Floating Wetland Islands: A Sustainable Solution for Lake Management

Nick Decker, PA State Parks Resource Manager, and Cory Speroff and Katie Walston of Princeton Hydro position a floating island of native plants in the lake at Frances Slocum State Park

Looking for a unique and creative way to manage nutrient runoff in freshwater lakes? Installing Floating Wetland Islands (FWI) is a low-cost, effective green infrastructure solution used to mitigate phosporus and nitrogen stormwater pollution often emanating from highly developed communities and/or argricultural lands.

FWIs are designed to mimic natural wetlands in a sustainable, efficient, and powerful way. They improve water quality by assimilating and removing excess nutrients that could fuel algae growth; provide valuable ecological habitat for a variety of beneficial species; help mitigate wave and wind erosion impacts; provide an aesthetic element; and add significant biodiversity enhancement within open freshwater environments.

“A pound of phosphorus can produce 1,100 lbs of algae each year. And, each 250-square foot island can remove 10 lbs of phosphorus annually.” explains Princeton Hydro Staff Scientist Katie Walston. “So, that’s 11,000 lbs of algae that is mitigated each year from each 250 square foot of FWI installed!”

This illustration, created by Staff Scientist Ivy Babson, conveys the functionality of a Floating Wetland Island

This illustration, created by Staff Scientist Ivy Babson, conveys the functionality of a Floating Wetland Island

Typically, FWIs consist of a constructed floating mat with vegetation planted directly into the material. Once the islands are anchored in the lake, the plants thrive and grow, extending their root systems through the mat and absorbing and removing excess nutrients from the water column such as phosphorus and nitrogen.

Native plants on the floating island designed by Princeton Hydro that will help reduce the phosphers and algae in the lake at Frances Slocum State ParkThe plants uptake a lot of nutrients, but the workhorse of the FWIs is the microbial community. The matrix used within the islands has a very high surface area and it promotes microbial growth, which performs the majority of the nutrient uptake. Additionally, the root growth from the plants continues to increase the surface area for the microbial biofilm to grow on. Both the plants and microbes acting together help optimize nutrient removal.

Princeton Hydro has designed and installed numerous FWIs in waterbodies large and small for the purpose of harmful algal bloom control, fisheries enhancement, stormwater management, shoreline preservation, wastewater treatment, and more. FWIs are also highly adaptable and can be sized, configured, and planted to fit the needs of nearly any lake, pond, or reservoir.

Greenwood Lake

Recently, the Princeton Hydro team completed a FWI installation in Belcher’s Creek, the main tributary of Greenwood Lake. The lake, a 1,920-acre waterbody located in  both Passaic County, New Jersey and Orange County, New York, is a highly valued ecological and recreational resource for both states and has a substantial impact on the local economies. In addition, the lake serves as a headwater supply of potable water that flows to the Monksville Reservoir and eventually into the Wanaque Reservoir, where it supplies over 3 million people and thousands of businesses with drinking water. 

Since the lake was negatively impacted by HABs during the 2019 summer season, Greenwood Lake Commission (GWLC) has made a stronger effort to eliminate HABs and any factors that contribute to cyanobacteria blooms for 2020 and into the future. Factors being addressed include pollutant loading in the watershed, especially that of Belcher’s Creek. The installation of FWIs in Belcher’s Creek will immediately address nutrients in the water before it enters Greenwood Lake and help decrease total phosphorus loading. In turn this will help reduce HABs, improve water quality throughout the Greenwood Lake watershed, and create important habitat for beneficial aquatic, insect, bird and wildlife species.

“In addition to the direct environmental benefits of FWIs, the planting events themselves, which involve individuals from the local lake communities, have long-lasting positive impacts,” said Dr. Jack Szczepanski, Princeton Hydro Senior Project Manager, Aquatics Resources. “When community members come together to help plant FWIs, it gives them a deepened sense of ownership and strengthens their connection to the lake. This, in turn, encourages continued stewardship of the watershed and creates a broader awareness of how human behaviors impact the lake and its water quality. And, real water quality improvements begin at the watershed level with how people treat their land.”

The project was partially funded by the New Jersey Department of Environmental Protection’s (NJDEP) Water Quality Restoration Grants for Nonpoint Source Pollution Program under Section 319(h) of the federal Clean Water Act. As part of the statewide HAB response strategy, the NJDEP made $13.5 million in funding available for local projects that improve water quality and help prevent, mitigate and manage HABs in the state’s lakes and ponds. The GWLC was awarded one of the NJDEPs matching grants, which provided $2 in funding for every $1 invested by the grant applicant. For this project, the GWLC purchased the FWIs and NJDEP provided the 2:1 cash match in order for the GWLC to implement additional HAB prevention and mitigation strategies in critical locations throughout the watershed.

Check out the photos from last month’s installation:

Here are a few more examples of FWI design and installation projects we’ve completed:

Frances Slocum Lake

Officials with the state Department of Conservation and Natural Resources, Luzerne Conservation District, Nanticoke Conservation Club, and students at Rock Solid Academy in Shavertown teamed up with Princeton Hydro to install two floating islands on the lake. They were planted natives to the area, including Green Bulrush, Broadleaf Arrowhead, Blue Flag Iris, Shallow Sedge, and Spotted Joe-Pye.

Princeton Hydro also installed solar-powered aeration systems in the middle of the FWIs. Aeration systems provide additional water quality improvements, help prevent water around the islands from stratifying, promotes “through-column” mixing, and helps to minimize the occurrence of phytoplankton blooms. The use of solar-powered aeration, whether installed on a FWI or along the shoreline, creates a sustainable, cost-effective, zero-energy water treatment solution, and eliminates the need to run direct-wired electrical lines to remote locations. Learn more.

