FARGO — Federal regulators have given the go-ahead for TC Energy's Keystone Pipeline to resume operation after a leak spilled 383,000 gallons of oil in northeast North Dakota in late October.

TC Energy said the pipeline will operate at reduced pressure with the volume of oil moving through it gradually increasing until it reaches normal conditions again. The Alberta, Canada-based energy company said it will be monitoring rights of way, valve sites and pump stations with crews on land and in the air as the system is fully reactivated.

Federal authorities allowed the pipeline to resume service after approving TC Energy's repair and restart plan, the company announced Sunday, Nov. 10.

The Keystone Pipeline, which carries oil from Alberta to refineries in Texas and Illinois, leaked the equivalent of 9,120 barrels — enough to fill about half an Olympic-size swimming pool — in a rural area 3 miles northwest of Edinburg on Oct. 30. TC Energy said a computer system monitoring the pipeline noticed the leak at about 10:20 p.m. CST and shut down the system.

Walsh County Emergency Manager Brent Nelson said the oil initially sprayed out of the ground "like a whale blowing its water up in the air" and spread across the wetlands area near the leak. Oil was spread over a roughly 2,500-yard area.

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About half of the spilled oil had been recovered by Nov. 4, TC Energy spokesperson Robynn Tysver told Forum News Service. Tysver said the company had about 200 personnel working 24 hours a day on cleanup and remediation efforts.

On Nov. 5, the U.S. Pipeline and Hazardous Materials Safety Administration ordered the pipeline be shut down until TC Energy took corrective actions to prevent future spills. Associate Administrator Alan Mayberry wrote in the order that continued operation of the affected segment "would be hazardous to life, property and the environment" without corrective measures.

Those measures included shutting down the affected segment, developing a return-to-service plan and conducting a number of tests including testing the failed pipeline segment in a third-party lab.

The pipeline is up and running once again, but officials have not yet determined what caused the Keystone Pipeline to leak. TC Energy said it will continue working with federal pipeline authorities and the North Dakota Department of Environmental Quality to investigate.