The Arizona Corporation Commission is criticizing recent actions by the U.S. Environmental Protection Agency to clean up the state’s power plants.

The commission voted Tuesday to file an amicus brief in federal appeals court supporting the state’s challenge to pollution control upgrades at three coal-fired power plants.

The EPA partially approved Arizona’s air quality plan for the Cholla, Coronado and Apache generating stations. But the agency set its own limits for nitrogen oxide emissions and gave the plants’ operators five years to comply.

The commission says the EPA’s decision doesn’t strike the right balance of environmental stewardship and protection of Arizona’s economy.

The commission says it also will weigh in against a proposal for pollution control upgrades at the Navajo Generating Station. Public comments are due Aug. 5.