DNR: More review of Milepost 7 expansion not needed

SILVER BAY — Minnesota regulators said a more rigorous environmental review and additional dam safety permits are not needed for the expansion of a basin holding back mine waste near Lake Superior.

Earlier this month, the Minnesota Department of Natural Resources said Northshore Mining’s planned expansion of its Milepost 7 tailings basin is within the size and footprint considered in the original 19751976 environmental impact statement and, therefore, not considered an expansion.

Under owner Cleveland- Cliffs’ plan, the basin’s footprint and height would increase to the maximum allowed in its nearly 50-yearold permit: an area of 2,800 acres and dam wall heights of up to 1,315 feet above sea level — 650 acres more than its current area and about 60-75 feet above the current dam elevation. The plan would include the relocation of a railroad, extension of two dams, construction of a switchback, and development of a “clay borrow site.”

In doing so, the “remnants” of Big 39 and Little 39 creeks, tributaries of the Beaver River, would be covered, requiring the mining company to rehab almost four miles of nearby streams at six different sites.

“Our review confirms that potential environmental impacts from the proposed project match those studied in prior environmental review and/or are subject to robust ongoing regulatory oversight,” DNR Assistant Commissioner Jess Richards said in a news release.

Cliffs plans to build up the dam using an upstream cons t r uc t ion method, which has come under scrutiny after dams using that met hod have failed, causing pollution and killing hundreds. But the DNR said Milepost 7’s 1977 master permit and 1985 permit to mine sufficiently regulated the dam. Richards said the dams were “some of the most closely regulated dams in the state, meeting all applicable factors of safety and state dam safety laws.”

“We are not surprised, but we are disappointed,” Paula Maccabee, Advocacy Director and Counsel for WaterLegacy, said in a news release. “The DNR’s denial of an (environmental impact statement) and failure to require Cliffs to secure a dam safety permit do not protect human safety or Lake Superior waters. The Mile Post 7 expansion is too risky, and new environmental analysis is long overdue.”

In 2021, the DNR said the project did not need an environmental impact statement or the less-stringent environmental assessment worksheet, though it ended up completing the latter in April 2023 as the project’s impact on Big 39 and Little 39 creeks required such a review.

The famed basin was completed in 1980 after then-owner Reserve Mining was forced to stop its decades-long practice of dumping tailings — the fine pieces of waste rock left behind after taconite is crushed and stripped of its iron — directly into Lake Superior and years of court battles over the tailings’ pollution and asbestos-like fibers found in the drinking water of Duluth.

Northshore mines iron ore from its Peter Mitchell Mine near Babbitt, processes the material into pellets at its Silver Bay facility, and sends the tailings to Milepost 7.