A lawsuit filed in 2011 has led to an agreement designed to reduce pollution impacting national parks throughout the Southwest. Additionally, the settlement reached with the U.S. Environmental Protection Agency and the owners of the Four Corners Power Plant in New Mexico calls for $8.2 million in penalties and other mitigation costs.

The settlement was announced Wednesday by the National Parks Conservation Association, which along with other organizations was represented by Earthjustice in the action.

“For far too long, the irresponsible management of Four Corners has denied the Navajo people the basic human right to clean, healthy air in our communities,” said Lori Goodman, board member of Diné Citizens Against Ruining Our Environment. “Now with this settlement, Four Corners will have to take steps to stop poisoning our air and start moving toward a healthier future.”

Four Corners, located on the Navajo Nation in New Mexico, is responsible for dirtying the air in Grand Canyon National Park and 15 other national parks in the Southwest, NPCA said in a release, adding that "over the last 30 years, the owners of the plant made changes that resulted in additional pollution."

Under the consent decree, the plant is to reduce emissions of nitrogen oxides and sulfur dioxide –major contributors to both respiratory health problems and haze in the parks. The owners will also pay $1.5 million in civil penalties and $6.7 million in healthcare and other mitigation costs for the affected communities, the NPCA release said.

“Pollution from Four Corners has sickened local communities for decades despite plenty of opportunities for the plant to clean up its act,” said Nicole Horseherder of To’ Nizhoni Ani. “Today's agreement provides a much needed investment in the health and well-being of those residents.”

“After years of dangerous pollution, this settlement is a welcome shift toward a cleaner, more just future for the people and parks of the Southwest,” said Kevin Dahl, Arizona senior program manager for NPCA. “Clearer skies over parks like Mesa Verde and Petrified Forest are good news for visitors, nearby communities, and the local economy.”

Once the nation’s single largest source of nitrogen oxide emissions, Four Corners’ pollution has long been recognized as a threat to the region’s health, said NPCA. In 2009, NPCA and Diné CARE submitted comments to the EPA demonstrating that the Regional Haze Rule—the Clean Air Act program designed to reduce air pollution in national parks—required Four Corners to clean up its emissions. The following year, the EPA proposed limits that cut 85 percent of the plant’s nitrogen oxide emissions.

Plant owners offered their own pollution mitigation plan, which called for closing the first three coal units at Four Corners and installing best controls for nitrous oxide pollution at the remaining two units. Those first three units closed at the end of 2013.