Tribal Nations, environmental advocates, and business owners are vowing to carry on their fight after Michigan approved key permits this week for a proposed tunnel to ship oil and natural gas liquids beneath the Straits of Mackinac through the Line 5 pipeline.

The project proposed by Calgary-based pipeliner Enbridge Inc. will knowingly desecrate ancestral burial grounds, damage fragile ecosystems, and imperil the state’s multi-billion dollar freshwater economy.

“For generations, Michigan’s administrations, regardless of political party, have far too often chosen powerful corporate interests over the voices and rights of tribal nations and over the voices and rights of their citizens,” said Whitney Gravelle, president of the Bay Mills Indian Community, during a media briefing organized by the Oil and Water Don’t Mix Coalition. “The decision made this week continues that pattern, and is unacceptable.”

Represented by Earthjustice and the Native American Rights Fund, the Bay Mills Indian Community has led Michigan Tribal Nations’ efforts to oppose the tunnel project from its inception. Describing the straits as “sacred” to the Anishinaabe (Ojibwe) people, as “religious ground where our ceremony and where our creation story begins,” Gravelle vowed that her Nation would fight on.

“Our relationship with these waters did not begin with a permit, did not begin with this project, and it will not end with one.”

The construction permit from Michigan’s Department of Environment, Great Lakes, and Energy (EGLE) allows Enbridge to build on lake bottomlands and in wetlands, while another one from the state Department of Natural Resources covers wildlife and rare plant protections. That combination means Enbridge has cleared two major regulatory hurdles in its years-long pursuit to replace the 6.4-kilometre twinned stretch of its Line 5 pipeline that currently sits on the bottom of the Strait of Mackinac with a single “oil tunnel.”

According to Enbridge, the US$800-million project, which would see a concrete-lined, V-shaped tunnel drilled deep beneath the bed of the strait, will lessen or eliminate risk of a catastrophic oil spill from the current stretch of the 73-year-old pipeline.  The existing set-up consists of two pipelines, running in parallel along the bed, some 300 metres apart.

Some 23 million gallons of oil and natural gas liquids flow through the pipelines daily, en route from Superior, Wisconsin, to Sarnia, Ontario. Both pipes were damaged in 2018 by an anchor strike.

“Officials with the company have long contended the tunnel would ‘make a safe pipeline safer’,” reports the Canadian Press.

But Line 5 has been plagued with safety issues, most recently a June 27 spill of between 1,600 and 1,900 gallons (6,000 to 7,000 litres) of drilling fluid (known as a “frac-out”) into a prized wetland in Wisconsin. Drilling fluid contains significant amounts of bentonite clay and is highly toxic to aquatic ecosystems.

The U.S. National Wildlife Federation says Line 5 has experienced 35 known spills over its lifetime, including a 69,000-gallon (more than 260,000 litres) spill, also in Wisconsin, in 2024. Enbridge was also responsible for the 3.19 million litres of diluted bitumen that spilled into a tributary of the Kalamazoo River in July, 2010, following a two-metre rupture in its Line 6B pipeline. 

The tunnel plan has met with fierce resistance since its inception, with Enbridge’s March, 2026 release of a 2022 geotechnical baseline report only deepening concerns that the project poses a profound danger to local communities and ecosystems, reports Michigan Advance. A central worry is that unstable bedrock could lead to tunnel collapse.

In explaining their decision to approve the permit, Michigan environmental officials acknowledged the project will have “significant impacts,” identifying harms to threatened or endangered species and the destruction of the ancestral burial grounds of local Tribal Nations as key losses, reports the Canadian Press.

“The magnitude of impacts to recognized historic and cultural values of this proposed project exceeds that of any other that EGLE has reviewed,” the government department said.

But state regulators ruled that the imperative to remove an “unacceptable” oil spill risk outweighed all possible harms, and that mandated mitigation measures would help to lessen any damages.

