OAKLAND (CBS SF) — The U.S. Coast Guard is reportedly investigating whether a cargo ship currently anchored at the Port of Oakland played a part in the massive oil spill in fouling beaches in Southern California.

According to the Associated Press, the Rotterdam Express, a German-flagged ship, made three unusual movements over two days that appear to put it over the pipeline.

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Captain John Konrad, who publishes a website on the maritime and offshore industry said there are many unanswered questions as they look into whether or not the Rotterdam Express had anything to do with the oil spill.

Workers clean contaminants from the Talbert Marsh on Wednesday, October 6, 2021, the fifth day after an oil spill off the coast of Huntington Beach threatens the ecosystem.(Photo by Mindy Schauer/MediaNews Group/Orange County Register via Getty Images)

“Did he have the right charts? Did the vessel traffic service advise him? Was this an old pipeline that maybe wasn’t properly charted? These are the questions we have to ask,” Konrad said.

The ruptured pipeline may have spilled nearly 150,000 gallons of crude oil into the ocean, according to the U.S. Coast Guard.

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Skytruth, an environmental nonprofit organization that uses satellite technology to track incidents such as oil spills, said the Rotterdam Express never came closer than 1,500 feet from the line and it’s unlikely the ship’s anchor is to blame.

Federal transportation investigators say a backup of cargo ships at California ports may also have played a role in the spill, as ships have been forced to drop anchor off the coast because of overcrowding at ports and berths.

Like Oakland, Southern California is experiencing heavy container ship traffic during the pandemic. Mark del Hierro, a longshoreman, told KPIX 5, “There’s no space to put the containers, there’s lack of equipment, not enough chassis.”

A spokesperson for Hapag Lloyd, which operates the Rotterdam Express, told the AP the company is fully cooperating with the investigation. The company said the ship was in the area but was “pretty far away from the pipeline.”

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Andrea Nakano contributed to this report.