US Army Corps of Engineers approves permit for Line 5 tunnel under Straits of Mackinac

Aug 13, 2026

The U.S. Army Corps of Engineers approved a key permit on August 12, 2026, for Enbridge Energy to construct a concrete tunnel beneath the Straits of Mackinac for the Line 5 oil pipeline. Issued under the Trump administration's expedited energy initiatives, the decision was praised by Enbridge but heavily criticized by Native American tribes as a violation of treaty rights and sacred spaces. Despite federal approval, the project faces major delays after the Michigan Supreme Court overturned a key state permit in July 2026.

Army Corps tunnel permit

▪The U.S. Army Corps of Engineers' permit allows Enbridge Energy to work within federally regulated waterways but does not regulate the operation of the Line 5 pipeline or the substances transported.
▪The U.S. Army Corps of Engineers determined that the Line 5 tunnel project is not contrary to the public interest and complies with Clean Water Act guidelines.
▪The U.S. Army Corps of Engineers issued a permit to Enbridge Energy on August 12, 2026, to construct a concrete tunnel beneath the Straits of Mackinac to house the Line 5 oil pipeline.

Trump energy policy acceleration

▪The U.S. Army Corps of Engineers issued the Line 5 tunnel permit under the Trump administration's 'Building Infrastructure, No Paperwork' initiative to expedite critical energy projects.
▪Assistant Secretary of the Army for Civil Works Adam Telle stated that the Line 5 tunnel approval aligns with President Trump's vision to ensure national energy dominance by cutting regulatory red tape.

Tribal treaty rights opposition

▪Bay Mills Indian Community President Whitney Gravelle and Native American Rights Fund Managing Attorney David Gover condemned the Line 5 permit as a breach of treaty rights that threatens sacred spaces.
▪Michigan Native American tribes withdrew as cooperating agencies in March 2025, protesting that the federal fast-tracking of the Line 5 tunnel review short-circuited the evaluation of environmental impacts.

Endangered species impacts

▪The U.S. Army Corps of Engineers noted that the Line 5 tunnel project would adversely affect Houghton’s goldenrod and dwarf lake iris, which are federally listed threatened species.
▪The U.S. Army Corps of Engineers stated that planned mitigation efforts would prevent reductions in the overall recovery, numbers, or distribution of the threatened plant species.

Archaeological site damage

▪The U.S. Army Corps of Engineers acknowledged that the Line 5 tunnel project would cause major, permanent, adverse effects on historic properties, including archaeological sites.
▪Anishinaabe tribal nations stated that the permanent adverse effects of the Line 5 tunnel project on historic properties and archaeological sites cannot be mitigated.

Michigan Supreme Court challenge

▪The Michigan Supreme Court overturned a key permit for the Line 5 tunnel in July 2026, ordering state regulators to reconsider the environmental impacts of the pipeline's continued operation.
▪The Michigan Supreme Court ruled that the Michigan Public Service Commission failed to examine potential alternatives or consider the effects of the Line 5 tunnel project on public trust resources.