‘Very Minor’ Oil Spill Hits the Beach at Bolsa Chica : Pollution: Offshore rigs are suspected, but the source is uncertain. Cleanup begins on fouled stretch over a mile long.

At least 168 gallons of oil fouled more than a mile of Bolsa Chica State Beach early Tuesday evening and investigators said leaking offshore oil rigs may be the source of the spill, U.S. Coast Guard officials said.

Coast Guard Lt. Vincent Campos said an emergency cleanup crew hired by Unocal, which operates three offshore oil platforms in the area, was dispatched to the scene.

“It’s a very minor spill,” Campos said. “We don’t have anything from Fish and Game yet, but it may have involved a couple of birds.”

Bolsa Chica is located just north of the main stretch of Huntington Beach that was soiled when almost 400,000 gallons of crude oil spewed from the crippled tanker American Trader 1.3 miles offshore in February.

Although Tuesday’s spill was minor by comparison, it was enough to leave a mile and a quarter of the state beach covered with small patches of oil. Petty Officer Lindsay Dew said the heaviest patch was an eighth of a mile long, in some sections 12 to 15 feet wide.

Several Coast Guard officials estimated the total amount of oil spilled at four barrels, or 168 gallons, which they said can easily spread over large areas of ocean in a thin film. By late Tuesday, officials stressed the spill appeared to be minor.

“We know of no animal life being affected,” said Dew. “The oil has all washed up on shore. We don’t believe there’s any left in the water.”

State and federal wildlife officials were not immediately available for comment, but officials at the scene said only one duck had been found covered in oil. However, the grunion were supposed to run overnight and they too could be affected, officials said.

The California Department of Fish and Game also dispatched a team to take samples of the sand and to observe wildlife in the area.

Although the source of the spill was not yet determined, Unocal decided to take responsibility for the cleanup. Company spokesman Barry Lane said the firm’s emergency crews would work with shovels to remove the contaminated sand by the sackful. He said the company took on the job because “We operate in that area and we have people there.”

A Coast Guard spokesman said a 20-person cleanup crew from Long Beach-based Chempro, the same company that worked on the American Trader oil spill, would work through the night and could have the entire spill cleaned by early this morning.

Lane said the firm operates platforms Eva, Edith and Esther, all of which are between one and three miles off the beach.

Shell Oil Co. also has platforms in the same area, the Coast Guard said.

Tuesday’s spill was discovered on the beach shortly after 6 p.m., officials said.

Huntington Beach Mayor Thomas J. Mays said a Shell Oil helicopter spotted the slick before it hit the beach.

“It’s really a shame we have to continue going through these problems,” he said. “We’ve had minor problems with the platforms off the coast before, but I believe this is the first time the oil got to the beach.”

Unocal’s Lane said his company reported a 10-gallon spill at Platform Eva to the Coast Guard on Monday night but he said that incident is believed to be unrelated to the oil that washed up on Bolsa Chica.

“We sent a crew out at dawn looking for any oil on the water and couldn’t find any,” Lane said of the Monday night incident. He said a shield designed to trap oil had failed because of high winds, which sprayed the crude around the platform.