The Dakota Access Pipeline isn’t the only interstate liquids pipe facing an uncertain future. The fate of Enbridge’s Line 5, which batches either light crude oil or a propane/butanes mix from Superior, WI, through Michigan and into Ontario, also hangs in the balance as the company renews its battle with Michigan’s top elected officials to keep the 67-year-old pipeline open and its effort win regulatory approval to replace the pipe’s most important water crossing. Line 5 supporters say that closing the 540-Mb/d pipeline would slash supplies to residential and commercial propane consumers in the Great Lakes State, steam crackers in Ontario, and refineries and gasoline blenders in three states and two Canadian provinces. Critics of Line 5 counter that there are plenty of supply alternatives. Today we discuss the pipeline, what it transports, and who it serves, as well as challenges it faces.

