(Photo by Alan Stark - CC BY 2.0)

Cholla Power Plant in northeastern Arizona.

Conservationists are calling on the state to impose tighter restrictions on a coal-fired power plant in northeastern Arizona. The public comment period for the permit ended Tuesday.

The Cholla Power Plant has been a source of contention for some time. In 2012, the Environmental Protection Agency shot down Arizona’s plan to improve visibility in National Parks. The state then sued the EPA.

Now, APS and PacifiCorp, which run Cholla, along with the state have a new proposal. It requires two of the coal fired units to shut down in 2025, but keeps the status quo until then.

Kevin Dahl with the National Parks Conservation Association said his organization is concerned “that leaves the area places like Petrified Forest and Grand Canyon National Parks with less clean air for the next ten years."

Dahl's organization would like the utility to implement "cost effective controls," which he said will "prevent a whole bunch of nitrogen oxides from being released into air.”

But the state and the utilities argue that is actually not cost effective, especially because the proposed permit requires the plant to shut down the units eventually. 

“This permit actually provides us a path forward for achieving environmental benefits, while reducing the economic impact to the state," said Eric Massey, director of the air quality division for the Arizona Department of Environmental Quality.  

He said that will give APS enough time "to plan for the change in electricity generation.”

The state will now seek approval from the EPA.