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Did O.C. oil spill come from natural seepage or drilling? Cause under investigation

Huntington Beach, CA - March 08: Andrew Christenson, who got oil stuck to his feet, and his dog Lola check out tar balls at the high tide line at Huntington Dog Beach in Huntington Beach Friday, March 8, 2024. Roughly 2.5-mile-long oil slick was spotted today off the coast of Huntington Beach, but its source remained unclear. According to the Coast Guard, the slick is about 1.5 miles off the coast. ``Aerial surveys are planned to assess the size and potential impacts,'' Coast Guard officials said on social media. Photo taken in Huntington Beach Friday, March 8, 2024. (Allen J. Schaben / Los Angeles Times)
Andrew Christenson, who got oil stuck to his feet, and his dog, Lola, check out tar balls at the high tide line Friday at Huntington Dog Beach in Huntington Beach. (Allen J. Schaben / Los Angeles Times)

For the record:
2:24 p.m. March 11, 2024: An earlier version of this article stated that a Coast Guard official said the oil spill was caused by natural seepage from the ocean floor off Huntington Beach. Officials later announced the cause is still under investigation.

Coast Guard officials have not determined what caused an oil sheen that appeared off Huntington Beach last week, officials said Monday afternoon.

The sheen was first reported Thursday evening about 2.5 nautical miles off Huntington Beach near two oil platforms, Emmy and Eva. By Sunday morning, officials were no longer seeing a sheen in the water, according to the Coast Guard, but they had skimmed about 85 gallons of oil from the ocean and removed about 1,050 pounds of oily waste and tar balls from the shoreline.

Coast Guard spokesperson Richard Uranga said on Monday testing had revealed the oil was from a natural seep. Hours later, however, another Coast Guard official, Rick Brahm, told The Times that was not the case. Officials are still trying to determine what caused the spill.

Read more: Oil sheen confirmed off Huntington Beach; Coast Guard investigating

The location of the seep is not far from the site of a large spill in 2021 that occurred when a ship's anchor punctured an underwater oil pipeline in San Pedro Bay, sending 25,000 gallons of crude gushing into the waters off Huntington Beach. Cleanup from that spill spanned months and resulted in criminal charges and years of litigation.

"This situation isn't even remotely close to what we saw in 2021," said Jennifer Carey, a Huntington Beach spokesperson.

The Coast Guard and the California Department of Fish and Wildlife collected samples from the sheen and tar balls to help them determine whether the oil came from a platform, a pipeline or a vessel, or through a naturally occurring oil seep in which crude oil leaks from fractures in the seafloor.

The waters off Southern California are home to hundreds of naturally occurring oil and gas seeps. Such seeps account for nearly half the oil released into the ocean each year, according to the National Oceanic and Atmospheric Administration.

Investigators are using a technology that enables them to basically fingerprint the oil they gather in the ocean and match it, Orange County Supervisor Katrina Foley said.

"They have a database of all of the different kinds of crude and petroleum and oil generated from these different rigs and vessels," she said, "so they can pretty much match it to a particular operator."

The tests, however, have been unable to identify a source. The preliminary laboratory results show that the sheen is "lightly weathered crude oil" and not a refined material like gasoline or diesel, the Coast Guard said in a statement.

The samples are consistent with local crude oil, rather than imported crude oil that could be carried by ship to California. The sheen did not match archived samples from nearby oil platforms, according to the agency.

Although the official cleanup effort has been completed, tar balls continued to wash up Monday on the sand in Huntington Beach, including at the popular dog beach. City officials do not have plans to close the beaches but advise visitors not to touch any tar that washes up along the shore.

One bird — a Brandt's cormorant — that had oil on it died over the weekend. An injured snowy plover that was captured did not have oil on it but also died. Officials are caring for a common loon and a western grebe that were recovered with oil on their bodies.

Neighboring beach cities have not reported any signs of oil residue on their shores.

Read more: The O.C. oil spill could have been a much bigger disaster. Here is what went right

When the oil sheen was first reported, there were some surfers who were hesitant to head into the water. Locals remember the months-long ordeal after the 2021 spill. But by Monday morning — with cleanup crews gone — the overall sense of concern had dissipated, said Jakob Sorensen, an employee at Katin Surf Shop.

"There are some people heading back in to test the waters," Sorensen said.

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This story originally appeared in Los Angeles Times.