Catalina Island was cleaning up Thursday, a day after waves from Hurricane Marie caused significant damage.
Estimates of costs from the damage were not immediately available.
Waves tore through the boatyard at Pebbly Beach on the east end of the island, upending boats and scattering lumber across the area.
Some of the wood apparently floated into Avalon Harbor, where it smashed into moorings and pilings, according to Los Angeles County harbor officials.
"We've got large pieces of lumber floating around pilings," said Orne Carstarphen of the Avalon Harbor Patrol. "There's a lot of hazards and number of moorings that have been damaged."
He said crews spent the day pulling debris from the water and moving boats from damaged moorings. "At this time," Carstarphen said Wednesday evening, "no more moorings are available."
The last time Pebbly Beach received major damage was in September 1997, according to the Los Angeles County lifeguard division.
County Supervisor Don Knabe, whose district includes Catalina, posted photos on Twitter that showed boats and a small bus upended by the surging waters. Another photo showed that the pier at White's Landing had been partially destroyed by big waves.
Knabe's office said Wednesday evening that county officials were still assessing the damage and had not determined the level of assistance that would be needed for cleanup operations.
Earlier Wednesday at the Port of Long Beach, officials said waves up to 15 feet forced crews to halt operations at two terminals as the big surf combined with high morning tides.
The Malibu Pier continued to be closed Wednesday after huge waves damaged pilings. One surfer who lost his board was rescued Wednesday afternoon by lifeguards from beneath the pier as he clung to a piling, officials said.
On Wednesday night, a structure on Pacific Coast Highway north of Malibu slid down a hill and partially entered the water as surf crashed on the shoreline, according to television news footage. It was not immediately clear whether anyone was inside the structure.