Rural mayors and councillors booed deputy premier Sarah Hoffman on Thursday when she defended the phase-out of Alberta's coal-fired power plants at a question-and-answer session.

"I know the direct costs on families and the health care system from the impacts of coal," said Hoffman, who is also health minister.

At that point, delegates at the the fall meeting of the Alberta Association of Municipal Districts and Counties began to boo and jeer.

"And I know that doesn't make anybody excited," Hoffman said, "but I know when you can't breathe, nothing else matters."

The reaction came as the government continues to face harsh criticism for its environmental policies, which include the decommissioning of coal plants by 2030 and the controversial carbon tax, set to take effect Jan. 1, 2017.

Jim Rennie, mayor of Woodlands County, asked delegates to respond if they thought the coal phase-out was "the worst plan in Alberta's history."

There were hundreds of delegates in the room and nearly everyone jeered.

Rennie reminded cabinet that the delegates represent rural Alberta. He urged them to listen and protect jobs.

"With the exception of Minister [Brian] Mason, who I have a great deal of respect for, everyone of us has been elected longer than you have," he said.

Premier Rachel Notley received a tepid reception to her speech at the AAMDC Thursday. (CBC )

The government wants to decommission the remaining coal plants that were slated for closure under federal regulations by 2030.

Communities such as Hanna and Grande Cache that rely on coal for jobs are worried about the economic impact.

The question-and-answer session was followed by a tepidly received speech from Premier Rachel Notley, in which she acknowledged that not everyone is onside with her government's climate plan.

"I understand some of you have been critical of that plan," she said. "That's fine. Healthy debate is just that. Healthy. Changes of this magnitude are always challenging.

"Nevertheless, this issue is key to repositioning our economy in the years and decades to come. We must do this to address new trends that we must face and cannot avoid."

Notley told the crowd that the climate plan is a choice her government must make.