Sulfide Mining is Destructive and Dangerous

Sulfide ores contain metals (such as nickel, copper and cobalt) that are bonded to sulfur, forming sulfide minerals. When these ores are exposed to air and moisture, a chemical reaction occurs that generates sulfuric acid that migrates into the surrounding environment and, through leaching, releases heavy metals present in the waste rock, pit walls, and tailings basins of mining operations. The sulfuric acid along with dissolved heavy metals released onto the land will seep into the rich aquifers below and then into streams and lakes at levels that are toxic to fish and other aquatic life. This type of pollution is commonly referred to as Acid Mine Drainage (AMD) and has the potential to devastate entire ecosystems. The close proximity of sulfide mines to valued water bodies such as lakes and rivers of the Mississippi watershed intensifies the magnitude of this issue. All of the water bodies in the Tamarack area are linked by multiple aquifers.

To make matters worse, the sulfide mining industry has a poor history of stewardship, integrity and accountability. To date, no sulfide mine has been able to operate without causing some form of pollution in the surrounding environment. Talon Metals (who plans to mine in Tamarack, Minnesota) points to the Flambeau Mine in Wisconsin and the Michigan Eagle Mine as a model cases of environmental stewardship; however, both sites have serious environmental issues (see below).

Sulfide Mines Lead To Contaminated Water

Many organizations have noted that anytime a sulfide mine has been built in a water rich area, the water has been contaminated. Of course, new mines open over time so no single reference can ever be "up to date" in support of this statement. Nevertheless, we can show that no mine has been found to not contaminate the local water based environment, particularly in wetland areas.

Thus we have not found a Nickel / Copper mine that has not polluted. Some people raise the question as to whether the Wisconsin Flambeau mine or Michigan Eagle mine have polluted the local environment or not.

Flambeau Mine Wisconsin

The Flambeau Mine is a very small open pit mine (32 acre pit) on a 161 acre mine site which operated for only for 4 years. Despite the short exposure to sulfide mine contamination, significant issues exist.

Here we note that the federal district court found that the mine discharged copper contamination at levels exceeding state standards However, the Seventh Circuit Court of Appeals then ruled that this case could not proceed further, since Flambeau was entitled to a "permit shield" because it had no notice its state permit wasn’t valid so was entitled to rely on that permit. Nevertheless, the court did rule that the mine did release pollution.

Although the state of Wisconsin considers the Flambeau Mine a successful reclamation, significant contamination of the surrounding area has been documented. Specifically, surface water runoff from the mine site does not meet Wisconsin surface water quality standards. Runoff is polluting a stream which flows into the Flambeau River. Multiple water samples between 2004 and 2008 show significantly elevated levels of copper, exceeding standards. Studies show that the stream is almost devoid of life, including vegetation and fish. Researchers believe this is because of the high metal levels. At one location, the copper level was approximately 10 times the acute water quality standard, and the zinc level is approximately twice the acute water quality standard. Copper and Zinc combined impact on aquatic organisms is greater than that of either by itself. (

One of the difficulties facing the metals-mining industry has been its inability to predict the quality of the water mining will leave behind. The Flambeau mine is a case in point. The mine permit application predicted the level of manganese in water entering the Flambeau River would be a quarter of what it actually is (between 2,000 and 2,500 micrograms per liter). The Environmental Impact Statement painted an even rosier picture, assuring the public that the highest level of manganese within the backfilled mine pit would be 400 micrograms per liter; the actual level is as high as 40,000 micrograms per liter in one area. The groundwater standard for manganese is 300 micrograms per liter, set to protect drinking water.

According to Flambeau’s permit application, manganese levels are likely to remain high for more than 4,000 years. Wisconsin (and Minnesota) law allows mining companies to pollute the groundwater at mine sites, and Flambeau’s polluted groundwater does not violate the law. But 4,000 years is a long time, and we cannot know how conditions will change over that kind of time frame. This is pollution that has been bequeathed to future generations and most likely to a future civilization that does not have access to our records. Is this really what we want to emulate in Minnesota?

In addition, consider:

This independent work was done by experienced PhD scientists and demonstrate significant pollution from the Flambeau Mine. Indeed, the Flambeau Mine Corporation does not deny any of this nor do they produce additional results to argue an opposite claim.

The issue is that the state of Wisconsin failed to properly baseline the area and did not implement monitoring at points susceptible to sulfide contamination. As such the state of Wisconsin refuses to acknowledge that the pollution was caused by the mine but claims that these events "could have" been present prior to mining. Nevertheless, local observers beg to differ. A significant failure by the state DNR DOES NOT mean the Flambeau Mine is clean!

Eagle Mine Wisconsin

The Eagle Mine is still in operation and historically we see that AMD often does not manifest for a number of years after closure.

However, even now given just a few years of operation, we see significant anomalies in monitoring when looking at the official mine report to the Michigan Government. Consider the document:

Eagle Mine does a very poor job at managing dust – a possible cause of the water contamination demonstrated in the above referenced Eagle Mine Exception report. After including an air filtration system in its original permit, Eagle sought to have it removed in 2013, which the MDEQ approved, blowing a plume of unfiltered mine emissions out over the Salmon Trout River and the Yellow Dog Plains. No stack monitoring is taking place, and the emissions have not been measured since September 2014, before the mine was in full operation. (Source: Mining Action Group and

The Eagle Mine TDRSA (Temporary Development Rock Storage Area) is lined with both a primary and secondary lining. A leak detection system is installed between the liners to monitor primary lining integrity. A total of approximately 55 gallons of water was purged from the leak detection sump in 2020, a larger volume than 2019. Thus we see that the lining system does leak after only a few years of operation. The leak levels are currently very small at this point but as noted in the document, increasing slightly over time.

More information related to Eagle Mine environmental impact can be found in their annual report to the state of Michigan.

Indeed one cannot find a Sulfide Mine that is not damaging in a wet environment.

Sulfide Mining Perpetrates Environmental Injustice

The existence of a sulfide mine in an area harms communities. The inevitable contamination of local water will negatively impact the wild rice beds that are currently used to sustain many in the community. In addition, fish and wildlife are negatively impacted resulting.

Contamination from the Talon Tamarack mine from wind blown dust and leaky linings will have a long lasting impact on the local environment.

Property values drop as nobody wants to buy property that is or will certainly be contaminated in the future. Who wants property next to a toxic mine?

Additional References

For more information on the dangers of sulfide mining:

Sierra Club (

Mining Action Group (

Mine EPA Superfund Sites - use your browser to search on keyword "mine"

Earthworks - Copper Sulfide Mining (

U.S. Copper Porphyry Mines Report providing 14 detailed case studies on mining polution.
Sahoo, P. K., Kim, K., Equeenuddin, S. M., & Powell, M. A. (2013). Current approaches for mitigating acid mine drainage. Reviews of environmental contamination and toxicology, 226, 1–32.
Onello, E., Allert, D., Bauer, S., Ipsen, J., Saracino, M., Wegerson, K., Wendland, D., & Pearson, J. (2016). Sulfide Mining and Human Health in Minnesota. Minnesota medicine, 99(8), 51–55.

Official mine report to the Michigan Government (

Protecting our waters and communities from the dangers of sulfide mining