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United States: EPA Regulations on Power Plant Mercury Emissions Stuck Down

(Feb. 2, 2008) On February 8, the U.S. Court of Appeals for the District of Columbia Circuit invalidated two rules promulgated by the Environmental Protection Agency ("EPA") concerning electric utility steam generating units ("EGUs"). The first rule removed coal- and oil-fired EGUs from the list of sources whose emissions are regulated under section 112 of the Clean Air Act ("CAA"). The second rule set mercury emission standards for coal-fired EGUs pursuant to Section 111 of the CAA, establishing a more lenient standard than would have been required under Section 112.

In December 2000, the EPA listed coal- and oil-fired power plants under section 112 of the CAA, stating it was "appropriate and necessary" to regulate mercury emissions of EGUs under this section. Once listed, a source of pollutants can be removed from the list only after the EPA has determined that "emissions from no source in the category or subcategory concerned . . . exceed a level which is adequate to protect public health with an ample margin of safety and no adverse environmental effect will result from emissions from any source." In 2005 the EPA removed EGUs from the section 112 list, and promulgated regulations concerning EGU mercury emissions under the more lenient section 111.

The court found that the EPA had not made the specific findings required by section 112 in order to remove a source of hazardous air pollutants from the list; as a result, the delisting was invalid. It ruled that section 112 was unambiguous, and the EPA's interpretation of the statute violated the section's plain language. The court held that the regulations promulgated under section 111 were also invalid, since EGUs were still governed by the provisions of section 112. (State of New Jersey v. Environmental Protection Agency, No. 05-1097 (D.C. Cir. Feb. 8, 2008) available at