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Water Chestnut

Information regarding water chestnut invasion

Weed Removal Video                                                                                             


Water Chestnut Infestation

Water chestnut was first discovered in Connecticut in 1999 and can be found in the following locations: scattered sites along the Connecticut River from Hartford to Lyme, both in the main stem river and in a number of coves (including White Oaks Cove, Keeney Cove, Hamburg Cove) and connected ponds. Water chestnut has also been found in a number of other waters scattered throughout CT including the Mattabesset, Hockanum and Podunk Rivers, small ponds in Eastford, Thompson and West Hartford, Bantam Lake (eradicated, non found in the last several years), Mudge Pond and at the confluence of the Still River and the Housatonic River.

Anglers fishing in the Connecticut River, its tributaries, and elsewhere should be on the lookout for this highly invasive plant. DEEP and other organizations are involved in eradication efforts.

Water chestnut is a rooted, annual aquatic plant with triangular-shaped floating and feather-like submerged leaves. Its sharp, spiny fruits wash ashore and can inflict painful wounds if stepped on. Dense water chestnut growth can make fishing, boating, swimming and other recreational activities nearly impossible.

If you find this plant, contact Harry Yamalis at 860-424-3034 or

For many years excessive weed growth threatened to disrupt the ecological and recreational balance maintained within Quaddick Lake. The encroachment of nuisance vegetation, especially non-native species like variable watermilfoil (Myriophyllum heterophyllum), fanwort (Cabomba caroliniana) and bladderwort (Utricularia) was seriously hindering the spread of wildlife as well as human access and enjoyment of the lake. The ever-present trend of continued development and "cultural eutrophication" emphasized the importance of a well-rounded plan to manage Quaddick Lake.

Over the years, several methods of weed control have been attempted sporadically but, in order to regulate and control the weed growth, an ongoing management program was required. In 2007, the Quaddick Lake Association created a Lake Management Committee to focus on comprehensively evaluating available techniques to address this issue and then to educate the community and Association so the membership can determine the best method to use to control the problematic growth as an annual effort. (Nuisance Aquatic Vegetation Management (1.8 mb pdf) is a guidebook produced by the State of Connecticut Department of Environmental Protection and Pesticides Management Program, regarding the invasive vegetation issues that affect our lake.

One of the primary charters of the Association's Lake Management Committee is to ensure that residents within the watershed area are properly informed about the factors that contribute to weed growth and the options that are viable to control the growth. This website is the primary vehicle to deliver this information. Review some Do's and Don'ts for lake-front Residents.


In 2001 and again in 2007/08, Aquatic Control Technology, Inc. was contracted to complete a diagnostic assessment of the exotic, invasive vegetation in the lake. The methods determined as viable to effectively control this vegetation in Quaddick Lake were drawdowns, hydro-raking and/or chemical treatments. You can read the entire original (report here).


A drawdown is lowering the water level in the winter until the exposed bottom freezes, to kill roots of vegetative places and susceptible seeds of certain rooted aquatic plant species. Drawdowns have been used on Quaddick Lake in the past for rooted plant control, to prevent ice damage and to allow for repair of docks and shoreline areas. View an example of the 3-4 foot drawdown.

Following the Quaddick Lake Association meeting on August 27th 2006, it was determined that the first step in the lake management program will be to lower the lake's water level (drawdown) annually. Divers will inspect the drain pipe's grate to make sure it is clear of debris each September and then the State of Connecticut will begin generating electricity by drawing water through the pipe and over the Red Bridge Dam in early October. Under normal weather conditions, this should lower the water level of the lake, until the lake is down about 5 feet in January.

The lake should freeze in early January to an average thickness of 8-10 inches. About 2/3rds of Upper Quaddick will experience significant contact between the ice and the weeds on the bottom of the lake. After sustaining a period of 30 days of surface contact, the ice causes significant damage to the root systems of the weeds within the contact area.

The State of Connecticut will stop drawing water from the lake in late March. With good timing and some luck, the snow melting and periodic rains will quickly raise the water level back to its normal condition. This forces the ice off the surface, thus uprooting the weeds frozen in the ice. This also allows for the lake to stay cooler for a longer period of time. The cooler water holds the initial new growth at bay and delays the surge of weeds until later in the summer.


Mechanical raking (Hydro-Raking) is a widely used and effective technique for area selective removal of nuisance, rooted vegetation. In some situations the Hydro-Rake is also used to clear accumulations of unconsolidated bottom debris (i.e. decaying leaves, peat, muck). The Hydro-Rake can best be described as a floating barge upon which is mounted a backhoe with several different size and functioning rake attachments. The Hydro-Rake is powered by a Diesel engine which drives the hydraulically operated paddle wheel propulsion system and back-hoe functions. The Hydro-Rake can operate in water as shallow as 1.0 -1.5 feet and can remove nuisance vegetation and bottom debris from variable water depths as shallow as a few inches to a maximum depth of 12 feet. Duration of nuisance plant control varies, but is typically "summer long" for species such as water milfoil (Myriophyllum sp.) to 2-3 years or longer for plants with well developed root systems (i.e. waterlilies, cattails, etc.)

The Hydro-Rake works from the water and can therefore access coves and shoreline areas otherwise inaccessible to conventional machinery. Damage to valuable shoreline habitat and waterfront property are avoided with the Hydro-Rake. The Hydro-Rake deposits each rake full (maximum 500 lbs.) of material directly on-shore. Upland disposal of Hydro-Raked material will be handled by the customer in conjunction with the Lake Association and taken to a central collection point where it will be disposed of by the Town of Thompson.

When deemed necessary, the Quaddick Lake Association can make arrangements with Aquatic Control Technologies to Hydro-Rake beachfronts and shorelines for lakefront homeowners at a discounted rate. In extreme cases, the Association may cover the costs of delivery of the machine ($1000) but homeowners are required to contract ACT individually by completing and submitting a sign-up form.

The Hydro-Rake deposits each rake full of material directly on-shore and then permanent disposal of the Hydro-Raked material is handled by the homeowner in conjunction with the Lake Association and taken to central collection points around the lake where it is picked up and disposed of by the Town.


The only herbicide that is effective against fanwort is fluridone, commonly called Sonar, and is only available from only one manufacturer. The use of this product has been used to resolve the overgrowth of the fanwort. The good news is that Sonar is harmless to fish, animals and humans. It is used to treat drinking water reservoirs. EPA permissible limits in drinking water are about three times greater than the concentration needed to kill the weeds. It is very effective against fanwort if necessary concentrations are maintained for approximately six weeks…..not an easy task given the flow rate of water through Quaddick, but doable if rains are not too heavy. It also greatly reduces the milfoil and somewhat reduces bladderwort for the first year. Treatment is guaranteed for two years for the fanwort, with the expectation that it would be three years or more before fanwort was a problem again. The bad news is that treating upper Quaddick alone costs between 100,000 and $150,000. Adding lower Quaddick, which occasionally sees fanwort and the other weeds in shallower areas, raises the cost to about $175,000. The view of the Lake Management committee is that, if herbicide treatment is required, it is best to treat both upper and lower sections of the lake. If the problem is kept in check by re-treatment before things get out of hand as they are now, it should not be necessary to spend this amount of money at one time again. Ongoing maintenance over 10 years will average about $36,000 per year.

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