spectrum that have recently spoken up about the project: that Pebble is the wrong mine for Bristol Bay.”

Adam Kolton, executive director of the Alaska Wilderness League, called the halt a "positive step."

"This has always been the wrong mine in the wrong place," Kolton said.

Alaska’s Republican congressional delegation has, in the past, taken a soft stance on the issue, voicing support for the mine if damage to the fishery can be prevented. Environmental groups and the Bristol Bay Native Corp. say harm to the fishery cannot be ruled out.

Now, Alaska Republican Sens. Lisa Murkowski and Dan Sullivan made more pointed statements on the Corps' announcement Monday, noting they strongly support Alaska's mining and resource development industry but that they "agree" with the rejection of the proposal as it currently stands.

Alaska Republican Rep. Don Young, the state's only member of the U.S. House, had a slightly more combative response, suggesting the permitting process had fallen victim to political posturing.

"Very frankly, I am concerned we are talking about this at all because this is state land. I support our 10th Amendment, and I am a staunch defender of our right to manage our own lands," Young said. "From day one, this project has been subject to the political whims, decisions, and opinions of federal agencies and bureaucrats who disagree with how we Alaskans choose to live and work."

Pebble CEO Tom Collier, in a statement Monday, discounted the impact of the most recent decision, calling the Army Corps' statement "a normal letter in the permitting process."

"A clear reading of the letter shows it is entirely unrelated to recent tweets about Pebble and one-sided news shows. The White House had nothing to do with the letter, nor is it the show-stopper described by several in the news media over the weekend," Collier said. "The letter does not ask for a delay or pause in the permitting process."

The Corps stated that "the project, as currently proposed, cannot be permitted under section 404 of the Clean Water Act."

Contact staff writer Erin McGroarty at 459-7544. Follow her on Twitter: @FDNMpolitics.