Michigan Supreme Court Sends Enbridge Line 5 Tunnel Permit Back for Review
The Michigan Supreme Court has ruled 6-1 to send a key permit for Enbridge’s Line 5 tunnel project back to state regulators for reconsideration, according to an Associated Press report carried by Daily Commercial News, further delaying construction on the contested Great Lakes crossing.
Background and Legal Fallout
The permit in question covers plans to bury a 4-mile stretch of Line 5, the 73-year-old pipeline carrying petroleum from Superior, Wisconsin, to Sarnia, Ontario, in a tunnel beneath the Straits of Mackinac. The Michigan Public Service Commission granted the tunnel permit in 2023, but four Michigan tribal nations and several environmental groups sued, arguing regulators failed to properly weigh the project’s long-term environmental impact.
The court found the commission did not adequately assess whether the tunnel would extend the pipeline’s operational lifetime, potentially compounding environmental harm, and was inconsistent in comparing alternatives such as rail or truck transport. Regulators also failed to evaluate impacts on fishing, boating and other public trust rights tied to the Great Lakes, the court said.
Enbridge spokesman Ryan Duffy called the ruling another delay in a project under review for nearly a decade, saying the tunnel would “enhance environmental protection of the Great Lakes while maintaining critical energy reliability for the region.” Attorney David Gover of the Native American Rights Fund countered that routing more than half a million barrels of oil daily through the Great Lakes is a bad idea regardless of whether the line sits in a tunnel or on the lakebed. Michigan Gov. Gretchen Whitmer has separately pursued shutting down the straits segment of Line 5 since 2020.
What It Means for Subcontractors
- Tunnel-boring, marine, and geotechnical contractors positioned for mobilization on the Straits of Mackinac crossing should expect no near-term notice to proceed until the Public Service Commission completes a new review with no set timeline.
- Firms tracking subcontract packages for the tunnel, including E&I, pipefitting, and specialty marine construction work, should treat pre-2023-permit bid preparation as outdated and wait for a reissued permit decision before committing crews or equipment.
- Companies with pending vendor agreements tied to the project should confirm contract language addresses regulatory delay risk, since this is now the second major legal setback after the original 2023 approval.
- Contractors in Michigan and Ontario supply chains linked to Line 5 operations should monitor parallel litigation over Gov. Whitmer’s separate effort to shut down the straits segment, as that case could affect the pipeline’s operating status independent of the tunnel permit outcome.
