Line 5 ships 540,000 barrels per day of crude and refined products from Superior, Wisconsin, to Sarnia, Ontario, but the state of Michigan ordered Enbridge to shut it down due to worries a leak could develop in a four-mile section running beneath the Straits of Mackinac in the Great Lakes.
Enbridge ignored Michigan’s order and the sides are embroiled in a legal battle. The government of Canada has been pushing counterparts in the United States to intervene, and Monday’s move marks a step up in Ottawa’s efforts to help safeguard the pipeline.
In a letter to the federal judge presiding over the case, Gordon Giffin, legal counsel for the Canadian government, said Canada had formally invoked Article Six of the 1977 Transit Pipelines Treaty.
The treaty has never been invoked before.
Line 5 is governed by the provisions of the 1977 agreement, which guarantees the uninterrupted transit of light crude oil and natural gas liquids between the two countries, Canada’s Foreign Affairs Minister Marc Garneau said in a statement.
“Today, Canada is formally invoking the dispute settlement provision of the 1977 Agreement to ensure its full application,” Garneau said.
The U.S. State Department did not immediately respond to requests for comment.
Article Six is the process used by the treaty to resolve disputes, and Giffin’s letter asked the court to halt any proceedings related to Michigan’s Line 5 shutdown order while that is ongoing, a move criticised by environmental campaigners.
“The government of Canada took an action today that ignores the risk of an oil spill in the Great Lakes and seems clearly designed to delay a legal decision to shut down Enbridge’s twin Line 5 oil pipeline in the Straits of Mackinac,” said Sean McBrearty, co-ordinator for environmentalists Oil & Water Don’t Mix.
Earlier this year Enbridge and Michigan took part in court-ordered mediation, but Enbridge spokeswoman Tracy Larsson said Michigan has said it is not committed to further talks.
“We greatly appreciate the efforts of ‘Team Canada’ – from the Government of Canada to the provinces of Ontario, Quebec, Alberta and Saskatchewan for their commitments and efforts to keep Line 5 open,” she said in an email.