A rupture in the oil pipelines buried beneath the Straits of Mackinac poses a threat to 700 miles of Great Lakes shoreline.

That’s the conclusion drawn by a University of Michigan researcher specializing in hydrodynamics in a study released Thursday that focuses on the controversial pair of pipelines owned by Enbridge Energy.

Line 5, as the lines are known, carries light crude oil and natural gas liquids — as much as 500,000 barrels a day. It has been operating for more than 60 years but has been getting increased attention following the Enbridge oil line rupture near Kalamazoo in 2010 that sent an estimated 840,000 gallons of heavy crude into the Kalamazoo River.

With funding from the National Wildlife Federation, University of Michigan Water Center research scientist David Schwab ran computer simulations of 840 spill scenarios on Line 5 to reach his conclusions, which included:

-- A single oil spill could affect as many as 152 miles of shoreline on Lake Michigan and Lake Huron.

-- In all 840 simulations, oil contamination reached a combined 720 miles of shoreline on both sides of the U.S.-Canadian border.

-- The areas of highest risk include Mackinac and Bois Blanc islands, Beaver Island, Cross Village, Harbor Springs and Cheboygan.

“Until now, no one knew exactly how much shoreline was vulnerable to spills in the Straits of Mackinac,” Schwab said. “These findings show that under the right conditions, a spill in the Straits of Mackinac could affect a significant amount of shoreline and open-water areas in either Lake Michigan or Lake Huron, or both, very quickly.

“We hope this information will inform spill-response planning and will help government officials make sound decisions about the oil pipeline beneath the straits.”

U.S. Rep. Debbie Dingell, D-Dearborn, said the study reinforces the need for Congress “this year to implement higher standards for pipelines operating under the Great Lakes, as well as provide safety regulators the resources they need to do their jobs.

“Congresswoman Candice Miller and I are also closely monitoring the proposed use of pipelines under the St. Clair and Detroit Rivers, which provide drinking water to millions, to ensure all risks are assessed and Michigan residents have an opportunity to make their voices heard. We must all work together to protect the Great Lakes, now and for the future.”

The work was done with $12,000 from the National Wildlife Federation, an environmental group that has been critical of pipeline oversight.

“This was the intellectual work of the University of Michigan without our control or influence over it,” said Mike Shriberg, the National Wildlife Federation's Great Lakes regional executive director. “Like all academic studies, it needed funding to happen, and we were happy to provide that.”

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