Polymet Mining Corp (PLM)

[Robert H]

PolyMet Reports Completion Of Drafting of Preliminary EIS

St. Paul, Minnesota, May 13, 2013 – PolyMet Mining Corp. (TSX: POM; NYSE MKT: PLM) (“PolyMet” or the “Company”) has been notified by the Minnesota Department of Natural Resources (“MDNR”) that ERM, the independent EIS Contractor, has completed drafting the preliminary supplemental draft Environmental Impact Statement (“EIS”) analyzing PolyMet’s 100%-owned copper-nickel-precious metals NorthMet project located in the established mining district of the Mesabi Iron Range in northeastern Minnesota.

The NorthMet preliminary supplemental draft EIS will be reviewed by the Co-Lead Agencies (MDNR, the US Army Corps of Engineers, and the US Forest Service) and the Cooperating Agencies (the U.S. Environmental Protection Agency and the Bois Forte, Fond du Lac, and Grand Portage Tribal Governments) prior to publication of the supplemental draft EIS for public review later this summer.

“This is a very important step toward completion of the environmental review and issuance of the permits we need to build and operate the NorthMet Project,” stated Jon Cherry, President and CEO of PolyMet. “The Agencies and their EIS Contractor have been engaged in very detailed review of the project design, which includes several project modifications in response to public and regulatory comments. The project modifications and improvements, such as the addition of a Reverse Osmosis water treatment plant, demonstrate our commitment to construct and operate NorthMet in a way that protects the environment.”