Trump delays controversial Alaska mine after 'impassioned' plea by Don Jr who uses region as fishing spot

President Donald Trump has delayed a permit for a controversial mine in Alaska, reportedly after pleas from his son, Don Jr, who previously took a fishing trip to the wilderness beauty spot.

In a seemingly stunning reversal, the US Army Corps of Engineers said in a letter to the developer released on Monday that the proposed gold and copper mine, at the headwaters of the world´s largest sockeye salmon fishery, would cause "unavoidable adverse impacts".

During a fundraiser earlier this month, Don Jr made an "impassioned" plea to his father that the mine was a bad move, the Washington Post reported. Fox News host Tucker Carlson, who among other prominent network voices seems to wield significant influence over the president's decisions, upped the ante and also argued against the project.

"As a sportsman who has spent plenty of time in the area I agree 100%. The headwaters of Bristol Bay and the surrounding fishery are too unique and fragile to take any chances with," Donald Trump Jr. has tweeted.

Although environmentalists and some Alaskan residents have long fought against the project, the president's son was an unlikely boost of support.

"The public began to realise that this project, far from being dead, was on the verge of getting a permit and moving forward," Joel Reynolds, Western director and senior attorney at the Natural Resources Defense Council (NRDC) told The Independent. "People who had serious concerns but had not said anything began to come out of the woodwork, including very well-connected Republican voices like Donald Trump Jr, Nick Ayers and Tucker Carlson.

"They have access to Trump and began to let him know that his administration was ignoring science and about to permit a project that would compromise one of the great natural ecosystems on earth and the source of about 50 per cent of all the sockeye salmon on the planet."

Mr Reynolds added: "[The corps] appeared to be not hearing the concerns of scientists, Bristol Bay residents and others, including NRDC, that the devastation the project would cause cannot be fixed. This is the wrong mine in the wrong place. It will destroy thousands of acres of pristine wetlands and almost 200 miles of streams. All of that would have to be mitigated by the company."

The company´s current mitigation plan includes making sewage treatment upgrades, adding culverts and picking up debris along the beach, he said.

The corps is now giving Pebble Limited Partnership 90 days to come up with a mitigation plan for the thousands of acres and miles of streams to secure a key federal permit to proceed.

Once filed, the corps said it will decide if the plan for Pebble Mine is sufficient, David Hobbie, the corps' regional regulatory division chief said in a letter to James Fueg, vice president for permitting at the partnership.

Just last month, the corps said in an environmental review that the proposed mine under normal operations "would not be expected to have a measurable effect on fish numbers and result in long-term changes to the health of the commercial fisheries in Bristol Bay".

The mining company said the letter is a normal part of the process, and it is working on a mitigation plan.

"A clear reading of the letter shows it is entirely unrelated to recent tweets about Pebble and one-sided news shows," Pebble CEO Tom Collier said in a statement. "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."

Mr Collier said nothing in the letter came as a surprise, and the company was informed six weeks ago about how the corps was leaning toward mitigation plans.

"We began at that time focusing on a preliminary plan. We built two temporary camps in the watershed housing a total of about 25 people," he said. "A number of teams from those camps have been mapping the wetlands in the region for about four weeks now."

Under a section of the Clean Water Act, the corps found "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," the letter to Mr Fueg says.

Accordingly, the corps is asking for compensatory mitigation of 2,825 acres of wetlands, 132.5 acres of open waters and 129.5 miles of streams within the Koktuli River watershed for direct and indirect impacts.

The corps also determined mitigation is required for unavoidable impacts to aquatic resources from discharges along with the transportation corridor and the port site. That amount to 460 acres of wetlands, 231 acres of open water and 55 miles of streams.

The corps did not respond to a request for comment by The Independent.

For now, the future of the project hangs in the balance.

"We are waiting for and advocating for a denial of the permit. That´s what´s going to matter at the end of the day," Jim Murphy, legal advocacy director at the National Wildlife Federation told AP.

"They´ve asked for additional mitigation which I think will be very difficult, I would say impossible for the mine to come up with," Mr Murphy said "But I also feel that there was no way, even without these requirements, that the mine could operate in compliance with the Clean Water Act."

If it does get the permit from the corps, the project would still face a state permitting process, along with political, economic and, likely, legal challenges. The Pebble partnership is owned by Canada-based Northern Dynasty Minerals Ltd., which has been looking for a partner for the venture for years.

The mine, long a source of controversy and litigation, was seen by many as getting a second wind under the Trump administration.

Under President Barack Obama, the US Environmental Protection had proposed restricting development in southwest Alaska´s Bristol Bay region. But the agency never finalised the restrictions and, under the Trump administration, allowed the Pebble partnership to go through permitting.

Associated Press contributed to this report