The U.S. Department of Justice (DOJ) has proposed changes to a 2016 consent decree with Enbridge Energy that could require the company to fix previously identified cracks in its Lakehead pipeline system, which includes Line 5.

The proposed modifications focus on how Enbridge handles circumferential cracks, which encircle a pipe rather than run lengthwise. 

The Lakehead System spans the Midwest and includes the controversial Line 5, a 71-year-old pipeline that traverses Michigan and runs beneath the Straits of Mackinac.

If approved, the changes could require Enbridge to re-evaluate these cracks using "new methods tailored to address the unique threats posed by circumferential cracks," according to a Federal Register notice published Monday. 

This reassessment would consider all stresses that might cause cracks to grow and fail, with Enbridge being responsible for scheduling any repairs deemed necessary.

The proposal stems from a 2010 oil spill from Enbridge's Line 6b near Marshall, Michigan. The rupture released over a million gallons of oil into Talmadge Creek and the Kalamazoo River, going undetected for several hours.

The DOJ and Enbridge reached a settlement agreement in 2016 to resolve lawsuits concerning the Marshall spill and a separate incident that year in Romeoville, Illinois.