On February 10, the Minnesota Supreme Court issued a ruling regarding the 2018 NPDES/SDS Permit to U. S. Steel for its Minntac tailings basin. The ruling clearly establishes that groundwater is a Class 1 water, intended for drinking, culinary or food processing use, and other domestic uses. Thus, the U.S. Environmental Protection Agency’s secondary drinking water standards, which include the 250 mg/L sulfate standard, are applicable to all groundwater in Minnesota.
The ruling clarifies that seepage to groundwater will be regulated by Minnesota’s State Disposal System (SDS) permit. The MPCA must still determine whether it will regulate seepage to groundwater from tailings basins, landfills, ponds, or other impoundments under the National Pollution Discharge Elimination System permit and the Clean Water Act. The MPCA has been instructed to make this determination, based on the recent Supreme Court of the United States’ Maui decision.
Click here for a more detailed summary of the ruling and what it means for Barr's clients.