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There are issues with Minnesota’s abandoned mines; the possibility of a toxic spill isn’t one of them

Yellow mine waste water from the Gold King Mine is seen in San Juan County, Colorado, earlier this month.

Federal environmental officials knew they were dealing in dangerous territory. The abandoned Gold King mine in Colorado had spent much of the 20th century filling up with melted snow and rainwater that, combined with the mine’s tailings, had turned into an acidic toxic stew.

Over the years, various officials in the region tried to clean up Gold King. Most recently, it was the Environmental Protection Agency. On Aug. 5, while investigating a leak from the mine, a team contracted by the agency inadvertently shook loose debris that had been acting as a dam holding back the pollutants. Mustard yellow toxins poured into the Animas River.

The incident brought into question the future, and potential danger, of thousands of abandoned mines across the nation, including those in Minnesota, a state with a long history with mining. The North Star state is home to more than 100 abandoned mines dotting the Iron Range, and some are still being monitored by state officials as potentially harmful to the environment. 

Still, there are a number of reasons an environmental catastrophe like what happened in Colorado is unlikely to happen in Minnesota. Here’s why:

Iron rush v. gold rush

As in Colorado, Minnesota’s earliest miners were looking for gold, and in the 1850s, a lucky explorer discovered the precious metal embedded in some quartz near Lake Vermilion. The difference is that miners in Minnesota didn’t find much gold after that. What they found instead became far more precious to the region, though — iron ore, in huge quantities. 

The industry formed the backbone of the area’s economy for a century: By the 1950s, 82 percent of iron ore extracted from American mines originated in Minnesota.  As mines were excavated past the point of usefulness and iron ore resources dried up, mines were simply left behind.

There was no agency regulating mining and its impact on the natural world for much of the industry’s history in Minnesota. But in 1969, state lawmakers recognized the impacts mining has on the environment, and the Legislature passed the first “reclamation” laws regulating safety and environmental concerns at old mining sites.

Lawmakers expanded on that law in 1977, giving the Iron Range Rehabilitation and Resources Board (commonly called the “I triple-R B”) tax funds and authority to manage all mines operated before 1980. All mines built or operated since then are under the management of the Department of Natural Resources (which handles permitting for new mine projects) and the Minnesota Pollution Control Agency (which manages water-quality issues related to mines). Some private companies own mine sites, but they are under permit and regulation by the DNR or the MPCA, officials say.

East slope of the Soudan underground mine's 27th level.
Minnesota Department of Natural Resources
West stope of the Soudan underground mine’s 27th level.

There was little oversight involved in Colorado’s Gold King mine. In 1872, the federal government approved the General Mining law, which meant anyone could stake out a claim on federal land for no fee and start mining for things like platinum, gold, silver, copper and lead. Individual miners and small groups began digging veins and tunnels into mountains to find gold. Since there was no environmental regulation to speak of, miners simply left the Gold King mine behind in the 1920s when the money dried up. The mine was passed among private owners for years afterward, with local officials in nearby towns hesitant to wade into talks of environmental protection.

“The state of knowledge now — for both the industry and for regulators — is vastly superior,” says Richard Clark, who works in the mine supervising division of the MPCA. “Those mining methods and waste management methods would not be allowed now.”


A major reason Minnesota’s abandoned mines are less risky than others boils down to geology. When metals like gold are mined, they are extracted from sulfide ore. When water hits sulfide ore, it can turn into acidic drainage. After Gold King’s operators abandoned the mine in the 1920s, they left sulfide exposed in open tunnels that filled with snowmelt and rainwater. Minnesota’s iron ore is found mostly in oxide ores, and there is a very low rate of sulfide extracted in typical iron ore mining. And unlike sulfide ore, when oxide ore is exposed to water, it turns to rust.

Which isn’t to say regulators and environmentalists don’t have any concerns about Minnesota’s abandoned mines. A handful of old mining or drilling sites are problematic and are maintained or monitored by state officials. That includes the former Soudan underground iron mine near Lake Vermilion, which is now a state park. In 2006, the DNR was fined by the MPCA for discharging water from the site that exceeded some water-quality standards.

And while Minnesota has not conducted so-called sulfide mining like Colorado, several companies have drilled to explore metal possibilities under the state’s surface. In the 1970s, a company called International Nickel drilled exploratory holes at a site near Ely. Another company, AMAX, conducted similar drilling near Babbitt. The iron mine Dunka Pit, run by LTV Steel Mining Company, excavated a significant quantity of sulfide ore to access iron buried beneath it, and some of the sulfide ore was found to be leaching contaminants into Birch Lake’s Bob Bay, in violation of water-quality standards.

