Four Corners Generating Station

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Not to be confused with Navajo Generating Station.
The Four Corners Generating Station shown in a 1972 photograph.

The Four Corners Generating Station is a coal-fired power plant located near Fruitland, New Mexico, United States, on property located within the Navajo Indian Reservation that is leased from the Navajo Nation.


The Four Corners Generating Station originally consisted of five units with a total rated generating capacity of about 2,040 megawatts. Units 1, 2, and 3 (permanently shut down in 2014 as part of a $182 million plan for Arizona Public Service Co. to meet environmental regulations)[1] had a combined generating capacity of 560 megawatts while units 4 and 5 each have a generating capacity of 770 MW. Units 1, 2 and 3 opened in 1963-64 and Units 4 and 5 opened in 1969-70.

The Arizona Public Service Company (APS) owns 100% of Units 1, 2, and 3, while Units 4 and 5 are operated by APS but owned by five companies, with APS owning 63%,[2] Public Service Company of New Mexico 13%, Salt River Project 10%, Tucson Electric Power 7%, and El Paso Electric 7%.

The station is cooled using water from Morgan Lake, which is man-made and is replenished by about 28 million gallons of water each day from the San Juan River. The plant burns sub-bituminous coal delivered from the nearby Navajo Coal Mine by the Navajo Mine Railroad.


The Four Corners Generating Station was constructed on property that was leased from the Navajo Nation in a renegotiated agreement that will expire in 2041.[3] Unit 1 and Unit 2 were completed in 1963, Unit 3 was completed in 1964, Unit 4 was completed in 1969, and Unit 5 was completed in 1970.

In 1975, New Mexico enacted a tax on the generation of electricity and an in-state credit such that only electricity exported out-of-state was subject to the tax. Objections to this tax led to two United States Supreme Court cases. In Arizona v. New Mexico (1976), on a motion seeking to invoke the original jurisdiction of the Supreme Court, the court initially decided not to be involved and denied the motion, leaving the matter to the state court.[4] The owners of Four Corners filed an action in state court to declare the tax invalid, leading to the United States Supreme Court decision Arizona Public Service Co. v. Snead (1979), which held that the tax violated the Supremacy Clause of the United States Constitution.[5]

In November 2010, APS announced that it would purchase the SCE share of Units 4 and 5, add air pollution control systems to these units, and shutdown Units 1, 2, and 3.[3][6] Following the shutdown of Units 1 through 3, the capacity of Four Corners will be 1,540 megawatts. This proposed transaction is being reviewed by various regulatory authorities and should close in the last half of 2012.[3]


  1. ^
  2. ^
  3. ^ a b c "Pinnacle West SEC Form 8-K". Nov 8, 2010. Retrieved Mar 3, 2011. 
  4. ^ Arizona v. New Mexico, 425 U.S. 794 (1976).
  5. ^ Arizona Public Service Co. v. Snead, 441 U.S. 141 (1979).
  6. ^ Helms, Kathy (Nov 25, 2010). "AZ Public Service To Buy Edison's Share In Four Corner's Coal Plant". Gallup Independent. Retrieved Mar 3, 2011. 

Coordinates: 36°41′17″N 108°28′37″W / 36.688°N 108.477°W / 36.688; -108.477