Company seeks to expand massive lake of mine waste near North Shore

A mining company wants to expand its already massive tailings lake near Silver Bay to accommodate six times more taconite waste than currently sits there — but one environmental group is suing to force a new study of the potential for a major spill or other harm.

Located about 3 miles from Lake Superior, Northshore Mining’s artificial basin known as Mile Post 7 stores waste from more than four decades of extraction. Three dams contain a 2,150-acre basin built in the late 1970s to end the practice of dumping mining waste into Lake Superior, one of Minnesota’s most infamous cases of industrial pollution. Many in the small communities around it don’t know the lake is there, because it’s mostly hidden from surrounding roads. But the basin, covering an area five times bigger than Bde Maka Ska in Minneapolis, is visible on satellite images, a huge white splotch along the North Shore.

The owner of Northshore, Cleveland-Cliffs, did not respond to multiple requests for comment.

The Department of Natural Resources last completed an environmental impact statement for the site in 1976. Still, the DNR has repeatedly monitored and tested the site so a new one isn’t necessary, said Jess Richards, a DNR assistant commissioner.

“This is one of the most studied and litigated mine sites in the whole state,” Richards said in an interview. “We have four decades worth of data and information.”

The agency has noted in court filings that a failure of the dams that hold back the tailings would be “catastrophic.” More details about what would happen in a failure are hard to come by, because the safety plans available to the public are heavily redacted.

Richards said the three dams that hold the waste are safe.

“Should the public just trust the DNR?” he said. “I would say yes.”

The environmental group WaterLegacy disagrees. This spring, after receiving hundreds of public comments on the issue, the DNR announced it would not do a deeper study than a basic environmental assessment worksheet. WaterLegacy sued in April in a bid for a deeper probe of the project, including what might happen if there was a major failure at Mile Post 7.

Paula Maccabee, the attorney for WaterLegacy, said Northshore Mining’s proposed expansion of Milepost 7 is “taller and bigger than anything they’ve ever studied before.” Therefore, she said, it’s “ludicrous” that DNR is not compiling a new environmental impact statement, the highest level of review.

Reserve Mining started processing taconite in Silver Bay in 1956, and the company “built the whole community,” said current Mayor Wade LeBlanc.

Separating taconite from ore creates huge quantities of waste rock, some as fine as dust. For years, the company dumped its waste directly into Lake Superior, as much as 67,000 tons a day, according to news reports.

After public concern about the practice grew in the late 1960s, the federal government sued Reserve to stop its dumping. A federal judge found Reserve violated federal law by dumping its waste, including asbestos-like fibers that had polluted the lake and drinking water in North Shore communities, including Duluth.

From then on, the waste would be dumped on the ground and contained by natural ridges and man-made dams. Though the environmental impact statement recommended putting the waste lake in a different location, the state Supreme Court in 1977 ordered it placed just inland of Silver Bay, where Northshore processes the ore it mines.

The DNR says the Supreme Court ruling has stopped it from considering alternatives to the Mile Post 7 basin, as an environmental impact statement would require.

After ore is crushed, sorted with magnets and concentrated into taconite pellets in Silver Bay, a slurry of wastewater and tiny fragments of leftover rock is piped from the lakeside plant back to Mile Post 7. Larger pieces of waste rock are shipped by rail to form the dam walls.

Reserve originally planned to aggressively mine the Peter Mitchell site, exhausting the site in 40 years, the DNR wrote in its most recent court brief that. The pit is the source of ore sent to Silver Bay. Downturns in the steel industry in the 1980s, and slow production since 2005, have postponed a tailings basin expansion that was originally permitted in 1977, the agency wrote.

Reserve filed for bankruptcy in 1986. After some changes in ownership, Cliffs became the sole owner in 1994.

In recent years, Northshore’s operations have been inconsistent and Cliffs has called it a “swing operation” that is only opened when needed. It was shuttered in 2022, and then called back workers in 2023.

LeBlanc said the company is still the most important employer in town — his son works there — and estimated 500 people work for Northshore now.

Though the footprint of Mile Post 7 would grow by 30% and the volume of tailings could ultimately be six times higher, the DNR asserts the project isn’t really an expansion that triggers a higher level of review.

Tailings basins often grow over time — larger pieces of waste rock are used to construct dam walls, and water and finer particles settle inside. Dams at Mile Post 7 were already permitted in 1977 to reach the final height Northshore wants today.

The only reason the DNR is doing any environmental review now is because Northshore plans to move a rail line and improve nearby trout streams as part of the expansion, Richards said. The agency has prepared an environmental assessment worksheet, but in March rejected the more detailed environmental impact statement WaterLegacy and others had asked for.

The question before the agency was, “are the impacts any different than they were when they were studied back in the ′70s? Our conclusion is that they weren’t,” Richards said.

LeBlanc said he is not concerned about the growing lake. “You’ve got to put faith in state agencies, and if they feel it’s safe, that’s what they’re there for.”

But WaterLegacy argues that a full public assessment of the risks has never been completed, in part because Northshore has changed the construction method to build the dam walls.

The permit originally required a “downstream” dam, which expands out from the pond and stays wholly supported by the ground. Northshore switched construction methods roughly two decades ago, and now parts of the dam walls rest on top of saturated fine tailings. It also uses less material in the dam walls, which can be cheaper for mining companies but creates a dynamic that Maccabee described as “more soup, less bowl.”

“The dam construction methods they’re using right now were never assessed [in an environmental impact statement],” Maccabee added.

The DNR maintains that its own monitoring, and Northshore’s inspections, show the dams are stable and safe, and the agency is not concerned about the dams continuing to grow in height.

Northshore must plan for what would happen if a dam broke, but the public versions of these documents are redacted because the DNR says the reports contain “security information” that might enable a bad actor to damage the dams or disrupt emergency response. It has not sent unredacted reports to a tribal government that asked for it, the Grand Portage Band of Lake Superior Chippewa.

WaterLegacy and others also worry about the risks of a warming climate, which has brought extreme rain events throughout the state, including a deluge this spring that washed out roads along the North Shore.

Jeff Dickson, who lives in nearby Finland, Minn., and works as a floodplain manager for the Federal Emergency Management Agency (FEMA), said the DNR cannot “rest their laurels on a design that was done 50-some years ago, and not take into account current conditions.” Dickson was not commenting on behalf of FEMA.

Richards said that more recent permits for the site have factored in updated climate data, and a DNR spokeswoman added that the final basin is designed to include 10 feet between the top of the lake and the top of the dam walls.

But that permitting process has not fully satisfied the groups who worry about the big lake above Lake Superior.

“There’s five decades of work to keep these tailings out of Lake Superior,” said JT Haines, an attorney with the Minnesota Center for Environmental Advocacy. The group is not involved in WaterLegacy’s court challenge but previously urged the DNR to complete a full study.

If a dam broke, “You could just completely void all that work over those decades, and I gather DNR doesn’t think that’s an immediate risk, but those are the stakes we’re worried about,” Haines said.