Coast Guard reviewing request to ban anchors in Mackinac Straits after pipeline damage

Mackinac Bridge | Susan J. Demas
Updated with comment from Enbridge, 4:31 p.m. 7/28/20

Leaders of nine prominent environmental groups in Michigan are urging the U.S. Coast Guard to consider banning the use of anchors in the Straits of Mackinac, following reports that one of Canadian oil company Enbridge’s own contracted vessels may have caused damage to a support anchor on its Line 5 pipeline.

“Anything short of prohibiting anchoring in the Straits of Mackinac excepting emergencies poses an unacceptable risk to navigation and submerged pipelines,” the groups’ letter to Capt. Anthony Jones reads. “… Moreover, Enbridge has clearly demonstrated an inability to protect its own pipelines from damage inflicted by contractors under its supervision and control.”

In response, Cmdr. Mike Hjerstedt, who heads the Prevention Department in Sault Ste. Marie, wrote back Friday afternoon that the emailed letter was “well received.”

“We will begin our review of the information you provided as soon as possible,” Hjerstedt said.

Enbridge spokesperson Ryan Duffy said in an email Tuesday afternoon that the company has implemented measures to prevent anchor strikes along the east and west legs of Line 5, and that the incidents in question were more likely caused by a dragging cable rather than an anchor.

“Our investigation did not determine the identity of the vessels that caused the issues on the east and west segments.  It did determine they were likely caused by a dragging cable, and that there was no threat to the safety of the pipelines,” Duffy said.*

Friday’s letter to the Coast Guard was signed by representatives of Oil & Water Don’t Mix, Clean Water Action, FLOW (For Love of Water), Groundwork Center for Resilient Communities, Michigan Environmental Council, Northern Michigan Environmental Action Council, Sierra Club Michigan, Straits Area Concerned Citizens for Peace, Justice & the Environment and TC 350.

All groups are opposed to Enbridge’s continued operations in the Straits.

Straits of Mackinac | Laina G Stebbins

Copies of the letter were also sent to Gov. Gretchen Whitmer and U.S. Sens. Debbie Stabenow (D-Lansing) and Gary Peters (D-Bloomfield Twp.). Whitmer spokespersons did not immediately respond to a request for comment.

Since October 2018, certain areas of the Straits have been designated a Regulated Navigation Area (RNA) to give the Coast Guard stronger authority to protect against anchor strikes and other damage to submerged pipelines and cables. The federal rule — contained in section 165.944 of 33 CFR (Code of Federal Regulations) — prohibits anchoring or loitering within the RNA unless authorized by the Captain of the Port of Sault Ste. Marie or a designated representative.

The rule’s creation was prompted by a ship’s anchor strike to Line 5 and an electrical line in the spring of 2018. The environmental groups argue that, given the new information from Enbridge about its own vessels possibly causing the newest incident, it is prudent to ban anchoring in the Straits until the threat of further damage is removed.

Given that the Line 5 incidents involved vessels under the jurisdiction of the Captain of the Port, the letter asks Captain Anthony Jones to:

  • Confirm and provide documentation on whether all vessels and barges anchoring in the Straits (including but not limited to the RNA) have been in compliance with 33 CFR § 165.944 since the RNA was established in 2018.
  • Establish a temporary rule prohibiting all future anchoring in the Straits, and revoke any existing authorizations granted to anchor in the Straits of Mackinac within the RNA.

The letter further specifies that the temporary anchor ban “should continue until potential anchoring or other related damage to Enbridge’s Line 5 pipelines has been removed as a threat to navigation and the Great Lakes.”

Enbridge: Boat anchor, wire cable may have caused Line 5 damage

An Enbridge investigation report shared with the state on Wednesday revealed that the company has narrowed down the culprit for the east leg’s support anchor damage to five possible vessels.

Notably, four of the five were Enbridge-contracted vessels doing work related to the company’s preparations to build an underwater, tunnel-encased replacement pipeline for Line 5.

Three of the Enbridge vessels were tugboats carrying barges ranging from 17 to 23 meters long. Two were performing a geotechnical investigation; another was performing area maintenance with “significant operations in the area.”

The other possible Enbridge culprit was the company’s 72-meter geotechnical drilling vessel, which was confirmed to have anchored in the area.

The only non-Enbridge vessel listed as possibly causing the damage is a 12-meter dredging vessel if it was dragging a very long cable.

Nick Assendelft, a spokesperson for the Michigan Department of Environment, Great Lakes and Energy (EGLE), said the department is reviewing the report and declined to comment further.