An oil pipeline that runs through the area where Lakes Huron and Michigan meet also crosses other Michigan waterways at nearly 400 locations, dozens of which are considered particularly sensitive, a report disclosed Friday.
Enbridge Inc., the Canadian company that owns Line 5, listed the water crossings in one of three reports submitted to the state under a 2017 agreement with Gov. Rick Snyder, whose administration is expected to determine the pipeline's long-term future by October. Environmental groups want it decommissioned, contending the 65-year-old line is outdated and vulnerable to leaks, while the company says it's in good shape.
A report earlier this month outlined several options for the nearly 5-mile-long section beneath the Straits of Mackinac, including placing the pipeline in a tunnel or trench.
The newly released documents deal with related topics, including measures that could be taken to prevent leaks from the pipeline in the straits area resulting from ship anchor strikes or other causes, and to improve leak detection.
Line 5 carries light crude oil and natural gas liquids used to make propane. Its 645-mile-long route extends from Superior, Wisconsin, to Sarnia, Ontario, and includes large sections of northern Michigan.
The report on crossings other than the straits identifies nearly 400 sites where Line 5 crosses a Michigan stream, wetland or other water body.
It designates 74 locations as "prioritized," meaning they are sensitive areas that could be particularly vulnerable in the event of a spill, such as endangered species habitat or places near drinking-water intake pipes. Some are on iconic waterways such as the AuSable, Sturgeon, Manistique and Rapid rivers and the Upper Peninsula's Lake Gogebic. State agencies, independent specialists and Enbridge identified the sites.
Enbridge says it evaluated each of the high-priority locations for probability of failure resulting from cracks, corrosion or dents and found "a high level of safety," although further study is planned. Crossings will be assessed for vulnerability to stress, insufficient channel width and depth, susceptibility to flood damage and other potential dangers, the report says.
"This is just a starting point toward making long-term improvements," Enbridge spokesman Michael Barnes said. "We share the state's commitment to protecting these natural resources."
Environmental groups said the report bolsters their case for shutting down Line 5.
"Enbridge claims their world-class pipeline safety measures will keep us safe but the reality is we have seen time and again failure after failure," said Anne Woiwode, chair of the Sierra Club's Michigan chapter.