This story originally appeared on CityLab and is part of the Climate Desk collaboration.

If you can bypass the cheese display at the Goose Island Whole Foods in Chicago, there’s a strange sight out the building’s back doors. In the river below float 80 coconut-fiber beds, replete with native grasses, shrubs, and even river birch trees. Most days, you’ll also see Nick Wesley, co-founder of the nonprofit Urban Rivers, inspecting the beds from a kayak pulled up alongside.

The plants he’s tending are the beginnings of the Wild Mile. The initiative, led by Urban Rivers, aims to transform the steel-walled North Branch Canal of the Chicago River into a lush wildlife haven. Work began in June 2017 and will continue through 2020, when the area is planned to have forests, wetlands, and public walkways and kayak access points.

Since the waterway isn’t natural—the canal was carved and walled with concrete and metal for ships in the 19th century—there are no riverbanks to restore. So Wesley and his team opted for faux edges (which need anchoring, lest they float away). By 2020, Urban Rivers wants the canal to house birds, fish, trees, and mussels. To do that, it has to build a habitat almost from scratch.

Nick Wesley checks the condition of some of the coconut-fiber beds. Dylan Wallace/Courtesy of Urban Rivers

Urban Rivers chose a particularly barren mile of water to populate. That’s the point—the project wants to draw attention to somewhat forgotten regions of the river. Like the rest of the river, it’s suffered from Chicago’s notorious sewage pollution. The North Branch Canal sits downstream of the O’Brien Water Reclamation Plant, which transformed into the world’s largest UV-light sanitation facility after the EPA demanded in 2011 that the river reach cleanliness standards that every other major US city managed years ago.

Although improving water quality has attracted more wildlife recently, the river is still regularly polluted, and it’s still not swimmable like the EPA wants it to be. Last year, Urban Rivers confirmed what kind of contaminants they’d be dealing with, Wesley said. “We looked into the water quality to see baseline what it is, and it’s not good.”

The Wild Mile would like to turn that diagnosis around via the floating plants. Each island is produced by Biomatrix, a company that has supplied similar garden rafts to water clean-up efforts around the world. Plants are embedded in the coconut-fiber bed as if it’s normal dirt, but their root systems reach into the water below to suss out nutrients. The plants also take in, store, and break down pollutants.