CHEYENNE, Wyo. (AP) – Lawyers have finished filing mountainous briefs in a case pitting the federal government and two Indian tribes against the state of Wyoming and local governments over whether the city of Riverton is legally Indian Country.

Lawyers filed thousands of pages of briefs and exhibits this week with the 10th Circuit Court of Appeals in Denver.

The filings generally are repeats of earlier material, only updated so they all can cite a common appendix of documents. With that last step out of the way, it’s now up to the court to schedule oral arguments, which lawyers expect sometime this winter.

The case concerns a 2013 ruling by the U.S. Environmental Protection Agency that the city of Riverton and surrounding lands are legally part of the Wind River Indian Reservation.

The EPA addressed the issue in granting an application from the Northern Arapaho and Eastern Shoshone tribes to treat their shared reservation as a separate state under air quality statutes.

The EPA concluded that a 1905 federal law that opened over 1.4 million acres of the Wind River Indian Reservation to settlement by non-Indians didn’t extinguish the land’s reservation status.

The agency’s decision prompted immediate protests from Gov. Matt Mead and local government officials, who appealed it to court. Mead has maintained that it’s up to Congress to determine reservation boundaries.

“I firmly believe that a decision of this significance should not come from a regulatory agency, especially when it goes against over 100 years of history, law and practice,” Mead said early last year in announcing the state’s appeal.

Mead and other state officials have warned that an ultimate finding that Riverton and surrounding lands remain on the reservation would have an effect on provision of state services in the area including law enforcement, education and environmental regulation.

Michael J. McGrady, supervisor of the Natural Resources Section in the Wyoming attorney general’s office, declined comment Friday on the state’s case.

The EPA and the tribes maintain that the question of whether the 1905 congressional action reduced the size of the reservation shouldn’t be litigated again because they say the courts already rejected that argument in a 1980s lawsuit over water rights in the Bighorn River.

“Historically, Wyoming has shown a proclivity to marginalize the interests of Native American tribes,” the Northern Arapaho Tribe stated in its brief filed this week. “This is not the first time that Wyoming has sought a court ruling that would strip the 1905 Act area of its reservation status.”

Andy Baldwin, a lawyer for the Northern Arapaho Tribe, declined comment on Friday.

Lawyers for Riverton and Fremont County say the court ruling on the Bighorn River water rights doesn’t settle the reservation boundary question.

The Wyoming Farm Bureau also has weighed in on the case, saying it would burden its members in the disputed area to find themselves suddenly subject to tribal jurisdiction.

“The state of Wyoming has exercised civil and criminal jurisdiction over the disputed area since the 1905 Act,” the Farm Bureau stated in its brief.

Steven J. Lechner, lawyer with the Mountain States Legal Foundation – a Colorado-based law firm that specializes in representing private property rights – is representing the Farm Bureau.

A court ruling upholding the EPA decision that Riverton and surrounding lands are Indian Country would throw the area into confusion, Lechner said.

He said Farm Bureau members in the affected area would be left unclear about where to go to get government services such as air quality permits.