The Mackinac Center’s Energy and Environmental Policy Initiative scored an important win in April for Michigan’s environment and economy. The Defense Department’s decision to expedite its environmental review for the Line 5 Tunnel project came after years of advocacy for a plan that could provide reliable and affordable energy while also protecting the environment and our natural resources.

We recently partnered with the Institute for Energy Research to expand our impact and show that principled collaboration can safely move mountains — or, in this case, pipelines. As Michigan’s governor and attorney general work to shut down the crucial Line 5 pipeline, we have been making a strong case for a project that will enhance energy security in the Midwest, foster economic growth, safeguard the Great Lakes and protect Michigan’s environment.

The Line 5 Tunnel, proposed by Enbridge, would relocate a 4-mile segment of the pipeline to a concrete- lined tunnel 100 feet below the Straits of Mackinac. Moving the pipeline would protect the waters of the Great Lakes from the potential for an oil spill. It would also ensure the continued flow of 540,000 barrels of essential fuels each day. These fuels account for 55% of Michigan’s propane needs, support regional refineries, provide nearly 34,000 jobs to the region and contribute more than $20 billion to the regional economy.

When bureaucratic delays threatened this vital project, we stepped in.

In February 2025, Mackinac and IER co-wrote a letter to Secretary of Defense Pete Hegseth, urging the U.S. Army Corps of Engineers to expedite the federal Environmental Impact Statement process for the tunnel. Our efforts were consistent with a presidential executive order declaring a national energy emergency.

On April 15, the Army Corps announced that it would expedite the process for the Line 5 Tunnel project, one of more than 600 potential projects. The public draft of the environmental impact statement was published May 30. This is good news for Michigan and the nation. Rapid agency responses to major infrastructure projects help to promote energy reliability. They also reduce the costs and burdens of navigating complex permitting processes.

The Mackinac Center’s partnership with the Institute for Energy Research combines our deep understanding of Michigan’s needs with the institute’s national policy expertise. Our arguments have resonated in both Washington, D.C., and Lansing. The collaboration has been featured in several news outlets, including Bridge Michigan and Bloomberg. It also encouraged successful efforts to pass a resolution in the Michigan House urging federal officials to accelerate approval of permits. The resolution underscores how aligning with like-minded organizations magnifies our voice and influence.

The fight to secure a safer and more reliable pipeline isn’t over. The federal process has taken so long that Enbridge has had to reapply for the state permits that the Michigan Public Service Commission approved in December 2023. But Mackinac remains committed to supporting this project and other energy solutions that benefit all Michiganders.