TransCanada: 16,800 gallons of oil leaked in South Dakota

TransCanada estimates that about 16,800 gallons of oil leaked into a field in South Dakota as part of a spill that has shut the Keystone pipeline down while officials investigate.

The company says it reported the 400-barrel estimate Thursday to the National Response Centre and the Pipeline and Hazardous Materials Administration. It says the estimate is based on the excavation of soil to expose more than 100 feet of pipe and takes into account factors including oil observed in the soil and the potential area affected.

TransCanada hasn't yet said what caused the leak, which was reported Saturday. The company has told customers the pipeline will remain closed until early next week.

About 100 workers are at the site, which is approximately 4 miles from the Freeman pump station in Hutchinson County, said TransCanada spokesman Mark Cooper. He said specialists at the site affirm that the leak is being controlled and there is no significant environmental impact and no threat to public safety.

The pipeline runs from Alberta, Canada, to refineries in Illinois and Cushing, Oklahoma, passing through the eastern Dakotas, Nebraska, Kansas and Missouri. The Keystone pipeline can handle 550,000 barrels, or about 23 million gallons, daily. It's part of a pipeline system that also would have included the Keystone XL pipeline had President Barack Obama not rejected that project last November.

Analysts say the shutdown will have a short-term impact in which less-heavy Canadian crude will be getting to the market, but the system is already oversupplied so consumers are unlikely to see an impact at the pump.