State officials have given Enbridge Inc. permission to install 22 more anchor supports along twin pipelines at the bottom of the waterway linking Lakes Michigan and Huron.
The Michigan Department of Environmental Quality issued a permit last week allowing the supports for Line 5 in the Straits of Mackinac.
Enbridge says it's a "proactive" step to fasten the pipelines to the lake bottom and keep them in place when currents erode dirt beneath them.
The underwater pipes are part of a line that carries 23 million gallons of crude oil daily between Superior, Wisconsin, and Sarnia, Ontario.
Mlive.com reports that the underwater segment already has 128 support anchors.
Environmentalist groups that want the 65-year-old pipelines decommissioned say the extra supports won't make Line 5 safe or prevent a catastrophic spill.
