Four Corners Steam Plant

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Four Corners Steam Plant is an operating power station of at least 1636-megawatts (MW) in Fruitland, San Juan, New Mexico, United States with multiple units, some of which are not currently operating.


Table 1: Project-level location details

Plant name Location Coordinates (WGS 84)
Four Corners Steam Plant Fruitland, San Juan, New Mexico, United States 36.689369, -108.480339 (exact)

The map below shows the exact location of the power station.

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Unit-level coordinates (WGS 84):

  • Unit 2, Unit 3, Unit 4, Unit 5, Unit 1: 36.689369, -108.480339

Project Details

Table 2: Unit-level details

Unit name Status Fuel(s) Capacity (MW) Technology Start year Retired year
Unit 2 retired coal - subbituminous 190.1 subcritical 1963 2013
Unit 3 retired coal - subbituminous 253.4 subcritical 1964 2013
Unit 4 operating coal - subbituminous 818.1 supercritical 1969 2031 (planned)
Unit 5 operating coal - subbituminous 818.1 supercritical 1970 2031 (planned)
Unit 1 retired coal - subbituminous 190.1 subcritical 1963 2013

Table 3: Unit-level ownership and operator details

Unit name Owner
Unit 2 Arizona Public Service Co [100.0%]
Unit 3 Arizona Public Service Co [100.0%]
Unit 4 Public Service Company of New Mexico [13.0%], Salt River Project (SRP) [10.0%], Tucson Electric Power Co [7.0%], Arizona Public Service Co [63.0%], 4C Acquisition LLC [7.0%]
Unit 5 Arizona Public Service Co [63.0%], El Paso Electric Co [7.0%], Public Service Company of New Mexico [13.0%], Salt River Project (SRP) [10.0%], Tucson Electric Power Co [7.0%]
Unit 1 Arizona Public Service Co [100.0%]

Retirement discussions

In December 2013, APS closed three of the oldest coal units (built 1963-4) to comply with EPA regulations, but said it would keep Units 4 and 5 active (built in 1969-70).[1]

In 2018, the state Public Regulation Commission accepted a Public Service Company (PNM) of New Mexico three-year plan that called for shuttering two coal-fired power plants in the northwestern part of the state and more reliance on renewable energy, along with fossil gas and nuclear energy. PNM was planning to close Four Corners Power Plant by 2031.[2]

In March 2021, Arizona Public Service Co. (APS), an owner and operator of the Four Corners Power Plant, announced plans of an agreement among plant owners Navajo Transitional Energy Company (NTEC), Public Service Company of New Mexico (PNM), Salt River Project (SRP) and Tucson Electric Power (TEP) to move toward operating the plant seasonally beginning fall 2023, subject to necessary approvals.[3]

In December 2021, as noted below, regulators rejected PNM's plan to transfer its 13% share of the plant to Navajo Transitional Energy Co. (NTEC). Unable to find a buyer for its Four Corners share, PNM had agreed to pay NTEC $75 million to take PNM's share of the plant. Exiting coal generation in 2024, rather than 2031, would have eliminated 6.5 years of Four Corners coal plant costs, said PNM.[4][5]

Emissions Data

  • 2006 CO2 Emissions: 16,395,797 tons
  • 2006 SO2 Emissions: 15,192 tons
  • 2006 SO2 Emissions per MWh:
  • 2006 NOx Emissions: 44,649 tons
  • 2005 Mercury Emissions: 563 lb.

Legal challenges

In July 2007 the EPA, as a result of a legal challenge by the Sierra Club and others, issued a plan to regulate pollution from the Four Corners plant. However, the Sierra Club believed that instead of issuing a plan to protect public health, the agency simply created a plan to "fill the gap they left by not regulating Four Corners in the first place."

On July 5, 2007 the Sierra Club took legal action against the EPA to force the agency to "live up to their responsibility to the health and safety of local communities."[6]

Four Corners in the Crosshairs.

On February 18, 2010, a coalition of environmental groups petitioned the U.S. Department of Interior and Department of Agriculture to declare the Four Corners plant in violation of the Clean Air Act and require reduced pollution.[7] The petitioners (including Earthjustice, the Sierra Club, the San Juan Citizens Alliance, the Center for Biological Diversity, Dooda Desert Rock, Diné CARE, WildEarth Guardians and the Grand Canyon Trust) note that the plant is the largest source of air pollution in New Mexico and is less than 200 miles from 16 national parks and wilderness areas.[8]


APS to purchase SCE share and close Four Corners Steam Plant Units 1, 2, and 3

On November 8, 2010, Arizona Public Service announced that it had entered into an agreement to purchase Southern California Edison's share of Four Corners Steam Plant Units 4 and 5, which it plans to retrofit with additional emission controls. The company will close Units 1, 2, and 3. There will be no layoffs at the plant, which employs 549 workers, 74 percent of whom are Navajo.[9] Closing the three units will reduce the capacity of Four Corners by 633 megawatts (nameplate capacity) or 560 megawatts (net summer capacity). Units 1 and 2 were built in 1963, and Unit 3 was built in 1964.

