Several Minnesota environmental groups are appealing the air and water permits issued last month for a project that could become the state's first copper-nickel mine.

The groups - Minnesota Center for Environmental Advocacy, Center for Biological Diversity and Friends of the Boundary Waters Wilderness - argue in filings made through the Minnesota Court of Appeals Tuesday that the Minnesota Pollution Control Agency was wrong in issuing the permits for PolyMet’s proposed copper-nickel mine near Hoyt Lakes because the agency failed to consider the possibility of a larger project.

A separate appeal filed by WaterLegacy focused on the water permits argues the MPCA should have held a contested case hearing, barred seepage that would cause water-quality violations and required pollution monitoring of nearby streams and wetlands. The group also contends that the MPCA “exceeded its authority” when issuing the permit “that would shield PolyMet from liability and preclude citizen enforcement of violations of water quality standards under the (Clean Water Act).”

In a statement, Minnesota Center for Environmental Advocacy CEO Kathryn Hoffman urged the MPCA to reconsider its air permits and require PolyMet “to install the best air emission technology available prior to construction.”

“By turning a blind eye to PolyMet’s plans for faster and more intense mining, the MPCA permits for PolyMet allow them to skirt the law and avoid stronger environmental protections,” Hoffman said.

The groups argue a report released by PolyMet in March outlines the company's plans to recover 118,000 tons of ore per day instead of 32,000 tons per day, the amount listed by the company in permit applications.

According to the MPCA, the air-emission permit sets requirements and enforces regulations on air pollutants and equipment emitting air pollutants while the water-quality permit sets limits and requirements on pollutant discharge and disposal systems

Reiterating a similar statement made in the past, PolyMet spokesperson Bruce Richardson said the company only intends to build the mine plan it has formally applied for.

“All the permits we have received from the state are based on a mine plan that was the subject of a 14-year-long environmental review and permitting process. We have no other mine proposals. Our focus right now is on building the mine for which we have received permits,” Richardson said. “Beyond that, we will not comment since this is the subject of active litigation.”

Last month, several of the same groups appealed mining permits issued to PolyMet by the Minnesota Department of Natural Resources in November.

PolyMet still needs a wetlands permit from the Army Corps of Engineers.

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.