From an article in the Wausau Daily Herald:

ROTHSCHILD — The massive coal-fired power plant Weston 4 must limit the visibility of pollutants leaving its main smokestack but does not need tighter controls for other emissions, an appeals court ruled today.

A three-judge panel of the District 4 Court of Appeals agreed with the Sierra Club that the state Department of Natural Resources erred when it did not require the smokestack for the plant’s main boiler to follow a federal visibility standard for pollutants on its air pollution permit.

Limiting the visibility of emissions effectively limits the amount of harmful particulate matter that becomes airborne. The DNR and the plant’s operator, Wisconsin Public Service Corp. of Green Bay, argued the visibility standard was unnecessary because emissions of particulate matter and sulfuric acid from the boiler were controlled in other ways.

The appeals court sided with the environmental group, which argued that the visibility standard was clearly required under the Clean Air Act. The rule will require continuous monitoring to ensure the pollution leaving the smokestack meets an opacity standard — that it is much closer to invisible than a thick black cloud of dust.

The court rejected the Sierra Club’s argument that the plant needs to install different technology to further reduce emissions of sulfur dioxide and nitrogen oxide. The court found the limits set by the DNR were appropriate.

The $774 million plant near Wausau opened in 2008. It is owned by WPS and Dairyland Power Cooperative of La Crosse, and they say it is one of the cleanest coal plants in the nation.

The Sierra Club says it is nonetheless one of the largest pollution sources in central Wisconsin and has fought for years to strengthen the air permit.