The Great Lakes Tunnel Project

On Dec. 19, 2018, Enbridge announced that it had reached an agreement with the Mackinac Straits Corridor Authority (MSCA) on the future of Enbridge's Line 5 light oil and natural gas liquids (NGL) pipeline at the Straits of Mackinac.
The Great Lakes Tunnel, a $500-million private investment by Enbridge in Michigan, will be built deep under the Straits to house Line 5. While Line 5 has operated safely and reliably in the Straits for more than 65 years, the Great Lakes Tunnel will be bored through rock, as much as 100 feet below the lakebed—virtually eliminating the chance of a pipeline incident in the Straits.
The Great Lakes Tunnel is a massive undertaking. It will be built by Michigan labor, and harness the knowledge and experience of industry-leading tunnel engineers. Pending receipt of necessary permits and approvals, Enbridge anticipates beginning construction of the Great Lakes Tunnel in 2021 to house a replacement Line 5 segment in the Straits.


https://www.enbridge.com/projects-and-infrastructure/public-awareness/line-5-michigan/great-lakes-tunnel-project#:~:text=The%20Great%20Lakes%20Tunnel%2C%20a,Straits%20to%20house%20Line%205.