
Court Decision Clears Path for $500M Protective Tunnel Project in Straits of Mackinac
MICHIGAN, Feb. 20, 2025 – A key ruling from the Michigan Court of Appeals has allowed Enbridge to continue its plan to build a protective tunnel around a segment of its Line 5 pipeline in the Straits of Mackinac, which connects Lake Michigan and Lake Huron. The $500 million project aims to secure the pipeline, which has been transporting crude oil and natural gas liquids since 1953.
The court’s decision rejected objections from environmental groups and Native American tribes, who argued that the Michigan Public Service Commission (PSC) had failed to fully evaluate the necessity of the pipeline before issuing the permits. In its ruling, the court affirmed that the PSC’s issuance of permits was valid, allowing the tunnel construction to proceed.

“The Public Service Commission acted within its authority and properly issued the necessary permits for the Line 5 tunnel project,” the Michigan Court of Appeals stated. “Environmental concerns and the potential need for pipeline infrastructure have been taken into consideration.”
Details of the Tunnel Construction
The protective tunnel would be constructed around a four-mile section of Line 5, located beneath the Straits of Mackinac, where environmental groups have raised concerns about the risk of an oil spill in the Great Lakes. The tunnel would house the pipeline and provide a secure, leak-resistant barrier, aimed at preventing accidents that could have devastating environmental impacts.
Environmental Concerns Over Pipeline Safety
Concerns about the safety of Line 5 have intensified in recent years, particularly after Enbridge reported in 2017 that engineers had discovered gaps in the pipeline’s coating, heightening fears of an oil spill in the Great Lakes. These fears escalated in 2018 when a boat anchor damaged the pipeline, prompting further calls for stronger protections.

The new tunnel is seen as a response to these safety concerns, as it would house the pipeline in a controlled environment, reducing the risk of leaks or damage from external factors.
Remaining Legal Challenges and Permits
Although the state court ruling allows the tunnel project to move forward, Enbridge still needs to secure federal construction permits from the U.S. Army Corps of Engineers. Additionally, the Michigan Attorney General’s Office filed a lawsuit in 2019 seeking to revoke the easement that allows the pipeline to run beneath the Straits. This case remains pending in Ingham County and a ruling is expected soon.
The outcome of the case could still affect the timeline for the project, as the court could potentially block the tunnel’s construction if it rules against the easement.
Opposition and the Future of Line 5
Opponents of the tunnel project, including environmental groups and Native American tribes, argue that the pipeline poses a significant threat to the region’s waterways and ecosystem. They fear that the construction of the tunnel could result in further environmental degradation and put the Great Lakes at risk.
There is also concern that the Trump administration could expedite the process under the National Energy Emergency declaration, which could speed up the permitting process for critical energy infrastructure projects.
A Complex Battle Over Energy and Environmental Concerns
The debate surrounding Line 5 and the new tunnel is part of a larger national conversation about energy infrastructure, environmental protection, and the balance between economic development and sustainability. As the project moves forward, it is likely to face continued legal and public scrutiny, particularly from groups advocating for stronger environmental protections and the preservation of the Great Lakes.
“This project is critical for the continued transportation of energy resources in the region, but we are committed to ensuring the highest safety standards are maintained throughout its construction,” said Enbridge spokesperson Diana Walker.
As of now, Enbridge remains on track to begin construction on the protective tunnel, pending further legal developments and federal approvals. The decision from Michigan’s highest court has cleared a major hurdle for the company, but it is just one chapter in the ongoing saga of Line 5’s future.
The Road Ahead
With environmental challenges, legal battles, and federal permits still on the horizon, the fate of the Line 5 tunnel project remains uncertain. However, for now, the Michigan Court of Appeals’ ruling has allowed Enbridge to push ahead with plans to secure the pipeline and mitigate the environmental risks associated with its operation. The next steps will depend heavily on the outcome of related lawsuits and federal approval processes.
Originally reported by Carl Surran in Seeking Alpha.
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