BioHaven Floating Islands














Portland District, U.S. Army Corps of Engineers (Summer Lake, OR)

BioHaven® Floating Islands are constructed floating treatment wetlands composed of a buoyant mat planted with wetland or garden plants . They are used to filter nitrates, phosphates, heavy metals, and other run-off contaminants while creating a micro-habitat for surrounding species, enhancing the ecology of the water body. These buoyant mats are constructed with a matrix of fibers in which one could describe as a “pot-scrub” or “loofah”. This matrix is composed of 100% recycled plastic from drinking bottles whose layers are bonded together using marine foam, another factor in providing the mats’ buoyancy. Floating Islands may be customized to any form or size. Larger islands are built using a modular system, reinforced for extra buoyancy, yet still maintaining flexibility of movement in water. Floating Islands may be installed in ponds, lakes, rivers, or streams; they are typically anchored or tethered in place however, they sometimes are left to float freely across the water’s surface.














In February 2009, the U.S. Army Corps of Engineers installed an experimental application of a Floating Island in the Summer Lake Wildlife Area at Dutch Lake, Oregon, to address an endangered salmon population. Caspian terns annually feast on over 4 million juvenile salmon in the Columbia River estuary. The floating island was launched in order to deter the Caspian terns from the estuary and to create a new habitat and nesting location. This island is the largest of its kind, 22,000 square-fee, and was launched without any vegetation, as it was prohibited.












A crew of 13 installers assembled the modular 22,000-square-foot island on a ramp adjacent to the lake. Each of the 328 modules measured 5 feet by 14 feet, using 200 pounds of polypropylene from recycled carpet and 125 pounds of polyester from recycled plastic drinking bottles. With only a 5-week window between the waterfowl hunting and bird migrating seasons, the island had to be quickly constructed upon the arrival of its parts. As pieces were assembled, they were partially slid into the lake, leaving one side afloat in water and the other still on dry territory to connect to the next group of modules. The crew stapled tree fabric along the top of modules in several groupings to prevent plant growth, over which they spread a 7-inch layer of pumice as the tern’s nesting material. Once completed, the island was brought to the middle of the water by boats and was anchored in place. In mid-May, researchers had counted a range of individuals from 8-33, while some were digging in preparation for egg-laying. On May 17, the first tern egg was spotted on the floating island, followed by an additional eight tern nests with eggs. The Army Corps is currently designing a 30,000-square-foot floating island for Sheepy Lake in Northern California, part of a plan to build eight more islands.

Other applications of BioHaven® Floating Islands include the Chicago River in the Diversey Park area, Zoo Montana’s Otter Enclosure, and the Lake Simcoe Watershed Project in Barrie, Ontario, while Floating Island International, the creators of the floating islands, continuously do their own research and record their findings in Montana.

-- Catherine De Almeida