Every day, nearly 23 million gallons of oil flow through two aging pipelines in the heart of the Great Lakes, just 1.5 miles west of the Mackinac Bridge. Constructed during the Eisenhower administration in 1953, the two 20-inch-in-diameter “Line 5” pipelines owned by Canadian company Enbridge, Inc., lie exposed at the bottom of the Straits of Mackinac - a busy shipping channel.

Location of Line 5 Pipelines in the Straits of Mackinac

Enbridge’s pipelines, which run about 1,000 feet apart at depths ranging from 100 - 270 feet, have laid on the bottom of the Straits for more than six decades. Enbridge installed several support structures under the pipelines in 2006 and again in 2010 and 2018, following the company’s oil spill into the Kalamazoo River - the nation’s largest-ever land-based oil spill. Now, hundreds of supports elevate 3-miles of the pipeline off the lakebed into the turbulent current. This design was never approved and makes the pipeline unsafe.


Line 5 Beneath the Straits of Mackinac - Photo courtesy NWF

Enbridge officials have said that properly maintained pipelines can last indefinitely, but the company’s history of major spills in Michigan and across North America proves otherwise. Today, much of the oil flowing through the Line 5 pipelines (90 to 95% of it) is coming from Canada and taking a shortcut through Michigan and the Straits of Mackinac before crossing back into Canada near Port Huron.

Line 5 has spilled 33 times and at least 1.1 million gallons along its length since 1968.

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The pipelines in the Straits of Mackinac cross one of the most ecologically sensitive areas in the world. The Great Lakes are home to 21 percent of the world's fresh surface water. The pristine Straits area supports bountiful fisheries, provides drinking water to thousands of people, and anchors a thriving tourism industry with historic and beautiful Mackinac Island right in the center of it all. This area is the definition of Pure Michigan.

A number of troubling factors have come together that cause grave concern:

  • An anchor strike from a ship in peril in 2018 gashed and dented both underwater pipelines
  • Enbridge contractors severely damaged pipeline supports in 2019, but all Enbridge safety measures missed the damage, which wasn't even discovered until June 2020 - at which point the pipeline was temporarily shut down to inspect the damage (subsequently reopened)
  • The tarnished safety record of Enbridge, Inc., the Canadian company that operates the pipeline including the largest inland oil spill when its Line 6B spilled 1.1 million gallons of tar sands bitumen into the Kalamazoo River in 2010
  • There are ongoing issues of compliance with the contract between the pipeline company and the State of Michigan (the Easement) including 8 known violations 
  • The age, location, and questionable condition of the pipeline
  • An increase in the volume and pressure of fluids moving through the pipelines
  • The lack of transparency about safety inspections and what petroleum products are being transported through Line 5 in the Great Lakes
  • The lack of proactive regulatory environments in Michigan and at the federal level
  • University of Michigan scientists modeled the currents in the Straits of Mackinac and called it "the worst possible place for an oil spill in the Great Lakes."
  • Line 5 is a shortcut for Canada's benefit with less than 5 to 10% of the product used in Michigan.
  • Scientists warn that we have less than 10 years to reduce carbon emissions by half or face dire consequences from a dangerously overheating climate. It is even more urgent to move away from dirty fuels like the ones carried by Line 5

NOVEMBER 2020 UPDATE: After an 18-month-long review of the easement that allowed Enbridge to occupy the Great Lakes bottomlands for their oil pipelines, the Department of Natural Resources found several incurable violations of the easement. WATCH THE NEW VIDEO about why Gretchen Whitmer ordered the pipeline to be shut down. Attorney General Dana Nessel filed a legal action in Ingham Circuit Court on Whitmer’s behalf to force the shutdown. Enbridge is allowed 180 days (by May 12, 2021) to arrange an orderly shutdown and the state to ensure a transition for the tiny amount of propane this pipeline does supply to Michigan (1/2 of 1% of the volume carried by Line 5). Enbridge promptly filed a federal lawsuit challenging the shutdown order.

JANUARY 2021 UPDATE 1: Enbridge sends a letter to Gov. Whitmer stating it has no intention of obeying the order.

JANUARY 2021 UPDATE 2: Enbridge is urging the Canadian government and businesses to badger Gov. Whitmer to reverse her Line 5 shutdown order. TAKE ACTION and sign the petition calling on President Biden to use the power of the federal government to fight back.

