If oil burst from a pipeline under the Mackinac Bridge it’s a crapshoot whether it would most harm Lake Huron or Lake Michigan.
But neither direction is good, according to a University of Michigan computer model released Thursday. And both are possible at the same time.
The model shows six scenarios of where oil would end up if a 61-year-old pipeline would break beneath the Straits of Mackinac, the body of water that separates Michigan’s Upper and Lower Peninsulas.
“You see an immense amount of area that could be impacted,” said David Schwab, a research scientist at the University of Michigan’s Water Center who did the study. “All six show that oil could affect islands in both lakes and shorelines on the north and south side of the straits.
“I can’t think in my experience of another place in the Great Lakes where an oil spill would have as wide of an impact in as short a period of time,” said Schwab, who recently retired from the National Oceanic and Atmospheric Administration after 30 years studying Great Lakes currents.
The pipeline is operated by Enbridge Inc., the company still cleaning up the Kalamazoo River after its highly publicized pipeline break near Marshall, Mich., four years ago.
The company’s pipeline across the straits – known as Line 5 – has come under increasing scrutiny, much of it generated by the National Wildlife Federation which with the university’s Graham Sustainability Institute helped support creation of the video.
Michigan regulatory officials have established a task force on pipeline safety to examine that pipeline and others. Michigan Attorney General Bill Schuette and Department of Environmental Quality Director Dan Wyant have asked Enbridge for documentation of its compliance with a state pipeline easement and for information on inspections and spill response.
In December, U.S. senators Carl Levin and Debbie Stabenow of Michigan and Dick Durbin of Illinois asked federal regulators to review the line’s safety.
Enbridge officials insist the pipeline is safe and have increased how much oil moves through it. Enbridge did not immediately respond for a request for a comment on the study.
The National Wildlife Federation wants to know how long the pipeline should last and when it will be replaced, said Andy Buchsbaum, the executive director of the group’s Great Lakes Regional Center in Ann Arbor. It also wants shutdown procedures for when automated alarms signal possible failures.
“It does not make sense playing Russian roulette in the Great Lakes,” Buchsbaum said. “All infrastructure eventually fails.”
The 20 days of modeling assumes a million gallon spill — about the amount contained by the pipeline in the straits — that takes 12 hours to stop, Schwab said. Tricky currents in the strait that can shift east or west on the surface and vary direction by depth, and assumptions of where a rupture happens required modeling multiple scenarios.
The oil could reach as far west as Lake Michigan’s Beaver Island or as far southeast as Lake Huron’s Rogers City, the study said. Some scenarios show it striking popular Mackinac Island and Bois Blanc Island or the shoreline near Wilderness State Park.
A spill could harm people, wildlife, fish and even disrupt navigation through the five-mile wide strait, Buchsbaum said. The group is considering a possible follow-up study of the ecological and economic costs of such a spill.