Navajo Transitional Energy Company

St. Louis-based Peabody declined to comment.

Litigation is a key tool to enforce many environmental laws.

As a tribal entity, NTEC normally would be able to claim sovereign immunity.

The agreement calls for NTEC to make one payment right away, then monthly for a year.

Negotiations between NTEC and Montana continue.

It agreed to pay tens of millions of dollars in royalties and taxes accumulated since May.

Officials say part of the agreement was that the Navajo Transitional Energy Company would pay royalties accumulated since May.

The Montana Department of Environmental Quality and the Navajo Transitional Energy Company have been negotiating.

CEO Clark Moseley said in a statement that the company appreciated efforts by the state to keep Spring Creek working.