This Saturday is California's annual coastal cleanup, and if history is any guide, more than 70,000 people are expected to flock to beaches, lakes and streams to remove trash.
But this year there's a major new question hanging over the event: Will the army of volunteers find debris from last year's Japanese tsunami?
Although much of the millions of tons of wood, plastic and other trash that was swept out to sea during the disaster eventually sank, large amounts continue to float across the Pacific. And some items have already been linked to the tsunami: a 66-foot-long section of dock washed ashore in Newport, Oregon, in June; whole abandoned fishing boats were found off Washington and British Columbia; and other refuse with Japanese writing has washed ashore, including a soccer ball found off an Alaskan island and traced back to a Japanese schoolboy.
Scientists say the debris is not radioactive, since it washed out to see before the Fukushima nuclear power plant melted down.
So far no large debris has been found on California beaches. Computer models estimating wind patterns and ocean currents have projected that 2013 might be the year where California's shoreline could see the biggest arrival of debris.
But organizers of Saturday's event say they won't be surprised if some early material turns up over the weekend as volunteers scour the state's 1,100-mile coastline.
"The likelihood is pretty high," said Eben Schwartz, statewide coastal cleanup coordinator with the California Coastal Commission. "Our volunteers on the North Coast are already starting to find items that are typical of tsunami debris and in greater amounts than normal."
People participating in adopt-a-beach cleanups in Humboldt and Mendocino counties this summer have found large pieces of polystyrene foam, buoys with Japanese writing and pieces of houses, he said. An empty plastic bottle of dish soap with Japanese writing was found on Rio del Mar Beach near Santa Cruz in March, and a buoy with Japanese writing was found there in July.
People have reported hundreds of such objects along the West Coast, according to NOAA, the National Oceanic and Atmospheric Administration. NOAA has confirmed only about a dozen of those are from the tsunami, however, and it will never be known how many are routine trash and how many are part of the wave of debris that washed west after a 9.0 quake rocked Japan on March 11, 2011.
NOAA looks for specific markings, such as serial numbers or the names of cities, to confirm objects and then works to find the owners in Japan.
This year, Coastal Commission officials are distributing special tsunami debris reporting forms on about 30 beaches statewide where tides typically bring in lots of ocean debris. The goal is to establish a baseline, so that if more debris turns up in the coming months and years, scientists can track it better.
"By participating, you are not just doing your civic duty and cleaning up beaches, you are also participating in a global science project," said Jared Blumenfeld, administrator for California for the U.S. Environmental Protection Agency.
Ever since the earthquake and tsunami, which killed roughly 16,000 people and generated waves up to 133 feet high, scientists have tried to track the debris. But it has proved very difficult.
About 5 million tons washed out to sea, according to the Japanese Ministry of the Environment. Roughly 70 percent sank in the waters off Japan, the agency estimates, leaving 1.5 million tons floating toward North America.
Because it is spread over a vast area of the Pacific three times the size of the United States, individual pieces can't be easily seen from satellites. Computer models from the University of Hawaii say the bulk of the material is in a remote area north of Hawaii and slowly moving west.
Because of current patterns, Oregon, Washington and Alaska may end up getting far more than California, said Jan Hafner, a University of Hawaii researcher who has been tracking the debris.
"Potentially it is going to be a problem," Hafner said. "But how serious, we do not know."
Paul Rogers covers resources and environmental issues. Contact him at 408-920-5045. Follow him at Twitter.com/PaulRogersSJMN
Volunteers are still needed for Saturday's coastal cleanup, which runs from 9 a.m. to noon in every coastal county and every Bay Area county, where volunteers clean streams and lakes in inland areas. To volunteer, call 1-800-COAST-4U or go to www.coastal.ca.gov.