Green Lake resides in the heart of Seattle and is surrounded by the most used park in Washington. The Friends of Green Lake (FOGL) is a grassroots organization of citizens; devoted to maintaining a healthy lake. This organization was formed in response to toxic algae blooms and remains instrumental in water quality improvements and shoreline restoration. FOGL recently assembled a leadership team of experts for the design, purchase, planting, installation, and maintenance of constructed floating wetlands in the lake. This project aims to improve native bird habitat, fish habitat, water quality, aesthetic value, and wetland education. Herrera team members committed to this project include: Rob Zisette, aquatic scientist, project manager, and design lead; Eliza Spear, wetland scientist and permitting lead; and Eric Marshall, CAD technician and project plans lead.
Constructed floating wetlands mimic natural floating bog mats. These wetlands also enhance functional values at a relatively low cost, seeing that they do not require land purchase or excavation. As shown by Herrera for the Hicklin Lake Floating Wetland Project in 2013, constructed floating wetlands are easily planted in one day by a team of volunteers, native plant survival is high in fully saturated conditions, and invasive species weeding is rarely needed. The thick biofilm of attached algae and bacteria growing on the plant roots extending below the wetland matrix benefit water quality through nutrient uptake and benefit fish from the abundance of aquatic insects feeding on the biofilm.
Herrera teams with Biomatrix Water for floating wetland projects as they have proven to make the best engineered wetlands in the world with HDPE tubing for exceptional durability and longevity, natural coir fiber matrix for excellent plant support, modular units of varied shapes with quick-connect stainless steel corners, submerged media columns for increased biofilm, tree pods for three-dimensional structure, wave barriers for protection in high wake areas, submerged platforms for protected juvenile fish foraging habitat, and clip-on fencing for protection from grazing Canada geese.
This project aims to demonstrate this unique and cost-effective restoration approach at a highly visible location for many Seattle residents in hopes of promoting more constructed floating wetlands in our region. The project team has developed a work plan and preliminary design to maximize the site-specific function and benefit of the floating wetlands. The current concept is for two 680-square-feet islands with a curvilinear shape to be anchored next to each other in an isolated area near a national refuge with a focus on native bird habitat while benefiting fish and water quality.
The project team is currently in the process of obtaining permits before the submittal of a $40,000 grant application in September 2021 to finalize the design with public input and purchase the wetlands for installation by volunteers in April 2022. FOGL also plans to design and install education signs on shore and include webcams on and under the wetlands for citizens to see all the wildlife activities they bring to Green Lake.