Crude oil spills in Yellowstone River after pipeline leak
A BP cleanup crew shovels oil from a beach on May 24, 2010 at Port Fourchon, Louisiana (AFP)

Crews worked on Monday to clean up crude oil that spilled in and near the Yellowstone River in eastern Montana even as Bridger Pipeline LLC tried to determine what caused the weekend breach, the Wall Street Journal reported.

The release of crude oil from Bridger's Poplar Pipeline system near Glendive, Montana began on Saturday morning, the company said in a statement.

Bridger said its initial estimate was that 300-1,200 barrels of crude oil had been released. The company, however, did not provide the amount of oil spilled into the river.

Oil has been seen in the river in spots 15 and 25 miles downstream from Glendive, with some of the oil trapped under ice, the Journal said.

The company completed the process of shutting down the pipeline within an hour of the oil release. The pipeline remains shut in.

The company is testing the water in Glendive for any contamination.

The Poplar pipeline, which moves crude from Bakken basin to nearby hubs, was last inspected in 2012 and is at least 8 feet below the Yellowstone River bed, where it crosses the river near Glendive, WSJ said, quoting Bridger spokesman Bill Salvin.

Bridger Pipeline, a unit of True Cos, operates crude oil gathering and transportation systems in the Williston Basin of eastern Montana and western North Dakota and in the Powder River Basin of Wyoming.

(Reporting by Ashutosh Pandey in Bengaluru; Editing by Joyjeet Das)