Be On The Lookout For Water Chestnut In RI Lakes, Ponds

NORTH KINGSTOWN, RI — The Rhode Island Department of Environmental Management is asking residents to keep an eye out for, and report, water chestnut plants in the state's lakes and ponds after the invasive species showed up in Barney Pond in Lincoln during an annual survey in June. While the water chestnut was introduced to the United States from Asia as an ornamental plant, it is a menace to ponds as it establishes itself and spreads rapidly.

The water chestnut roots itself in the bottom of the waterway and forms dense, floating mats that cover the surface — limiting light to other aquatic plants and quickly displacing native species, according to the RI DEM. In advanced cases, the invasion may impede boating, fishing, swimming and lower dissolved oxygen in the water, creating the potential for fish kills. Water chestnut plants also have sharp barbs that wash up on the shoreline and cause a potential hazard to humans and pets.

DEM is surveying lakes, ponds, and rivers across the state this summer as part of an annual monitoring program to identify aquatic #invasivespecies.- https://t.co/Zfvn1f3GNu pic.twitter.com/1w7sv7QRL9
— Rhode Island DEM (@RhodeIslandDEM) August 9, 2019

According to the DEM, the water chestnut was first observed in Rhode Island in Belleville Pond in North Kingstown in 2007. As of 2017, it has been documented in eight state lakes or ponds — including Valley Falls Pond in Central Falls; Central Pond and Turner Reservoir in East Providence; Porters Pond in Foster; Solitude Springs Farm Ponds in Hopkinton; Belleville Ponds in North Kingstown; Chapman Pond in Westerly; and Sylvestre Pond in Woonsocket.

The DEM asks if you think you have spotted the plant or seed in a new location, please take a picture and report it to DEM at DEM.WaterResources@dem.ri.gov.

"It is much easier and cost effective to remove a small patch of water chestnut than manage an entire lake covered with plants, so early detection is key," said Katie DeGoosh-DiMarzio, Environmental Analyst with DEM's Office of Water Resources in a statement. "Public awareness of invasive plants is the most effective way to combat the spread of aquatic invasive species from one lake to another by preventing the inadvertent transport of a hitch-hiking plant fragment."

A seemingly small problem can quickly grow large and expensive. Vermont spent $400,000 in treating a water chestnut invasion in 2009, and has spent more than $10 million on the problem since 1982, while the DEM reports the cost to treat a 1.3-mile stretch of the Sudbury in Massachusetts was $60,000 in 2017 — with continued treatments and monitoring necessary for the next 12 years.

"Many of the aquatic invasive plants in Rhode Island can reproduce from just one small plant fragment and do not need entire root systems to successfully establish in a new spot," DeGoosh-DiMarzio said. "Cleaning off every bit of plant from recreational gear used at one pond is essential before visiting another — this includes boats, kayaks, canoes, motors, trailers, paddles, jet skis, fishing gear, waders, water tubes, and anchors."