Michigan's attorney general says a tugboat dragged its anchor as it passed through the waterway connecting Lake Huron and Lake Michigan, causing recent damage to underwater oil and electrical lines.

Attorney General Bill Schuette said in a statement Tuesday that he notified Vanenkevort Tug and Barge that he's planning civil action against the company because of the damage believed to have happened April 1 in the Straits of Mackinac.

The Associated Press sent an email seeking comment from Vanenkevort, based in Escanaba, Michigan.

Two electric cables leaked 600 gallons of insulation fluid containing mineral oil and benzene. Enbridge Inc.'s twin Line 5 pipelines carry crude oil and liquefied natural gas. The company has said that the pipelines were dented, but said the integrity of the lines weren't compromised.

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