Army Corps Permits Line 5 Tunnel, But Michigan Court Fight Stalls Start
The U.S. Army Corps of Engineers issued a permit Aug. 12 for construction of a four-mile tunnel to enclose Enbridge’s Line 5 pipeline under the Straits of Mackinac, ENR Midwest reports, though the project remains tied up in Michigan state court.
Market Impact
The tunnel would fully enclose twin oil and gas pipelines that form part of the 645-mile Line 5 system running from Superior, Wisconsin, to Sarnia, Ontario. The Corps’ 54-page decision found the tunnel design complies with federal environmental, cultural, engineering and community requirements, and authorizes Enbridge to work in federally regulated waters. Notably, the Corps does not regulate the pipeline’s design, operation, or contents.
The permit came under the Trump administration’s “Building Infrastructure, Not Paperwork” initiative. Assistant Secretary of the Army for Civil Works Adam Telle said the move “cuts unneeded red tape” and “accelerates the delivery of critical infrastructure.” Enbridge spokesperson Ryan Duffy called it “a significant step forward,” noting the Corps spent more than six years on its review. But the federal green light doesn’t clear the path to construction. On July 31, the Michigan Supreme Court vacated the Michigan Public Service Commission’s December 2023 approval, ruling the commission failed to properly apply the Michigan Environmental Protection Act. Bay Mills Indian Community President Whitney Gravelle called the federal decision “shameful” and a breach of treaty trust obligations tied to the 1836 Treaty of Washington. Earthjustice, representing the tribe, warned the tunnel method has never been attempted anywhere else and would turn the Straits into “a construction zone for more than six years.” Project costs have climbed from an estimated $500 million in 2019 to more than $750 million, according to earlier ENR reporting.
What It Means for Subcontractors
- Hold off on mobilizing crews or equipment for the Straits crossing until the Michigan Public Service Commission issues a corrected approval addressing the Michigan Environmental Protection Act deficiencies cited by the state Supreme Court on July 31.
- Tunneling, HDD, and marine construction subs bidding on the Great Lakes Tunnel Project should factor a multi-year timeline into scheduling, given Earthjustice’s estimate that construction could span more than six years once state approval clears.
- Track cost escalation risk before locking in bid pricing: the overall project has grown from $500 million in 2019 to over $750 million per ENR’s prior reporting, a signal that materials and labor contracts on this job may need built-in escalation clauses.
- Firms working with Enbridge on federally regulated waters should note the Corps’ permit covers construction methodology only, not pipeline operation, so separate state and environmental compliance packages will still govern scope of work once Michigan’s court process resolves.
