HUNTINGTON BEACH, Calif.—Federal and state investigators on Monday were focusing on a 41-year-old pipeline as the likely source of an oil spill that killed wildlife and fouled the coast of southern California, and an approaching storm threatened cleanup efforts. The weekend spill sent 3,000 barrels of crude oil (126,000 gallons) into the Pacific Ocean. Authorities identified the line as the San Pedro Bay Pipeline that connects an offshore oil production platform to a site in Eureka, California. Huntington Beach, about 40 miles (65 km) south of Los Angeles, was hit hardest with some 13 square miles (34 square km) of ocean and portions of its coastline “covered in oil,” said Mayor Kim Carr. Cleanup crews dressed in white coveralls and helmets worked along a beach and wetlands running inland from the ocean on the eastern side of the coastal highway. Birds covered in oil washed up on shore, along with …