MINNEAPOLIS (AP) — A Minnesota regulatory panel on Tuesday signed off on Enbridge Energy’s planned Line 3 crude oil pipeline replacement across northern Minnesota, leaving only one minor state permit to go before construction can begin.

The independent Public Utilities Commission notified Enbridge in a filing that the company has complied with its pre-construction requirements. Enbridge said in a statement that the authorization to begin construction means only a final construction storm water permit is needed from the Minnesota Pollution Control Agency before construction can begin.

The approval came one day after the U.S. Army Corps of Engineers approved the final federal permit for the project. The PUC had approved the project several times before.

MPCA spokesman Darin Broton said his agency has 30 days from Monday to decide.

Line 3 begins in Alberta, Canada, and clips a corner of North Dakota before crossing Minnesota on its way to Enbridge’s terminal in Superior, Wisconsin. Enbridge wants to replace the Minnesota section because it was built in the 1960s, and its increasing maintenance needs mean the company can run it at only half its original capacity. Replacement segments in Canada, North Dakota and Wisconsin are already complete.

Opponents say the project threatens spills in pristine waters where Native Americans harvest wild rice and that the Canadian tar sands oil it would carry would aggravate climate change.