In the coming weeks and months, a weather phenomenon known as the “fall transition” will wash the artifacts of a national tragedy onto West Coast beaches.

The fall transition happens when the Northern Hemisphere storm track that governs prevailing winds sends those gusts in a completely different direction—from south to north and from offshore to inland—along with stuff that gets pushed around in the water. Right now, among the stuff that’s floating offshore is a whirlpool of junk known as the Pacific Gyre, which is estimated to hold 5 million pounds of bashed-in houses, fishing boats, docks, and dead bodies from the March 11, 2011, tsunami in Japan. The more buoyant relics of this disaster have been bobbing along for 18 months, with a few notable exceptions that have left state and federal officials scrambling to respond.

When a massive dock thunked its way onto Oregon’s Agate Beach this summer, pandemonium ensued. Not only was the thing huge—at 66 feet long, 8 feet tall, and 165 tons—it was covered in gnarly invasive species, and had script in Kanji on a small plaque at the bottom. After a little sleuthing by Portland’s Japanese consulate, everyone’s worst fears were confirmed: the first piece of debris from last spring’s disaster had finally hit the continental U.S., much sooner than anyone had expected.

Overnight, the “tsunami dock” became an instant tourist attraction and a headache for state parks officials, who manage the beach. They dispatched rangers in mostly futile attempts to keep rambunctious youngsters from turning the thing into a jungle gym, and they puzzled back in Salem about how to get rid of it, and how to pay for that.

Two months and $85,000 later, the dock was gone. A contractor cut it into pieces using a Rube Goldberg-looking contraption whereby a diamond saw looped around and under it and sliced. This was a huge disappointment to the fans who painted a mural on the side. But it was the only option, insisted those that run the Oregon Parks and Recreation Department. You can’t just leave stuff on the beach, they said. It sets a terrible precedent.

Over the next few months, Oregon and the rest of the West Coast will find that argument bolstered—by a need to keep the landing strip clear. The dock did indeed arrive early, months ahead of schedule, likely shoved faster than the currents would otherwise have carried it thanks to “windage,” an uncannily appropriate term used to describe how much of a thing is sticking out of the water, how much it creates a kind of accidental sail. The dock actually sailed across the Pacific, in other words, as much as it did float.

Which is to say there’s much more tsunami debris—with less windage—still out there. Of the 5 million tons of debris estimated to have washed into the ocean after the March 2011 quake, Japanese officials say 70 percent of it sank. The rest floated. There are two more docks, just like the one the state just spent four years of college tuition to remove. There are plastic bottles, fishing floats, lightbulbs, giant chunks of Styrofoam, small appliances, mannequin parts, buoys, even entire fishing vessels. A few weeks after the dock showed up in Oregon, a 20-foot fiberglass boat covered in pelagic gooseneck barnacles up to 3 feet long washed up at Cape Disappointment State Park, in Washington. The boat was also traced to the tsunami, Curt Hart of the Washington Department of Ecology told The Daily Beast. After determining that the owner “didn’t want it back,” the state checked it for radiation (all clear), blasted it clean and tossed it in a landfill.

Marine debris is not a new phenomenon. Litterbugs and careless ship crewmen and leaking landfills have conspired for decades to clog the world’s oceans with all sorts of junk, creating loosely affiliated “garbage patches” in certain gyres with clockwise, rotating currents that have a way of concentrating marine debris. That problem is the raison d’être for The 5 Gyres Institute, a Los Angeles-based nonprofit whose founders have spent much of the past three years sailing the world’s oceans with a “Manta Trawl” attached to the side of the boat, scooping up samples of trash so as to generate estimates of how much more is out there.

It’s frustrating for 5 Gyres’ policy coordinator Stiv Wilson to be reminded that people don’t seem to know how rubbish-laden the planet’s waterways actually are. “All these images, such stunning images when the tsunami first happened, the same pictures exist of what a river in Jakarta looks like every day,” he told The Daily Beast.