The future worries environmentalists more than the past

Many old mines are now simply open pits, which are monitored for safety. Underground mines can cave in, rocks can fall from pits, and they are often dangerous after a big rainfall. The IRRRB puts up fences and can patch up vertical shafts in old mines if they open up, says Dan Jordan, who works with IRRRB’s Mineland Reclamation Division. Depending on the community, reclaimed mines have also been turned into business parks, fishing piers, campgrounds, overlooks, gun clubs — even a blueberry patch.

Environmental groups are still worried about water contamination from mining, though their concerns arise more from active mining and proposed projects than from abandoned sites. State and federal environmental groups, including the EPA, are worried state pollution officials haven’t developed a clear plan to deal with waste rock and polluted water from the Minntac mine in Mountain Iron, for instance, which is leaking pollutants into the St. Louis River Watershed.

Steve Morse
Steve Morse

Even more, environmental groups are protesting the proposed NorthMet Project — better-known as PolyMet for the company that is planning it — which hopes to tap into one of the world’s largest known undeveloped deposits of copper and nickel near Hoyt Lakes (within the Lake Superior Basin) via sulfide-ore mining. Twin Metals, another proposed sulfide mining project, is several years behind NorthMet in the permitting process, but the project would directly affect Ely and the Boundary Waters Canoe Area Wilderness watershed.

“The lesson of [Colorado] is that these are highly dangerous activities, they are risky activities. When things go bad they go really bad and have really catastrophic impacts,” says Steve Morse, executive director of the Minnesota Environmental Partnership. “It’s the sulfide mining projects that are the biggest concern … we have these rose-colored glasses on as we look at it at this point. People just assume things are going to work, but this is a really dangerous thing we are doing. It’s kind of like playing with nuclear weapons.” 

Comments (12)

  1. Submitted by Dennis Litfin on 08/26/2015 - 12:54 pm.

    Well written, Briana,

    should be required reading for everyone in Minnesota, Wisc., and the U.P. where additional mines are being proposed without thorough study of their post- mining effects.

  2. Submitted by joe smith on 08/26/2015 - 01:41 pm.

    I have not heard anything lately on the Gold King mine spill. Last I heard the EPA chief was saying that the river did an unbelievable job of cleaning itself. A bit different coverage than the BP spill. I guess when the guilty party for causing the spill is the EPA things go a lot smoother for you. I am sure we will be reading many articles about the danger of mining as Polymet gets closer to operation. For those of us who are pro mining we are hoping the EPA has a another accident up here and they go into cover up mode, the permits will be approved ASAP.

  3. Submitted by Tom Karas on 08/26/2015 - 03:13 pm.

    Thank you Mr Smith

    Just to add to the pile of fun arguments that the pro-mining folks can dream up. If this is the type of reasoning you can envision to speed up the permit process, well, it speaks volumes of the value of your arguments in general. Hoping that the EPA has another accident when it has to repair,fix,clean the leftovers from happy mine owners in MN who left the mess is comical. But if that’s the only card you got…………

    • Submitted by joe smith on 08/26/2015 - 05:50 pm.

      The best argument for Polymet is once they pass the requirements to get permitted, they get permitted. Once you pass the building code requirements for your house you start building. There are existing rules and regulations Polymet has to meet to get started.
      On a side note I see the EPA is not cooperating with authorities in the Gold KIng spill. Amazingly, when you are a run away Federal program supported by billions of dollars and revered by the liberals you don’t answer to the folks you work for…. USA citizens…

  4. Submitted by Gary Clements on 08/26/2015 - 08:41 pm.

    Misleading Headline

    Unfortunately, many people will not read past the opening of this article, and go away with the feeling that there is no danger in Minnesota’s proposed sulfide ore / copper mining operations.
    Indeed, the danger is huge, and “toxic spill” is poorly defined here as related to the proposed mines. No, it wouldn’t be “like the one in Colorado”, but it would be as dangerous to fish and wildlife and drinking water for centuries, because the leaching out of mercury and arsenic that naturally occurs in the ground, over long periods of time, is what happens when air and water mix with the huge waste piles of finely crushed rock after the roughly 2% of the copper/nickel is extracted, and the runoff enters ground water, rivers, marshes and lakes.
    No, this isn’t exactly a “toxic spill” where the flow happens all at once, but it is toxic and it does happen, and it never stops, not for centuries. And there is NO sulfide ore / copper mine that has ceased operation without subsequent pollution of this type. None. And especially none in a wetlands environment.
    As far as modern regulations and pollution standards are concerned, Minnesota has the unfortunate track record of non-enforcement of our so-called “strong environmental protections”. There are mines operating now in violation of pollution standards, some of which are operating without a permit, as permits have expired and not renewed. Without the will to enforce the statutes, there is NO oversight, no protection.
    So, wake up, fellow Minnesotans…. do not be fooled by the smooth talk of the mega-companies from Chile and Switzerland (you did know that the profits from these mines are headed OUT of the U.S., didn’t you?) who are the major owners of the Polymet and the Twin Metals companies. They have no interest in protecting Minnesota…. only in their own financial gain.

