Amherst, S.D. • TransCanada Corp. says its Keystone pipeline has leaked an estimated 210,000 gallons of oil in South Dakota.

The company said that crews shut down the pipeline Thursday morning after a drop in pressure was detected resulting from an oil leak that’s under investigation.

The section of pipe in Marshall County, South Dakota, has been isolated and the company says emergency response procedures were activated.

Brian Walsh, an environmental scientist manager at the South Dakota Department of Environment and Natural Resources, says officials don’t believe the leak has affected any surface water bodies or threatened any drinking water systems.

TransCanada says that expects the pipeline to remain shut down as the company responds to the leak.

The Keystone pipeline is part of a 2,687-mile system that also is to include the proposed Keystone XL pipeline.