(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.