  5. Submitted by Rod Loper on 08/27/2015 - 07:56 am.

    Sulfide permits were compromised

    from the start. Minnesota agencies tossed aside a dry process for tailings disposal as “too expensive”
    to the companies. Check out the Star Tribune opinion page for today. “High standards” my eye.

  6. Submitted by Ray Schoch on 08/27/2015 - 09:36 am.

    Apples and oranges

    Many, many issues in this piece deserve further exploration, but I’ll just mention a few.

    First of all, iron mining and sulfide mining are *not at all the same thing.* As the piece presents, but fails to emphasize, iron mining residues largely oxidize and turn to rust. Rust is not exactly wonderful for water quality and the environment, but it’s not nearly as poisonous as the mining residue from sulfide mining.

    The recent Animas River mine spill in Colorado is the result of sulfide mining. Yes, an EPA contractor (i.e., a private business hired by the EPA to do the work – not actual government employees) bungled the job they were supposed to do, but the EPA isn’t responsible for the pollution itself. That pollution is a direct result of the 1872 mining act – which is, I might add, still on the books and the law of the land. That law pointedly ignores any and all environmental consequences of mining, and mining interests lobby strongly in Congress to keep it that way. The fact that the water in the Animas River is no longer yellow doesn’t mean the river is no longer polluted. Sulfide mining, by definition, produces residue that is *acidic,* and at more than trivial levels. It kills plant life, it kills fish, it kills animals that drink the water.

    Sulfide mining is what’s being proposed for the PolyMet site. Should PolyMet fail to keep its promise to monitor and clean up any pollution in perpetuity – a promise that no mining company in the history of mining has ever kept – it’s not just that Minnesota taxpayers will be left holding the bag for the costs of the cleanup after PolyMet declares bankruptcy, or through other legal maneuverings (e.g., disincorporation – legally ceasing to exist) manages to avoid having to fulfill its costly cleanup obligation, the environmental damage to what is among Minnesota’s most valuable and pristine areas will be both profound and long-lasting. It could easily be centuries before the watershed that’s polluted with mine waste once again reaches a level of toxicity that animals and humans can tolerate.

    I think we can rest assured that, should the worst-case scenario come to pass, Mr. Smith and his mining-friendly neighbors will be petitioning the state government in St. Paul for massive amounts of relief (i.e., money) to either treat poisoned water, or compensate them for the loss of livelihood and home they’ve incurred as a direct result of their own political and environmental short-sightedness. A job for 15 or 20 years does not make centuries of environmental damage somehow worth the tradeoff. Much of the water in Colorado is not fit to drink, but it’s not something the general public is aware of because the sources of the pollution are – as in the Animas River case – abandoned mines in remote areas of the state. I think the PolyMet situation is potentially very similar to the ugly scene in the mountains above Silverton, CO.

  7. Submitted by joe smith on 08/27/2015 - 10:34 am.

    So the problem with copper mining is not the mining, it is the regulations that are in place that cover them. When pro business folks raise the issue of over regulation in most areas of production in America the liberals howl that the EPA, DNR, MPCA are there to protect us, the people, vs the evil company or corporation and defend them to the end!!! When the very same agencies rule in favor for permitting an industry that liberals don’t like, those same agencies are pawns for the evil corporations….. Which one is it?
    Just ridiculous the arguments you hear from some. As I have said for yrs, the anti mining, logging, oil and gas folks just don’t want those industries up and running in America. Just come out and say it! The convoluted reasoning behind a simple belief that mining, logging oil and gas are bad for everyone, actually distracts from any discussion. I have always wondered if the Greenies that hate the usage of our natural resources live in a house (lumber) drive a car (mining, oil) heat or cool the structure they live in (oil, gas,logging), use a cell phone (mining), the list goes on and on.

