AUGUSTA, Maine — Department of Environmental Protection Commissioner Patricia Aho has resigned to take a job with Republican U.S. Sen. Susan Collins, according to Gov. Paul LePage.

Aho served as commissioner since 2011 after previously serving as the agency’s deputy commissioner.

Aho will become Collins’ state office representative in Augusta, covering Kennebec, Lincoln and Knox counties.

Early in LePage’s first term, Aho was instrumental in advancing the governor’s goal of streamlining the environmental permitting process and, according to LePage, made improvements in the department’s role of assisting and educating individuals and businesses about the state’s environmental laws.

“Pattie has been a tremendous asset to the administration by improving efficiency and accountability throughout the Department of Environmental Protection,” said LePage in a written statement.

Aho was also at the helm as new commercial metallic mineral mining regulations were ushered through a complex and lengthy rulemaking process — twice — though those rules have twice been rejected by the Legislature over LePage’s objections. She has at times been at the center of controversy for actions she took as commissioner that some argue were too in line with her prior role as a lobbyist for Pierce Atwood LLC.

For example, a Superior Court judge rejected a ruling by Aho regarding noise complaints about a wind power project on Vinalhaven. Aho ruled that Fox Islands Wind, which is represented by Pierce Atwood, would have to abide by state noise limits only when the weather is the same as it was on two days in July 2010.

Maine Superior Court Judge Michaela Murphy overturned Aho’s ruling in 2014.

Murphy said Aho’s involvement in the issue could be viewed as “antithetical to the common notions of impartiality which Maine citizens understandably expect from decision-makers in Maine agencies.”

The Maine Supreme Judicial Court overturned Murphy’s ruling in May 2015, writing in its decision that “agencies have a great deal of discretion when it comes to enforcement of the laws under their jurisdiction.”

Aho’s work drew praise from Maine groups including the Environmental & Energy Technology Council of Maine, where Aho and some of her staff presented a talk called the “ State of the Environment” in June.

“Many of our business members feel that Commissioner Aho’s DEP team has been proactive in helping them navigate the complex regulatory and permitting maze,” wrote Jeff Marks, the organization’s executive director. “Despite some controversy in decisions on hazardous chemicals, wind development and water quality issues, she understood that small and large companies alike often faced environmental compliance challenges and sought to alleviate their concerns with an eye toward cleaner air, water and lands.”

Aho thanked her staff.

“Working with a dedicated staff, it has been my privilege to work to improve regulatory reform, increase accountability and transparency and modernize DEP’s approach to doing business,” said Aho in a prepared statement.

Collins said Aho’s experience will be valuable on state and federal issues.

“I have known Pattie for a long time and I’m very happy to have her joining the staff,” said Collins.

LePage on Monday announced the appointment of Avery Day as acting DEP commissioner, effective Sept. 7. Day, a lawyer and former public policy advocate at Pierce Atwood, serves as LePage’s senior policy adviser on environmental protection; agriculture, conservation and forestry; inland fisheries and wildlife and marine resources.

Christopher Cousins

Christopher Cousins has worked as a journalist in Maine for more than 15 years and covered state government for numerous media organizations before joining the Bangor Daily News in 2009.