David Gover, managing attorney for the Native American Rights Fund, told media the exhumation of the bodies of ancestors in burial grounds that now stand to be bulldozed will be a “tortuous” process for the tribes forced to experience it.

“Before the bulldozing starts, [Enbridge] is going to say, ‘Okay, tribes, go out there and recover your ancestors as best you can’,” Grover said. “That’s atrocious. What is more sacred than how we treat our dead?”

The Natural Resources permit requires Enbridge to preserve seeds from two rare plant species—Houghton’s Goldenrod and dwarf lake iris—that are likewise in line to be chewed up by bulldozers. Enbridge is also being instructed to restrict its tree clearing along shorelines to winter months to avoid disturbing local bat populations.

Those restrictions do not impress Nichole Keway Biber, Michigan water justice organizer at Clean Water Action and tribal citizen of the Little Traverse Bay Bands of Odawa Indians. Biber condemned the permit process as inherently “piecemeal,” capable of neither addressing cumulative impacts nor respecting the irreplaceable value of every plant and animal that stands to be wiped out by the tunnel construction.

Ashley Rudzinski, climate and environment program director for the Groundwork Center for Resilient Communities, questioned Michigan’s decision to greenlight the permits on economic as well as ethical grounds.

“The Great Lakes are the lifeblood of this place. They are woven into our culture and our communities, and they are the defining feature of our state,” Rudzinski told the media briefing. “There is no ‘Pure Michigan’ brand or the 1.5 million jobs and $60 billion in wages that are annually tied to our freshwater economy without them.”

Juliette King McAvoy, vice president  of King Orchards, a multi-generation fruit grower in the region, echoed Rudzinski’s message. “One spill, one drilling accident under the lak bed, and it’s not just an ecological disaster,” McAvoy said. “It’s an economic one.

“That’s why King Orchards has helped to fund the Great Lakes Business Network, which now includes nearly 250 businesses joined together across the Great Lakes region to to fight this issue—farmers, brewers, outfitters, retailers, manufacturers. We don’t always agree on everything, but we are united on this issue,” McAvoy added. “Line 5 is bad for business, and this decision is indefensible.”  

Too many “urgent and unanswered questions” remain in the wake of Michigan’s granting of the permits, said Beth Wallace, Great Lakes climate and energy director for the U.S. National Wildlife Federation. Those questions include whether the Mackinac Bridge, located roughly 2.5 kilometres east of the current pipelines, could “face stability issues” during or after drilling, Wallace said.

Asked about next steps, Gover said the Bay Mills Indian community is “looking at all available legal options,” one of which is to challenge the permit in Michigan’s administrative courts.

Opponents of the tunnel are also awaiting Michigan’s Supreme Court’s soon-to-be-announced decision whether to overturn a separate state permit for the tunnel in a challenge brought by four Tribal Nations, including Bay Mills, and two environmental groups. “Enbridge cannot begin construction until it has secured further needed permits from state agencies and from the U.S. Army Corps of Engineers, Earth Justice wrote in a release.

Asked to comment on the possibility that Enbridge’s push to build a tunnel— which will take at least six years once shovels hit the ground—is a ploy to keep on pumping fossil fuels through its existing pipeline as long as possible, Gover cited a 2021 depreciation report filed by Enbridge indicating that Line 5 could be a stranded asset by 2040.

“So we’re going to spend the next six to 10 years building this tunnel, and then by 2040, it’s a stranded asset because the oil demand isn’t there,” Gover said. “It’s just absurd. So are they cynical? Are they hypocritical? Are they sneaky? Yeah, definitely.”

“I mean, they’re making $1.8 million a day off of this, and so delay, delay, delay is [Enbridge’s] best friend,” added Rudzinski. “It doesn’t really matter to them because they’re going to keep cashing a cheque every day that Line 5 stays online.”

[Disclosure: The Energy Mix Productions professional services team is currently engaged in a project on the Line 5 pipeline. No one from that team was involved in researching, writing, or editing this story.]