Princeton Hydro also installs solar-powered aeration systems on FWIs, creating a sustainable, cost-effective, holistic water treatment solution.
Harveys Lake

Princeton Hydro, along with project partners, installed five floating wetland islands in Harveys Lake in order to assimilate and reduce nutrients already in the lake. The islands were placed in areas with high concentrations of nutrients, placed 50 feet from the shoreline and tethered in place with steel cables and anchored. A 250-square-foot FWI is estimated to remove up to 10 pounds of nutrients per year, which is significant when it comes to algae. Learn more.

Volunteers install native plants in one of the FWIs installed in Harveys Lake. Photo by: Mark Moran, The Citizen’s Voice.
lake hopatcong

Through a nonpoint source pollution grant awarded by NJDEP to the Lake Hopatcong Commission, Jefferson Township was able to install FWIs in order to deliver better water quality to Ashley Cove and Lake Hopatcong. The primary goal of the project was to reduce high levels of algae-causing phosphorus present in the lake. In each FWI, indigenous plants, Milkweed and Hibiscus, among other vegetation, were planted along with peat and mulch. Learn more.

Casey Hurt, right, and Richard Ampomah maneuver one of two floating wetland islands in Ashley Cove.
Lake Holiday

Two interconnected sets of FWIs were installed in Lake Holiday in the tributary coves of Isaac’s and Yeider’s Creeks. The strategic placement of the islands eliminates interference with normal boat traffic. In order to minimize movement, the FWIs were secured to trees along the bank with coated cable and protective bands and anchored to the lake bottom with submerged concrete blocks. Learn more.

Senior Scientist Katie Walston installs goose netting around the vegetation in order to prevent geese and other unwanted species from feeding on the plants.

Over the coming weeks, our team will be in Asbury Park, New Jersey installing FWIs in Sunset Lake. Stay tuned for more! For additional information about floating wetland islands and water quality management, go here: bit.ly/pondlake.

Preventing Zika Virus & Other Mosquito-Borne Diseases

The start of mosquito season is right around the corner. Princeton Hydro offers simple solutions to reduce mosquito exposure and eliminate mosquito breeding.

Concerns about Zika virus (transmitted by the Aedes aegypti mosquito) arose in Brazil last May and have since quickly escalated. With cases confirmed in over 20 countries across Central and South America, the World Health Organization (WHO) recently declared the virus an international public health emergency. WHO reported that Zika could infect as many as 4 million people by the end of 2016. Additionally, West Nile virus remains a concern throughout the U.S. along with other mosquito-borne illnesses that affect humans, pets and livestock.

With spring rains and warmer temperatures on the horizon, mosquitos of all types will soon be buzzing. As predicted by the National Center for Atmospheric Research, by June we can expect mosquitos carrying the Zika virus to arrive in the Mid-Atlantic States. There are many simple measures that public and private pond and land owners can take in advance of mosquito season to reduce mosquito breeding and lessen the spread of mosquito-borne illnesses without resorting to the use of chemicals.

Here are three simple mosquito-prevention tips for ponds:

  • Eliminate stagnant water by installing a sub-surface aeration system. This will keep the pond thoroughly mixed and properly circulated. Subsurface aeration systems are the most cost-effective and energy-efficient way to maintain proper pond circulation and mixing. DSC02027Agitating the water’s surface interferes with the female mosquito’s ability to lay eggs and the success of mosquito larvae.
  • Along the shoreline of the pond, maintain or create an aquascaped edge dominated by native, non-invasive vegetation. As opposed to a sterile lawn edge, an aquascaped edge provides habitat for mosquito-eating amphibians, fish, birds, and beneficial insects.
  • Prevent grass clippings and lawn fertilizer from entering the pond. Doing so decreases the chance of an algae bloom which could create the still water conditions that favor mosquito breeding.

Additionally, you may want to consider hiring a certified professional to assess your pond and develop a customized management plan. Having your pond inspected by an expert helps you stay informed about your pond’s ecological status and implement measures to prevent/remedy conditions that could create mosquito breeding habitat and promote mosquito related problems.

But that’s not all!

Here are seven things you can do around your home or business property to prevent mosquito breeding:

  • Stagnant water is the perfect habitat for mosquito breeding. IMG_0695Check your property for areas where water easily collects: empty flower pots, buckets, old tires, tire ruts, low spots in lawns and trash cans.
  • Clear clogged rain gutters and storm drains, and keep them free of debris.
  • Regularly change the water in bird baths and pet dishes.
  • Store canoes and small boats upside-down.
  • Check tarps and grill covers for pooled water, and shake them out after a rain storm.
  • Repair leaky outside faucets, pipes and hoses to prevent puddles from forming.

Simply put, if you want to limit mosquito breeding in your pond or on your property, take the time to implement long-term management measures that integrate natural solutions, thereby creating an inhospitable environment for mosquitos. As noted above, this can be accomplished without resorting to chemicals! In addition to keeping your pond properly circulated, employ preventative practices that eliminate potential mosquito-breeding areas around your property, and regularly inspect areas to help quickly identify and resolve developing mosquito populations.

Princeton Hydro offers a full complement of services, including detailed water quality analysis, adaptive management plans and field services covering all areas of pond maintenance. Our team of certified lake and pond managers, wetland scientists, and water resource engineers can provide you with the expertise needed to diagnose the cause of pond problems and develop solutions that are environmentally sound and cost-effective. Contact Princeton Hydro to discuss how we can help you!

Read an interesting article about the origins of Zika here.