Floating wetland islands installed to improve water quality

June 17, 2022| Environment

By: Holly Odgers

This month, nine Floating Wetland Islands were installed in Ashley Cove and Landing Channel with help from staff and volunteers from the Lake Hopatcong Foundation, Lake Hopatcong Commission, and Princeton Hydro, an environmental consultant for Lake Hopatcong.

These floating wetland islands are woven rafts of recycled polymer that float on the water’s surface and house a host of native wetland vegetation.

According to Princeton Hydro, these man-made islands mimic natural wetlands in a sustainable and efficient way. They provide a low-cost, effective method of improving water quality by assimilating and removing excess nutrients, like phosphorus, that could fuel algae growth.

Once positioned in their desired location, the islands are anchored in place but can rise and fall with water levels. As the plants grow, their root systems stretch through the polymer beds and down into the lake creating excellent habitat for beneficial water-cleaning microorganisms, which colonize the underside of the islands. The plants and microbes act together for optimal nutrient removal.

It is estimated that one 250-square-foot floating wetland island has a surface area equal to approximately one acre of natural wetland making it a powerhouse for nutrient removal. Princeton Hydro asserts these floating ecosystems can remove approximately ten lbs. of phosphorus each year. Since a pound of phosphorus can produce 1,100 lbs. of algae each year, that means each 250-square-feet of floating wetland island can mitigate up to 11,000 pounds of algae!

Once established, the islands require very little maintenance, and in addition to removing phosphorus that can feed nuisance aquatic plant growth and algae, they also provide excellent refuge habitat for beneficial forage fish and can provide protection from shoreline erosion.

The installation of these floating wetland islands is part of a series of water quality initiatives on Lake Hopatcong funded by a State of NJ Department of Environmental Protection Harmful Algal Bloom Grant and a 319(h) Grant awarded to the Lake Hopatcong Commission and the Lake Hopatcong Foundation.