An aging pipeline that carries oil along the bottom of the ecologically sensitive and turbulent Straits of Mackinac, where Lake Michigan and Lake Huron meet, is in such a state of disrepair it could burst at any moment and cause catastrophic damage to the Great Lakes, environmentalists warn. Line 5, a 1,000-kilometre-long pipeline owned by Calgary-based Enbridge, carries up to 540,000 barrels of oil and natural gas liquids a day from Wisconsin to Sarnia, Ont., where it is shipped to other refineries in Ontario and Quebec.