The Minnesota Court of Appeals on Monday upheld the Enbridge Line 3 project’s water quality certification, which regulates construction impacts on wetlands and bodies of water along the route, dealing another blow to opponents of the nearly complete pipeline.

In a decision issued Monday, the three-judge panel unanimously agreed to affirm the decision by the Minnesota Pollution Control Agency awarding the project a 401 certification, a permit granted by state regulators if the project's impact on water falls within the state's standard. The permit then allows the U.S. Army Corps of Engineers to issue a 404 permit if construction-related impacts to U.S. water comply with federal laws and regulations, which the Army Corps said Line 3 met in November, allowing Enbridge to discharge dredged and fill material into rivers and streams.

"We conclude that the MPCA’s section 401 certification is not affected by legal error and is supported by substantial evidence in the record," Judge Tracy M. Smith wrote in the opinion. "We therefore affirm the MPCA’s decision."

Opponents of Line 3, including the Friends of the Headwaters, Sierra Club, Red Lake Band of Chippewa Indians and White Earth Band of Ojibwe, had argued the MPCA failed to consider route alternatives, wetland restoration, the pipeline's operational impact and effects on climate and tribes before granting its certification.

"MPCA's approval of the permits for Line 3 put Minnesota's waterways at risk, and we can already see the resulting damage as Enbridge has already had dozens of drilling fluid spills during the course of construction," Sierra Club North Star Chapter Director Margaret Levin said in a statement Monday, referring to 28 drilling fluid spills reported earlier this month. "It's disappointing that the court will not hold MPCA accountable for their failure to protect our clean water, and now it's more urgent than ever that President Biden step in, live up to his commitments to climate action and environmental justice, and stop Line 3.”

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A separate federal lawsuit targets the Army Corps' 404 permit. But under Joe Biden, the Army Corps has continued its defense of the Line 3's permits.

In a statement, Enbridge spokesperson Juli Kellner said: "Today’s decision is an important affirmation of the Minnesota Pollution Control Agency’s approval for Line 3’s 401 Certification, confirming that wetlands and waterbodies are being appropriately protected during construction."

Once complete, the new pipeline will carry 760,000 barrels of oil per day from Alberta, Canada, to Enbridge's terminal in Superior. The new lines in North Dakota, Canada and Wisconsin are already complete.

Last week, the company said work on Line 3 was more than 90% complete. The pipeline is expected to be operational in the fourth quarter of this year.