ST. PAUL  — The Department of Natural Resources has rejected a request by environmentalists to extend the public comment period on the draft dam safety permits for the planned PolyMet copper-nickel mine in northeastern Minnesota.

The DNR said in a statement Friday the 30-day comment period will close as scheduled Oct. 16.

Five environmental groups told the DNR in their requests this month that 30 days wasn’t enough time for them or the public to submit adequate responses. They cited the importance of the permits to the project, the complexity of the issues involved, the thousands of pages of supporting documents and the potential safety risks.

The groups were the Minnesota Center for Environmental Advocacy, WaterLegacy, the Center for Biological Diversity, Friends of the Cloquet Valley State Forest and the Izaak Walton League.