CENTRALIA, Wash. - A final agreement between the Washington Department of Ecology and TransAlta, the company that owns the coal-fired power plant in Centralia, was released on Monday. It outlines plans to reduce the plant's haze-causing nitrogen oxide pollution and mercury contamination.

Conservation groups had been waiting on the sidelines for a year during the closed-door negotiations. Now, they say the final plan is no different than a draft they saw months ago, and doesn't do enough to fix the problems. Jannette Brimmer, an attorney for Earthjustice, says a 50 percent mercury reduction starting in 2012 is one example.

"It's much, much less than what technology shows they can do. Mercury removal, with the kind of technology that TransAlta is going to use, can be 90 percent or better. So, they're not doing much and what they are doing, that 50 percent, is essentially voluntary."

Earthjustice represents several groups, including the National Parks Conservation Association (NPCA) and the Sierra Club, that have been demanding the Centralia plant clean up or close.

In the agreement, TransAlta cites data saying it is responsible for only a fraction of the nitrogen oxide that makes up the haze in the region. The company also says it will burn a type of coal obtained from the Powder River Basin area of Wyoming and Montana that contains less sulfur, ash and nitrogen. But NPCA attorney Stephanie Kodish says those positions are nothing new.

"The substantial visibility impairment that results from TransAlta's coal plant is still dramatic, on a dozen Class I protected National Parks and Wilderness Areas, as well as the Columbia River Gorge. Our concerns remain outstanding and unaddressed through this agreement."

The Ecology Department says the agreement satisfies what is known as the "Best Available Retrofit Technology" for such a plant and that, as an older coal plant, Centralia should not be held to the same pollution standards as newer plants.

The agreement and related documents are online at www.ecy.wa.gov.