MARCH 2021 UPDATE 1: The state and Enbridge informed a Grand Rapids U.S. District Judge plan to enter into mediation in the case in hopes of finding a potential resolution to the shutdown order. If Enbridge still refuses to shut down by May 12, they will be trespassing and in violation of state law.

MAY 2021 UPDATE: On the eve that the May 12 shutdown order takes effect, Governor Whitmer threatened to go after Enbridge’s profits from a Great Lakes oil pipeline if the company defies her order to shut it down.

bridge-ice.jpgSign the Petition to President BidenThe Straits of Mackinac is a natural and cultural treasure held by Michigan in trust for its residents. The Straits, which link Lake Michigan and Lake Huron and separate Michigan's Upper Peninsula from its Lower Peninsula, are capable of generating powerful currents that can create a flow of water more than 10 times greater than the flow over Niagara Falls. The strong underwater currents, fierce winds, and extreme winter weather conditions - sometimes including feet-thick ice cover - at the Straits make them ecologically sensitive and would make cleanup or recovery from a pipeline spill especially difficult.

The time is now to fully examine the use of these public waters and Great Lakes bottomlands by a private corporation and to ensure the protection and preservation of the Straits of Mackinac. We all must act now to Keep Oil Out of the Great Lakes.


Enbridge Inc. owns and operates a large system of pipelines that carry petroleum products and natural gas fluids to refineries in various destinations, including Texas and other U.S. states, and throughout North America, and for export overseas. This crude oil is a raw product that becomes gasoline and other transportation fuels.

View the Enbridge Liquid Pipelines Map

Enbridge’s Line 5 is a 645-mile petroleum pipeline that is part of the larger Enbridge Lakehead System. Line 5 carries oil from Superior, Wisconsin, across Michigan’s Upper Peninsula, through northern Michigan, down to the thumb region, and under the St. Clair River to Sarnia, Ontario. Along the way, the pipeline crosses through the Straits of Mackinac, 400 rivers, streams, and wetlands. In northern Michigan, it goes through almost 10 miles of wetlands and runs right next to


See the short film, "Oil & Water" that exposes the problem

many of our sparkling inland lakes. Line 5 is 30 inches in diameter, except when crossing the Straits of Mackinac, where it splits into two 20-inch pipes that lie about 1,000 feet apart. Construction was completed in 1953, and the twin pipelines under the Straits now carry approximately 540,000 barrels, or 22.7 million gallons, of oil and natural gas liquids per day.

In addition to Line 5, the Enbridge Lakehead system includes other pipelines that move through petroleum products across the Great Lakes region. This system of pipelines is the primary transporter of crude oil from western Canada to the United States, with approximately 4,700 miles of pipe and 60 pumping stations serving all the major refineries in the Great Lakes, Midwest, and Ontario. In recent years, as the production of tar sands oil in Canada and crude oil in North Dakota has exploded, there has been a dramatic increase in the number of new pipelines proposed to carry this fuel to refineries and coastal export terminals.


Line 5 carries synthetic crude oil from Superior, Wisconsin. The original sources are tar sands bitumen from Canada, which has been refined to a “light” oil or “high sour.” Enbridge states that “heavy” diluted bitumen, which is a less refined and more corrosive product that was released into the Kalamazoo River in 2010, does not currently run through Line 5. This pipeline also carries crude oil that originated in the Bakken oil fields of North Dakota.

Line 5 terminates in Sarnia, Canada, just across the St. Clair River from Marysville, Michigan. The pipeline was bored or tunneled just below the river bed. In 2010, adjoining Line 6B was replaced under the St. Clair River after it was found to have a dent. Sarnia, Ontario is home to many refineries that produce gasoline and other commercial petroleum products. In short, much of the oil transported through Line 5 originates in western Canada, is shipped through Michigan and the Great Lakes, and refined in Canada for markets back in Canada and overseas.

Enbridge moves Canadian Oil from Alberta to Montreal

In 2015 the Enbridge Line 9 pipeline which used to transport oil from Montreal to Sarnia was reversed as part of the company's Eastern Canadian Refinery Access Initiative. According to Enbridge's website (screengrab here), the pipeline was reversed from (Sarnia) to "Montreal (Line 9B) in an eastward direction to allow for discounted western Canadian crude, which can be sourced from a number of locations in Alberta, Saskatchewan, Manitoba, and the Bakken region to access Quebec refining markets."

If you wonder where the oil from Line 5 ends up, you need to consider this reversal - the product in Line 5 is not for Michigan. It's for Canada's benefit.

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