Tracking the federal permitting process regarding the proposed Pebble Mine continues to be anything but simple.

The U.S. Army Corps of Engineers has finished its final Environmental Impact Statement for the copper-gold-molybdenum mine, which, if developed, would be the largest mine in North America and built in an area that drains into Bristol Bay, home of the world’s largest sockeye salmon fishery.

The EIS released in July stated that Pebble Mine operations “would not be expected to have a measurable effect on fish numbers" in the Bristol Bay watershed.

Then, opposition to the mine was voiced by the president’s son, Donald Trump Jr., and Fox News commentator Tucker Carlson, both of whom are sport anglers. Nick Ayers, a senior advisor to the Trump campaign and former aide to Vice President Mike Pence, weighed in with opposition, as well.

President Donald Trump on Aug. 5 said he would “listen to both sides” on the issue.

The Corps of Engineers has sent a letter dated Aug. 20 to the Pebble Limited Partnership, stating that the Corps was developing a Record of Decision for the mine proposal.

“As part of the ROD the (Corps of Engineers) District made Clean Water Act Section 404(b) (1) factual determinations that discharges at the mine site would cause unavoidable adverse impacts to aquatic resources and, preliminarily, that those adverse impacts would result in significant degradation to those aquatic resources,” wrote David S. Hobbie, the Corps’ regional regulatory division chief.

The Corps was giving the Pebble Limited Partners 90 days to submit a “compensatory mitigation plan” for the proposed mine, Hobbie wrote.

According to federal regulations, Hobbie wrote, “compensatory mitigation means the restoration (re-establishment or rehabilitation), establishment (creation), enhancement, and/or in certain circumstances, preservation of wetlands, streams and other aquatic resources.”

 Then, on Monday, the Corps announced that, because Pebble Mine likely would result in significant degradation of the environment and significant adverse effects on the aquatic system or human environment, the project as proposed “cannot be permitted under section 404 of the Clean Water Act.”

The announcement did not reference the Aug. 20 letter or mitigation measures.

So, what does that mean?

All three members of Alaska’s congressional delegation issued statements on the topic Monday.

Sen. Dan Sullivan’s five-paragraph statement, like those of Sen. Lisa Murkowski and Rep. Don Young, voiced strong support for a scientific process for evaluating proposed resource development projects. Sullivan added that the federal process for the proposed Pebble Mine had heard, considered and respected the voices of all Alaskans.

“Finally, I have been clear that given the important aquatic system and world-class fishery resources at stake, Pebble, like all resource development projects in Alaska, has to pass a high bar — a bar that the Trump administration has determined Pebble has not met,” Sullivan said. “I support this conclusion — based on the best available science and a rigorous, fair process — that a federal permit cannot be issued.”

Murkowski said that federal officials, “after years of extensive process and scientific study, ... have determined the Pebble project, as proposed, does not meet the high bar for large-scale development in Bristol Bay.

“I understand, respect, and support this decision,” Murkowski said. “I agree that a permit should not be issued. And I thank the administration for its commitment to the protection of this world-class watershed and salmon fishery.”

Young was the only member of the Alaska delegation to reference the Corps’ request for a mitigation plan. Young said his consistent position has been to allow the scientific process to determine what effects, “if any,” the proposed mine would have on Bristol Bay.

“And that meant letting the science, not politicians, environmental activists, or bureaucrats make a determination about the future of the proposed Pebble project,” Young said. “Today's announcement by the Army Corps indicates a significant amount of compensatory mitigation is needed to offset the potential environmental impacts of the proposed mine at this present time. While not an outright veto of the project, this is a steep hill for the company to climb.”

Pebble Limited Partnership CEO Tom Collier issued a statement on Monday that focused on the mitigation request, but did not mention the Corps’ Monday statement that the Clean Water Act permit can’t be issued.

Collier said the Pebble Limited Partnership had been anticipating the mitigation plan request, and that the partnership has been working on the details of a mitigation plan with the Corps of Engineers and State of Alaska.

“The letter we received today is a normal letter in the permitting process and we are well into an effort to present a mitigation plan to the USACE that complies with the requirements of their letter,” Collier said in the statement. “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.

“... Based on our understanding of the substance of the letter, our discussions with the state, our substantial work in the field and our discussions with the USACE we believe our final Comprehensive Management Plan submission will be submitted within weeks and will satisfy all of the requirements of the letter,” Collier said.

The apparent key concept at the moment pertains to the Pebble Mine as currently proposed, absent a mitigation plan. The Pebble Limited Partnership has time to develop a plan, and have it considered as part of the federal permitting process.

We’ve heard a lot about Pebble since the early 2000s. The past decade has been a long series of ups and downs, with project ownership changes; significant opposition by commercial fishing, tribal and environmental concerns; and twists and turns in various permitting processes.

It’s been difficult to follow, and the events of recent days have continued that trend.