An initial analysis of the tar balls that washed ashore in the South Bay last month, coating the area’s most popular beaches, links the oil to the Refugio pipeline spill near Santa Barbara.

Plains All American Pipeline announced Monday that it received the results of six of nine samples collected May 27 from Manhattan Beach. Two were consistent with the oil from the pipeline release and the other four were consistent with natural seeps in the Santa Barbara region. Results from the remaining three samples are still pending.

Also on Monday, the California Department of Fish and Wildlife announced that a single tar ball collected from Manhattan Beach matched the Refugio oil spill, according to the state’s separate analysis.

“It tells us that Refugio oil did make it down to Manhattan Beach. That’s what we know,” said Alexia Retallack of the department’s Office of Spill Prevention and Response. “The preponderance — how much and how prolific — is still under investigation.”

Retallack emphasized that the source of all of the tar balls in the South Bay cannot be determined based on the one sample.

The investigation into the South Bay incident will continue, she said, as the state still awaits results from the analysis of nearly 100 samples from the South Bay and Refugio. Eventually, the attorney general will decide whether to file any charges, she said.

The Plains All American Pipeline Line No. 901 ruptured on May 19, spilling more than 100,000 gallons of crude oil, with approximately 21,000 gallons making it to the ocean at Refugio State Beach in Santa Barbara County. More than 1,000 crews responded for cleanup, which continues today at the shoreline. Beaches have remained closed and hundreds of dead birds and mammals have been collected.

A week later, officials closed an eight-mile stretch of South Bay beaches from El Segundo south to Torrance Beach for two days as tar balls washed ashore, blanketing the sand. One week later, the tar balls landed in Long Beach, closing four miles of shoreline, and continued to pop up on beaches as far south as San Clemente. Results from the Long Beach tar samples have not been released.

Plains All American sent the South Bay samples collected by the U.S. Coast Guard to labs in Massachusetts and UC Santa Barbara. Those labs conducted chemical “fingerprinting,” which determines the source of shoreline crude after a spill.

The state used Petroleum Chemistry Laboratory in Rancho Cordova for a thorough analysis, conducting a series of tests on the samples to determine the source. The analysis of each tar ball is “exhaustive,” Retallack said, as it includes independent peer review and corroboration of the methods used and interpretation of results. The state lab determined that the Manhattan Beach tar ball did not match local natural seep oil or oil from vessels in the vicinity around the time of the incident.

According to the National Oceanic and Atmospheric Administration, tar balls are remnants of oil spills — crude oil when mixed with water thickens due to wind and waves in a process called “weathering.”

“It is not uncommon for tar balls to appear on Southern California beaches from natural seeps or oil production facilities,” Retallack said. “But the amount that Manhattan Beach experienced was unusual. That’s what really drew attention to it.”

U.S. Rep. Ted Lieu, who represents the coastal South Bay, said Monday’s news underscored the danger of oil spills to the area’s coastline.

“That’s why I am firmly against coastline drilling, whether it’s in Hermosa Beach or the Arctic,” he said. “Any oil spill underscores the need for America to abandon the dirty, destructive fuels of the 18th century and invest in clean 21st century energy solutions.”

Lieu demanded that Plains All American Pipeline pay for any cleanup costs and penalties stemming from the oil spills.

“If Plains All American Pipeline wavers in any way, I will look into ways to ensure that they accept responsibility for the cleanup cost,” he said.

Meredith Matthews of Plains All American said no determination has been made at this point if the company will pay for the South Bay cleanup costs. She said the cause of the pipeline rupture is still under investigation.

The company is awaiting additional details on the tar ball sample results, Matthews said. Once the full report is available, she said, it will be released to the public.