The partial shutdown of two coal-fired power plants on the Navajo Nation would have been enough for the tribe to meet the federal government's proposed limits for carbon dioxide emissions.
But the final rule issued by the U.S. Environmental Protection Agency this week creates uncertainty.
The new targets in the EPA's Clean Power Plan are more stringent than proposed last year. The utilities that operate the coal-fired Navajo Generating Station near the Arizona-Utah border and the Four Corners Power Plant in northwestern New Mexico say previous and planned shutdowns of units might not be enough to satisfy the limits.
Since states don't have jurisdiction over reservations, the tribes can create implementation plans or defer to the federal government.
The limits on the reservation plants won't factor into state goals.
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