Toxic Mining near the Boundary Waters

Copper-sulfide mining from PolyMet, Twin Metals and Teck, threaten the water-rich environment of Northeastern Minnesota. Through bringing together individuals and organizations across the country, we have successfully pushed back against this multi-billion-dollar industry.

Despite many hard-won victories, the threat remains.

The Movement to Protect the Boundary Waters Canoe Area from Copper-Sulfide Mining

The reason copper mining near the Boundary Waters is so particularly dangerous is water.

Water is the lifeblood of the BWCA and of northeastern Minnesota. Water is what makes this such a unique ecosystem.

Waters is also what makes this area so vulnerable to sulfide mining.

Science of copper-nickel mining in Minnesota

The fundamental danger of copper-nickel mining around the BWCA has to do with the fact that the ore contains a minute amount of copper and nickel. It’s not 50% copper, or 25% copper, not 10% copper or even 5% copper. Less than 1% of the ore body contains anything of value.

Because of this, an enormous amount of rock needs to be crushed and pulverized to extract small amount of copper and nickel.

This requires a huge amount of energy and would create a huge amount of waste rock.

This is where the real danger comes in.

When these sulfide-bearing ores are crushed and exposed to water or oxygen, they create a chemical reaction that produces sulfuric acid. Which is the same as battery acid. This is similar to how iron produces rust when exposed to oxygen or water, only much more hazardous.

It’s so polluting that according to the EPA, sulfide mining is part of the most toxic industry in the country. It is far more toxic than Minnesota’s traditional form of iron mining, and has never been done in the state.

It was never a question of if, but when this mine would pollute.

Image showing the harmful waste that could be created by Twin Metal Mining.

Acid mine drainage and water

The sheer amount of water in northern Minnesota makes the Boundary Waters and Lake Superior particularly vulnerable to the dangers of PolyMet and Twin Metals.

Pollution from sulfide mining is nearly impossible to contain and can last for hundreds, even thousands of years.

In fact, each day over 50-million gallons of contaminated wastewater spills from closed or abandoned mines throughout the United States.

The pollution produced by these mines would not stay contained in one localized area. As water moves, the streams and lakes and rivers would act as a conveyor belt that would spread the pollution over millions of acres.

The clean water and seemingly endless waterways that make so many people treasure this area would also amplify the effects of acid mine drainage.

In addition to acidifying lakes and rivers, sulfuric acid leaches out heavy metals such as mercury, lead, arsenic and other toxins from the rock to produce acid mine drainage. This type of mining is so toxic that there has never been a sulfide mine that has not contaminated surrounding water sources.

It’s all but guaranteed that acid mine drainage from these mines will contaminate the Boundary Waters and cause irreparable damage to northern Minnesota.

Toxic mine waste runoff could spill into the Boundary Waters.

Speak Up for Clean Water

Friends of the Boundary Waters Wilderness has introduced a Prove It First bill into the Minnesota legislature. If signed into law, it would stop Twin Metals and other dangerous mines from polluting our water.

This common-sense piece of legislation is simple. Before a copper-sulfide mine could be permitted in Minnesota, there must be independent proof that a similar mine has operated for at least ten years without causing pollution and that a mine has been closed for at least ten years without causing pollution.

Learn more about the mining proposals

Photo: Benjamin Olson

Twin Metals

The victory over Twin Metals’ copper-sulfide mine, which could have contaminated over two million acres of pristine water throughout the BWCA, Quetico and Voyageurs National Park, is an incredible story, and helps us understand the challenges ahead.

Photo: Rob Levine


PolyMet is the snowplow leading to other copper-sulfide mines near the BWCA. Though we have won astonishing victories against this dangerous project, the fight for environmental justice is far from over.

Teck‘s Mega Mine

The most recent threat to emerge, the proposed joint venture between Teck and PolyMet would impact two watersheds and potentially pollute both the Boundary Waters and Lake Superior. Learn more about what we are doing to stop this dangerous project.

Do Your Part to Protect the Boundary Waters

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