  8. Submitted by richard owens on 08/27/2015 - 02:53 pm.

    Preserving Minnesota’s Lake Superior watershed is our duty.

    Extraction and depletion must not destroy the water, air or plant and animal life that lives there. The risks of sulfide mining there are great and the assurances are thin.

    Your arguments that commenters oppose all extraction or use of natural resources is disingenuous.

    Not every problem is solved by Republican canned talking points. (are any?)

    In fact they are worse than worthless when adults are having a discussion about decisions that will affect future generations. Please offer your science in lieu of conservative disdain.

    To the point: How much pollution do you think can be tolerated in exchange for how many jobs?
    How much destruction of the watershed is “worth it.”?

    What limits should be placed on Corporate miners in MN?

    What should be their responsibility?

    What should be their liability?

    Surely Mr. Smith, you have limits to your tolerance for environmental loss.

  9. Submitted by Bill Willy on 08/27/2015 - 07:34 pm.

    One word and a couple unbreakable laws

    It occurred to me a few weeks ago that there’s a word that sums up everything companies like Polymet, Glencore/Xstrata ( and Twin Metals are proposing and claiming they can do safely in an environmentally friendly way:


    It doesn’t matter what mining company people think or say; it doesn’t matter what people at the DNR or MPCA think or say; it doesn’t matter what you or I or anyone else thinks or says: If toxic water is “stored” at an elevation higher than its surrounding area that toxic water WILL make its way into that surrounding area because Gravity ensures that ALL water makes its way downhill, and there is nothing we human beings can do to alter that Fundamental Law of Nature.

    No rule or regulation, no “earthen dam,” no “pit liner,” no anything humans can engineer can override that law. It could be “held at bay” for varying periods of time — depending on how many billions of dollars mining companies would be willing to spend on “legitimate containment and treatment facilities” — but beside the fact that mining companies have no interest or intention of doing anything but the minimum (or the project would be a bust before it got started), time has no influence on Gravity. It has been here doing what it does for all time, and that’s how long it will continue to ensure water keeps moving downhill, come what may.

    Or, as Bob “Ranger Crooner” Dylan put it one time: “That river just keeps on rollin’ though – – no matter what gets in the way or which way the wind blows.”

    “The proposed PolyMet copper-nickel mine would be built near [Hoyt Lakes and] the headwaters of the St. Louis River, which travels 195 miles through forests and wetlands before emptying into Lake Superior.”

    Polymet Hoyt Lakes processing and tailings reservoir elevation: 1,473 feet

    Duluth/Lake Superior elevation: 607 feet

    Boundary Waters Entry Point 32 – South Kawishiwi River elevation: 1,201 feet

    The question of, “Will we be able to keep mining waste pollution ‘out of the environment’?” is no question at all. Gravity guarantees we won’t. The only question is, “Is the waste generated by copper-nickel mining toxic, and what would that mean in terms of ruining, despoiling, killing some or all of whatever it touches or mixes with?”

    If the answer to that question is, “Highly toxic and likely to do great irreparable damage,” then everyone can rest assured great irreparable damage will be done to some of Minnesota’s most valuable irreplaceable assets if the people of Minnesota allow copper-nickel mining to proceed.

    It’s that simple. Pipe it, store it, pile it up, do whatever anyone can think of. It wouldn’t matter. Gravity and constantly increasing water pressure would pull and push on the reservoir walls like chained whales until, one inevitable day, they gave way and the poison they held back rushed for lower ground. And all the while the rain and snow would be falling and melting and moving downhill, carrying along whatever toxins are in or on it, and nothing anyone could do would prevent it.

    Anyone thinking or saying copper-nickel mining can be done in an environmentally friendly way is either working for Polymet or not thinking clearly, is confused, and has forgotten or overlooked those fundamental laws of Nature that have governed the relationship between Gravity and Water since the Earth was formed.

    Again: The issue is not whether or not the Kawishiwi River, the Boundary Waters, the St. Louis River system and Lake Superior would become polluted. They would. The only issue or question is whether Minnesotans are willing to trade the incredible eco/water system our Crown Jewels are made of for whatever it is mining companies, their share holders and their proponents are “promising” Minnesotans they will get in exchange.

    Which, beyond a handful of short-term jobs and a little more “production tax” money for the IRRRB, is what?

    • Submitted by Richard O'Neil on 08/29/2015 - 01:51 pm.

      The IRRRB exists to protect the jobs of the miners living (and voting) in the Iron Range area, They do not protect the environment.

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