Michigan environmental regulators are reviewing previously issued permits for the Line 5 tunnel project following a July 31 Michigan Supreme Court decision that increased environmental review requirements. Gov. Gretchen Whitmer (D) and Phil Roos, director of the Michigan Department of Environment, Great Lakes and Energy (EGLE), announced the move on Wednesday, September 9, 2026. The announcement does not revoke the permits, but Roos stated that conditions in the permits prevent construction from proceeding until legal questions are resolved.
The Line 5 pipeline, owned by the Canadian firm Enbridge Energy, has transported petroleum through the Straits of Mackinac for 73 years. In 2018, the tunnel project was proposed to move the pipeline from the open lakebed to a new tunnel beneath it to prevent potential ruptures. While originally targeted for completion by 2024, the project has faced delays due to ongoing litigation.
The Michigan Supreme Court recently vacated a separate permit issued by the Michigan Public Service Commission, ruling the agency failed to adequately consider alternatives or environmental impacts. Gov. Whitmer subsequently sent a letter on Wednesday to Enbridge CEO Gregory Ebel, requesting the shutdown of the existing lakebed pipeline within months. Whitmer argued that Enbridge should pursue alternatives rather than waiting for a tunnel that could be a decade away.
The scale of the project involves a dual-pipeline system that has operated for over seven decades. While Enbridge intended to complete the tunnel by 2024, the recent court ruling and EGLE's permit review suggest the project could be delayed by several additional years. A federal court ruling previously held that Michigan lacked the authority to shut down the federally regulated pipeline, a decision the state appealed in January 2026. For residents, the immediate status is a continued reliance on the existing open-water pipeline while the legal status of the protective tunnel remains unresolved.
The knock-on effects include a potential precedent for future state environmental reviews in Michigan, as the Supreme Court now requires broader analysis of how projects impact natural resources and the public's right to use the Great Lakes. If the pipeline is eventually shut down, it would force a shift to alternative transport methods, which past analyses cited by Gov. Whitmer suggest would have little impact on energy access, though tunnel supporters dispute this. The next steps depend on the outcome of the state's appeal in federal court and the rework of the Public Service Commission's environmental review.