The battle over the future of Enbridge’s Line 5 light crude oil pipeline through Michigan is heating up. In recent weeks, Michigan’s new attorney general filed suit to throw out the 1953 easement the state granted to allow the pipeline to be laid under the Straits of Mackinac — the narrow waterway between Michigan’s upper and lower peninsulas — and to block implementation of an agreement Enbridge and the state’s then-governor reached last fall to replace the section of Line 5 under the straits by the mid-2020s. Enbridge is pressing ahead, maintaining that the existing pipeline is safe and the 2018 agreement is legal and fully enforceable. All that raises two questions: just how important is Line 5 to the Michigan and Eastern Canadian refineries, and what would those refineries do if the pipeline were to cease operations? Today, we discuss recent developments and examine the issues at hand.
Enbridge’s Line 5, part of the Canadian midstream company’s much larger Mainline/Lakehead crude oil pipeline system, has been an important conduit for moving Western Canadian and Bakken crude oil and NGLs across Michigan’s upper and lower peninsulas — and into Ontario — for more than 65 years. Line 5 (purple line in Figure 1) is one of multiple Enbridge pipelines out of the company’s terminal in Superior, WI. The 540-Mb/d pipeline transports “batches” of either light crude, light synthetic crude or mixed NGLs 645 miles east/southeast through Michigan to Sarnia, ON. The crude oils and NGLs are sourced primarily in Western Canada (but also in the Bakken) and are bound for Michigan, Ontario and Quebec. At the Straits of Mackinac (dashed red oval) — the four-mile-wide water passage between Michigan’s upper and lower peninsulas (and Lake Michigan and Lake Huron) — the 30-inch-diameter, single-pipe Line 5 splits into two 20-inch-diameter, parallel pipes that are anchored along the straits’ lakebed.
Enbridge has been under increasing pressure from environmental groups to shut Line 5 since 2010 (see Tunnel of Crude), when a rupture on the company’s Line 78 (formerly Line 6B, neon-green line in Figure 1) across southern Michigan resulted in a major oil spill into a tributary of the Kalamazoo River. In recent years, Enbridge had been working with Michigan state officials on steps to help minimize the risk of a rupture on Line 5, especially the underwater section at the Straits of Mackinac. In November 2017, Enbridge and the state agreed that the midstream company would replace the Line 5 section under the St. Clair River (between Michigan and Ontario) as soon as permits for the project are in hand. (Canada National Energy Board, or NEB, approved plans for the project last Friday, July 12.) The company and state also committed to completing a detailed analysis of options for replacing the pipe’s Straits of Mackinac section, and to taking a series of steps to ensure the safe operation in the interim — including a plan under which Enbridge will temporarily shut down the straits portion of Line 5 during sustained periods of adverse weather (waves eight feet or higher).