Birch Lake near BWCA added to impaired waters list due to sulfate pollution

Birch Lake near the Boundary Waters Canoe Area Wilderness has been added to the impaired waters list after a study found elevated levels of sulfate in the water. 

The Minnesota Control Pollution Agency (MCPA) released its 2024 impaired waters list, which added 199 impairments in 54 bodies of water. For the first time, the list includes Birch Lake and a portion of the Dunkan River after an environmentalist’s water monitoring study found sulfate levels were higher than state standards.  

The data collected by the Northeastern Minnesotans for Wilderness (NMW) and the Campaign to Save the Boundary Waters indicate every sample taken from the western end of Birch Lake had sulfate concentration levels above state standards. 

The waterways are near the proposed Twin Metals copper-nickel mine in the region, which is currently stalled by the federal government due to potential environmental harm. During Wednesday's press conference, environmentalists voiced their concerns that sulfate and copper mining pose a threat to the wilderness.

"It is widely known that sulfate or copper mining is a dangerous source of acid, heavy metals and sulfate pollution. Birch Lakes status as impaired for sulfate has now been added to the growing list of reasons as to why the boundary waters and its watershed is an entirely inappropriate place for sulfate or copper mining," said Ingrid Lyons, Executive Director of NMW and the Campaign to Save the Boundary Waters, during the press conference Wednesday, 

The NMW said their study tracked the origin of the sulfate pollution from runoff in the Dunka River and the "Unnamed Creek" from open-pit taconite mines. The Unnamed Creek specifically "receives acid mine drainage (AMD) with extremely high sulfate levels flowing from massive piles of weakly mineralized copper-nickel-sulfide waste rock," according to a press release. 

Environmentalists say the next step is sending the study’s findings to the EPA to get Birch Lake on the final impaired waters list. Once added, it would ensure no new permits could be issued that would increase sulfate levels, and the lake would be eligible for remediation under the Clean Water Act.