One of the largest crude oil spills in the United States in nearly a decade, more than 14,000 barrels of crude oil spilt into a creek in Kansas, prompting Canadian company TC Energy to shut down its Keystone pipeline in the country.

The leak, which happened in Kansas about 20 miles (32 km) south of a crucial intersection in Steele City, Nebraska, has no known cause. The pipeline has experienced three spills totalling several thousand barrels of crude oil since it was first opened in 2010.

The Keystone pipeline, which has a capacity of 622,000 barrels per day, is crucial for transporting heavy Canadian crude from Alberta to American refineries. Gulf Coast and the Midwest. How long the closure will be in effect is unknown.

There have been no effects on drinking water wells or the public, the U.S Environmental Protection Agency said in a statement, though the surface water of Mill Creek was affected.

This would be the biggest crude oil leak since a Tesoro pipeline spilt more than 20,000 barrels of oil in North Dakota in October 2013, according to PHMSA data.

The leak, which happened close to the 1,000-person town of Washington, Kansas, is also being looked into by PHMSA.

According to PHMSA data, there have been seven spills at the Keystone pipeline since it started operating in June 2010. The most significant occurred in South Dakota in December 2017, when more than 6,600 barrels spilt, according to PHMSA data.

According to Bill Caram, executive director of the nonprofit Pipeline Safety Trust, "it is troubling to see so many failures and so much oil spilt from any pipeline, but it is especially troubling from such a relatively new pipeline."

According to a source with firsthand knowledge, TC declared force majeure due to the outage, which is a legal term for unforeseen external events that prevent one party from performing its obligations under a contract. An inquiry for comment from TC was not answered.

Two Keystone shippers claimed that TC had not yet informed them of the potential length of the pipeline closure.

The closure of Keystone will prevent deliveries of Canadian crude to the Gulf, where it is refined or exported, as well as to the U.S. storage hub in Cushing, Oklahoma.

Because there is little demand for heavy, sour Canadian oil, the discount on Western Canada Select (WCS) heavy oil from Alberta to U.S. crude is expected to increase as a result of the shutdown.

According to one broker, WCS for December delivery traded at $33.50 a barrel less than WTI, up from the settlement on Wednesday of $27.50 a barrel less.

According to Rory Johnston, editor-in-chief of the energy newsletter Commodity Context, "it's really a worst-case scenario if this outage is prolonged," adding that if the price drops even further, shippers might decide to transport crude by rail.

Additionally, heavy Gulf Coast grades and grades from Latin America might see an increase in price, according to analysts.

The Keystone pipeline roughly splits at Steele City, with one segment transporting crude oil to Illinois refineries and the other south to Oklahoma and the Gulf Coast.

If the spill is located south of the junction, TC may be able to quickly restart the segment to Illinois, RBC analyst Robert Kwan said in a note.

Due to the involvement of a water body, this shutdown may last longer than previous ones, which have typically lasted two weeks, according to Kwan.

In Toronto, TC stock ended with a 0.1% loss.