Public concerns have particularly focused on the risk of a spill under the Straits of Mackinac , and the difficulty of controlling any spill that might occur . According to Enbridge , the pipes under the straits have never leaked , are monitored 24 hours a day , and are regularly inspected by underwater autonomous vehicles . However , there have been numerous spills elsewhere in Michigan from Enbridge pipelines , including a major Line 5 spill at Crystal Falls in 1999 , as well as the 2010 Kalamazoo River oil spill on Line 6
Kalamazoo River oil spill
Kalamazoo River oil spill
Enbridge Line 5