A proposed copper and nickel mine near Minnesota's Boundary Waters Wilderness Area is once again a focal point of debate after Congress and the Trump administration overturned a federal mining ban. The move allows Twin Metals Minnesota, a subsidiary of Chilean mining giant Antofagasta, to pursue its project, which environmentalists warn could threaten the ecologically sensitive region.
The Boundary Waters, a million-acre wilderness area bordering Canada, is known for its extensive network of lakes and streams and is a popular destination for tourism. It also provides habitat for threatened species such as the gray wolf and Canada lynx. Environmental advocates express concern that pollution from the proposed mine, located just outside the wilderness boundary, could leach into the Boundary Waters ecosystem. While mining is prohibited within the wilderness area itself, the region's hydrology means that any contamination could flow into the protected lands, potentially harming forests, wildlife, and the traditional livelihoods of Native American communities who rely on the area for fishing, hunting, and harvesting wild rice.
“It’s not a matter of if this mine is going to pollute, it’s a matter of when,” said Ingrid Lyons, executive director of Northeastern Minnesotans for Wilderness. Critics argue that mines are inherently polluting, and even modern operations carry risks.
Twin Metals Minnesota contends that the project can be developed safely and responsibly, meeting stringent federal and state environmental regulations. The company also argues that the minerals are essential for clean energy technologies, such as electric vehicle batteries, and that if the metals are not sourced from Minnesota, they may come from countries with less rigorous environmental standards. "Any proposed project in this region, including Twin Metals, must undergo a yearslong, multi-agency regulatory review before earning permits to begin construction of a mine,” stated Kathy Graul, a spokesperson for Twin Metals.
The proposed mine would extract copper and nickel from the Duluth Complex, a large deposit beneath the Boundary Waters. According to Twin Metals, the process would involve excavating ore deep underground, crushing it, and then separating the valuable minerals. The company plans to store some of the leftover rock, known as tailings, underground and pile the remainder on nearby land. The company estimates it has invested $650 million in the project over more than a decade.
Recent years have seen significant hurdles for the project. In 2022, the Biden administration canceled Twin Metals's two federal mining leases and, in early 2023, imposed a 20-year pause on new leases in the region. However, congressional Republicans, led by Minnesota Rep. Pete Stauber, used the Congressional Review Act to overturn this pause, preventing future administrations from enacting similar protections without congressional approval.
This congressional action does not automatically reinstate Twin Metals's leases, which were previously challenged in court. The company's ability to proceed hinges on the outcome of those legal challenges and potential congressional action to re-issue the leases. Even if federal leases are secured, the project must still undergo rigorous review by federal and state agencies, and the Minnesota Department of Natural Resources has the authority to deny permits.
Concerns about potential pollution, particularly acid rock drainage, persist. This process occurs when sulfide-bearing rock reacts with air and water, creating sulfuric acid that can leach toxic heavy metals. While Twin Metals asserts its modern methods will prevent this, environmental advocates and researchers remain skeptical. Lee Frelich, a forest ecologist at the University of Minnesota, noted that harmful chemicals could impact the Boundary Waters ecosystem, affecting trees and aquatic life. Emily Onello, a physician and researcher at the University of Minnesota Medical School Duluth, added that sulfate pollution could harm wild rice, a vital resource for Indigenous peoples.
Researchers like Dustin Mulvaney of San José State University acknowledge that new mines are generally cleaner and better regulated than in the past but emphasize that impacts are still likely. A 2022 Interior Department report stated that hardrock mining of sulfide-bearing rock, regardless of how it is conducted, carries a risk of environmental contamination due to the potential long-term failure of mitigation technologies.
Proponents of the mine, including Rep. Stauber and Julie Lucas of MiningMinnesota, argue that the nation's need for minerals for the energy transition necessitates domestic sourcing. They emphasize the abundance of these critical minerals in the Duluth Complex. However, critics, such as Grace Wu at the University of California Santa Barbara, suggest that less risky alternatives exist. Mulvaney pointed out that copper is mined elsewhere in the U.S., such as Arizona, and that Michigan has an active nickel mine. He also highlighted the potential for increased copper recycling, noting that only about a third of post-consumer copper was recycled in 2023. "There’s no place that has to inherently be mined," Mulvaney stated.
Opposition is not arguing against mining in general but against its location. Minnesota State Representative Alex Falconer, who also works for the Save the Boundary Waters Campaign, believes society can choose where mining occurs, comparing it to a past decision by then-Interior Secretary Ryan Zinke to ban mining near Yellowstone National Park.
The immediate future of the mine remains uncertain, with the focus shifting to state-level proceedings. Rep. Falconer is supporting a state bill aimed at preventing Minnesota regulators from issuing permits for copper mining in the Boundary Waters watershed. The outcome of this legislative effort, alongside ongoing federal lease reviews, will determine whether the proposed mine moves forward.