Operation Deimos

The Keystone pipeline released an estimated 14,000 barrels of oil – roughly 588,000 gallons – into a creek and pastureland in Washington County, Kansas, on Dec. 7.

An oil spill in a creek in northeastern Kansas this week is the largest for an onshore crude pipeline in more than nine years and by far the biggest in the history of the Keystone pipeline, according to federal data.

TC Energy Corp. pushed back the full return of its Keystone oil pipeline by a week after a 14,000-barrel oil spill shut the critical conduit, according to people familiar with the matter.

An oil spill in a creek in northeastern Kansas has shut down a major pipeline from Canada through the Plains and to the Texas Gulf Coast...