The operator of the Keystone pipeline system has finished cleaning up a massive 2022 oil spill, and the creek affected by it is flowing naturally again.

TC Energy Corp. has pegged the cost of cleanup and remediation of December's oil spill from its Keystone pipeline at an estimated US$480 million.

The Calgary-based company says it will operate the pipeline under plans approved by U.S. regulators, including additional safety measures such as reduced operating pressure.

TC Energy received regulatory approval to restart the remaining segment of the Keystone pipeline that has been shut down since suffering the pipeline's worst oil spill on Dec. 7.

The Keystone pipeline suffered the worst leak in its history when about 14,000 barrels of oil spilled into a creek in Washington County, Kan., on Dec. 7.

The oil spilled from TC Energy Corp's ruptured Keystone pipeline was diluted bitumen, the U.S. Environmental Protection Agency said, adding complications to the cleanup.

TC Energy Corp. says it has restarted the section of the Keystone pipeline that was unaffected by last week's oil leak in Kansas.

The company says vacuum trucks and crews are operating around the clock with multiple booms set up downstream of the release point to contain the oil.

U.S. government data shows spills from TC Energy Corp.'s Keystone pipeline have increased in severity in recent years.

The effort to remove oil from the largest crude spill in the United States in nearly a decade will extend into next week, the U.S. Environmental Protection Agency said Friday.