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Enbridge: Line 5 pipeline is vital to Michigan

Enbridge is proud to call Michigan home and we are prepared to protect communities and waterways through the safe operation of our pipelines. Protecting the Great Lakes, inland waterways and the communities along the Line 5 route is our top priority.

Line 5 delivers vital energy to heat homes, to power cars and to fuel manufacturing throughout Michigan. The line transports 540,000 barrels per day of light crude oil and natural gas liquids, including propane. That’s enough to heat 85 percent or 240,000 of the homes in Northern Michigan. Also, approximately 30 percent of the oil transported on Line 5 stays in Michigan, fueling 120,000 passenger cars and light trucks each day.


Line 5 was built in 1953 to safely provide energy to Michigan residents and businesses and eliminate tanker traffic on the Great Lakes. Enbridge worked with Bechtel Corporation — the same firm that designed and built the Mackinac Bridge and the Hoover Dam — to plan, design and build Line 5 under the Straits of Mackinac. The Department of Naval Architecture, Marine Engineering at the University of Michigan and the Department of Civil Engineering at Columbia University were also consulted and participated in the design review.

The 645-mile pipeline connects Superior, Wisconsin and Sarnia Ontario. As it reaches the Straits of Mackinac, it splits into two, 20-inch diameter pipelines that are each 4.5 miles long. The crossing was specifically designed for the underwater environment in the Straits of Mackinac. It was over-engineered, using nearly one-inch thick steel — one of the thickest pipelines in our system. Also, the fiber-reinforced enamel coating serves as an additional layer of protection. The coating is widely recognized today as one of the strongest pipeline coating materials in the world, which has kept the line in very good condition. In short, the line was built to last.


Enbridge has operated Line 5 safely for more than 60 years. There are a number of measures in place to maintain the integrity and safety of Line 5.

First, a dedicated team of people monitor the line 24 hours a day, seven days a week. If there were a drop in pressure, remotely operated shutoff valves stop the flow into the Straits Crossing within three minutes. Also, oil that enters the system is tested for quality. We have performed more inspections on Line 5 crossing under the Straits than any other segment of pipeline in our system and that ensures the line remains in excellent condition.

To further preserve the integrity of the line, we operate Line 5 under the Straits at a reduced pressure, minimizing stress on the heavy-walled, carbon-steel pipe. This insures that the light crude oil and natural gas liquids safely make it to their destination.


We inspect Line 5 frequently and have extensive data verifying the line is fit for operation. At the Straits, data on the exterior of Line 5 is collected by highly trained divers and advanced underwater vehicles equipped with cameras. We inspect the interior with devices called “pigs.” They work like small MRI machines, traveling inside the line recording data on the pipe’s thickness and looking for cracks, dents or signs of corrosion.

In 2013, the National Transportation Safety Board Chairwoman, Deborah Hersman, testified before the Senate Commerce Committee and stated that, “if [a pipeline] is adequately maintained and inspected, age is not an issue.” Recent inspection reports show that Line 5, from engineering and integrity perspectives, is in excellent condition and remains fit for operation.

Enbridge inspection data is reviewed by the Pipeline Hazardous Materials Safety Administration and shared with state regulatory authorities and with state elected officials when requested. Enbridge is currently working with the Michigan Departments of Environmental Quality and Natural Resources and third parties to conduct an independent review of Enbridge’s integrity data.

Michigan Impact

A lot of people and businesses depend on the light crude oil and natural gas liquids delivered by Line 5. Without it, the state’s access to affordable, secure energy would be compromised. Line 5 is one of several pipelines in our network that support the Michigan economy.

We employ roughly 250 employees and contractors throughout Michigan to ensure the safe operation of our energy infrastructure.

We also provide $22.4 million in annual sales and property taxes to the state. Without Line 5, Michigan’s Detroit refinery would directly lose approximately 30 percent of its light oil feedstock. The rationing of Enbridge’s other pipelines in Michigan could cause the Detroit refinery to indirectly lose approximately another 20 percent. The cost to drivers and manufacturers in Michigan would be significant.


While we have no reason to anticipate a leak or spill on Line 5, we are well prepared for any incident. We have the resources, experience and training to ensure that people, wildlife and the environment are protected. Enbridge conducted a multi-agency emergency response exercise in the Straits of Mackinac in September 2015. The full-scale exercise included the U.S. Coast Guard, the U.S. Environmental Protection Agency, and the U.S. Department of Transportation’s Pipeline and Hazardous Materials Safety Administration (PHMSA), along with state and local agencies. We will participate in additional exercises this year as well. It’s part of our commitment to safety.
We want the people of Michigan to have confidence in the way we’re operating Line 5 and know that we are fully committed to protecting and caring for the Great Lakes.

For more information on Line 5, please visit

Bridge welcomes guest columns from a diverse range of people on issues relating to Michigan and its future. The views and assertions of these writers do not necessarily reflect those of Bridge or The Center for Michigan. Bridge does not endorse any individual guest commentary submission. If you are interested in submitting a guest commentary, please contact David Zeman. Click here for details and submission guidelines.

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