PolyMet’s Proposed NorthMet Mine

The Nature Conservancy is invested in Northeast Minnesota. The region’s forests provide clean water, jobs, wildlife habitat and recreation opportunities.

Mining companies are actively exploring and proposing new projects and the Conservancy is concerned about the potential impact of mining on priority conservation areas including the Boundary Waters Canoe Area Wilderness, the headwaters of the St. Louis and Cloquet rivers, and the St. Louis River Estuary.

PolyMet Mining’s proposal to develop the first open-pit copper-nickel mine in northeastern Minnesota has generated both support and opposition. Thousands of citizens and organizations, including The Nature Conservancy, have reviewed the project and filed comments.

The Conservancy’s review of the project’s Final Environmental Impact Statement (FEIS) finds it inadequate. Key information is missing or incomplete. Additional analysis and public review is needed to inform decisions.

Here are additional details about the Conservancy’s review of the FEIS:

Land Exchange

PolyMet’s NorthMet mine site lies on federal land in Superior National Forest. PolyMet plans to acquire and then trade 6,723 acres of private land for 6,650 acres of federal forest land. But when the Conservancy evaluated the trade on the ecological value of the lands, water and wildlife that would be impacted, conservation came up short.

“This is not an equal exchange,” says Doug Shaw, assistant state director of the Conservancy in Minnesota. “We’re losing high biodiversity, high ecological-value sites in exchange for sites of lower quality and lower value.”

The project will result in the loss of a significant amount of long-lived conifers and forestland in older growth stages. Three at-risk native plant communities occur within the project area: jack pine-black spruce woodlands, white pine-red pine forest and rich black spruce swamp. The project area’s lowland conifer forest and bog-type wetlands provide critical habitat for a number of declining and iconic species including mammals such as moose, wolves, lynx and northern bog lemmings as well as rare songbirds and butterflies.

A significant amount of carbon stored in the ground at the mine site would also be lost to the project. Northern peatlands have the highest density of carbon of any ecosystem on Earth. Keeping them intact is an important strategy to mitigate the risk and impact of climate change. 

The FEIS acknowledges the loss of these natural communities and the benefits they provide but failed to consider any alternative land exchanges of similar biologically diverse land.

Wetlands and Mitigation
The mine would be located in the headwaters of the St. Louis River, a wild, forested country of high biodiversity significance known as the Sand Lake/Seven Beavers landscape, where the Conservancy owns nearly 7,000 acres.

The Sand Lake/Seven Beavers’ lowland forest is rich in northern bird life and harbors many rare plants. The sponge-like peat regulates water flow into nearby streams, reducing erosion and protecting water quality.  More than 90 percent of the wetlands that would be lost to the mine are mapped by the state for their high quality and biological significance. 

“One thing to know about these kinds of wetlands is that they are very difficult to replace,” says Shaw.

Nearly 1,000 acres of wetlands would be lost and the mine would also indirectly impact thousands of additional acres of wetlands, which would be one of the largest permitted losses of wetlands in the state’s history.

The St. Louis River watershed has already lost nearly 15 percent of its wetlands, yet PolyMet has proposed most of its wetland mitigation outside the river’s watershed.

The FEIS should have placed a greater emphasis on avoiding and minimizing impacts to high quality wetlands and made a commitment to require a higher replacement ratio for wetlands that are lost. In addition, it should have prioritized replacement of wetlands within the St. Louis River watershed to maintain their hydrologic and ecological function including storing carbon and providing clean water.

Separate financial assurance to cover the cost of wetlands mitigation also should have been required.

Finally, the lack of any commitment to advance mitigation to compensate for the indirect impact to thousands of acres of wetlands from the project runs counter to state and federal policies of no net loss.

Risk Assessment

Sound engineering practice requires a risk assessment as an essential element of project planning and environmental review, however, the FEIS for the NorthMet Mine does not include one.

The FEIS anticipates centuries-long operation of the tailings dam and water containment, collection, and treatment systems. Over an extended period of time, there is a substantial risk that that one or more of these engineered systems will fail due to natural causes; equipment malfunction, breakage, or age; human error; or lack of funds for maintenance and repair.

A risk assessment would detail the probability and environmental consequences of potential failures for each of the following aspects during all phases of the project: the mine site, plant site, transportation corridor, tailings basins, stockpiles, and water containment and treatment systems.

The catastrophic failure of the tailings dam at the Mt. Polley Mine in Canada in 2014 is a recent example of a low-probability, high consequence failure.  Had that possibility been adequately characterized in the planning, design and environmental review process, the risk could have been mitigated. 

Financial Assurance
Because leachate is likely to seep from the mine pits, waste rock stockpiles, and tailings basin for decades and possibly centuries, PolyMet has proposed water treatment long after the mine is closed. But who’s going to pay for it? By then, PolyMet may no longer be in business.

Serious risks to the environment are associated with the reclamation, closure, and the perpetual operation and maintenance of treatment systems and engineered structures. It is well-documented, however, that mines frequently fail, go bankrupt and are abandoned

To minimize the risk that there will be inadequate funds to protect Minnesota’s lands and waters, it is critical to develop robust financial assurances and for them to be carefully scrutinized by state and federal agencies and the public.
“What if things go wrong?” asks Shaw. “A durable financial vehicle is needed — something that will survive changes in government or agencies, certainly changes in company ownership.”

A detailed financial assurance plan is not included in the FEIS, which is written from the perspective that assumes that everything will go as planned.

The PolyMet proposal is likely to be the first of several copper-nickel mining proposals for northeastern Minnesota. “Because of the importance of this project, we’ve got to do this right.”

Download a copy (PDF 1mb) of The Nature Conservancy’s comments on the FEIS. You may also download a copy (PDF 2mb) of our earlier comments on the project’s draft supplementary environmental impact statement.

If you have questions, please send them to us via e-mail at Minnesota@tnc.org


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