August 13, 2026.
Detroit — The U.S. Army Corps of Engineers, Detroit District, has issued a federal permit allowing Enbridge Energy, L.P. to conduct regulated activities associated with the proposed Line 5 Tunnel Project beneath the Straits of Mackinac.
The permit was issued August 12 following a federal review of the project. The Corps also released its Record of Decision outlining the analysis behind the decision.
The proposed project calls for construction of a tunnel beneath approximately four miles of lake-bed in the Straits of Mackinac. The tunnel would house a replacement segment of the existing Line 5 pipeline.
According to the Corps, the permit authorizes Enbridge to bore a 21-foot-diameter tunnel beneath the Straits and install a new 30-inch-diameter pipeline segment inside the tunnel. The new pipeline would replace two existing pipelines currently located on the lake-bed.
The Detroit District said its review considered requirements under several federal environmental and historic preservation laws, including the National Environmental Policy Act, Section 404 of the Clean Water Act, Section 10 of the Rivers and Harbors Act, the Endangered Species Act and the National Historic Preservation Act.
The Corps also said it fulfilled its federal Tribal Trust Responsibilities during the review process. The tribes disagree with that statement and are continuing their fight to stop the approval of this project.
Detroit District Commander Lt. Col. Donald K. Lew described the decision as the result of an extensive evaluation involving federal and state resource agencies, Tribes, and Enbridge.
The Corps said the permit authorizes activities in federally regulated waters but does not regulate the design or operation of the Line 5 pipeline itself or the substances transported through it.
The federal agency determined that issuing the permit complies with applicable federal laws and regulations and that the project, as authorized, would meet its stated purpose and need while protecting natural resources.
The decision represents another major federal step for the proposed tunnel project, which is intended to move the Line 5 pipeline away from its current location on the Straits lake-bed and into a protective underground tunnel.
The U.S. Army Corps of Engineers has made the Record of Decision and related project documents available through its Line 5 Tunnel Project public-review materials.
Source: U.S. Army Corps of Engineers, Detroit District, Aug. 12, 2026. Read the full Army Corps news release