The U.S. Coast Guard was working with state officials Saturday to determine the cause of a large oil slick in the waters off Santa Barbara County.
The 11/2- to 2-mile sheen was spotted Friday about five nautical miles from Summerland Beach, an area with a petroleum-rich sea floor that is home to numerous abandoned gas and oil wells.
Early Saturday morning, a Coast Guard helicopter flew over the slick to look for clues as to its source, according to Petty Officer Matthew West.
"We are still waiting to hear back," he said.
Oil and natural gas can enter the ocean naturally through fractures in the sea floor, known as seeps, that are common in Santa Barbara's waters. But slicks can also come from leaky wells or other sources of pollution.
"Because this was an area where there are a lot of naturally occurring seeps, it's important to determine whether it is one of those seeps or from a legacy gas or oil well," said Sheri Pemberton, public information officer for the California State Lands Commission.
The waters off Summerland, which is six miles east of Santa Barbara, were home to hundreds of largely unregulated oil and gas wells in the 19th century, according to the commission. Many drilling operations were abandoned in the early 1900s with little oversight and pose an environmental threat that the state is working to address.
Part of the investigation will be chemically analyzing the slick to see if it is consistent with the petroleum seeping naturally from the sea floor, said Eric Laughlin, a spokesman for the state Department of Fish and Wildlife.
That department is among several agencies working to address the slick. There have been no reports of injured wildlife.
"There are teams out there, but we are still waiting for a report from them," Laughlin said.
