Aging oil pipelines beneath the Straits of Mackinac an ever-present threat to the Great Lakes
Jeff Alexander and Beth Wallace
Scenic Waters Conceal A Major Oil Spill Hazard
Motorists who travel over the Mackinac Bridge in
northern Michigan are treated to one of the most
spectacular vistas in all the Great Lakes.
The five-mile-long bridge crosses a vast expanse of
cobalt water that extends far to the east and west, well
beyond the reach of the naked eye. The view is sublime,
From the bridge, which peaks at 199 feet above the
Straits of Mackinac, sightseers have a bird’s eye view of
waters that mark the confluence of Lake Michigan and
Lake Huron. What they cannot see from the bridge, or
anywhere else, is a looming threat that could devastate
the upper Great Lakes.
Just west of the Mackinac Bridge, below the water’s
surface, lie two pipelines, called Line 5, that carry a
total of 20 million gallons of crude oil and natural gas
fluids each day from Superior, Wisconsin to Sarnia,
Ontario. The pipelines were placed in the Straits of
Mackinac in 1953—the year President Dwight Eisenhower
took office and one year before McDonald’s opened its
first burger joint.
Download the full report: Sunken Hazard: Aging oil pipelines beneath the Straits of Mackinac an ever-present threat to the Great Lakes (pdf)
If either of those pipelines leaked, the resulting oil
slick would likely devastate some of the lakes’ most
bountiful fisheries, wildlife refuges, municipal drinking
water supplies and one of the region’s most popular
tourist attractions: Mackinac Island. A significant rupture
would cause an Exxon-Valdez scale oil spill spreading
through Lakes Huron and Michigan, the heart of the
largest freshwater seas in the world.
It’s not an empty risk: the pipelines are owned and
operated by Canadian-based Enbridge Energy and Line 5 is
part of the Lakehead system—one of the largest networks
of pipelines in the world. Enbridge Energy is the same firm
responsible for the largest and most costly inland oil spill in
American history. These interstate pipeline networks are
regulated federally by the Pipeline and Hazardous
Materials Safety Administration (PHMSA), which is a
federal agency under the Department of Transportation
that enforces pipeline safety rules and regulations.
An Enbridge pipeline that ruptured near Marshall,
Michigan, in July 2010 dumped about one million gallons
of tar sands oil into the Kalamazoo River system. Federal
investigators were scathing in their critique, likening
Enbridge to the “Keystone Kops” and determining that
Enbridge could have prevented the disaster if the company
had properly maintained the pipeline and fixed
dozens of known defects.
The Enbridge pipelines that cross the Straits of
Mackinac have never spilled oil into the conjoined waters
of lake Michigan and Huron, according
to government officials. But evidence is
mounting that there is reason to be
The Line 5 pipeline that crosses
the Straits has a history of problems,
just like the company that owns it.
Pipelines deteriorate as they age,
according to engineering experts, and the Line 5 pipes at the Straits have been subjected to
fierce underwater currents, intense external pressure and
varying water temperatures for nearly 60 years.
Compounding the threat is the fact that the pipelines
cross the world’s largest source of surface freshwater, a
sensitive ecosystem that cannot readily cope with large
quantities of crude oil.
Additionally, Enbridge has set out to expand its
Lakehead System—which includes Line 5—to carry more
diluted bitumen and tar sands oil from western Canada.
All of the lines within the Lakehead System transport
Alberta tar sands-derived crude oil. Most concerning is
the transportation of diluted raw tar sands oil or diluted
bitumen (DilBit). Transportation of this product requires
higher operating pressures, which in turn heats the line
and could pose significantly higher risks of spills.
In this report, National Wildlife Federation examines
the history of the Enbridge pipelines that cross the Straits
of Mackinac, Enbridge’s environmental track record and
what could happen if the pipes sprang a leak and pumped
crude oil into the northernmost reaches of lakes Michigan
This report is intended to point out the immediate
need for proactive and consistent action to properly
safeguard our Great Lakes from pipeline spills. History
has proven that agencies and pipeline operators continue
to favor a reactionary approach to pipeline oversight.
Unless action is taken, an oil spill in the Straits of
Mackinac isn’t a question of if—it’s a question of when.
We cannot allow Enbridge to play Russian roulette
with the Straits of Mackinac. This report is a call for action
to prevent Enbridge Energy’s widening oil stain from
reaching North America’s freshwater seas.