The state of Utah and a private power utility are fighting a mandate the federal government says will reduce pollution in national parks.

In July, the Environmental Protection Agency adopted a regional haze plan to reduce nitrogen oxide pollution in Grand Canyon, Arches, Zion, Bryce Canyon, and Capitol Reef National Parks.

The EPA is seeking more pollution controls at Rocky Mountain Power’s Hunter and Huntington coal fired power plants.

The agency rejected an alternative plan submitted by Utah that sought credit for last year’s closure of Rocky Mountain’s Carbon plant.

A federal law requires the restoration of “natural air conditions” in 156 parks by 2064.

A group of clean-air demonstrators delivered about 44,000 petitions to Rocky Mountain Power’s Salt Lake City Office in August in an attempt to dissuade the company from fighting the pollution controls.