Last year, Michigan Governor Gretchen Whitmer announced she would revoke a permit that allows Enbridge’s Line 5 pipeline to cross the Straits of Mackinac, citing environmental concerns. According to Whitmer, Enbridge has until May 12 to shut down the pipeline.

Unfortunately, the potential shutdown of Line 5, which carries approximately 540,000 barrels of Canadian oil and natural gas liquids each day from Wisconsin and Michigan to refineries in Ontario, will have immediate and devastating consequences for workers and businesses in Ontario and Quebec. And ironically, it will also be bad news for the environment.

Line 5 alone supplies almost half of Ontario’s crude oil and natural gas. Again, the impact on the province’s economy is difficult to overstate.

Specifically, Line 5 supplies western Canadian crude to Ontario’s four operating refineries (all located in Sarnia) where crude oil is refined into jet fuel, diesel, gasoline and petrochemicals. Indeed, much of the jet fuel used at Pearson International Airport comes from Line 5. Moreover, almost 5,000 workers are directly employed and another 23,500 indirectly employed in Sarnia alone.

Now consider Quebec. Line 5 is a critical supply source for Line 9, which runs from Sarnia to Montreal and delivers about two-thirds of the crude oil refined and consumed in the province. Quebec’s two operating refineries use this oil to produce gasoline for cars, jet fuel for the Montréal-Trudeau and Jean Lesage airports, and petrochemicals for manufacturing.

Simply put, a shutdown of Line 5 will threaten the energy supply of Canada’s two most populous provinces and will lead to job losses and spikes in energy prices that would increase the cost of almost everything, from food to driving cars to heating homes.

In addition to the devastating economic impacts, consider the potential environmental consequences. As long as demand for western Canadian oil in eastern Canada continues to exist, companies will find alternative modes of transportation to make up for the shortfall caused by disruptions in Line 5. In other words, the fuel this pipeline supplies will be transported by alternative modes of transportation even if it means resorting to less safe and more environmentally damaging alternatives such as rail and truck. And surely, if Line 5 ceases operations, transporting crude by rail and/or truck will increase, which will subsequently increase the risk of oil spills.

A recent study examined the safety of the three major modes of oil transport in North America, concluding that on an apples-to-apples basis, compared to pipelines, the risk of spills were twice as high by rail and 10 times higher by truck.

Even the U.S. energy secretary recently stated that “pipe is the best way to go” referring to the transportation of oil and the recent shutdown of the Colonial pipeline network.

Thankfully, Enbridge is fighting Governor Whitmer’s notice and vows to keep oil flowing. If Line 5 is shut down, it will have devastating economic and environmental consequences for Canada.