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. "Because of where they are, any failure will have exceptional, indeed catastrophic effects," their letter said. "And because the magnitude of the resulting harm is so great, there is no margin for error. It is imperative we pursue a proactive, comprehensive approach to ensure this risk is minimized, and work together to prevent tragedy before it strikes."