The Coast Guard launched a marine casualty investigation Friday into the cause of a line break that has so far spilled 600 gallons of dielectric fluid into the straits of Mackinac.
Officials with the Coast Guard say what they call “vessel activity” may have caused the two lines owned by American Transmission Company to break.
There are a total of nine utility lines beneath the straits - one is owned by Transmission Canada, six by American Transmission Company, including the two that broke, and two by Enbridge, one of which is the line 5 oil pipeline.
A spokesperson for the Coast Guard says the other two companies were told to check their lines for any potential damage.
Efforts are still underway to remove remaining fluid from the two broken lines beneath the straits.The Coast Guard says to date, 25 percent of fluid has been removed from one of the lines.
Officials say flyovers will continue, but so far there have been no signs of pollution or oil sheens on the water's surface.