The U.S. Army Corps of Engineers issued a permit on Thursday for the construction of a tunnel to house the Line 5 oil pipeline beneath the Straits of Mackinac. In its decision, the federal agency stated that the project was not contrary to the public interest.
The Line 5 pipeline, operated by Enbridge, carries crude oil and natural gas liquids between Wisconsin and Ontario, passing through Michigan. The proposed project involves excavating a tunnel deep beneath the lakebed to replace the existing dual pipelines that currently sit on the bottom of the straits, a waterway connecting Lake Michigan and Lake Huron.
The federal approval follows a multi-year review process by the Army Corps of Engineers, which is responsible for regulating construction in U.S. navigable waters. While the agency has now granted the necessary federal permit, the project has faced long-standing opposition from environmental groups and several Indigenous tribes who cite risks of a potential spill in the Great Lakes.
A person living in the Upper Peninsula of Michigan or parts of Ontario would notice the direct impact on their energy bills and fuel availability if the line were to be decommissioned rather than housed in the new tunnel. Conversely, tribal members and shorefront property owners would notice changes in the legal and physical protections afforded to the straits. The federal permit sets a precedent for how the U.S. government balances aging energy infrastructure maintenance against environmental and tribal treaty concerns in ecologically sensitive zones.
What happens next is the potential for further legal challenges in federal court. While Enbridge now holds the federal permit from the Army Corps of Engineers, the project remains subject to ongoing litigation between the company and the State of Michigan, which has previously sought to revoke the pipeline's 1953 easement. Construction dates and specific deadlines for the tunnel's completion were not reported in the agency's announcement.