A large dock that floated onto an Oregon beach is debris from last year's tsunami in Japan, Japan's consulate in Portland said Wednesday.
The 66-foot-long dock, which had been in use in an area hit by the March 2011 tsunami, is the largest piece of debris discovered on North America's shores so far.
"It’s one of four floating docks washed away by the tsunami, which means there are three more floating somewhere possibly," OregonLive.com quoted Deputy Consul General Hirofumi Murabayashi as saying.
A check for any radiation from Japan's Fukushima nuclear plant came up negative, said Oregon Department of Parks and Recreation spokesman Chris Havel.
The department is overseeing efforts to remove the dock but hasn't decided yet whether to demolish it on site or have it towed off. "You can't preplan for stuff like this," Havel told msnbc.com.
A starfish native to Japan was found clutching to the structure, Havel said, adding that another concern is to keep out any nonnative species that might have hitched a ride on the dock.
The dock, which is 19 feet wide and 7 feet high, washed ashore Tuesday on Agate Beach, a mile north of Newport in central Oregon.
Small groups had already gathered to see the dock and state police were posted to keep people from climbing on it.
"I think that's going to change to large crowds," Havel said.
Some tsunami debris has begun arriving in recent weeks, including a soccer ball that washed up in Alaska and a shipping container holding a Harley-Davidson motorcycle with Japanese license plates that turned up in British Columbia.
Most debris is not expected until winter.
Anyone finding debris thought to be from the tsunami is advised to report it to DisasterDebris@noaa.gov.
The Associated Press contributed to this report.
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