On an overcast June morning, I step from the rubber-sided Zodiac boat on to a floating barge at the mouth of Ballona Creek, where it meets Santa Monica Bay on the west side of Los Angeles. The first thing I notice? Salty air is the only smell, despite six giant waste bins sitting atop the tennis court-sized barge.

The contraption is actually two barges – a smaller platform sits nestled inside the larger boat. A floating barrier directs rubbish into the device, where a conveyor belt scoops it up. An automated shuttle then distributes the waste into six dumpsters on a separate barge, sending an alert to crews when it is full. Above, solar panels form the ceiling and a conveyor belt runs slowly, dropping bits of plastic and waste into each of the bins. The whole thing can hold about 20,000lbs (9,070kg) of rubbish – the same as one fully loaded lorry.

Since it is the dry season in LA there is not much waste being washed down the river by rainfall. But I still see what the problems are: polystyrene takeaway containers, noodle cups, bottle caps, a yellow pencil, a palm frond dotted with colourful pieces of microplastics. They are all caught up in the boat’s conveyor belt. It’s a pretty representative sample, says James Patterson, the operations manager with the nonprofit Ocean Cleanup, which created the system. “You get a wide variety of basic plastics – a lot of bottles, cups, to-go containers, things from restaurants. That’s typically what we see out here,” he says.

When the waste is pulled out, it is sorted and sent to refuse facilities. “We want to make sure that from start to finish, we’re pulling the trash out in a responsible way, and it’s getting sorted or stored in a responsible manner,” Patterson says. “We don’t want a circular battery of trash here.”

This particular barge is a model for others being deployed around the world. Ocean Cleanup operates in 10 places, with 21 Interceptor systems – in countries including Malaysia, Indonesia, Vietnam, Guatemala, Jamaica and the Dominican Republic. It aims to clean up the 30 most-polluted cities by 2030.

The big idea? Stop waste from ever reaching the ocean. “Instead of specific rivers, the goal is to clean up an entire area, because that’s how you get an actual genuine impact on society and on the environment,” Patterson says.

In this creek, the end of a 130 sq mile urban drainage network in LA County, the boat stopped 143,710lbs of rubbish from entering the ocean in 2025. Ocean Cleanup will launch two more boats in the LA area – in the San Gabriel River and the Los Angeles River. It is already having an impact on the coastal communities, Patterson says. Beach cities south of the project have lowered their budgets for beach grooming: there is simply less waste on the sand, so they don’t need to be cleaned as often.

Ocean Cleanup’s founder, the Dutch inventor and entrepreneur Boyan Slat, was originally inspired to use technology to battle the Giant Pacific Garbage Patch, and created the skimming technologies that can scoop a soupy crud of waste off the surface of water. But in researching solutions, the nonprofit pivoted to rivers – the arteries that carry rubbish into the world’s oceans.

Rivers are key. Research by Ocean Cleanup has shown that just 1,000 of the world’s rivers are responsible for nearly 80% of plastic emissions into the ocean, and 90% of all pollution in the ocean comes from rivers. “We have to turn the faucet off before we can scoop the ocean, or else all we’re doing is taking out legacy trash to replace it with new trash,” Patterson says. “Before you can clean out the Great Pacific Garbage Patch, you really need to turn off the source.”

Work on designing the autonomous boat started in 2017, and this pilot project in LA began in 2022. It cost about $1.3m to design and permit, and another $1.5m to secure the boat and booms in place. Maintenance each year costs $650,000 – and the Interceptor is being provided to LA County free from Ocean Cleanup.

It’s not a perfect system. As we stand on the barge, I point to a red plastic cup floating outside the barrier on the surface. Patterson winces. “When something like that escapes, it hurts,” he says. But that cup is an outlier. The most difficult kind of trash, the public works employees agree, is large logs.

Each river requires its own special system. “There’s no one size fits all,” Patterson says. “Every river is different in how they act, where you can deploy, what the local government and permitting timelines look like, and just the conditions of nature.”

Patterson adds the boats rarely have issues with wildlife – except for birds. Seagulls like to sit and defecate on the barge, which can corrode the metal.

As we step off the Interceptor back to the Zodiac that will return us to shore, I look back at the metal container and comment how straightforward it all seems: gather the floating debris, hold it for later disposal. From the outside it looks complicated. “It may seem simple,” Patterson says, “but, truly, a master of engineering goes on inside of these.”