Mackinac Spill Still Under Investigation

Mackinac Bridge Winter

The Coast Guard, in coordination with local, state and federal partners, is working with the American Transmission Company to respond to a leak from a utility line in the Straits of Mackinac, approximately two miles west of the Mackinac Bridge.

The Coast Guard received notification that an electrical line cased with mineral oil might be leaking into the Straits of Mackinac yesterday afternoon. Upon notification, Coast Guard crews traveled to the area to investigate, and a Coast Guard helicopter crew conducted an overflight but neither detected an oil sheen.

The utility line’s owner, the American Transmission Company, determined that there is a leak in the utility line that crosses the Straits of Mackinac, approximately 12,000 to 15,000 feet off shore. The leaking product is composed predominately of mineral oil which is used to insulate the utility line. American Transmission Company has taken action to control the leak including securing the utility line which is currently inoperable. There is no impact to power supply to the local communities. The cause of the leak is currently under investigation.

Coast Guard Sector Sault Sainte Marie personnel are working with the Environmental Protection Agency, Michigan Department of Environmental Quality, the National Oceanographic and Atmospheric Administration, U.S. Fish and Wildlife, local tribes, and county emergency managers to oversee the pollution response.

“Safety of the public and our responders is our top priority,” said Captain Marko Broz, U.S. Coast Guard Federal On Scene Coordinator. “We are further committed to protecting the environment and ensuring a proactive response.”

“The DEQ is working closely with the American Transmission Company and federal, state, local, and tribal partners to coordinate an efficient response, protect the natural resources of the Great Lakes, and ensure public health and safety,” said Scott Schaefer of Michigan DEQ.

Coast Guard responders will remain on scene and continue to coordinate with partner agencies and the American Transmission Company in response to the spill.


  1. A very scary thing, they say approx 550 gallons of the coolant that has leaked so far is known to be highly toxic to at least one type of aquatic insect in the Great Lakes but is considered less of a threat to fish. The fluid is a mineral-based synthetic oil used for insulation that can be harmful if released into the environment, said Jackie Olson, spokeswoman for American Transmission Co., which operates the cables. It was too early to know what ecological damage might have been done in the Straits of Mackinac.

    Another even scarier thing is Enbridge’s Line5 (Two lines) that run under the Mackinac Straits as well, carrying crude oil, that are 13 years past their life expectancy. Enbridge claims that they are in pristine condition even though divers have noticed broken and totally missing supports. If these lines rupture it could cause irreparable damage to the great lakes for years to come. Many parties and groups have been trying to get these decommissioned before the unthinkable happens, with no luck so far.

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