Perhaps you saw the cursory coverage last week of WaterLegacy’s challenge to the PolyMet land exchange, prerequisite for its NorthMet copper/nickel mine near Babbitt.

Ho-hum, right? Another incremental step in PolyMet Mining Corp.’s forward march brings another environmentalist effort to roll boulders into its path. Not the first challenge to the land exchange since the U.S. Forest Service gave it final approval on Jan. 9. Not even a challenge on the overall merits of the exchange — just some procedural points.

Wrong.

WaterLegacy’s claim strikes me for multiple reasons as highly problematic for PolyMet and also for the Forest Service, which has less at stake in the outcome but bears more responsibility for the current situation. Here are three:

• Rather than raising intricate, science-based environmental objections to the land exchange — as the Center for Biological Diversity has said it will do, in asserting that the trade authorizes destruction of habitat important to protected species — WaterLegacy is stating a problem that can be measured in dollars. Better yet, taxpayer dollars.

It asks whether the Forest Service did its duty to the public financial interest by getting fair market value for the portion of the Superior National Forest it is trading away. Then it makes a powerful, easily grasped and documented case that the land may be worth many times the $550 per acre value set by the agency.

• The result not only looks like a “sweetheart deal” for PolyMet, in the words of WaterLegacy’s attorney, Paula Maccabee, but raises a potential problem that the mining company can’t solve by simply writing a bigger check. If a court agrees with Maccabee, both the Forest Service and the company are back at Square One on the land exchange — and PolyMet’s way forward could be really tough.

Under the law, the feds can trade away the acreage PolyMet wants for private land that aligns with its management objectives for the Superior, but they can’t simply sell it. If a court agrees that the Forest Service undervalued its land, PolyMet would have to find more private land — maybe a lot more — with willing sellers, and in just the right locations, to put on the scales.

• Finally, Maccabee makes a strong case that all information about the financial aspects of the land exchange — from the instructions given to the appraisers through the final valuations — were shielded from public view in a process that is supposed to be open to public review and comment.