What was intitially reported as a 3-mile-long ribbon of oil on a Pacifica beach was probably kelp or an algae bloom that washed ashore, according to an official.
However, Rob Roberts of the California Department of Fish and Game said tar balls had washed ashore in San Mateo County and China Beach in San Francisco.
He said the oil does not appear to be from the Nov. 7 spill from the cargo ship Cosco Busan.
Crews continued cleaning up oil on the coastline Tuesday as samples were sent off to Sacramento to test for a “fingerprint” that should determine where the oil came from.
Roberts said he expected the test results, which were sent to the lab Tuesday, to be released today.
The consistency of the tar balls, Roberts said, pointed to the oil being from a source other than the Cosco Busan.
“Until we think otherwise, we’re treating it as if it was not from the Cosco Busan,” said Coast Guard Petty Officer Alan Haraf.
According to Roberts, it was surfers in Pacifica who reported oil on the beach Monday. The reports of tar balls on San Francisco’s Ocean Beach were also incorrect, Roberts said.
Coast Guard officials had received reports of oil and tar balls as far north as Marin, but the northernmost oil found by cleanup crews Tuesday was in San Francisco, Roberts said.
Authorities are treating the spills as “an unknown mystery tar ball incident,” Roberts said.
Tar balls are commonly found on shorelines because of natural seepage on the ocean floor or accidental or intentional discharges from ships, he said.
A total of 80 contracted cleaners funded by the Coast Guard hit beaches Tuesday to rid the beaches of the black substances.
At one point Tuesday, 50 cleaners were working at Fitzgerald Marine Reserve in Moss Beach, 20 at Pacifica State Beach and seven at Rockaway Beach in Pacifica, the Coast Guard said.
Other beaches with reported oil were Mavericks, Poplar, Montara and Linda Mar beaches, Roberts said. Even more cleanup personnel will hit the beaches today, said Coast Guard Petty Officer Jonathan Cilley.
Crews picked up six five-gallon bags of tar balls on Monday and more on Tuesday, Cilley said.
There were no reports of oiled marine life on any of the beaches as of Tuesday afternoon, said San Mateo County Health Department spokeswoman Beverly Thames.