DULUTH -- Several Minnesota environmental groups are appealing permits issued last month for a proposed copper-nickel mine in northern Minnesota.

In filings through the Minnesota Court of Appeals on Monday, Dec. 3, the Minnesota Center for Environmental Advocacy, WaterLegacy, Duluth for Clean Water, Center for Biological Diversity and Friends of the Boundary Waters Wilderness argued the Minnesota Department of Natural Resources failed to set attainable standards for PolyMet’s proposed copper-nickel mine near Hoyt Lakes when issuing key permits last month disregarded safety concerns regarding the dam holding back the tailings basin and should have held a contested case hearing  on the controversial mine. In a separate filing, the groups argue Minnesota’s non-ferrous mining rules are vague and, therefore, unenforceable.

“Our challenges to the permit to mine are primarily about what information is lacking and the fact that the permits, as written, don’t actually create enforceable standards against which PolyMet would be measured,” Aaron Klemz, director of public engagement for the Minnesota Center for Environmental Advocacy, said Monday afternoon.

In a statement Monday afternoon, DNR assistant commissioner Barb Naramore stood by the department's decision to grant PolyMet its permits.

“We understand that one or more organizations have appealed permit decisions that we made on the PolyMet project. We will be reviewing those appeals. We are confident that the permit decisions we made on November 1 are based on sound science, provide strong protections for Minnesota taxpayers, and are fully consistent with state law,” Naramore said. “These decisions are the product of more than 14 years of exhaustive review and reflect our careful consideration of more than 80,000 public comments.”

Chris Knopf, executive director of Friends of the Boundary Waters Wilderness, said that a contested case hearing, which would require an administrative law judge to examine additional evidence and testimony on the project, should be held on PolyMet as it has been on other large-scale projects in northern Minnesota, such as Enbridge Energy’s Line 3 oil pipeline.

But the DNR has argued it could only call for a contested case hearing if a project met certain criteria: Is there a material dispute of fact? Is that issue within the DNR's jurisdiction? Would the contested case process bring forward more information and insight?

When announcing the PolyMet permits last month, DNR commissioner Tom Landwehr said the project did not meet standards required for a contested case hearing.

"Our careful analysis of those conditions concluded that none of those met the three conditions in state statute so we declined to convene a contested case hearing," Landwehr said at the time.

Last month, the groups asked the DNR to suspend the permits issued to PolyMet until the Minnesota Court of Appeals rules on whether an additional environment review of the project is needed.

PolyMet still needs a wetlands permit from the Army Corps of Engineers and water and air quality permits from the Minnesota Pollution Control Agency.

If fully approved, the PolyMet mine would be the first of mine of its kind in the state.

PolyMet declined to comment Monday citing active litigation.

Opponents argue the project could send tainted runoff into the St. Louis River watershed and Lake Superior, while supporters say the project will provide more than 300 jobs on the Iron Range and move the area's economy away from iron ore dependence.