(Reuters) – The U.S. Coast Guard said on Saturday it did not observe any remaining recoverable oil sheen during a morning overflight off the coast of Huntington beach, California.

On Friday, the agency said it was trying to identify the source of an oil spill off the coast after the sheen, estimated at 2.5 miles (4 km) in length and 0.5 miles (800 meters) in width, was discovered when a Coast Guard helicopter flew over the site at sunrise.

“Tar balls were observed along the shoreline in Huntington Beach, and onshore recovery teams will assess the shoreline and remove them as needed,” according to the Coast Guard’s statement.

The investigation into the cause of the sheen is currently underway, the agency said.

The Coast Guard said on Saturday they do not believe the sheen and a potential spill of produced water from an offshore platform off Huntington beach on Friday were related.

Beta Offshore, a subsidiary of Amplify Energy (NYSE:) Corp, reported the incident at Platform Elly off Huntington beach on Friday, according to a regulatory filing.

“At this time, we have no indication that this sheen is related to our operations”, Amplify Energy said in a statement on Friday.

In 2021, a spill occurred off the coast of Huntington Beach when an underwater pipeline running from the Elly platform to Long Beach leaked about 588 barrels (24,696 gallons) of oil.