Update on March 6: Former Maine DEP Commissioner Paul Mercer has decided not to accept a job offer to be regional administrator to the EPA’s Region 1 office in Boston. An internal email to staffers last week said Mercer was supposed to begin work on March 4, but the appointment hadn’t yet been publicly announced as of the publish date of this story. An EPA spokesperson wouldn’t comment, beyond saying in a written statement, “We have no personnel announcements in Region 1 at this time.” Mercer confirmed to WGBH News that he’s not accepting the job and said only that it was for personal reasons.

The former commissioner of Maine's Department of Environmental Protection has been appointed to head the New England region's federal EPA office, WGBH News has learned.

Paul Mercer is expected to take the lead of EPA's Region 1 office on Monday. The appointment has not yet been officially announced, but was communicated to staff in an email on Thursday. Mercer declined to be interviewed by WGBH News, since the formal announcement of his appointment has not been made.

The appointment is being met with optimism from some environmentalists and lawmakers who worked with Mercer in Maine.

"From our perspective, he's probably about as solid an individual to fill that position as we could expect under this current administration," said Pete Didisheim, advocacy director for the Natural Resources Council of Maine. "Given who our president is right now, and the harsh anti-environmental record that they've been pursuing, I think Paul Mercer comes in with a strong appreciation generally for the importance of a clean environment, clean air, clean water, the role of EPA. And I would hope that he would stand up for the the those values in that mission on behalf of the New England states."

Mercer headed the Maine DEP under Republican Gov. Paul LePage, who had a contentious relationship with environmentalists in the state.

"The mantra of the LePage era was to not enforce environmental laws, and the number of enforcement cases collapsed throughout those eight years," Didisheim said. "And I would say that didn't change while Paul Mercer was the commissioner. I don't think that enforcement activities have happened at nearly the level that they need to for the regulated community to be held accountable and for the people of Maine to understand that our laws will be enforced."

Despite that, Didisheim is optimistic about Mercer's role heading the EPA in New England.

"I do think that he also understands the broad range of environmental issues across New England, and I think he will bring a solid technical background and will work well with a professional staff, both at the headquarters and across the different departments within the New England states," he said.

Sean Mahoney of the Conservation Law Foundation's Maine office, agreed.

"From all that we could tell, he was a leader at the DEP that respected the staff, respected their expertise, and respected the importance of science and facts," he said.

Mahoney said Mercer's style led to some important accomplishments in Maine. Mercer managed to get a $30 million bond for water infrastructure passed. Maine voters approved the bond last November.

"There were some fairly controversial things — such as new regulations to govern metallic mining in the state — that under his predecessor were extremely controversial but that under Mr. Mercer seemed to proceed in a more transparent way, in a way that listened more to the experts within the department," Mahoney said.

And he said he hoped that style would continue at the EPA, under a federal administration that has been hostile to environmental regulations.

"I would hope that, even in a Trump administration, that Mr. Mercer would be able to follow that similar type of North Star, where he relies on the experience and expertise of the EPA staff and makes decisions in a way that is as apolitical as possible," Mahoney said.

Mercer is a graduate of the Maine Maritime Academy and served as a marine engineer aboard US merchant vessels. He has been an associate professor and department chair in the engineering department at the Academy. He's also been a principal at engineering firms in Maine, focusing on renewables, solid fuels and biomass energy systems.

When Mercer led the Maine DEP, he often crossed paths with former state Sen. Tom Saviello, a Republican who chaired the legislature’s Environment and Natural Resources Committee. In an interview with WGBH News, Saviello likened Mercer's role heading the state environmental department under a governor who was hostile to environmental regulation to his new role at the EPA.

"I think he's going into a situation where the environment is not a priority to this present administration," he said. "And to put somebody like Paul in there is putting somebody who really does care about the environment. I'm actually surprised that he got the appointment, to tell you the truth."

Mercer is coming in to lead a regional office that includes workers who say they're demoralized by shrinking budgets and staff sizes, as well as attacks from President Donald Trump, who has criticized their regulatory role. Saviello says that should be a familiar role for him.

"He came into a department that was demoralized," Saviello said. "He turned them around. And then what he would do is he would go out in the field and he'd knock on a mill's door and say, ‘Hi, I'm Paul Mercer, the Commissioner of Environmental Protection. Can I come in and see the mill and tour it and get to know you guys and what your issues [are]?' That's what a good commissioner does."