These Floating Islands Aren't Real, but They Are Cleaning Up Rivers

While intensive farming has delivered a lot of cheap food to America, it's also delivered a lot of pollution.

The nation's 330 million acres of agricultural land are filled with enormous quantities of phosphorus and nitrogen fertilizer, some of which ends up in nearby waterways. The Environmental Protection Agency says more than half the nation's rivers and streams are now in "poor biological condition" as a result.

Bruce Kania's solution: recreate natural wetlands that can help purify the water and bring it back to life. Over the last decade, his Montana companyFloating Islands International has built more than 6,000 "biohavens" that are now quietly rejuvenating waterways across the country. And that's just the start. Some of his floating clean-up platforms now approach the size of football fields, and he's working on structures that could bobble in the ocean one day as well.

"We try and bio-mimic the patterns that nature employs," he says.

The islands are designed to grow "biofilms"—collections of microbes that consume the excessive nutrients in the water. Each platform is made up of a matrix of fibers derived from post-consumer plastic bottles, then infused with a buoyant marine foam. The plants on top, mostly perennials, grow in a peat layer. The biofilms congregate on the bottom of the structure, while roots from the plants peep through, offering additional pollution control.

Biofilms are naturally occurring—they're the green gunk you see on outside drains—and they've been used in wastewater plants for some time. Kania's innovation is to maximize the surface area underneath the structures to increase the water cleaning effect. He claims the artificial islands have many times the impact of naturally occurring versions.

Many of the islands he's built are in the shape of archipelagos. That helps fit with different watercourses and further increases contact between the water and the structure. Normally, Kania places the islands in a spot where the water is circulating most vigorously, again upping the effect.

Kania started Floating Islands International after moving to Montana in the late 1990s and becoming shocked at the state of some of the rivers near his home. "The greatest concentration of phosphorus pollution right now is in the northern Great Plains, including where we're located in Montana. That's really what's driven me personally to develop this technology," he says.

About 24 of the islands are at least 20,000 square feet by area, with one approaching 50,000 square feet. And Kania's now in discussions about building platforms as large as half a mile across. "We have learned how to grow real estate. So I'm pretty sure over the next few years we'll be launching livable islands under marine conditions," he says. "Islands in excess of a kilometer are on the drawing table."

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