Toxic metals in acid mine drainage (AMD) have polluted waters everywhere that sulfide-ore mining has been done in wet environments like in Minnesota, land of 10,000+ lakes. 

Sulfide oxidizes to sulfate, which increases bio-accumulation of existing elemental mercury, a well-known neurotoxin in humans and wildlife.  Just over the 10 ppm (parts per million) limit of sulfate in the water can demolish wild rice stands, as already has happened in parts of the St. Louis River watershed and others in Minnesota's mining country.

The U.S. EPA (Environmental protection Agency) has extensive information about AMD.

See a video overview (~27 min.) about sulfide mining by Friends of the Boundary Waters:  Precious Waters

Read The Report on the Mining Simulation project : nonferrous mineral project, 1989-1990.  This guidance seems to have been ignored (particularly public involvement) in the preparation of the PolyMet NorthMet EIS.  It was a joint effort, prepared by MDNR, Industry and Environmental representatives, informing the development of the Nonferrous Mineland Reclamation Rules.  MDNR, Industry and Envionmental representatives collaborated on this outline of mining best-practices and regulatory procedures for how MN law and rule would be applied to a hypothetical sulfide mine.

The Minnesota regional copper-nickel study, 1976-1979  funded by the MN legislature ( millions of our tax dollars) and published by the Minnesota Environmental Quality Board, is available at the MN Legislative Reference Library.  Portions of the 5-volume study are available electronically Taxpayers invested in this multi-year objective assessment of the mineral potential, processing options, and impacts, including to water, wildlife, hydrology, economy, and society.  The toxicity of Acid Mine Drainage (AMD) potential is very well-established for the Duluth Complex rock formations of northeastern MN.  However, the legislature did not act to embody much of what was learned in balanced legislation to protect the environment and public health while continuing to investigate whether non-ferrous mining could be done in Minnesota without irreparable harm.

MAJOR PUBLIC HEALTH RISKS OF METALLIC SULFIDE MINING, a report by Northeastern Minnesotans for Wilderness (Scroll down to the report)

SIGN and CIRCULATE a "NO Sulfide Mining" PETITION, because it has not been demonstrated safe -- collect signatures and distribute petitions

Acid Mine Drainage precipitates a
characteristically red, orange or yellow color.

What is Metallic Sulfide Mining?

Metallic sulfide mining is a Midwest US term for hardrock mining for metals in sulfur-bearing rock, as differentiated from coal, iron ore, or gravel extraction.  Metallic sulfide mining is the practice of extracting metals from a sulfide ore body.  In Minnesota, these metals include copper and nickel with trace amounts of cobalt, platinum, palladium, and gold.

Why is Metallic Sulfide Mining a Concern?

  • When sulfide ore, waste rock, pit walls or the tailings are exposed to air and moisture, a chemical reaction can create sulfuric acid. (Iron ores are in oxide, not sulfide, formations.)
  • Precipitation water can cause sulfuric acid compounds to drain from the mine site -- called acid mine drainage (AMD, sometimes called acid rock drainage or ARD). 
  • AMD can enter nearby surface water and groundwater resources and thereby harm people, plants, animals, metal and concrete structures.
  • There has never been a metallic sulfide mine that has not polluted water resources where water was present.
  • AMD also dissolves toxic heavy metals (e.g. lead, zinc, copper, and mercury), allowing them to enter surface water and groundwater.
  • AMD discharge and disruption of wetlands caused by metallic sulfide mining can also significantly increase the levels of toxic mercury in fish.
  • AMD can form red, orange or yellow sediments in the bottom of streams, which can disrupt the growth and reproduction of fish or kill aquatic plants and animals on which they feed.
  • AMD is very difficult to confine and treat (clean up) properly. It can be very expensive to clean up and has costly impacts on local communities.
  • It may take several years before AMD reaches toxic levels, and water contamination can then last for centuries, or even millennia.

Facts About Metallic Sulfide Mining in Minnesota

Minnesota’s water and sulfide mining are not a healthful mix.

