Oil hasn't contaminated waterways or drinking water sources, authorities say. It was detected about 6 a.m. Thursday by TransCanada and reported to state officials more than four hours later, said Brian Walsh, a manager with the South Dakota Department of Environment and Natural Resources. The Keystone XL pipeline has been opposed by environmental and Native American groups since it was proposed previous year. Emergency response procedures were then activated and the pipeline was shut down.
In the release the company said, crews safely shut down the pipeline at around 5 a.m. after a drop in pressure was detected in the operating system from the oil leak.
Walsh anticipates the clean up will take some time.
The leak, which it said happened about 35 kilometres south of its Ludden pump station on a right-of-way, comes as Nebraska Public Service Commission is set to vote on the Keystone XL project on November 20 to clear the last major regulatory hurdle for the $8 billion project.More news: Trump reverses elephant trophy ban
TransCanada emergency and safety crews, as well as contracted, nationally recognized experts are assessing the situation, with ongoing reports to federal officials. The estimated volume of the leak is approximately 5,000 barrels.
TransCanada has indicated that the pipeline from Hardisty, Alberta, to Cushing, Okla., and to Wood River/Patoka, Ill., is expected to remain shut down.
"The safety of the public and environment are out top priorities and we will continue to provide updates as they become available", TransCanada added.
Opponents of Keystone XL say the pipeline would pass through the Sandhills, an ecologically fragile region of grass-covered sand dunes, and would cross the land of farmers and ranchers who don't want it.