Floating Wetlands

In early October Kemah Lake installed two floating treatment wetlands through a DEP grant administered by the Sussex County Municipal Utilities Authority (SCMUA) – Wallkill River Management Group (WRWMG). Kemah Lake partnered with Lake Owassa in a demonstration project to improve lake water quality and manage potential harmful algal blooms (“HABs”). We were the first lakes to install them in Sussex County. Lake Hopatcong has 9 floating treatment wetlands as part of their lake management plan.

Floating treatment wetlands are planted with native wetland plants that help take up nutrients like phosphorus and nitrogen from the lake water. Pollutant removal can be accomplished two ways: 1) Microbes living in the lake will inhabit the polyethylene islands and will directly ingest HAB-causing cyanobacteria and 2) Plant roots will grow through the islands over time and can help take up nutrients like phosphorus and nitrogen from the lake water. These dual strategies reduce the likelihood of harmful algal bloom (HAB) development.

Floating treatment wetlands help reduce phosphorus, nitrogen, heavy metals and bacteria  that breakdown the nutrients in Kemah Lake. The nutrients feed cyanobacteria and are the building blocks for HABs. The floating wetlands have been studied and shown they are effective in reducing the use of chemicals to treat algae.

The islands are very compact and made from recycled polyethylene plastic with recessed pockets within which the plants are planted. Native plants were selected to remove nutrients through their roots that hang down in the water. The wetlands were installed near the causeway to catch the inflow from Bear Swamp and off the shoreline south of the Big Beach to capture runoff from the hill. The islands should not affect boat traffic and can be moved, if necessary.  They will remain in the lake over the winter. Each island has goose fencing to protect the plants from being eaten.

Kemah Lake will be monitoring the wetlands with our partners in the Paulins Kill Watershed to evaluate the effectiveness of these novel tools to improve the water quality of the lake. The floating treatment wetlands are part of our on-going efforts to protect and preserve our lake. Stay tuned to learn about workshops in 2023 for homeowners to design and install rain gardens.

We want to thank the following members for their help in assembling the floating wetlands and installing them: Mike Nicomini, Fred Malone, Dawn Latincsics, Marty Apryasz, Bob Carr and Bob Fox as well as Nathaniel Sajdak, Director of the Wallkill River Watershed and Education Outreach Specialist Kristine Rogers.