The 5-mile-wide straits link Lakes Huron and Michigan and flow near Mackinac Island, which is famed for its horse-drawn carriages and fudge shops. Several villages draw drinking water from the straits and cargo freighters and passenger ferries use it as a passageway. Sport anglers chase salmon and trout, while commercial crews harvest whitefish and perch for restaurants.
Hundreds of activists attended a rally to protest the pipeline last summer. Local residents haven't paid it much attention over the years, but a packed crowd grilled Enbridge representatives at a community meeting this month.
"It's a huge pipeline carrying oil in one of the most ecologically beneficial and sensitive places in the world," said Andy Buchsbaum, director of the National Wildlife Federation's Great Lakes office. "A massive oil spill there would have dire and irreversible consequences."
The Senate's second-ranking Democrat, Dick Durbin of Illinois, and Michigan Sens. Carl Levin and Debbie Stabenow sent a letter of concern to the federal Pipeline and Hazardous Materials Safety Administration in December. Agency head Cynthia Quarterman said Enbridge has agreed to step up its inspections of the Lakehead system since the Kalamazoo River spill.
"We've invested a lot of money, time and resources to ensure that we're using the best available technology to operate our pipelines with the utmost integrity," said Jackie Guthrie, spokeswoman for the company, based in Calgary, Alberta.
Now, line 5's segment beneath the straits is getting extra attention.
Enbridge has reached an agreement with Michigan Technological University to deploy a newly developed "autonomous underwater vehicle" to provide digital images of the pipeline eight times in the next two years. The device resembles a 7-foot-long missile with a tiny, whirring propeller and will be fitted with sonar devices, cameras and computers.
The equipment probably isn't capable of detecting cracks, but "never before have you been able to see this kind of detail," said Guy Meadows, a director of the university's Great Lakes Research Center.