A years-long legal battle is heating up again between the state of Michigan and Line 5 pipeline operator Enbridge Inc., with the state taking legal action on Nov. 13 aimed at shutting down the line in 180 days. The twin pipeline carries light crude oil and natural gas liquids beneath the Straits of Mackinac.

Canada-based Enbridge says it will fight the state’s revocation of an easement granted 67 years ago that allows for extension of the 4-mile pipeline through the straits that connect Lake Michigan and Lake Huron.

“We will be responding in court,” said Enbridge spokesperson Ryan Duffy in an email.

Echoing concerns of environmentalists who have long wanted to see the pipeline closed, Gov. Gretchen Whitmer (D), said in a statement that safety and environmental concerns spurred the decision to cease the transport of oil through the under-water pipeline.

“Enbridge has routinely refused to take action to protect our Great Lakes and the millions of Americans who depend on them for clean drinking water and good jobs,” she said. Further, Whitmer alleged that Enbridge “repeatedly violated the terms of the 1953 easement by ignoring structural problems that put our Great Lakes and our families at risk.

“Most importantly, Enbridge has imposed on the people of Michigan an unacceptable risk of a catastrophic oil spill in the Great Lakes that could devastate our economy and way of life.”

Enbridge contends that the state has no credible basis to shut down the two-legged pipeline that transports about 23 million gallons of light crude oil and natural gas liquids daily between Superior, Wis., and Sarnia, Ontario.

“Line 5 remains safe, as envisioned by the 1953 Easement, and as recently validated by our federal safety regulator,” Vern Yu, the company’s president for liquids pipelines, said in a statement.

The pipeline operator also accused the Michigan Dept. of Natural Resources, a plaintiff in the case, of not being transparent when it conducted an assessment of the pipeline’s easement compliance, and further asserted that the DNR rejected the company’s offer to allow technical experts to discuss any questions or clarifications related to its review.

The company asserts that a 2018 agreement “contemplated periodic meetings on pipeline issues to avoid just this kind of situation.”

“With today’s actions by the Governor and Attorney General, based on historical Line 5 compliance, Enbridge finally will have an opportunity to review the DNR’s analysis and provide a thorough response through the legal process,” the company says.

The state says in its termination notice that it never should have granted the easement in the first place.

“Placing the pipes beneath a busy shipping lane, with no cover to protect from anchor strikes, violated the state’s duty to protect the public’s interest in Great Lakes waters and bottomlands,” the notice states.

The governor's order does not affect an agreement reached in 2018 with former Gov. Rick Snyder (R), which allows for the replacement of the pipeline’s underwater portion with a new segment that would be contained within a tunnel to be drilled through bedrock beneath the straits.

Enbridge is continuing to advance the $500-million Great Tunnel project and is seeking the required state and federal permits.

The company says that shutting down Line 5 would cause shortages of light crude oil for refineries in Michigan, Ohio, Pennsylvania and eastern Canada, create propane shortages in northern Michigan, and increase shipments of oil by rail or truck.

Environmental groups have said the pipeline poses a threat, even though it has never been ruptured since it opened.

“It’s 67 years old. It’s exceeded its life cycle and is under engineered to withstand the forces of nature,” said Roger Gauthier, treasurer of the Straits of Mackinac Alliance, a group of individuals and businesses seeking to eliminate the threat of crude oil and natural gas pipelines in the Straits.

Environmentalists also don’t want to see another spill similar especially one similar to the spill that occurred in 2010 on another Enbridge oil transmission line near the Kalamazoo River. That spill affected more than 35 miles of river, and took four years to clean up at a cost of $1 billion, according to a report in The Detroit News.