SALEM (AP) — Oregon regulators want to cut haze-causing pollutants from Portland General Electric’s Boardman coal plant by 65 percent by 2014, which would require $400 million worth of added controls.

The DEQ says the proposal also would cut emissions of sulfur dioxide and oxides of nitrogen by 81 percent within 10 years.

The plant 150 miles east of Portland is the largest stationary source of the pollutants in Oregon. A study this year concluded that it is responsible for more than half the haze in the Columbia Gorge at times of the winter.

Environmental groups have threatened to sue for more stringent controls at Oregon’s only coal plant. They say their original reaction is that the DEQ proposal isn’t enough.