Two of the Southwest's largest coal-fired power plants straddle the San Juan River in New Mexico, one within clear view of the other.

But one of them didn't factor into the Obama administration's plans to reduce carbon dioxide emissions across the nation because it is on an American Indian reservation.

The U.S. Environmental Protection Agency said it will delay emission standards for four power plants on reservations to talk further with the tribes and give them an opportunity to create their own cleanup plans. If they decline, the federal government will craft plans for them.

The two power plants on the Navajo Nation are among the country's top emitters of carbon dioxide. The other two generating stations are in northeastern Utah and western Arizona.