The chair of the executive committee for the Yukon Environmental and Socio-economic Assessment Board is leaving the post today.

Stephen Mills explained in an interview Wednesday that he will be taking a position later this month as director of the implementation and reconciliation branch with the Yukon government's aboriginal relations division.

Executive committee member Ken McKinnon, the previous chair, will sit as acting chair until a replacement is appointed, he explained.

Mills said the recent death of his son played a major role in his decision.

It emphasized to him that nobody is entirely in control of his or her future, and that when opportunities arise, it's important to seize them, he said.

Mills said he always had career goals other than to the serve on the board, though he has nothing but praise and high esteem for his colleagues and staff at YESAB.

"We have developed a really good organization that is well-respected,” said the chair. "It is considered a model in Canada, and internationally.”

The 49-year-old citizen of the Vuntut Gwitchin First Nation has been involved in the Yukon's aboriginal movement to achieve self-determination for the territory's First Nations for more than three decades.

He was directly involved in the development of the environmental and socio-economic review process going back to 1997 as a negotiator on behalf of the Council of Yukon First Nations (CYFN).

In 2004, the CYFN appointed Mills to the three-member executive committee, and he was reappointed by the council in 2007.

He served in that position until 2010, when he was selected by federal Aboriginal Affairs Minister Chuck Strahl to succeed McKinnon as chair. He was reappointed as chair last year.

"It's a tough decision for me,” said Mills. "I have been working on YESAA and implementing it for over a decade and a half, 17 years, I guess.”

"When I was reappointed and asked to come on for another term as chair, I said at that time it was likely I would pursue another opportunity at the end of my three years.”

Now a year into his second term as head of the assessment board, Mills said when the opportunity came up for a new challenge, he knew he had to take it.

"It's an area I am really interested in,” he said.

"I really do think there is a lot of opportunity to implement the (land claim and self-government) agreements and work with First Nations in implementing those agreements.

"I have never been one to shy away from difficult issues. I like to be one who is part of the solutions of these issues.”

Mills said one of the things he needs to wrap up before his departure was the executive committee's final recommendation regarding Yukon Energy's proposal for a new $42-million generating station powered by natural gas trucked up from B.C.

On the whole, the committee chair believes he's leaving what has become the best assessment regime in Canada.

Mills said he has every confidence the assessment board will be successful in continuing that direction.

"What I am really happy to see is we have a lot of long-term employees and a lot of dedicated staff,” he said. "I have really enjoyed my time here. You know you have a good organization when employees want to stay.

"It's been great to develop this relationship with our board and members of staff.”

McKinnon described Mills this morning as a leader and pleasure to work with, a person who doesn't take himself too seriously but handles the serious work.

"He is obviously incredibly smart,” said McKinnon, who has also been with the assessment board since the beginning.

"Obviously, with the number of projects we have had, heading into the 2000s since we opened our door in 2005, he had to be incredibly hard-working.

"Pressure does not bother him.”

McKinnon said Mills is the type of guy who drops a bit of humour to simmer down the heat, and there's lot of it.

The assessment board and its 40 employees are always under the gun to get things done, whether the pressure is coming from project proponents, the Yukon government or wherever, he said.

McKinnon said the work by the assessment board is taken very seriously, because it is serious work.

Mills, he said, has done a fine job managing the organization and its obligations.

"It has just been an incredible pleasure working with him over the years.”

Mills will begin his new position with Aboriginal Affairs on June 16.

The job was vacated by Dermot Flynn, a longtime senior official and negotiator with the Yukon government.