"This is definitely something that allows PNM to continue to provide reliable power at really the lowest cost possible in an environmentally responsible way," he said.
While the agreement just misses the haze requirement by an amount undetectable by the human eye, supporters say it will result in significant reductions in greenhouse gas emissions such as carbon dioxide as well as sulfur dioxide, nitrogen oxide and mercury emissions. In many cases, the percentages would be cut in half.
The agreement is the basis for developing a state implementation plan that would have to be approved by a state regulatory panel and then the EPA. That process could take a year or two, said EPA regional administrator Ron Curry.
"We're hopeful that everybody sees there are more benefits here than anything else," Curry said. "Any agreement like this, where you start as far apart as they were years ago and even months ago, there has to be some give and take."
Environmentalists said closing part of the aging San Juan plant marks the beginning of a shift in a state that has relied heavily on coal-fired power.
Given the extensive infrastructure surrounding natural gas development in the Four Corners, PNM officials acknowledged Friday that it would not be out of the realm of possibility to see a large gas-fired plant in the region in the next 15 years.