In a win for tribal cultural rights, the U.S. Department of the Interior said Monday that it intends to cancel an oil and gas lease on national forest land in the Badger-Two Medicine region. The cancellation could be finalized before the end of the year, but a District of Columbia federal court must sign off on it.

DOI attorneys filed a court memorandum Monday that said not only would they cancel the Solonex LLC lease on 6,200 acres in the Badger-Two Medicine south of Glacier National Park but also they didn’t see any reason to delay the cancellation. Interior Secretary Sally Jewell would make the final decision given the court's approval.

After trying to negotiate with Solonex to no avail, Blackfeet tribal Chairman Harry Barnes and other tribal leaders applauded the news, according to indianz.com.

“Badger-Two Medicine is too sacred to develop,” Barnes said. “We’re grateful this administration has taken a critical step toward permanent protection of this site that is like a church -- a divine sanctuary -- to our people.”

In 1981, Solonex owner Sidney Longwell applied for the lease, which then-Interior Secretary James Watt approved in 1982 along with several other leases without conducting studies of how surface disturbance would affect the environment.

On Monday, the attorneys said the main justification for cancellation was that the lease was illegally issued in the first place.

Assistant Attorney General John C. Cruden wrote that the Bureau of Land Management “has tentatively concluded the Lease was issued without properly complying with (the National Environmental Policy Act) and the (National Historic Preservation Act). For example, in this case, the agencies authorized and issued the Lease without the benefit of an Environmental Impact Statement to inform its decision-making.”

They cited judicial rejection of two other Montana leases issued without EIS studies around the same time. They also argued that Congress has since put a permanent ban on any new oil and gas leases in the Badger-Two Medicine.

Since the 1980s, Longwell’s lease has been held up by numerous Forest Service delays and suspensions, 11 appeals, seven ethnographic studies and one archeological study.

In 2012, the Lewis and Clark National Forest finally concluded under the NHPA that the lease area overlays areas of tribal historical significance. That led to Solonex’s recent lawsuit.

The DOI had previously predicted that cancellation of the lease would take until March 30 because the BLM, which oversees all oil and gas leases on federal land, would need time to review the decision.

But in the document filed Monday, the attorneys said the decision could be completed by Dec. 11. BLM would not need to do an environmental assessment because Solonex had not yet begun any exploration therefore, “cancellation thus does not alter the environmental status quo.”

Solonex has 10 days to respond to the DOI filing.

Blackfeet leaders expect Solonex to challenge the DOI decision and indicated that they would push for permanent protection of the Badger-Two Medicine. They have the support of Sen. Jon Tester, who asked the Obama Administration in July to cancel the other 18 leases that exist in the Badger-Two Medicine.