PORTLAND, Ore. -- New rules are expected to mean Portland General Electric will spend millions to clean up pollution at its Boardman coal-fired plant.

KGW photo

Columbia River Gorge

New filters and scrubbers at the plant are expected to reduce acid rain and the haze clouding the Columbia River Gorge, Mount Hood and Hells Canyon.

The utility company predicts rates will rise 3 to 4 percent when that work is combined with reductions in mercury emissions.

The decision came last week from the Oregon Environmental Quality Commission. The National Park Service and a coalition of environmental groups say the rules do too little too slowly.

The Boardman plant is 150 miles east of Portland. It is the largest stationary source of sulfur dioxide and nitrogen oxides in Oregon.