The Keystone pipeline system, which carries crude oil from Canada to the United States, was shut down on Tuesday morning because of an oil spill in southeastern North Dakota, government and company officials said.
The pipeline ruptured north of Fort Ransom, N.D., said Bill Suess, manager of the spill investigation program at the North Dakota Department of Environmental Quality, a state agency. The size and cause of the spill in that city, about 78 miles southwest of Fargo, were not known, he said, and the authorities had also not said when the pipeline could be back in operation.
Mr. Suess said a pipeline employee who was working on a pump station heard a “mechanical bang,” then reported the spill at 7:44 a.m. The pipeline was shut down in about two minutes, he said.
“As of right now, the spill is confined to an agricultural field south of the pump station,” Mr. Suess said.
He said a nearby stream had been isolated as a precaution, but it had not been affected.
The pipeline system stretches 2,687 miles. In 2024, it carried about 626,000 barrels of crude oil per day, according to South Bow, the infrastructure company that operates the pipeline. It was previously operated by TC Energy, the company behind the Keystone XL pipeline project, which planned on expanding the pipeline system but was opposed by environmentalists and Indigenous groups. The Keystone XL project was terminated by the company in 2021. South Bow was spun off from TC Energy in October 2024.
Solomiya Lyaskovska, a spokeswoman for South Bow, said it had sent people and equipment to the rupture site.
Ms. Lyaskovska said in an email that the shutdown came “after control center leak detection systems detected a pressure drop in the system.”
“The affected segment has been isolated, and operations and containment resources have been mobilized to site,” she said. “Our primary focus right now is the safety of on-site personnel and mitigating risk to the environment.”
In December 2022, more than 500,000 gallons of crude oil spilled from the pipeline in Washington County, Kan. The pipeline’s operator at the time, TC Energy, said in February 2023 that the spill was caused by “bending stress” on the pipe and a “weld flaw.”
In October 2019, the pipeline leaked about 383,000 gallons of crude oil in Edinburg, N.D., about 155 miles north of Fort Ransom. State environmental regulators said that the spill covered an estimated half-acre of wetland.