COEUR D'ALENE, Idaho (AP) -- The Idaho Board of Environmental Quality has voted unanimously against having the state take part in a federal program that could encourage companies to build coal-fired power plants in the state.

Meeting Thursday, board members voted to send a temporary "opt-out" policy proposal to Gov. Jim Risch. By signing the proposal, Risch would include Idaho as one of the states declining to take part in the U.S. Environmental Protection Agency's Clean Air Mercury Rule.

Risch took part in the meeting and asked board members not to act until he had time to make a final decision about the program around the end of August.

But Toni Hardesty, state Department of Environmental Quality director, told board members their decision met the governor's timetable, as the temporary policy would need to be signed by Risch by Aug. 23, allowing time for public comment before the board meets in October to consider a permanent state rule.

Coal plants emit mercury that can cause neurological damage and other health problems. The Clean Air Mercury Rule allows power plants to buy emissions reduction credits from plants whose emissions fall below target levels, rather than installing their own mercury emissions controls. Because the number of credits is limited, the rule helps maintain a balance in the amount of pollution nationwide.

However, by trading credits some areas could see an increase in mercury pollution.

The Idaho Conservation League asked the board not to participate in the program.

"The board did a very important thing here," Justin Hayes, program director of the Idaho Conservation League, told The Spokesman-Review. "They recognized how important dealing with mercury is to protect human health."

Coal-fired power is a hot topic in Idaho, especially after a California utility owner proposed building a $1.4 billion power plant in Jerome County and another company said it wanted to erect an $850 million coal-gasification plant near Pocatello. The 2006 Legislature passed a two-year moratorium on coal plants, and a subcommittee is meeting this summer to update Idaho's 1984 energy plan.

Earlier this month, 33 of 35 state senators signed a petition urging Risch to opt out of the federal pollution trading program.

The Idaho Association of Commerce and Industry asked the board not to opt out of the federal program because coal plants could bring more jobs to the state.

The vote Thursday also directed the Idaho Department of Environmental Quality to write a proposal that creates a mercury emissions rule for Idaho. By writing its own conditions for an emissions credit trading scheme, Idaho could still opt into the federal "cap and trade" program later.