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Mercury Regulation

Mercury and Air Toxics Standards (MATS) Rule

On December 16, 2011 EPA Administrator Jackson signed a final rule regulating mercury and other hazardous air pollutant (HAPs) emissions from coal- and oil-based power plants, and revising new source performance standards (NSPS) for all fossil fuel-based power plants.  The final Mercury and Air Toxics Standards (MATS) rule was published on February 16, 2012 and became effective April 16.  EPA expects that most facilities will upgrade currently installed controls and/or install one or more controls to comply with this rule in the 2015-2016 timeframe.

The final rule establishes emission limits for mercury, filterable particulate matter and hydrogen chloride, and work practice standards for organics and dioxins.  The final rule also includes NSPS for nitrogen oxides, sulfur dioxide and filterable particulate matter.

History of Mercury Regulation
  • On December 20, 2000, EPA issued a “regulatory determination” under the Clean Air Act that regulation of mercury is “appropriate and necessary” for coal- and oil-fired power plants.”
  • In 2001-2002, EPA held meetings of a Utility MACT Working Group under the Clean Air Act Advisory Committee (CAAAC).  In October 2002, the final report of the Working Group was submitted to the CAAAC. 
  • On December 15, 2003, EPA issued Proposed Mercury Rules for coal- and oil-based power plants. The proposed mercury rules primarily focus on coal-based power plants, and include two alternative control plans: 
    • A proven, market-based cap-and-trade approach that would require emissions reductions from new and existing facilities in two phases, or 
    • A MACT standard.  
  • On March 15, 2005, EPA issued its final CAMR for coal-based power plants. The CAMR utilized a market-based cap-and-trade approach under section 111 of the CAA to require emissions reductions in two phases: a cap of 38 tons in 2010, and 15 tons after 2018, for a total reduction of 70 percent from current levels. In addition to the CAMR, EPA published a final Agency action which reversed the regulatory finding that it issued in December 2000.
  • On February 8, 2008, the U.S. Court of Appeals for the District of Columbia Circuit issued an opinion in a case, which was initiated by 15 states and other groups, challenging the CAMR and EPA's decision to "delist" mercury as a hazardous air pollutant. The Court held that EPA's reversal of the December 2000 regulatory finding was unlawful. The Court vacated both the reversal and the CAMR, and sent the CAMR back to EPA for reconsideration.
  • On February 6, 2009, the Obama Administration indicated that it would accept the Court of Appeals' decision and would develop new MACT standards for the utility industry under section 112 of the CAA.
  • In October 2009 EPA agreed to a proposed consent decree which required EPA to propose standards addressing mercury and other emissions by March 16, 2011, and finalize standards by November 16, 2011.
  • On April 15, 2010, the consent decree was approved.
  • On March 16, 2011, the EPA Administrator issued the Mercury and Air Toxics Standards (MATS) proposal as per the consent decree.
  • On December 16, 2011, EPA released the final MATS rule. 
  • On April 16, 2012 the final MATS rule was effective​.
  • On April 16, 2015 compliance with the MATS rule began.