Cleanup workers scour the sand in Huntington Beach, California, after an oil spill from a pipeline leak.
CNN  — 

When crude oil leaked into the Pacific Ocean off the coast of Southern California earlier this month, the amount spilled was about 25,000 gallons, officials said Friday.

“We have a high degree of confidence that the spill amount is approximately 588 barrels of oil,” US Coast Guard spokesperson Amy Stork said. “This is consistent with NOAA scientific data, overflight observations and shoreline assessment team findings.”

The amount, equal to about 25,000 gallons, is more than five times lower than the previously estimated 131,000 gallons.

The spill was caused by a leak in a pipeline operated by Houston-based Amplify Energy that is connected to an oil rig.

Investigators believe the crack in the pipeline, which was likely caused by a ship’s anchor dragging along the ocean floor, might have begun as long as a year ago.

The California Department of Justice announced Monday that it is working with federal, state, and local authorities to determine the exact cause of the spill.

Earlier this week, the city of Huntington Beach reopened its shoreline after water testing results came back with non-detectable amounts of oil-associated toxins in ocean water.

On a website dedicated to the response to the spill, the city said water quality will be tested twice a week for at least two more weeks.

The Oiled Wildlife Network reported that as of Thursday 84 birds were recovered, 53 of which were found dead. Fourteen dead fish were found, the group said.

Crack may have started in 2020

The pipeline was intact in October 2020 before it was deflected or deviated by 105 feet, eventually leading to damage to its casing and a 13-inch crack, Jason Neubauer, chief of the office of investigations and analysis for the US Coast Guard, said last week.

Video released by the Coast Guard showed marine growth on the damaged portion of the pipeline, which was initially enclosed in concrete. Neubauer explained the linear fracture on the pipeline could have been a crack, which got gradually worse over time.

“This event could be multiple incidents and strikes on the pipeline after the initial event, that we’re pretty confident occurred several months to a year ago,” Neubauer said.

Investigators are also examining geological events, including heavy weather in mid-January, which may have contributed to the crack. A section of the pipe will be taken to the National Transportation Safety Board lab, so investigators can determine when and how the leak occurred.

While similar anchor strikes have happened over the past 10 years, Neubauer said there was only one event which led to an oil spill, which he called a “rare occurrence.”

CNN’s Claire Colbert contributed to this report.