The Minnesota Court of Appeals hears arguments Thursday in a case involving the proposed expansion of the state's largest taconite mine.
U.S. Steel has proposed a 483-acre extension at Minntac in Mountain Iron. The company says it would extend the mine's life through 2031. An environmental review last year by the Minnesota Department of Natural Resources concluded the expansion would not create any significant environmental problems.
The Minnesota Center for Environmental Advocacy sued, arguing the agency should have completed a more thorough review. Minntac, the group says, is already polluting surrounding waterways and shouldn't be allowed to expand until it addresses those issues.
U.S. Steel has worked closely to resolve those issues and operates under a Clean Water Act permit, according to the DNR.