Taiga Wetlands – How Volunteers Restored Habitat in an Urban Lake with Constructed Floating Wetlands: Presentation by FOGL President Rob Zisette at the Society of Wetland Scientists national conference in Spokane on June 30, 2023 and at The Hearthstone at Green Lake on July 10, 2023.
Abstract: The Friends of Green Lake (FOGL) received a generous donation in memory of Taiga Hinkley to benefit Green Lake in Seattle, Washington. After consideration of the many needs for this impaired urban lake, FOGL selected a floating wetlands project to cost-effectively restore aquatic habitat and improve water quality. We assembled a volunteer team of technical experts and interested citizens to design, permit, purchase, plant, install, and maintain constructed floating wetlands for improvement of native bird habitat, fish habitat, water quality, aesthetic value, and wetland education for Green Lake in Seattle, Washington.
We won a $50,000 grant from Seattle Neighborhoods after first obtaining an HPA permit, and selected Biomatrix Water in Scotland to provide a total of 40 wetland modules for constructing two 680 ft2 islands. A team of over 30 volunteers planted, assembled, and anchored both islands in one day on May 30, 2022 that included an array of floating, submerged, open water, and elevated tree modules planted with 1,086 native plants of 32 species to create diverse habitat. The modules are comprised of non-polluting sustainable materials including recycled HDPE tubing for high buoyancy, flexible stainless-steel connections for durability, and a coir fiber matrix for a natural plant substrate. A robust anchoring system was designed from engineering calculations and short, perimeter fencing was installed to successfully exclude Canada geese and allow passage of small waterfowl underneath. After two sweltering summer months, monitoring results in July 2022 showed 100 percent survival of the plants and extensive use by native waterfowl that sustained through the winter without any vandalism.
Wood duck and tree swallow housings were installed on the islands in March 2023. Unfortunately, a pair of Canada geese jumped the fencing and built a nest on each island in the spring of 2023 that killed many of the plants in the process.
FOGL designed an educational sign (see Taiga Wetlands page) that was installed in May 2023 at an excellent viewpoint of the islands for thousands of daily users of the Green Lake Park trail. We plan to plant more goose-hardy plants in the fall, conduct nutrient uptake measurements next year, and provide minor maintenance by volunteers for at least the next 20 years.