Tracking Invasive European Water Chestnut
European Water Chestnut (Trapa Natans) is an invasive aquatic plant, originally brought to the United States in the late 19th century. This plant has spread rapidly along the East Coast, outcompeting native plants for space and nutrients, and now threatens the health of many of CT’s rivers and lakes. It was first identified in the Pomperaug River Watershed at Lake Stibbs (Southbury Training School Pond) in 2016 by field staff of CT DEEP's Inland Fisheries Division. PRWC has been working to control its spread in Lake Stibbs and downstream since 2020. In the summers of 2020 and 2021, over 1,000 European water chestnut seeds were discovered and removed from Transylvania Brook (downstream of Lake Stibbs) by Pomperaug River Watershed Coalition's (PRWC) Dr. Marc J. Taylor summer interns and Youth Conservation Corps members.
Thanks to generous grant funding by the Southbury Community Trust Fund (through CT DEEP's Aquatic Invasive Species Control Grant Program) PRWC was able to prioritize tracking and removing invasive water chestnut during the 2024 summer field season. PRWC efforts support its goal of restoring the health and recreational function of Lake Stibbs and preventing invasive water chestnut from impacting areas downstream in the Pomperaug River and Lake Zoar.
To provide an updated scope of the spread of invasive water chestnut downstream of Lake Stibbs, a stream walk survey was planned. Over 4 days, PRWC’s Marc J. Taylor summer interns walked 1.5 miles of Transylvania Brook documenting the location and condition of water chestnut and removing as much as possible. Thousands of chestnut seeds and 35 water chestnut plants were documented and removed during this stream walk.
A similar documentation strategy was employed for sections of the lower Pomperaug River and Lake Zoar via kayak through 3 paddling programs. These paddles resulted in the removal of 4 bushels of water chestnut from the lower Pomperaug River and Lake Zoar.
These paddles also resulted in the identification of a well-established patch of water chestnut in the lower Pomperaug River that will need further attention to remove fully.
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PRWC volunteers, interns, and staff were successful in removing over 147 bushels (approximately 3,800 lbs.) of European water chestnut plants and seeds from Lake Stibbs through four invasive water chestnut hand pulling days in June and July 2024.
Pomperaug River Watershed Coalition plans to continue its work to protect the Pomperaug River and Aquifer by restoring the health and recreational function of Lake Stibbs and preventing invasive water chestnut from impacting habitats and recreation areas downstream in the Pomperaug River and Lake Zoar.
Further downstream spread of invasive European water chestnut would be detrimental to important cold-water habitats and to the boating, fishing, and swimming opportunities provided in Lake Zoar. Removing this invasive plant therefore benefits residents by improving and protecting habitat and water quality for the rainbow, brown, and wild brook trout that provides Southbury some of the best freshwater sport fishing in the region, while also extending environmental education, youth development, and service opportunities to the community.
Want to Get Involved?
Pomperaug River Watershed Coalition will need ongoing support from community members to help identify and manage invasive European water chestnut in the Pomperaug River Watershed. If you are interested in participating in future invasive water chestnut tracking and removal projects with PRWC, let us know by filling out our volunteer interest form.
Seen This Plant?
If you spot invasive water chestnut in lakes, rivers, or streams within the Pomperaug River Watershed, please report it to PRWC by filling out our public water chestnut observation form.
