A leak in the Keystone Pipeline released at least 210,000 gallons of oil, and the pipeline has since been shut off.

The oil was likely diluted bitumen, or dilbit, a mixture of tarry oil and thinning agents that let the commodity flow through the pipe. But the drop in pressure indicated that instead of heading through on its appointed course, the oil was out of the pipe and spreading through the ground near Amherst, South Dakota, creating a large stain on the browning fall landscape.

In a statement, pipeline operator TransCanada says that “the section of pipe along a right-of-way approximately 35 miles (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.”

Early estimates put the total spilled at 5,000 barrels, or 210,000 gallons of dilbit seeping through the landscape.

NPR Reports that the South Dakota Department of Environment and Natural Resources was not informed of the leak until about 10:30 am local time, several hours after the incident.

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