Oil emitted from the ocean floor where plates divide is the assumed source of the dime- to dinner plate-sized tar balls that have reportedly appeared as far north as Ocean Beach and as far south as Carmel Beach since Monday, Coast Guard Petty Officer Jonathon Cilley said.
Once released from the ground underwater oil condenses and hardens, forming tar balls, according to Cilley.
"That happens naturally every so often," Cilley said.
The Coast Guard's Unified Command cleanup efforts in San Mateo County, which began Monday after the first tar ball sightings, will wrap up today and officials will reassess the situation Thursday to decide if further cleanup is necessary, according to Cilley.
Oil recovery at Pacifica State Beach, Rockaway Beach and JV Fitzgerald Marine Reserve, where many tar balls were sighted, resumed at sunrise today with nearly 100 Coast Guard members and contracted personnel cleaning the shoreline, Cilley said.
There have been no reports of wildlife impacted by the oil, but the large population of seals at the marine reserve had officials working quickly to protect the mammals, according to Cilley.
Although the oil sighted since Monday didn't come from November's spill, Cilley said that after the incident the Coast Guard prepared in case oil washed ashore.
"We had teams in place in the event reoiling did occur," Cilley said, referring to the response effort after the Cosco Busan container ship clipped a San Francisco-Oakland Bay Bridge tower on Nov. 7, gashing a hole in the vessel's side.
Nearly 17,000 gallons of the 58,000 gallons spilled were reportedly collected using a barrier of absorbent material. About 4,060 gallons evaporated and 580 dispersed, according to the Coast Guard.
In addition to cleaning the San Mateo County shoreline today, officials planned to examine all areas where oil was reportedly sighted, Cilley said.
Cleanup crews were headed to Monterey County this morning to assist with oil cleanup, according to Cilley.
