Arizona Attorney General Tom Horne is asking the U.S. 9th Circuit Court of Appeals to overturn the Environmental Protection Agency's decision to require three Arizona power plants to reduce their emissions.

The EPA is requiring the Cholla, Coronado and Apache generating stations to retrofit the operations to reduce visible pollution. All are coal-fired.

The Clean Air Act calls for improved visibility at national parks like the Grand Canyon. The EPA says the plants need to reduce their emissions in order to come into compliance with the law.

Horne says the proposed rule is what he calls a “bureaucratic overreach” and that is why he wants the 9th Circuit to step in.

“These regulations have nothing to do with health, they only have to do with visibility," Horne said. "And the difference in visibility is not perceptible to the human eye.”

Horne’s challenge deals specifically with the Cholla, Coronado and Apache power plants but could also affect the Navajo Generating Station near Page, which is subject to similar requirements.