TransCanada issued a statement Thursday afternoon after the Keystone Pipeline leaked approximately 210,000 gallons in South Dakota.
TransCanada says that expects the pipeline to remain shut down as the company responds to the leak.
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. It already had been approved by most of the states along the route.
The pipeline transports crude from Alberta, Canada, to refineries in IL and Oklahoma, passing through the eastern Dakotas, Nebraska, Kansas and Missouri.More news: 'Lord of the Rings' TV Series Heading to Amazon
Amherst is about 200 miles north of Sioux Falls, S.D., and about 25 miles from the state's border with North Dakota.
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.
Keystone XL, if built, would cut diagonally through South Dakota. TransCanada is providing State and Federal regulators, including the Pipelines and Hazardous Materials Safety Administration (PHMSA) and the National Response Center (NRC), with accurate and confirmed information on an ongoing basis.
The Keystone Pipeline is part of a 2,687-mile system that also is to include the proposed Keystone XL pipeline, which has faced persistent opposition from environmental groups, American Indian tribes and some landowners. President Donald Trump reversed that decision swiftly after taking office, which placed the final permitting decision in the hands of Nebraska.