Let this idea grow on you: using mushrooms to clean up dirty, polluted urban streams. That’s what environmentalists are trying in Oregon. Volunteers for Ocean Blue Project, an ecological restoration nonprofit, are placing mushroom spawn in burlap sacks with a mixture of coffee grounds and straw to grow in. Then, they put the bags in the paths of storm drains, where contaminated water will filter through them.

Here’s how it should work: The underground part of mushrooms, called mycelium, will break down pollutants like E. coli, pesticides, and oil, The Corvallis Gazette-Times reports. The volunteers placed their first test bag in a drainage chute in Corvallis’ Sequoia Creek on Sunday.

According to a recent Oregon Department of Environmental Quality water sampling, water in the Willamette River contained flame retardants, metals, pesticides, and chemicals from consumer products. Ocean Blue will conduct its own tests of water samples to monitor the effects of the mushroom bags. Signs will warn passerby not to eat the toxic mushrooms in the sacks, says Ocean Blue President Richard Arterbury.

Read the full story over at The Corvallis Gazette-Times.