Still, the tsunami debris has presented Wilson and other conservationists with a rare opportunity. The Agate Beach dock inspired tens of thousands of tourists to flock there and get a glimpse of it, and that’s not a fad that will fade just because the dock is gone. Beachcombers who have long pored over Oregon’s shores for interesting stuff now have an entirely new mission: find tsunami debris. Bear witness to a piece of history. “These are the artifacts of human lives,” Wilson said.

And it’s up to state parks officials and conservationists alike to remind people what to do with that stuff—providing, of course, that they don’t want to keep it. Beach cleanups organized by the Oregon chapter of the Surfrider Foundation have doubled in frequency since the tsunami dock arrived, and the number of people calling to participate in them has skyrocketed, said Gus Gates, the nonprofit’s policy manager. Calls to the state beach-cleanup coordinators have numbered in the thousands.

“Everyone I talk to, they’re still looking for the next Harley to wash up,” Gates said, referring to the Harley-Davisdon motorcycle—still in its shipping container—that washed up on a British Columbia beach this year. “They’re thinking they might find something like that. Something cool.”

This is the happy ending to a twofold tragedy: the devastating tsunami itself, and the trash that was already in the ocean long before the earth started shaking in Japan last year. Most tsunami debris won’t be readily identifiable as such. It’s just ordinary household items. Whether it’s trash or historical artifact, though, people will still be picking it up. Still throwing it away, wiping the beaches clean of anything else they see, and they’re being reminded as they do so of just how permanent those little plastic water and soda bottles are, how they live forever.

“You can’t really tell if it’s tsunami debris or just trash,” Gates said. “But it doesn’t belong there.”

It’s a treasure hunt-turned-community-service project. In Washington, after the boat washed up in June, crews cleaned 57 miles of beach, end to end, Hart said.

“The beaches in the southern part of the state never seemed so clean,” he said.

It’s also an art project. On Oregon’s southern coast, in Bandon, Angela Haseltine Pozzi has long been collecting trash and turning it into sculpture at the nonprofit Washed Ashore. Now, she’s expecting an influx of new material. She’s planning an exhibit dedicated to the tsunami victims and using its debris. And she realizes she needs to be careful about how to pull that off.

“A lot of people are interested, amazed, horrified by the imagery,” Pozzi said. “To actually see that thing, to make that connection, it has to be done in a very sensitive way.”

Pozzi says Washed Ashore uses every last bit of material it collects. The tsunami debris is different, not just because it comes from Japan, but because it includes “a huge amount of Styrofoam.” That’ll force her to adapt the art, she said, probably by replacing the recycled welded steel framework she now uses as a hollow structure with Styrofoam as a base.

It’s a good thing that volunteers have mobilized to pick up tsunami debris—there’s little in the way of funds coming from the states or federal government. NOAA has provided each of the three West Coast states with $50,000 for cleanup; in Oregon, that’s a tenth of what the state has spent so far on tsunami debris. NOAA spokeswoman Keeley Belva said the agency has done some concerted marine-debris cleanups—a recent research expedition in the northwest Hawaiian Islands, for example, netted 50 tons of material—but the tsunami debris is spread out across an area that is three times as big as the continental U.S. There’s little the agency can do but monitor it, and tell people what to do when they find it.

“Who could possibly manage it?” said Al Pazar, a crab fisherman from Florence, Ore., who doesn’t run his boat at night “unless absolutely necessary” because of the debris. “It’s in God’s hands.”

Soon, currents and winds that now head north-to-south will switch, pushing debris on shore. Unwieldy trash piles or not, the coming treasure hunts are sure to be interesting ones. In April, a soccer ball turned up on a remote Alaskan island with Japanese writing on it. The beachcombers who found it traced the ball to a school and actually got it back to the owner, 16-year-old Misaki Murakami. The boy had lost everything in the disaster, and was glad to have it back. His classmates had given it to him in 2005.

On it, the students wrote “Hang in there, Murakami!!”