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.
"ATC does not believe that installing high voltage electric lines in close proximity to high pressure oil or gas lines is a good idea," the letter reads.
Instead, he says the company can use new cables in the Straits that wouldn't rely on mineral oil.