LOS ANGELES — Beaches along the Santa Barbara County coast remained open to swimmers, surfers and sunbathers Friday as the Coast Guard worked to determine whether an oil slick that materialized just offshore this week was simply the result of natural ocean-floor seepage.
That's the conclusion Jordan Clark, professor of earth science and environmental studies at the University of California, Santa Barbara, suspects authorities will find when laboratory analyses of the slick come back, probably sometime early next week.
The oil is floating in the Santa Barbara Channel above the Coal Oil Point seep field, a region Clark said is known for releasing methane and also about 100 barrels of liquid petroleum per day.
"If you fly in to Santa Barbara airport you can often see slicks on the water out there. It's reasonable for a slick this size to be spotted in the seepage area," Clark said of the 3-mile sheen first spotted Wednesday about 1,000 yards off the coast of Goleta.
Coast Guard Petty Officer Andrea Anderson said samples of the spill were collected Wednesday and Thursday and were being sent to a lab for analysis.
"They expect to hear back about the results in a couple days," she said Thursday.
Although the slick was large, it wasn't thick and gooey enough to be scooped up, Coast Guard Petty Officer Sondra-Kay Kneen said. It should simply break up and deplete on its own in the days ahead, she said.
The Santa Barbara County Department of Public Health said the slick provided no threat to public health and safety, although officials advised people to avoid contact with the oil.
That's in contrast to the mass closure that occurred in the same area in May when a broken pipeline spilled 100,000 gallons of crude oil, fouling sands, seabirds and fishing areas for miles.
This week's oil slick was located about 12 miles away from the site where the onshore pipeline operated by Texas-based Plains All American ruptured at Refugio State Beach.
Cleanup of that spill has been pegged at nearly $100 million.
This week's sheen was seen floating near the channel's Platform Holly oil facility Wednesday, but officials with Venoco Inc., which operates the platform, said it could not have come from there.
Zach Shulman, the company's director for corporate finance and investor relations, said the platform has been shut down since May.
"We do operate a pipeline that runs along the seafloor that connects the platform to an onshore facility," he said in an email. "That pipeline was previously evacuated of oil, and is currently filled with sea water."
Clark said ocean-floor seepage generally increases when the platform is not active.
--Associated Press writer Linda Zhang contributed to this story.