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Serving Northern St. Louis County, Minnesota


Mining vs. water

Dunka site exposes breakdown in mine regulation


SUPERIOR NATIONAL FOREST—As state and federal regulators work to finalize the environmental review on PolyMet Mining’s proposed NorthMet copper-nickel mining operation, impacts to water remain near the top of the list of concerns.

Unlike other mining in northeastern Minnesota, the ore that PolyMet proposes to mine is part of what’s known as the Duluth Complex, a zone of sulfide-bearing rock that stretches from southeastern St. Louis County in an arc through central Lake and Cook counties. The sulfide rock contains copper, nickel, platinum and other valuable metals, but it is also known to leach acid, metals, sulfates, and other potentially toxic chemicals when exposed to air and water. To critics, this process, known as acid rock drainage, has come to symbolize the dangers associated with the mining of sulfide ores.

While NorthMet would be the first copper-nickel mine in northeastern Minnesota, it wouldn’t be the first time that a significant amount of low-grade sulfide-bearing rock was exposed as part of a mining operation in the region.

For 30 years, beginning in 1964, LTV Steel operated the Dunka Mine, located just three miles southeast of Babbitt. While LTV mined taconite at the site, a layer of the Duluth Complex lay on top of the iron ore along one end of the mine. In exposing the iron ore, LTV removed an estimated 50 million tons of sulfide-bearing rock that it stockpiled at the mine site, where it remains to this day.

When state regulators and PolyMet officials say they can mitigate the risks of acid rock drainage at NorthMet, Dunka provides a good example of the challenges and the economic and political pressures that regulators could face when proposals outlined in the NorthMet Supplemental Draft Environmental Impact Statement, or SDEIS meet realities on the ground.

At first glance, the story of Dunka looks encouraging. When state regulators realized back in the 1970s that the stockpiled ore was leaching highly toxic levels of copper, nickel, and other contaminants into a nearby creek that drained into Birch Lake’s Bob Bay, they took action. After conducting experiments at the site to better understand the degree of acid drainage actually taking place at Dunka and how best to contain it, officials with the Department of Natural Resources and the Pollution Control Agency required LTV to cap the top of the sulfide-bearing waste rock piles. They also required the company to install a water treatment plant and a series of engineered wetlands that were designed to capture metals and other contaminants.

And even environmentalists, like Paula Maccabee, an attorney for WaterLegacy who has fought hard for better enforcement of pollution rules at Minnesota mines, acknowledge that the work, completed mostly in the 1990s, reduced to some degree the level of toxic metals being discharged from the Dunka site. Indeed, an analysis conducted by the DNR in 2000 found that the capping of the sulfide rock stockpiles, by itself, reduced runoff by 55 percent and decreased nickel discharges by 82 percent.

However, as Maccabee points out, the water treatment plant built in the 1980s has been closed for decades and existing manmade wetlands, by themselves, still do not bring Dunka’s discharge in compliance with Minnesota water quality standards.

Even so, Richard Clark, of the Minnesota Pollution Control Agency’s Metallic Mining sector, states that Cliffs Natural Resources, which assumed ownership of Dunka after acquiring LTV assets following the company’s 2001 bankruptcy, has been in consistent compliance with the terms of its wastewater permit for Dunka.

A review of monitoring data as well as Cliffs’ wastewater permit by the Timberjay shows that both Maccabee and Clark are right. Cliffs has complied with its permit, yet its discharges don’t comply with water quality standards. In fact, the mine’s discharge regularly fails to meet water quality standards for several contaminants, including nickel, sulfates, and hardness, often by significant amounts.

These two seemingly incongruous facts are at the heart of what former state regulator Bruce Johnson sees as a fundamental breakdown in Minnesota’s regulatory process as it pertains to metallic mining. Cliffs can both violate water quality rules at Dunka and simultaneously meet the terms of its wastewater permit for Dunka, issued by the MPCA in 2000, because the permit includes no effluent limits in most cases. For most of the mine’s discharge, Cliffs’ permit only requires that the company monitor the pollution and file monthly reports with the MPCA.

That might be a surprise to most members of the general public, but it’s all too common according to Johnson, a biologist by training who spent decades working for the MPCA and the Minnesota Department of Natural Resources. Johnson was one of the lead DNR researchers on the 1970s-era copper-nickel study and he was involved in the development of the remediation plan for the Dunka Mine, so he’s as knowledgeable as anyone in the state about the science and the regulatory history of Dunka. According to Johnson, permits like the one currently regulating Dunka, which only require companies to monitor their pollution output and report it to the MPCA, do little to protect water quality and it’s one of the reasons he’s grown disenchanted with the state of environmental regulation in Minnesota. Johnson and his wife Maureen, herself a chemist by training who worked for the MPCA for years to clean up Superfund sites in Minnesota, both now serve as volunteer science advisors for Maccabee’s WaterLegacy. “We’re spending millions of dollars funding the MPCA,” said Johnson. “I think the public would be surprised at what’s going on.”

