CHEYENNE, Wyo. (AP) — The Northern Arapaho Tribe says the U.S. Department of Justice is trying to block tribal efforts to gain authority to monitor air quality on the Wind River Indian Reservation and the surrounding area.

Gov. Matt Mead, the Fremont County Commission and others are opposing a pending application from the Northern Arapaho Tribe and the Eastern Shoshone Tribe.

The tribes have asked the U.S. Environmental Protection Agency to recognize areas around Riverton as being within the reservation boundaries.

Wyoming maintains Congress excluded the areas from the reservation over a century ago.

The Northern Arapaho Business Council this month wrote U.S. Attorney General Eric Holder saying the Justice Department blocked the EPA from releasing a decision this summer.

A spokesman for the U.S. Attorney's Office in Cheyenne declined comment.