A Washington state spokesman says a crew has scrubbed a dock that washed ashore on a wilderness beach near Forks, Wash., and scraped off more than 400 pounds of organic material, including species native to Japan but not found in the United States.

The dock is considered likely debris from the March 2011 tsunami in Japan.

Ecology Department spokesman Curt Hart said a six-member team from Olympic National Park and the state Department of Fish and Wildlife removed protective bumpers and decontaminated the outer dock surface with a diluted bleach solution on Friday. The team put the organic material in an upland area outside the surf zone where the marine species won't survive.

Hart says initial lab results identified as many as 50 plant and animal species on the dock that are native to Japan, including algae, seaweed, mussels and barnacles.

State and federal officials will start planning next week how to remove the dock from the beach.

The Coast Guard spotted the dock Dec. 18 on a remote stretch of beach on the northwestern tip of Washington protected by Olympic National Park.