Quick Take:

Officials determine that between 25,000 and 131,000 gallons of oil were released in last weekend’s spill off the Orange County coast. Previous estimates were as much as 144,000 gallons.

Officials say the amount of oil that leaked from a pipeline off the Orange County coast, fouling stretches of sand and threatening ecologically sensitive areas from Huntington Beach to San Diego County, could be smaller than originally projected.

In the first days of the spill, officials warned that possibly 126,000 gallons had flowed out of a pipeline that runs from the Port of Long Beach to an offshore production and processing platform. That number was raised on Monday to potentially 144,000 gallons.

However, Capt. Rebecca Ore, commander of the U.S. Coast Guard’s Los Angeles-Long Beach sector, said Thursday that after further assessments officials had determined that a minimum of about 24,696 gallons, or 588 barrels, and a maximum of 131,000 gallons, or 3,134 barrels, of oil was released from the pipeline.

The 131,000-gallon estimate is a “maximum worst-case discharge that is a planning scenario based on a volume in a pipeline,” Ore said.

Officials were unable to narrow that estimate, leaving another unanswered question as the mystery surrounding how the leak occurred continues to unfold.

“We’re nearly a week into this, and while our cleanup and our emergency response is well underway, we still don’t know answers to how this happened, why it happened and who is ultimately responsible,” Orange County Supervisor Katrina Foley said.

Federal sources told The Times this week that the damage to the pipeline could best be explained by a ship’s anchor dragging across the ocean floor and hooking the pipeline.

There were multiple large cargo vessels in the immediate area of the leak before the oil was spotted. A final determination for the cause of the spill may take months, but Coast Guard investigators have come up with no other explanation, federal sources said.

Recovery efforts along the coast have continued to accelerate through the week.

Officials said they’ve made progress in the cleanup and hope to advance even further over the weekend. But a storm that meteorologists say could bring 20-mph winds to the region is moving in, raising concerns that more oil could reach shore. So far, much of the crude has remained offshore, but striations have been seen in Huntington Beach, Newport Beach and Laguna Beach.

Images from satellites over the oil spill Friday morning show some oil nearing the coast in Newport Beach, Laguna Beach and San Clemente.

As oil spill spreads, a team of biologists from the University of California Santa Cruz assess the overall biological habitat
Biologists from UC Santa Cruz and Tenera Consulting assess the Little Corona del Mar tide pools Wednesday. (Allen J. Schaben/Los Angeles Times) Credit: Allen J. Schaben / Los Angeles Times

Tar balls that officials suspect came from the oil spill have also washed up in Oceanside, Carlsbad, Encinitas and Del Mar in San Diego County over the past day.

“While it’s not impossible for this to occur naturally, the quantity is highly unusual, and it’s very likely these tar balls are the result of the oil spill,” San Diego County Supervisor Nathan Fletcher said.

San Diego Union-Tribune staff writer Joshua Emerson Smith contributed to this report

This story originally appeared in Los Angeles Times.