Enbridge Energy has maintained that their twin oil and natural gas liquid pipelines under Lake Michigan at the Straits of Mackinac are safe.
But what if one of them did break open? Where might the oil go?
Today, the University of Michigan’s Water Center released new computer simulations to help answer that question.
David Schwab is a hydrodynamics expert with the Water Center.
“I don’t know any place where the currents are as strong, and change direction as quickly, and as frequently as in the Straits of Mackinac,” Schwab said.
He says huge amounts of water can slosh between Lakes Michigan and Huron at the Straits -- at times, the volumes of water moving back and forth at the Straits is 10 times the amount that goes over Niagara Falls.
Schwab was the first person to simulate what might happen if there was an oil spill in the Straits. His first simulation, released in July 2014, was shared widely, but it simply showed where water currents might go.
He says the point of the new simulations released today are to give people more detail.
“Where we were actually looking at real oil, and not just the currents, and do many, many cases to answer the question of how far, how fast, and where oil might go from a leak in the pipeline,” said Schwab.
Schwab says conditions in the Straits of Mackinac change from day to day. His computer simulations looked at how a light crude oil spill might travel in 840 different situations – all different weather and water conditions.
The simulations show that up to 152 miles of coastline in Lakes Huron and Michigan could be hit by a single oil spill from Line 5. When all 840 simulated spills are plotted on a map, a total of 720 miles of shoreline in the U.S. and Canada are considered at risk.
Take a look at one of the simulations in the video below. (You can see more simulations here.)
The research finds that the areas most at risk after a spill are the areas close to the Straits, but the simulations show that, given certain weather conditions, oil could spread well out of the Straits area into Lakes Michigan and Huron.
More from the report:
This conclusion strongly supports the assertion that under the right weather conditions, a spill in the Straits could affect a significant amount of shoreline and open water area in either Lake Michigan or Lake Huron in a very short time.
Schwab’s models didn’t look at what might happen when the area is ice covered. Enbridge says ice acts as an oil boom, and prevents the oil from spreading too far. But researchers say how oil might move under ice in the Straits is still a big unknown.
Schwab also didn’t model how much oil might be cleaned up by crews that could get out on the water after a spill. This is a look at how the oil might travel if it were untouched. And as Keith Matheny of the Detroit Free Press reported, sometimes weather conditions in the Straits would prevent crews from getting to the oil in the first place.
Schwab ran all the different simulations for three different spill amounts – a 5,000 barrel oil spill (what Enbridge says is its worst case scenario), a 10,000 barrel spill, and a 25,000 barrel spill (around the amount of oil that spilled out of Enbridge’s Line 6B in 2010).
Schwab found that the smaller spills they tested could still have a big impact. They could hit nearly as much shoreline as a spill five times as big.
He says it’s not easy to define a “worst-case scenario.”
“So what I can tell from my simulations is the probability that oil would impact different areas,” says Schwab. “But who’s to say what’s worse? Is it worse in your marina, or my marina? Or worse in your water intake, or my water intake?”
The National Wildlife Federation paid for Schwab’s research.
The NWF’s Mike Shriberg says these models will help inform the state of Michigan. The state is in the process of hiring outside contractors to do what’s called a “risk analysis” and “alternatives analysis” on Line 5 in the Straits.
“This sets the frame for what the actual risk is. The next step in this is to look at all the assets that are at risk, whether it’s drinking water intakes, whether it’s marinas, whether it’s state parks – all these different things -- first you have to know where an oil spill could go, and then you start looking at the assets that are at risk, and that’s how you develop a full profile of risk,” says Shriberg.
Enbrige says there’s never been a spill from the two pipelines sitting at the bottom of Lake Michigan. They’ve been down there for 63 years.
They also say they have a good emergency response plan in place, and they continue to work to improve it.
Critics say – because of the extreme and varying conditions in the Straits – there’s no way to predict what might happen.
Update April 1, 2016, 11:22 a.m.
Enbridge officials looked over the study and e-mailed us a response. You can read the full response here. The company says the UM Water Center's report is based on 3 unrealistic assumptions:
- Volume out: The model and illustrations focus on an unrealistic volume of oil released. The worst case discharge is approximately 4,950 barrels, which is significantly lower than the volume assumed in this study. There are automatic shut off valves located on either side of the Straits of Mackinac that will shut down flow of product into the line within three minutes if there is a drop in pressure. We would immediately activate containment and clean up equipment and crews.
- Response: The model doesn’t take into consideration that we would move quickly to contain and clean-up any spill. We regularly test our emergency response plans for the Straits of Mackinac with local, state and federal response agencies – including the U.S. Coast Guard and U.S. EPA; most recently in September 2015.
- Product: The model assumes the only product in the line is crude oil. It doesn’t take into consideration that 20 percent of the product shipped in the twin pipes under the Straits is natural gas liquids which are light weight and will float to the water’s surface and not have the same impact as oil.
* Editor’s note: Enbridge is a financial supporter of Michigan Radio.