UNDER DONALD TRUMP, the US Environmental Protection Agency (EPA) has sought to roll back clean energy policy and questioned the Paris climate agreement. It was only a matter of time before it came for the Willamette River.

In a move that state and city officials are calling unprecedented, the EPA last week dropped a bombshell onto the 17-year struggle to clean up the toxic, 10-mile Portland Harbor Superfund site. The agency announced a secretive proposal it had reached with a number of river polluters—an arrangement that state officials say might set the cleanup process back a decade or more, and could give disproportionate power to parties who want to minimize their culpability for cleanup.

Exactly what’s in the agreement is unclear: It won’t be released to the public unless it’s signed, officials say. But the Oregon Department of Environmental Quality (DEQ), local tribes [PDF], and the city all responded to the plan with alarm, with Gov. Kate Brown saying it “undermines the progress we’ve made.”

State officials say the deal might upend the very standards upon which successfull cleanup is measured. And they warn it could roll back portions of the EPA’s “record of decision,” an extensive $1 billion plan for cleaning up the river that the feds released before Trump was inaugurated in January (in a move that looked designed to preclude his meddling).

Trump’s people have taken notice. Kevin Parrett, manager of the DEQ’s Northwest Region Cleanup Program, says the controversial deal appears to have been hashed out in the upper echelons of the EPA, which is controlled by industry-loving Administrator Scott Pruitt.

“These negotiations are occurring within the Pruitt administration,” Parrett tells the Mercury. “That’s another very unusual aspect.”

So who has the EPA reached the accord with? Parrett says he can’t say. All that’s been revealed so far is that it’s a group of so-called “potentially responsible parties” who will need to cover some of the cost of cleanup. The EPA didn’t respond to questions by the Mercury’s deadline.

“From our understanding, it’s a small group of parties that have been pretty transparent in trying to roll back this [record of decision],” Annie Von Burg, a City of Portland employee who oversees superfund efforts, said Monday.

Pressure from state, city, and tribal officials appears to have had an effect. As of Tuesday, the EPA had agreed to slow the process down, according to Parrett.