The 590,000 bbl/d Keystone pipeline was operating at reduced capacity on July 18, operator TC Energy said, after a pump station near Huron, S.D., was shut down due to damage to a third-party power utility.

TC Energy declared a force majeure on Keystone, which carries crude from Alberta to refineries in the U.S. Midwest. Repairs are underway, but the company said there is currently no timeline for restoration of full service.

The incident took place on July 17.

"Repairs are being undertaken and we are working to restore full service as soon as possible," TC Energy said in a statement.

In a shipper notice seen by Reuters, the company said the pump station facility had been isolated and would remain isolated until the power impact is resolved.