MINNEAPOLIS - An environmental group says the design for the proposed PolyMet copper-nickel mine in northeastern Minnesota has changed in significant ways that require regulators to take a fresh look.

WaterLegacy cites changes in the mine's tailings basin and wastewater treatment facilities, and a new disclosure of how much water would be pumped from the mine, in requesting a supplemental environmental review of the changes.

Attorney Paula Maccabee says the plans changed between when the DNR approved the final environmental review and when PolyMet started applying for permit. She calls it a "bait-and-switch" that cuts costs while increasing the risks of a catastrophic dam failure, pollution spills and damage to wetlands.

But PolyMet spokesman Bruce Richardson says the changes "do not have significant environmental effects" and shouldn't reopen the review process.