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On a morning in November 2017, while the residents of Lakeland, Florida, headed off to work, a small team of engineers parked what looked like an enormous lava lamp on the banks of Lake Bonnet. The ten-by-eight-foot water tank sat on a trailer fitted with a generator-powered pump. As the trailer gurgled to life, a hose pumped a swirling stream of green, algae-choked water into the tank.

Like many Florida waters, Lake Bonnet had become overrun with plant slime. In fact, all 50 states and many countries worldwide are struggling with epidemic levels of algae that can prove toxic to people and ecosystems. “” of algae along Florida’s Gulf Coast have killed tons of fish and marine mammals. Chinese lakes have turned into electric-green sludge. Beaches in Southern California are also experiencing explosions of algae and its related toxins: domoic acid and microsystin are among the algae-produced poisons that can kill off wildlife and cause illness in humans. Gulping it, swimming in it, or inhaling it (via sea mist) causes vomiting and diarrhea; extended contact can lead to cancer and liver failure.��In Florida, lifeguards have reported higher incidence of respiratory illness, and many marina workers��have taken to wearing air masks.

Battling the algae hasn’t been easy or practical, but at Lake Bonnet, engineers from a multinational firm called tested a brand-new technology that they think just might offer a solution to the global algae crisis. The water tank filters algae from water and��then turns it into plastic foam like the kind used by footwear companies to make billions of pairs of shoes each year.

That cushiony underfoot feeling you get from running shoes, sneakers, and hiking boots? It’s typically provided by ethylene-vinyl acetate (EVA) foam, which is made from toxic��petrochemicals.��But a handful of outdoor footwear companies, such as Bogs and Altra,��in conjunction with Aecom, have begun making shoes with an EVA-algae-based hybrid called Bloom.��As this new material gains traction, algae could help clean up an industry that’s notorious for harmful environmental impacts. You might start thanking algae for that spring in your step—and you might see cleaner waterways.

“It’s pretty amazing to watch,” says Laurie Smith, lakes and stormwater manager for the City of Lakeland. Smith and a number of other Florida water specialists attended the Lake Bonnet test to learn about the process and evaluate its potential for their districts. She witnessed how a pump drew water via a hose into the tank, where the slimy water mixed��with a coagulant that caused��the algae to clump together. (The tank can run from one location on the shore, although it’s set up on a portable trailer that can be easily relocated.) Then, air bubbles were pumped into the water. As they rose, they carried the algae to the tank’s surface, where it floated like foamed milk on a cappuccino. Engineers skimmed off the clumped algae, and a stream of crystal-clear water poured back into the lake.

The system processed 125 to 175 gallons of lake water per minute��and netted more than 300 pounds of algae in just one day.

“That’s an incredible amount of algae,” Smith says. “With most water-quality projects, we don’t see immediate impacts. But with this, we saw pollution coming out and clean water going back in, which is amazing. I’m very hopeful that as this technology gets refined, it could present a real solution [to the algae epidemic].”

Algae isn’t like an oil spill, which introduces foreign chemicals to waterways. The tiny, free-floating plants naturally occur in both marine and freshwater environments, and they occasionally explode to pestilential levels. In recent years, those blooms have become bigger, more frequent, and longer lasting. Climate change may be a factor: the earth’s water temperatures are creeping up. Plus, nitrogen and phosphorus—naturally present in most waterways—are now appearing in many lakes and coastlines. Rainwater flushes the nitrogen- and phosphorus-rich fertilizers from our lawns and farms into watersheds, where they stimulate algae production.

Turns out, overstimulated algae can cause big problems for communities and the waters they rely on. For four days in August 2014, some 500,000 residents of Toledo, Ohio, with their tap water because of an algae bloom in Lake Erie. In July 2018, Governor Rick Scott in seven South Florida counties after Lake Okeechobee became a cesspool of photosynthesizing microorganisms. Algae covered 90 percent of the lake’s 730 square miles and crippled the many businesses that rely on Okeechobee’s tourism and outdoor recreation for most of midsummer. Plus, these blooms��stink��like rotting food. So although “attack of the green slime” may sound like a C-grade��horror movie, in some areas, the crisis is real.

So far, the available remedies have proven to be inadequate, impractical, or both. Adding copper sulfate or alum to the water causes a quick die-off, but the chemicals also kill��fish. And they don’t remove the algae itself, so the phosphorus and nitrogen embedded in the cell walls of algae persist in the waterway and make subsequent blooms more likely, because algae feeds off phosphorus and nitrogen. Dredging removes the offending nutrients��but is wildly expensive—about $6 million for an 80-acre lake, Smith says—and there’s no good way to dispose of the dredged gunk. Other pro