Maccabee said she was stunned when Johnson first explained to her what was happening to the state’s regulatory process, particularly as it relates to mining. She said the current permitting process for the state’s mines is focused primarily on protecting mining companies from legal liability for their pollution, not on protecting the environment. “A permit like we see for Dunka protects the company even if their discharges violate water quality standards,” she said. “If they put it in the permit that all they have to do is monitor, then they don’t have to comply with the water quality rules.”

Clark acknowledges that Cliffs complies with its permit simply by monitoring and reporting its pollution discharges, but he says the data that Cliffs is collecting will help the agency as it works towards the issuance of a new permit.

Maccabee says that’s slim comfort considering that Cliffs’ current permit for Dunka expired a decade ago. And, at this point, agency officials say that they have no timeline for when a new draft permit might be proposed, much less when a final permit might ultimately be approved.

One thing, however, is certain. It’s going to take years. And it may never happen at all.

In the meantime, says Maccabee, the old permits provide Cliffs with legal protection, helping to keep the courts and the public from weighing in on behalf of clean water.

It’s just such situations, repeated across the Iron Range, that prompted WaterLegacy to petition the Environmental Protection Agency earlier this year to rescind the MPCA’s regulatory authority over the mining industry. Maccabee, in WaterLegacy’s petition, noted that virtually every mine on the Iron Range is operating on expired permits, in some cases with permits that have been expired for a quarter century. In those cases, companies are allowed to operate under rules that date back in many cases to the 1970s or 80s, before Congress updated the Clean Water Act in the 1990s.

Routine violations of standards

Because the MPCA requires Cliffs to provide monthly reports of their discharges from various points in and around the Dunka Mine, the actual effluent levels are publicly available. And even though capping of the waste rock stockpiles has significantly reduced the flow of metals like copper and nickel, monitoring reports show that discharges of those metals, particularly nickel, still routinely exceed a number of the limits written in state law and enforced under federal law. The mine includes seven known surface discharge points and most violate a number of water quality standards, often by significant amounts.

One of the worst is a discharge point labeled SD-009, located about midway along the mine’s southeast flank. According to the discharge monitoring reports that Cliffs routinely files with the MPCA, SD-009 routinely discharges water into the environment that would be in gross violation of state water quality standards for metals like copper and nickel, says Johnson, if the MPCA followed state and federal rules.

The water from SD-009 always exceeds standards for other pollution parameters, says Johnson, including hardness and conductivity, sometimes by as much as four times the allowable limits under either federal or state rules. Sulfate discharges are extremely high as well, averaging approximately 1,800 milligrams per liter (mg/l), but reading as high as 2,450 mg/l at times. That compares to the 10 mg/l sulfate standard currently in state rules for wild rice waters, a list that includes Birch Lake. The MPCA has since proposed a flexible sulfate standard for wild rice waters, but even if this proposal were adopted, it is highly unlikely that such high levels of sulfate would ever be allowed.

The MPCA, back in 2000, issued Cliffs a permit variance that allows the company to continue to discharge excess pollutants from SD-009 and a second point, known as SD-008. The permit and the variance both expired in 2005, but under permitting rules the mine can continue discharging under the old variance until its application for a new permit is acted upon by the MPCA.

The effects of the contaminant discharges at Dunka are apparent beyond the mine itself. Most of the mine’s contaminants discharge into Unnamed Creek, a natural stream that flows north to the southern tip of Birch Lake’s Bob Bay. Cliffs maintains a monitoring point, known as SW-001, at the mouth of the creek, where it enters Bob Bay, which is located about a mile downstream of the mine. While the dilution of the mine’s discharge by other uncontaminated runoff in the Unnamed Creek watershed helps reduce the contaminate concentration, the water entering Bob Bay is still far from meeting water quality standards under state and federal law. The monitoring reports filed by Cliffs show routine violations for nickel, hardness, conductivity and sulfates. Sulfate levels in the water entering Bob Bay have run as high at 1,840 mg/l per liter according to the reports.

The monitoring reports show some of the highest pollution readings during the winter months, and Johnson said two factors account for that trend. For one, stream flow is generally lowest during winter, which means there’s less water to dilute the steady discharge of contaminants that do escape the mine site. In addition, engineered wetlands at the site that are supposed to capture contaminants do not function during the winter, according to Johnson, which means the mine’s discharges are released essentially untreated. The MPCA acknowledges the higher pollutant concentrations in winter, and responded by writing allowances for the higher discharges into Cliff’s permit variance.

