TRAVERSE CITY, Mich. (AP) — Michigan’s attorney general and chief environmental regulator have asked the company that owns two oil pipelines stretched beneath an ecologically sensitive area of the Great Lakes for evidence that the 61-year-old lines are properly maintained and in good condition.

Attorney General Bill Schuette and Dan Wyant, director of the state Department of Environmental Quality, posed a lengthy series of questions and requested stacks of documentation in a letter sent Tuesday to Enbridge Inc. and made public Wednesday. They said the pipelines, which run beneath the Straits of Mackinac — the waterway linking Lakes Huron and Michigan — pose a unique safety risk.