Southern California Edison to divest from Four Corners

On March 30, 2010, Southern California Edison (SCE) informed Arizona Public Service (APS) of the company's intentions to divest its 48 percent stake of Four Corners Power Plant by 2016. According to APS, Southern California Edison announced it did not plan to sell its shares on the open market. Among the issues that may have prompted SCE to divest its interests are proposed legislative initiatives to regulate carbon from power plants, Best Available Retrofit Technology requirements for the plant by fall 2010, and the possible regulation of coal fly ash as a hazardous waste.[10]

In October 2010, the California Public Utilities Commission signaled that it would no longer allow investments at Four Corners Steam Plant after 2012, in compliance with SB 1368, the Emissions Performance Standard. The law, passed in 2006, prohibited new ownership investment in power plants that fail to meet minimum performance standard for carbon emissions. Southern California Edison owns 48% of two of the generating units at Four Corners.[11]

In November 2010 Edison International announced its intention to sell its share of the Four Corners Steam Plant to Pinnacle West Capital Corp. (PNW) unit Arizona Public Service Co. for the price of $294 million. Edison will sell its 48% stake in Units 4 and 5 of the plant, which at the time was still subject to approval from federal and state regulators in Arizona and California, Edison spokesman Gil Alexander said.[12]

2021 developments

In December 2021, regulators rejected Public Service Company of New Mexico's (PNM) plan to transfer its 13% share of the Four Corners coal plant to Navajo Transitional Energy Co. (NTEC), citing the utility's failure to identify or propose replacement resources for the 200 MW of power it owns. The decision by the New Mexico Public Regulation Commission (PRC) was "disconcerting," PNM said in a statement, as selling its share of the plant would have saved customers up to $300 million and helped the utility abandon coal generation almost seven years ahead of current plans. Environmental advocates cheered the decision, however. PNM's proposal could have left Four Corners operating "indefinitely," according to Sierra Club. And New Energy Economy (NEE) said the denial means PNM's investments in the plant will now face a prudence review.[4]

EPA proposes nitrogen oxides at Four Corners

In October 2010 the Environmental Protection Agency proposed pollution controls that would mean an 80 percent reduction in smog-causing nitrogen oxides from the Four Corners Power Plant on the Navajo Nation.

EPA officials said their proposal would require Arizona Public Service Company to install selective catalytic reduction on all five of its operating units.

Jared Blumenfeld, regional administrator for EPA's Region 9, said the Four Corners plant is the largest single source of nitrogen oxides in the United States.

The proposed controls would reduce emissions of nitrogen oxides from about 45,000 tons per year to 9,000 tons per year, and improve both public health and visibility at 16 national park sites in the area, the EPA stated.[13]

Judge Suspends Navajo Mine Permit

In early November 2010 a federal judge voided a permit for the expansion of the operating permit for the Navajo mine located on the Navajo reservation in New Mexico. It was one of two mines at the location that has sought expansion permits. The judge called for a more thorough review of the project’s impact on the environment and on cultural sites.

“This whole area has been utilized for thousands of years by indigenous people,” said Mr. Bartlett, a lawyer at the nonprofit Energy Minerals Law Center in Durango, Colorado. “This is where people have buried kin.”

The decision “sends a very clear signal that it’s time for this agency to do its job,” Mr. Bartlett added.

BHP Billiton owns the mine, which feeds the Four Corners Generating Station, also on Navajo land in New Mexico.[14]

Coal waste Sites



  1. "APS closes 3 units at 4 Corners power plant," AZ Central, Dec 30, 2013.
  2. "New Mexico regulators approve utility plan to shut San Juan coal plant, sell Four Corners stake" Archived by Waybackmachine, accessed on May 31, 20203.
  3. "APS announces plans for seasonal operations at Four Corners Power Plant," APS, March 12, 2021
  4. 4.0 4.1 "New Mexico denies PNM bid to exit Four Corners coal plant, citing lack of replacement resources," Utility Dive, December 16, 2021
  5. "PNM Accelerates Full Exit of Coal to 2024," PNM Resources, Inc., November 2, 2020
  6. “Cleaner Air for the Four Corners Power Plant in New Mexico" Sierra Club, accessed January 12, 2010
  7. "Environmental Groups Ask Feds to Require Reduced Pollution from Four Corners Power Plant", Jim Burnett, National Parks Traveler, February 19, 2010.
  8. "Air Quality: Request to clean up Four Corners timely", The Durango Herald, February 18, 2010.
  9. "APS Announces Landmark Accord for Four Corners Power Plant," APS press release, November 8, 2010
  10. "SCE divesting of Four Corners; APS looks to buy share," Kathy Helms, Gallup Independent" March 30, 2010.
  11. "California Gets Closer to Closing the Door on Coal" Noah Long, Natural Resource Defense Council, October 18, 2010.
  12. "Edison International To Sell Its Share Of Four Corners Plant" Dow Jones Newswire, November 9, 2010.
  13. "EPA proposes nitrogen oxides reduction at NM plant" Sue Major Holmes, Bloomberg, October 7, 2010.
  14. "Judge Suspends Navajo Mining Permit" Mireya Navarro, New York Times, November 1, 2010.

Articles and Resources


Additional data

To access additional data, including an interactive map of coal-fired power stations, a downloadable dataset, and summary data, please visit the Global Coal Plant Tracker on the Global Energy Monitor website.