This coverage is made possible through a partnership between IPR and Grist, a nonprofit environmental media organization.

At issue is the commission’s permit for Enbridge’s Line 5 tunnel project beneath the Straits of Mackinac.

The Canadian company Enbridge wants to relocate the existing dual pipelines running some four miles along the lakebed in the Straits of Mackinac into a proposed tunnel that would be built in the bedrock underneath the straits.

In December, the Michigan Public Service Commission approved the project. Since then, it has faced appeals from tribes and environmental groups. Now, the climate action network will join that legal opposition.

Opponents of the tunnel worry about Line 5 continuing to operate at all, risking a spill and billions of dollars of damage to the environment.

“The most viable and sensible course of action is to shut down Line 5, and focus on cleaner, better energy alternatives,” said Denise Keele, the network’s executive director, speaking as part of a panel held on Wednesday in Traverse City.

The event was called “Tunnel Vision: A Masterclass in Rejecting the Line 5 Oil Tunnel.” It was organized by Groundwork Center for Resilient Communities, Sierra Club, Progress Michigan, and Oil & Water Don’t Mix.

Keele didn’t say what exactly the appeal would argue, although she told the Traverse City Record-Eagle that it would use the state’s environmental protection law, including protections against methane emissions.

When the public service commission announced the permit, chair Dan Scripps said the tunnel would be the best way to reduce the risk of a “catastrophic” oil spill in the straits. Opponents of the project hold that the best way to address that risk is to shut down the pipeline. Enbridge maintains that the pipeline is necessary to transport oil and natural gas liquids.

The public service commission’s permit for Enbridge’s pipeline relocation plan was the first time a state agency considered greenhouse gas emissions in an analysis under Michigan’s environmental policy act.

The climate action network and the Environmental Law & Policy Center pushed for the commission to do so, winning an appeal in 2021.

“We decided to have our own day in court, and to challenge Enbridge, challenge the Michigan Public Service Commission and, frankly, challenge the law itself to recognize what we already know — that we are living in this climate crisis,” Keele said.

Previously, experts told the Michigan Public Service Commission that continuing to operate Line 5 in a tunnel would release tens of millions of tons of carbon dioxide into the atmosphere each year, compared to shutting down operations in the straits altogether.

But the commission said in its decision that proposed alternatives to the tunnel project, like transporting fuel by rail and truck, could be more harmful to the environment and that “there are no feasible and prudent alternatives to the Replacement Project pursuant to MEPA.”

MEPA is the Michigan Environmental Protection Act.

In an emailed statement to IPR, Enbridge spokesperson Ryan Duffy said “we are building the Great Lakes Tunnel as a sustainable way to ensure energy is delivered reliably and safely, while protecting the waters of Lake Michigan and Huron for Michiganders now, and generations to come.”

As for the legal challenges, Duffy said Enbridge officials believe the Michigan Court of Appeals will ultimately uphold the public service commission’s decision to green light the project.

Beyond the state Court of Appeals, the project still needs a federal permit from the U.S. Army Corps of Engineers. A decision is expected in 2026.

Editor’s note: Enbridge is among Interlochen Public Radio’s financial supporters. They have no role in decisions about our news coverage, which are made independently by the IPR newsroom.