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Contact EPA Pacific Southwest Air Program

Pacific Southwest, Region 9

Serving: Arizona, California, Hawaii, Nevada, Pacific Islands, Tribal Nations

Air Actions, Navajo Nation

Four Corners Power Plant

Final Federal Implementation Plan 4/30/07
PDF version of this fact sheet

Today’s Action

  • EPA is finalizing a Federal Implementation Plan (FIP) under the Clean Air Act (CAA) to regulate emissions from the Four Corners Power Plant (FCPP), located on the Navajo Indian Reservation in New Mexico.
  • This FIP will ensure protection of tribal air resources and air resources in the Four Corners area.
  • This FIP establishes federally enforceable emissions limitations for sulfur dioxide, nitrogen oxides, total particulate matter, and opacity, and a requirement for control measures for dust.


  • The plant was previously complying with emissions limits in the New Mexico State Implementation Plan. However, EPA’s promulgation of the Tribal Authority Rule clarified that State air quality regulations generally could not be extended to facilities located on the Indian reservation. It is therefore appropriate for EPA to issue federally enforceable emissions limitations for FCPP.
  • The FCPP is a 2,040 megawatt (MW) coal-fired power plant located on the Navajo Indian Reservation near Farmington, New Mexico. The FCPP consists of five units which became operational between 1962 and 1970. The Arizona Public Service Company (APS) is the operating agent for FCPP which is jointly owned by the APS, the Southern California Edison Company, the Salt River Project Agricultural Improvement and Power District (SRP), the Public Service Company of New Mexico, the El Paso Electric Company, and the Tucson Electric Power Company.
  • Existing pollution control equipment at FCPP includes baghouses and scrubbers for SO2 control and specific burners designed for NOx control.
  • On July 26, the Sierra Club filed a complaint in U.S. District Court for the District of New Mexico requesting that the EPA take final action on a federal plan. Consistent with a December proposed consent decree, the EPA finalized its 2006 proposed federal plan.

Contact Information

Colleen McKaughan (mckaughan.colleen@epa.gov)
Air Division
(520) 498-0118

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