Some of the crude oil that spilled from a pipeline into the waters off Southern California has been breaking up naturally in ocean currents, a Coast Guard official said Wednesday as authorities sought to determine the scope of the damage.

Coast Guard Petty Officer Steve Strohmaier said some of the oil has been pushed to the south by currents. Storms earlier in the week may also have helped disperse the oil, which he said could make it more challenging to skim as it spreads out.

“Most of this oil is separating and starting to float further south,” he said while accompanying reporters aboard a boat to the scene of the spill. “The biggest problem is the uncertainty, the amount that leaked into the water. We are at this point unsure of the total amount that leaked out.”

How much oil leaked remains unclear. The pipeline operator, Amplify Energy Corp., has publicly pegged the maximum amount of the spill at 126,000 gallons (572,807 liters) of heavy crude. But the company told federal investigators with the Pipeline and Hazardous Materials Safety Administration that initial measurements put the total only around 29,400 gallons (111,291 liters).

The water and shoreline are still off limits in Huntington Beach and several other areas, but people are allowed on the sand. Beachgoers played volleyball on the Huntington Beach sand Wednesday morning as walkers and bikers passed near the city’s famed pier. A few globs of oil were visible along the shoreline but no smell remained.

Investigators have said the spill may have been caused by a ship’s anchor that hooked, dragged and tore open an underwater pipeline. Federal officials also found that the pipeline owner did not quickly shut down operations after a safety system alerted to a possible spill.

“The Coast Guard is looking into a multitude of factors that may have caused the pipe to rupture, including corrosion, pipe failure, or an anchor strike,” Strohmaier said. “We are analyzing the electric charting systems from our vessel traffic service to see what ships were anchored or moving over the affected area on Friday.”

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Questions remained about the timeline of the weekend spill, which fouled beaches and a protected marshland, potentially closing them for weeks along with commercial and recreational fishing in a major hit to the local economy.

Some reports of a possible spill, a petroleum smell and an oily sheen on the waters off Huntington Beach came in Friday night but weren’t corroborated and the pipeline’s operator, Amplify Energy Corp., didn’t report a spill until the next morning, authorities said.

An alarm went off in a company control room at 2:30 a.m. Saturday that pressure had dropped in the pipeline, indicating a possible leak but Amplify waited until 6:01 a.m. to shut down the pipeline, according to preliminary findings of an investigation into the spill.

The Houston-based company took another three hours to notify the U.S. Coast Guard’s National Response Center for oil spills, investigators said, further slowing the response to an accident for which Amplify workers spent years preparing.

Amplify’s CEO Martyn Willsher refused to directly answer questions about the alarm when pressed on the issue by reporters Wednesday. He repeated his assertion that the company didn’t learn of the spill until a boat saw a sheen on the water at 8:09 a.m.

“We are conducting a full investigation into that to see if there’s anything that should have been noticed,” Willsher said, adding, “I’m not sure if there was a significant loss in pressure.”

He said the pipeline already was shut down by 6 a.m. Saturday, then re-started for five minutes for a “meter reading” before it was shut down again. Willsher did not say when it had been initially shut down or why.

The company’s spill-response plan calls for the immediate notification of a spill. Criminal charges have been brought in the past when a company took too long to notify federal and state officials of a spill.

On Tuesday, federal transportation investigators said the pipe was split open at a depth of about 98 feet (30 meters) and a nearly mile-long section was pulled along the sea floor, possibly by a ship’s anchor that hooked it and caused a partial tear, federal transportation investigators said.

“The pipeline has essentially been pulled like a bow string,” Willsher said. “At its widest point, it is 105 feet (32 meters) away from where it was.”

Huge cargo ships regularly cross above the pipeline as they head into the gigantic Los Angeles-Long Beach port complex. They are given coordinates where they are to anchor until unloading.

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Anchored cargo ships continually move because of shifting winds and tides, and an improperly set anchor weighing 10 tons (9 metric tons) or more can drag “whatever the anchor gets fouled on,” said Steven Browne, a professor of marine transportation at California State University Maritime Academy.

There was no indication whether investigators suspect that a particular ship was involved.

“We are going to make sure that we have answers as to how this happened, and to make sure that we hold the responsible party accountable,” said Congresswoman Katie Porter, a Democrat who chairs the oversight and investigations subcommittee of the House Natural Resources Committee. She represents a district a few miles inland from the spill area.

Animal rescuers ashore have been pleasantly surprised to find few birds covered in oil.

During a two-hour boat tour off Huntington Beach coastline, an AP video journalist saw no visible oil. Pelicans and other sea birds floated on calm waters, and four dolphins swam by the boat.

Meanwhile, Coast Guard officials defended their decision to wait until Saturday morning to investigate a possible spill first reported Friday night — some 10 hours earlier — near a cluster of boats that were anchored off Huntington Beach.

At 2:06 a.m. Saturday, the National Oceanic and Atmospheric Administration said satellite images showed the strong likelihood of an oil slick. The report was made to the National Response Center, a hazardous spill hotline staffed by the Coast Guard.

Residents in nearby Newport Beach had also complained Friday evening about a strong stench of petroleum, and police put out a notice to the public about it.

The Coast Guard was alerted to a sheen on the water by a “good Samaritan” but did not have enough corroborating evidence and was hindered by darkness and a lack of technology to seek out the spill, Coast Guard Rear Adm. Brian Penoyer told The Associated Press.

Penoyer said it was fairly common to get reports of oil sheens in a major seaport.

“In hindsight, it seems obvious, but they didn’t know that at that time,” Penoyer said.