Calcium also

a concern

The monitoring reports also show very high levels of calcium in the mine’s discharge, and some of that may be attributable to the engineered wetland, which uses limestone as a way to reduce the toxicity of metals, like copper. While calcium is not typically considered a serious pollutant by itself, the recent spread of invasive mollusks, such as zebra mussels, into lakes across Minnesota, has raised concerns about calcium levels, particularly for lakes north of the Laurentian Divide, where traditionally low calcium levels are believed to provide a natural protection against the survival of zebra mussels. Like most shellfish, zebra mussels require sufficient calcium in order to grow their protective shells. In most Minnesota lakes, natural calcium comes from limestone deposits formed in ancient seabeds. But the last glaciers scraped the Canadian Shield nearly bare of limestone, leaving little calcium behind. Research on the mollusks show that they require calcium levels of at least 20-25 mg/l in order to mature and reproduce. Most lakes in northern St. Louis and Lake counties fall well below that level, which may be one reason zebra mussels haven’t proven to be a problem in Canadian Shield lakes in Minnesota, at least so far.

Yet monitoring reports from 2013-2014 show that the water entering Bob Bay at SW-001 contains calcium ranging from a low of 30.6 mg/l to a high of 405 mg/l, with an average reading of approximately 100 mg/l. Whether that discharge has raised the calcium levels in Bob Bay or elsewhere in Birch Lake isn’t known, since the MPCA hasn’t tested the waters of the bay since the 1980s.

Impacts to aquatic environment

The question remains, however, whether the mine’s discharges are negatively affecting the aquatic environment. The MPCA’s Clark says there’s little sign of it. “The most recent biological monitoring for the Dunka site suggests a healthy aquatic system in Unnamed Creek,” he said. As part of their permit, Cliffs is required to undertake biological assessments of the aquatic life in Unnamed Creek, and Clark maintains those assessments indicate the presence of pollution intolerant species, like caddisflies.  “These measures suggest an appropriately healthy and diverse population of aquatic insects is present in Unnamed Creek,” said Clark.

Johnson strongly disputes that claim, noting that the only way to adequately determine the health of a creek is to compare it with other un-impacted streams in the area. Clark acknowledges that the MPCA doesn’t require Cliffs to assess aquatic life in other nearby streams, which, according to Johnson, makes any conclusions derived from Cliffs’ sampling suspect.

Johnson notes that state researchers did undertake such comparisons as part of the 1970s-era copper-nickel study, and those comparisons demonstrated at the time that the diversity of aquatic insects in Unnamed Creek (which was already receiving Dunka discharges) was more than 40 percent less than in unpolluted streams in the vicinity.

Among more sensitive families and genera of aquatic insects, the comparison found even greater impacts. The diversity of mayflies, for example, was reduced from the average of 11 different genera in neighboring streams, to just four in Unnamed Creek, a reduction of 64 percent. Such dramatic impacts to aquatic species violates the intent of the Clean Water Act, said Johnson. Federal rules indicate that receiving streams should maintain at least 95 percent of their species diversity.

In the 1970s, DNR researchers speculated that discharges from mine dewatering might have contributed to the disappearance of a number of species of more sensitive invertebrates in Unnamed Creek. But, according to Johnson, more recent data gathered by Cliffs, suggests it’s the ongoing contaminant discharge from waste rock runoff that’s causing the problem.

While Cliffs’ studies suggest there’s been no further reduction in species diversity in Unnamed Creek in recent years, Johnson said there should be evidence of actual recovery if the pollution problem was under control. So far, he notes, there’s no sign of that.

As for the caddisflies cited by Clark, Johnson notes that the copper-nickel study found them to be less sensitive to pollution than other insect varieties living in the area.

The MPCA does cite other evidence, including bio-assays, that agency officials believe points to lower levels of contaminants coming from the mine. Bio-assays are essentially experiments in which researchers add increasing concentrations of water from a tested lake or stream— in this case, Unnamed Creek— to a sample of uncontaminated water, to determine at what level the conditions might prove toxic to certain aquatic insects or minnows, like fatheads, known to be sensitive to pollution. Cliffs is required to conduct such bioassays on a regular schedule as part of its current permit and, to date, Clark explains, only one of 11 such tests run since 2012 indicated a level of toxicity harmful to certain stream organisms. And even that test passed when run a second time, notes Clark. Meanwhile, none of the tests indicated toxicity to fathead minnows, a fish species known to be sensitive to pollution.

