WINNIPEG, Manitoba, March 8 (Reuters) - TC Energy ( TRP )

temporarily shut down the Keystone oil pipeline on

Thursday to investigate a South Dakota landowner's report about

a possible leak that proved unfounded, the Canadian company and

a U.S. pipeline regulator said on Friday.

TC told the Pipeline and Hazardous Materials Safety

Administration (PHMSA) about the reported leak and conducted

aerial observation and water analysis that found no evidence of

a spill before restarting the line, PHMSA said.

A spokesperson for Calgary, Alberta-based TC Energy ( TRP ) said a

landowner in South Dakota's Marshall County noted a sheen in

water from his well, one mile from the pipeline corridor.

"This was not an operational incident. The pipeline was

shut down out of an abundance of caution," the TC spokesperson

said.

The shutdown of the 622,000 barrel-per-day (bpd) pipeline

interrupted the flow of Canadian oil from Alberta to Nebraska,

where the line splits, with one arm running east to the Midwest

and the other running south to the U.S. crude storage hub in

Cushing, Oklahoma.

The outage took down the entire Keystone system for five

hours, according to real-time pipeline monitoring by consultancy

Wood Mackenzie.

Wood Mackenzie said as of Friday morning, Keystone flows had

rebounded to their pre-shutdown level of more than 600,000 bpd.

The pipeline has been dogged by problems, most recently a

major spill in rural Kansas in 2022.

TC shares eased slightly in New York.