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EPA proposes pollution controls for nation’s largest source of NOx: Four Corners Power Plant

Release Date: 10/06/2010
Contact Information: Margot Perez-Sullivan, (415) 947-4149,

Move would reduce 36,000 tons of NOx - equal to taking half the gasoline cars and trucks in Arizona off the road - improving public health and visibility

SAN FRANCISCO – Today, the U.S. Environmental Protection Agency proposed requiring additional pollution controls for the Four Corners Power Plant located on the Navajo Nation near Farmington, New Mexico to improve visibility and human health. EPA’s proposal will require plant operators to install the most stringent pollution control technology available for this type of facility.  These controls will reduce emissions of nitrogen oxides (NOx) from approximately 45,000 tons per year to 9,000 tons per year.

Every year over 280 million people visit our nation’s most treasured parks and wilderness areas. Yet, many visitors aren’t able to see the spectacular vistas because of the veil of white or brown haze that hangs in the air, reducing visibility and dulling the natural beauty.  There are 16 national parks and wilderness areas in the vicinity of the Four Corners Power Plant, including the Mesa Verde and the Petrified Forest. These controls are estimated to reduce the visibility impact by an average of 57% at these areas.

In addition to reducing visibility, nitrogen oxides (NOx) react with other chemicals to form ozone and small particles, both harmful to the public’s health. Ozone forms when nitrogen oxides and volatile organic compounds react in the presence of heat and sunlight. Children, the elderly, people with lung diseases such as asthma, and people who work or exercise outside are at risk for adverse effects from ozone and particulate matter.  

“The Four Corners Power Plant is the largest source of nitrogen oxides in the nation,” said Jared Blumenfeld, EPA’s Regional Administrator for the Pacific Southwest Region. “Adding new pollution controls at this 45-year old plant will reduce these emissions by 80%—we will all be able to see the results and breathe cleaner, healthier air.”

The Clean Air Act’s Regional Haze Rule requires the use of Best Available Retrofit Technology at older coal-fired power plants to reduce haze and improve visibility. EPA’s proposal is achievable by installing and operating Selective Catalytic Reduction on all five units at the plant. The installation and operation of SCR is estimated to increase the electricity bill for the average Arizona Public Service residential customer by about 70 cents per week.

SCR is cost effective technology that will result in the greatest visibility improvement of all devices the agency considered. When the proposal is finalized, the Four Corners Power Plant will have five years to add the controls. 

EPA will continue to consult with the Navajo Nation and other affected tribes, and the Federal Land Managers before taking any final action. There will be a 60-day public comment period on the proposed action as well as two public hearings in the Four Corners area.  

For additional information on the proposed rulemaking and opportunities to provide input, please go to: