TransCanada Corporation crews safely shut down its Keystone pipeline at approximately 6 a.m. CST (5 a.m. MST) Thursday after a drop in pressure was detected in its operating system resulting from an oil leak that is under investigation.

The estimated volume of the leak is approximately 5,000 bbls. The section of pipe along a right-of-way approximately 56 kilometres south of the Ludden pump station in Marshall County, South Dakota was completely isolated within 15 minutes and emergency response procedures were activated.

Crews, including TransCanada specialists from emergency management, engineering, environmental management and safety as well as contracted, nationally recognized experts are assessing the situation. 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.

“TransCanada appreciates the collaborative support of local officials, emergency response personnel and commissioners in Marshall County, as well as the landowner who has given permission to access land for assessment, identification and clean-up activities,” the company stated.

“We have been keeping our shippers and customers up to date and have communicated that the pipeline from Hardisty, Alberta to Cushing, Oklahoma and to Wood River/Patoka, Illinois is expected to remain shut down as we respond to this incident,” the company added. “This does not affect the Marketlink pipeline system, which uses the facilities of the southern leg of the Keystone system from Cushing to the Gulf Coast.”

"PHMSA has deployed four technical experts to the site of the spill. The line has been shut in and our investigation is ongoing,” said Darius Kirkwood, a spokesman for the U.S. agency.

Keystone XL opponents seize on spill

Opponents of TransCanada's proposed Keystone XL pipeline seized on the spill, saying it highlighted the risks posed by the XL project, which has become a symbol for environmentalists of fossil-fuel pollution and global warming.

The Nebraska Public Service Commission, or PSC, is scheduled on Monday to announce a decision on whether the proposed pipeline route through the state is in the best interests of Nebraskans. It is not allowed to consider the potential of spills as the project already has an environmental permit.