Electrical cables in the Straits of Mackinac were severed when an anchor struck them last year. More than 400 gallons of mineral oil, acting as a coolant, leaked out.
The Line 5 oil pipelines were damaged during the same incident.
A proposed tunnel would house Line 5 and the electrical cables to avoid more damage, an idea Enbridge Energy supports and Governor Gretchen Whitmer says she is open to.
But in a letter, Vice President of American Transmission Company Tom Finco says that plan could be dangerous.