Sulfide Mining: Where will it take us?

500 Years

Acid mine drainage. Photo by Friends of the Boundary Waters Wilderness.
Acid mine drainage. Photo by Friends of the Boundary Waters Wilderness.

PolyMet Mining Corp. has offered Minnesota a Faustian bargain in the form of a sulfide mine in the Superior National Forest.  The company has promised 20 years of jobs, economic stimulus, and the revival of the mining economy of Northern Minnesota through the extraction of copper, nickel, and other metals.  An open-pit mine and prosperity.  Oh, and 500 years of toxic waste clean-up.

Why Sulfide Mining is Worse

It is true that Northern Minnesota’s culture is rich with the history of mining, but sulfide mining is new, and it is different from iron ore mining in one major way.  The copper and nickel are bound up in rock that also contains sulfide, which, when exposed to water and air, produces sulfuric acid.  In order to get to the desirable minerals, PolyMet will also have to pull out and set aside the waste rock—the current plan is to create 20-story rock towers to store it.  This will give the sulfide plenty of time to react with air and water, produce sulfates and sulfuric acid, leach heavy metals, and contaminate unknown amounts of water.  In particular, high concentrations of sulfates in the water may spell doom for the native wild rice populations in the area.  The potential for contamination is far worse with sulfide mining than it was with iron ore mining.

Regardless, PolyMet has promised to contain (almost) all the water from the mine site and the processing site—this includes even the rainwater that falls on the aforementioned toxic rock piles—and to clean that water using reverse osmosis.  The estimate is that it will take at least 500 years to suitably purify all the water to the point that it can be released back into the environment.

Mining Map

And in 20 years?

Northern Minnesota has been caught in the bust part of the “boom and bust” cycle of mining economies for decades, and the support for the prospect of economic development is understandable.  But we have to ask if this is just another 20-year boom followed by a 500-year bust, one that will leave the children of PolyMet’s miners returning home from college only to find that their hometown is struggling once again.

 

For more information on the proposals and the effects of sulfide mining, visit:

A special thank you to MPIRG UM Morris for raising awareness of this issue in Western MN.

By Ariel Herrod at CURE with support from Erik Hatlestad at MPIRG UM Morris
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Kelsey Olson

Kelsey Olson

Director of Environmental Stewardship

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Kelsey Olson (she/her) joined CURE in 2025 as its Director of Environmental Stewardship. As a skilled environmental naturalist, Kelsey’s work focuses broadly on environmental education and advocacy with a keen focus on rural land use and how that use impacts our environment and climate. Working Lands, how land is used to support agriculture and forestry, is a key focus of her work. She brings 15 years’ experience in public communication, environmental education, and rural community engagement – strong communication strategies are core in her work. This includes two terms of service with AmeriCorps in the VISTA program in Oregon and Maryland and a nearly 10-year career as a naturalist followed. She recently worked on communications and marketing for rural economic development.

Kelsey lives in New London, MN, with her young children, husband, dog, and two cats. They enjoy spending time together outside and finding small treasures in nature. Visits to Minneapolis often include visits to one of their favorite historical museums, the Minnesota Swedish Institute. Kelsey enjoys experimenting in the kitchen, whether this is canning local produce, making kombucha, or other treats!