A federal judge has rejected claims by environmental groups and Ojibwe bands that the Army Corps of Engineers failed to adequately review Enbridge's Line 3 pipeline.

The controversial 340-mile oil pipeline across Minnesota opened a year ago, but one lawsuit challenging it had yet to be concluded — until Friday.

"The court concludes that the Corps complied with its obligations to assess the environmental consequences associated with its permits to Enbridge," wrote Judge Colleen Kollar-Kotelly of the U.S District Court for the District of Columbia.

The Minnesota Public Utilities Commission (PUC), the state's primary pipeline regulator, approved Line 3 in early 2020. The Minnesota Pollution Control Agency (MPCA) approved a state water permit later that year.

Pipeline opponents appealed those decisions. But state courts rejected their challenges in 2021, while the pipeline was being constructed.

"Like Minnesota state government regulators, agencies, our courts and so-called leaders, the federal court has again failed Indian people and Minnesota's most pristine waterways and landscapes," wrote Winona LaDuke, head of the indigenous environmental group Honor the Earth, in a statement.

Enbridge, in statement, said it was pleased with the latest court decision. The company said the decision "acknowledges the thorough, inclusive and science-based review of the Line 3 Replacement Project by the U.S. Army Corps of Engineers." It also cited public participation and consultation with tribes.

The new Line 3 replaced a 1960's Enbridge pipeline that was corroding and operating at only 50 % capacity due to safety concerns. The pipeline transports a particularly viscous Canadian oil to Enbridge's terminal in Superior, Wis.

Pipeline opponents say the new Line 3, which partly follows a new route, has opened a new region of Minnesota lakes, streams and wild rice waters to oil spill degradation, as well as exacerbating climate change.

The Army Corps issued its water and wetlands permit for pipeline construction in November 2020, allowing Enbridge to drill beneath rivers and to discharge dredged material.

Soon thereafter, the Corps was sued by the Red Lake and White Earth bands and three environmental groups: Honor the Earth, Friends of the Headwaters and the Sierra Club.

They claimed the Corps did not properly evaluate the pipeline's impact on climate change and that the agency should have conducted its own environmental impact statement (EIS) on Line 3 — instead of relying on an EIS done by the state.

Their suit also alleged that the Corps failed to fully assess Line 3's impacts on the tribes' treaty rights to hunt, gather and fish.

Judge Kollar-Kotelly rejected all of those contentions.

She agreed with the Corps' argument that it regulates only the construction of the pipeline, and therefore has no purview over climate change effects caused by Line 3's operation.

The Corps consulted with tribes and reviewed comments from the PUC on environmental justice, she wrote.

And the Corps did not need to repeat the state's EIS, she wrote. "The Corps' regulations explicitly direct the district engineer to 'whenever practicable incorporate by reference and rely upon the reviews of other Federal and State agencies,'" the judge wrote.

The Corps' permit was the last approval Enbridge needed before starting construction in late 2020. That federal permit was intertwined with a water and wetlands permit granted by the MPCA, also in late 2020.

The Minnesota Court of Appeals upheld the MPCA permit in August 2021. Two months earlier, that same court — in a 2-1 opinion of a three-judge panel — also upheld the PUC's approval.

The Minnesota Supreme Court denied a petition by pipeline opponents further challenging the PUC's decision.