AMES, Iowa — Water quality in Iowa State University’s Lake LaVerne may soon get a boost with the installation of vegetated floating islands designed by a team of faculty and graduate students.
A recent algae bloom on the lake, caused by high levels of nitrogen and phosphorous, highlights the need to reduce pollutants and improve the health of the scenic lake on the west side of the Iowa State Memorial Union.
Austin Stewart, assistant professor of art and visual culture, and Mimi Wagner, associate professor of landscape architecture, both affiliate faculty in the master of design in sustainable environments graduate program; and John Downing, professor of ecology, evolution and organismal biology, are working with the Story Soil and Water Conservation District to develop a low-maintenance and inexpensive treatment solution to enhance the water quality of small ponds and lakes in central Iowa.
They’re using Lake LaVerne as a pilot project because of its public location, iconic status with alumni and students, and impaired condition, Stewart said.
“The university has been trying to fix the nutrient issues and has been doing treatments, but it continues to be a problem,” he said. “We’re looking to aid current efforts through a visually appealing, sustainable method known as VFIs (vegetated floating islands).”
VFIs are a small but rapidly growing field of research, mostly by a company called Floating Island International in Asia, Australia and India, with a few instances in the United States, Stewart said.
“Floating Island International produces a product called BioHaven, but their target audience is definitely more municipalities, water treatment centers and sewage treatment ponds where it is very expensive to install one of their items,” Stewart said.
The Lake LaVerne project aims to construct and monitor a series of low-cost, artistic VFIs and educate visitors about non-point source pollution like runoff and drainage, he said.
The Story Soil and Conservation District received a nearly $42,000 grant from the Iowa Watershed Improvement Review Board for the collaborative project, titled “Lake LaVerne Nutrient Pollution Reduction: Water Quality Enhancement in Small Ponds and Lakes Using Vegetated Floating Islands as Public Art.”
Stewart’s Sustainable Design Studio has spent the spring semester researching and developing the project in collaboration with the district. The six graduate students in the class examined what VFIs do, why they are a good solution for Lake LaVerne and what plants would work most effectively to absorb nutrients and contaminants through their roots.
The VFIs are expected to remove pollutants and reduce algae present in the water while also enhancing the setting and providing a healthy habitat for birds, insects, aquatic wildlife and fish, said Rebekka Brown, Burlington, Wisconsin, graduate student in sustainable environments.
Brown, who received her Bachelor of Industrial Design degree from Iowa State in 2013, said she focused on the systems side of design in her undergraduate studies and wanted to bring that background to the public education and engagement components of the project.
“I thought we could play a bigger role in influencing positive human behavior with design,” she said.
Brown teamed up with landscape architecture graduate student Shannon Hoy, Clive, and sustainable environments graduate student Sushmita Kotta, Hyderabad, India, to develop graphics for the project. Classmates Tara Bounds, Coon Rapids, landscape architecture; Shelley Vrchota, West Des Moines, sustainable environments; and Xi Zhang, Guangzhou, China, community and regional planning, have developed written materials, designed the public art components and coordinated public engagement efforts such as social media, posters and interactive website features.
The class developed a poster that won first place at the 9th Annual Iowa Water Conference in March.
The team has been allotted about 170 square feet of lake surface to work with, which they plan to divide among three small, round islands. The islands will be constructed on a base layer of polyflo, which provides a good surface for the microbial growth critical to proper filtration of phosphorous and nitrates, Stewart explained.
A layer of coconut coir bricks will serve as bedding for the plant material, including varieties such as woolgrass fox sedge, swamp milkweed and cutleaf coneflower. These will be filled in with a two-part marine foam that expands to secure the plants and provides more buoyancy so the islands will stay afloat. Coconut coir matting will be laid over the top of the bricks and foam to create an aesthetically pleasing visual appearance.
Steel arrows lined with solar panels and LED lights will be attached over each island to serve as indicators of the watershed flow into the lake and help connect the idea of land with water, Stewart said. The arrows will be lit for about an hour after sunset each evening and then shut off automatically.
Wagner, whose expertise is in water quality, wetlands and urban stormwater management, has worked with the students to assure the technical aspects of their design will function according to best practices. Stewart has advised them on the design and fabrication of the islands as public art.
“This project is really a proof of concept,” Stewart said. “The islands won’t be scaled to fully treat Lake LaVerne, but we’re collecting preliminary data now to hopefully launch something like this next year in full scale.”
What will really set these vegetated floating islands apart is that they will be aesthetically pleasing, something that major producers of VFIs tend to overlook, Stewart said.
“Along with the plants, there will be some small sculptures that are meant to represent the flow of the water in the watershed or the lake,” Stewart said.
A public event on Saturday, May 2, will feature the final assembly and launch of the three VFIs along the west side of Lake LaVerne. The event will begin at 2 p.m.
“We plan to have extra vegetation available so that people attending the event can create their own mini VFIs,” Stewart said.
Over the summer, Wagner and sustainable environments graduate research assistants will collect water samples both near and farther away from the islands. They will also collect vegetative tissue samples twice during the summer. Downing’s Limnology Lab at Iowa State will analyze all the samples for nutrient and carbon content. Analysis data will be used to estimate the nutrient uptake performance and ability of the floating island structures.
In addition to the islands themselves, the students have:
- designed informational signage to be installed around Lake LaVerne;
- created a website, laverne-islands.weebly.com, to inform the public about the project and provide resources for people to map their watersheds and design their own VFIs; and
- developed an environmental education package for high school students, which could be adapted for younger ages as well, to be used by teachers to engage students throughout Iowa in learning about the importance of enhancing water quality.
The project ultimately aims to develop design guidelines that would allow landowners and institutions to construct or purchase similar water-treatment systems of their own, Stewart said.
“VFIs are another potential tool to use to improve quality in Iowa streams and lakes,” said Jerry Neppel, an Iowa Department of Agriculture and Land Stewardship senior environmental specialist who provides administrative assistance to the Iowa Watershed Improvement Review Board. “This project will help determine under what conditions they work most effectively and estimate how much water-quality improvement can be expected.”