On a lake in St. Charles County, a floating island gently sways across the water. It’s anchored to the lake’s floor with four metal chain ropes, and the small plastic base holds 70 native plants.
The mini-floating island at the August A. Busch Conservation Area mimics natural wetlands and helps filter excess nutrients and toxins from the lake’s water.
It’s one of about a dozen artificial wetlands the Missouri Department of Conservation has installed over the past two years as part of a statewide quest to find more ways to improve water quality in Missouri’s lakes and ponds. Conservation agents and scientists are enthusiastic about the results so far and have plans to make their use more widespread.
“Floating islands [are] just one of those additional tools that we have in our water quality toolbox,” explained Frank Nelson, wetland systems manager with the Missouri Department of Conservation. ”I thought it might be a good time to see the application and hopefully success here in Missouri."
Agricultural and urban development have destroyed about 90% of Missouri’s natural wetlands. Artificial floating islands don’t restore the wetlands, but they are a promising solution to water pollution.
“Wetlands are like livers in the landscape,” said Carla Campbell, a water pollution researcher at the Missouri University of Science and Technology in Rolla. “If we can harness that ability that natural wetlands have to help remove pollutants from urban water bodies, that benefits everyone.”
An alternative to herbicides
Many lakes and ponds in the Midwest have unnaturally high amounts of nutrients like phosphorus that come from fertilizer or toxic heavy metals from stormwater. Nutrient excess harms the environment and causes algal blooms that are dangerous for fish, aquatic plants and humans because they suck up all the oxygen in the water and release even more toxins.
To treat algal blooms, people who manage neighborhood or municipal ponds often reach for herbicides. While chemical-based treatments work, Campbell said they don't solve the root issues.
“It'll make the water look clean, it’s going to look like a clean lake, it's not going to have all the green goo growing in it that people don't like to see. A lot of times, what's out of sight is out of mind, but it's not a long-term solution,” Campbell said.
Floating wetlands present a promising alternative. As native plant roots grow deep into a lake or pond, they suck up nutrients like phosphorus and naturally filter the water.
‘Sticker shock’
The floating wetland at the Busch Conservation area cost about $2,000. The State of Missouri purchased it from BioHaven, a Minnesota-based company that is one of the only manufacturers in the U.S. that sells the eco-friendly solution.
The high upfront cost can put off a lot of people. Still, Denise Otto, a fisheries biologist with the Department of Conservation, said the natural solution is worth the investment.
“HOAs or subdivisions might get sticker shock when they first look at a small wetland and see that it's almost $1,800,” Otto said. “Herbicides can be a couple hundred dollars, but then there's other herbicides that are over $2,000 a gallon, and you're fighting these plants year after year after year, then you have to do a cost benefit analysis and think maybe it actually is cheaper to get a wetland to get to the root of the problem.”
Otto and others with the Department of Conservation want more private landowners to install artificial wetlands.
The department is also designing its own plastic-free floating wetland model, and when it’s ready, Nelson said it plans to share the blueprints with university students who could take on manufacturing in order to make it more accessible.
“Nature isn't just out there, but it's in our neighborhoods, it's in our little park ponds, or if you have a favorite fishing pond, it can be right there as well,” Nelson said. “I think that's [the] Missouri Department of Conservation’s mission — is to help folks see that nature's all around them and it's beneficial for us. And likewise, we have responsibilities to be beneficial for nature itself.”
To learn more about how artificial floating wetlands work, what Missouri S&T researcher Carla Campbell found in her floating wetland experiments and why they are a promising solution to water pollution, listen to the full St. Louis on the Air conversation on Apple Podcast, Spotify and YouTube, or click the play button below.
“St. Louis on the Air” brings you the stories of St. Louis and the people who live, work and create in our region. The show is produced by Ulaa Kuziez, Miya Norfleet, Emily Woodbury, Danny Wicentowski, Elaine Cha and Alex Heuer. Jada Jones is our production assistant. The audio engineer is Aaron Doerr.