Johnson takes issue with those findings as well. He notes that when one of the bio-assays showed toxicity last summer, the testing company re-ran the test using water with a higher level of hardness, about 200 mg/l. Johnson said that makes a difference, since increased hardness makes metals like copper and nickel less toxic. He said the tests should be using water with the level of hardness found in Birch Lake, which is the receiving water for contaminants in Unnamed Creek. “Hardness in Birch Lake is about 46 milligrams per liter,” said Johnson. “According to the rules, the hardness should be based on natural conditions.” He calls the bio-assays, as conducted by Cliffs, “strategic advocacy, rather than science.”

Perhaps the larger question is whether the discharges, particularly the very high levels of sulfates, are affecting Bob Bay or Birch Lake as a whole. Research conducted for the state’s copper-nickel study in the 1970s, showed that fish and clams in Bob Bay exhibited very high levels of copper and nickel, although there was some evidence those levels may have been higher than normal even prior to mining at Dunka.

In addition, other more recent research, including studies on the Iron Range, suggest a strong connection between sulfate levels and the conversion of elemental mercury into the more highly toxic methyl mercury, which is responsible for fish consumption advisories on many lakes in northeastern Minnesota. Sulfate discharges from Dunka into Bob Bay are among the highest on the Iron Range. But despite these well-documented excesses, Clark says he’s unaware of any sampling of water or fish tissues in Bob Bay, at least by state officials, since the initial state remediation work back in the 1980s.

Who pays for


The state’s mining industry has fought for years for relief from some of Minnesota’s environmental laws, which are among the strictest in the country— at least on paper. Mining company representatives and their political supporters argue that the cost of cleaning up some of the industry’s longstanding pollution problems is too high in an era of intense global competition in the iron ore industry.

Such political pressure has, more than once, stood in the way of enforcement of clean water rules on the state’s mining industry. Indeed, earlier this year, the Legislature, led by the Iron Range delegation, blocked the MPCA from issuing a draft permit for U.S. Steel’s Minntac tailings basin after company officials told top state officials they wouldn’t accept enforcement of the standard as written.

While political pressure is one way that companies can avoid the cost of environmental clean-up, bankruptcy is another. LTV’s 2001 bankruptcy left the clean-up of Dunka in a legal limbo until Cliffs Natural Resources purchased LTV’s northeastern Minnesota mining property in later that year.

But Cliffs is facing extreme financial challenges of its own given a high debt load and the recent plunge in iron ore prices. The company’s stock has fallen dramatically in the past four years, from a high of $99.86 in July of 2011, to just $2.75 a share this past week. Industry analysts have been speculating for months about a possible bankruptcy of the heavily indebted company.

Given the company’s financial difficulties, there’s reason to believe that the MPCA will continue to delay any action on a new permit. The MPCA and Cliffs can avoid compliance with the federal Clean Water Act at present, because the company is operating under expired permits that were originally issued prior to enactment of current clean water laws and rules. But those rules require that any new permit that the MPCA issues, must come into compliance with current standards— and that would almost certainly require a major new investment in pollution control facilities at Dunka. MPCA’s Clark notes that the current wastewater treatment plant at Dunka isn’t designed to address all of the documented pollution at the site, so a new facility would likely be required. Reducing sulfate levels, in particular, would almost certainly require construction of a reverse osmosis facility, a water treatment method that is expensive to build and comes with ongoing operational costs. Would Cliffs, which inherited the pollution problems at Dunka, be willing to invest millions of dollars in such a clean-up effort? So far, neither the Legislature nor regulatory agencies in Minnesota have shown a willingness to force the issue against a politically-powerful mining industry.

Maccabee says the state needs to show it can truly regulate the taconite industry before it can credibly undertake a new and environmentally risky form of mining in the region. “Minnesota regulators need to act now and require a clean-up of Dunka mine pollution,” Maccabee said. “At least as important, Minnesota needs to learn the lessons of the Dunka mine project before embarking on copper-nickel mining in the Duluth Complex. Bankruptcy, volatile prices and the undue political influence of the mining industry all increase the risk of long-term violations of water quality standards.”

Cliffs Natural Resources was provided a draft of this story in advance and offered an opportunity to comment. The company did not respond.


3 comments on this item Please log in to comment by clicking here

  • snowshoe2

    Wow a lot to digest.

    Wednesday, October 7, 2015 Report this

  • chessie2go

    The same agencies that are allowing the taconite industry to continue polluting are the agencies prepared to permit PolyMet.

    This is not a good omen for the future of this land or the quality of our water.

    Thursday, October 8, 2015 Report this

  • I've learned to live with the taconite mines being out of compliance. If somebody wants to boost this new mining because of the need for jobs fine. But please don't also conveniently champion our environmental standards with your argument when they aren't even fully enforced.

    Friday, October 9, 2015 Report this