(CNN) — The Environmental Protection Agency told staff scientists that it was no longer opposing a controversial Alaska mining project that could devastate one of the world's most valuable wild salmon fisheries just one day after President Trump met with Alaska's governor, CNN has learned.

The EPA publicly announced the reversal July 30, but EPA staff sources tell CNN that they were informed of the decision a month earlier, during a hastily arranged video conference after Trump's meeting with Gov. Mike Dunleavy. The governor, a supporter of the project, emerged from that meeting saying the president assured him that he's "doing everything he can to work with us on our mining concerns."

The news came as a "total shock" to some top EPA scientists who were planning to oppose the project on environmental grounds, according to sources. Those sources asked to remain anonymous for fear of retribution.

The copper-and-gold mine planned near Bristol Bay, Alaska, known as Pebble Mine, was blocked by the Obama administration's EPA after scientists found that the mine would cause "complete loss of" the bay's fish habitat.

EPA insiders tell CNN that the timing of the agency's internal announcement suggests Trump was personally involved in the decision.

Dunleavy met with Trump aboard Air Force One on June 26, as the President's plane was on the tarmac in Alaska. The President had stopped there on his way to the G20 summit in Japan.

Four EPA sources with knowledge of the decision told CNN that senior agency officials in Washington summoned scientists and other staffers to an internal videoconference on June 27, the day after the Trump-Dunleavy meeting, to inform them of the agency's reversal. The details of that meeting are not on any official EPA calendar and have not previously been reported.

Those sources said the decision disregards the standard assessment process under the Clean Water Act, cutting scientists out of the process.

The EPA's new position on the project is the latest development in a decade-long battle that has pitted environmentalists, Alaskan Natives and the fishing industry against pro-mining interests in Alaska.