The valuable water resource:

  • There are thousands of lakes, thousands of miles of rivers and streams in the state, most numerous in the northeastern "Arrowhead" region.
  • It takes approximately 190 years for contaminants to cycle through the great lakes, even at current water levels, which would receive pollution from the PolyMet mine near Hoyt Lakes.
  • The Great Lakes contain 18% of the world's freshwater.
  • Nationally, AMD accounts for some of the largest and most expensive Superfund sites.  Minnesota can lead with legislation to prevent this pollution.  Other states have passed protective legislation AFTER experiencing damage.

The state of regulation

  • The waters around the PolyMet site are already classified as impaired waters, meaning they surpass the safe levels of various contaminants.
  • There are numerous existing inadequacies in the current state of enforcement in mining regulation, including permits exceeding pollution standards, sites operating under variances, unidentified and unassessed toxic grease barrels, decades of AMD violations from the Dunka Pit, and missing TMDL (Total Maximum Daily Load of contaminants) data for receiving waters.
  • The Minnesota Control Agency (MPCA) has claimed that it doesn't have the funding to adequately implement the laws that assess and protect wetlands and waters from the impacts of proposed mining.
  • Minnesota’s Department of Natural Resources (DNR) has an internal conflict of interest - to protect and to exploit Minnesota's resources.
  • Under the current (untried) nonferrous (non-iron) mining rule, lacking important explicit minimum standards of protection, the DNR Commissioner (a political appointee) has broad discretion to define financial assurance, operating and closure requirements.   Political will to strictly enforce the current regulatory protections has been lacking in governors, regardless of their political party.

Sulfide mining encouraged

  • The DNR Minerals division has been leasing non-ferrous mineral rights on state land aggressively for decades to encourage exploration and extraction.
  • Multinational mining corporations are exploring for non-ferrous metallic sulfide ore across the state, primarily in the prized lake district of northeastern MN. including adjacent to the Boundary Waters Canoe Area Wilderness.
  • PolyMet is the first to apply for a permit to operate a metallic sulfide mine in Minnesota. The PolyMet project would irreparably alter an area of land that includes about 6,700 acres of high quality public wetlands and forest land in the Superior National Forest, negatively impacting the St. Louis River watershed -- the second largest tributary to Lake Superior.
  • The company proposes to dig a series of 3 open pits over about 20 years.  It would alter water levels in nearby rivers, lakes, reservoirs and wetlands and affect water quality. The PolyMet company would store waste rock in huge piles up to 240 feet high and in liquid tailings slurries held in an indequately-designed impoundment, having the potential to collapse and spill.
  • The company seeks permits to mine under sulfide mining regulations that have never been tested and is resisting the need to obtain permits for discharge of pollutants into surface waters and to replace lost wetlands and forests.
  • Currently, after 5 years of pre-development, the mine plan is still incomplete and the safety of pollution controls and waste disposal systems is unproven.
  • Many community members are only now realizing the potential for irreversible harm to wetlands, water resources, wildlife and human health, which contribute substantially to the economy in the area.

Facts About Health and Sulfide Mining

  • The metals mining industry is a leader in the release of toxins.  Mining and processing of ores can introduce contaminants into the air, water, and soil of local communities.
  • Discharges to water near the source at the PolyMet project would exceed legal Maximum Contaminant Levels for arsenic, antimony, sulfuric acid compounds, iron, manganese, nickel and copper.  Similar violations of water quality standards are highly likely at other sites of proposed metallic sulfide mining sites in Minnesota.
  • Methyl mercury, a well-known neurotoxin causing nerve and brain damage, developmental disabilities and even autism, would increase in the surrounding environment, collecting in fish tissue.
  • Compared with iron and taconite ore, disturbing sulfide rock can produce more acidic discharge, more sulfate, and much more serious, permanently toxic pollution.

Minnesota's First Proposed Sulfide Mine Plan has Problems.

Because it has not been proven safe to mine sulfide ores in Minnesota, if you believe permitting agencies should not issue a permit to mine for PolyMet or any other company at this time, you can print or download, circulate and return the petition requesting "... all State and Federal authorities with jurisdiction to deny any request for a permit to mine metals associated with sulfur-bearing rock".


AMD in Rio Tinto River

Acid Mine Drainage in the Rio Tinto River (Spain) - one of the
world's most extreme cases of AMD pollution.


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