Water Chestnut

About Species
  • Feathered out floating leaves
  • Sometimes with white flower
  • Spiked chestnut below the surface
Last Seen
  • Lake Zoar
  • Housatonic River
  • Hudson River
  • Connecticut River
Wanted For
  • Creating thick mats on water which hurt boating and swimming
  • Killing native plants and fish by blocking sunlight
Favourite Hangouts
  • Boat props
  • Trailer wheels and plates
  • Backyard Ponds and Gardens
  • Hurting swimmers with spiked chestnuts
A Brief History

Water chestnut was introduced to the US in 1877 from Europe as a plant to add to small garden ponds. It was planted in many areas in Massachusetts, but quickly escaped to other water bodies by flowing through rivers, and moving through boats, birds, and just from people grabbing and moving them. It has since invaded water bodies throughout Connecticut including the Housatonic and Connecticut Rivers, Lake Lillinonah, and neighboring Hudson River in New York.

Remove if found

Properly dispose of all plants away from the lake in a trash receptacle.

Always CLEAN, DRAIN and DRY your boat, trailer, and equipment before entering Candlewood Lake.

Threats posed by this species

Water Chestnut grows on the surface of the water, sending a long root to the bottom of the lake bed, while its leaves and flower float on the top of the water. This means it can block sunlight for plants that grow deeper in the water, including important native species that fish use for habitats. It also can make lakes and rivers unappealing to swim in or look at, since the plants can cover the entire surface, covering almost all of the water.

How does this species spread?

Water chestnuts have a seed with spikes that allow them to grab hold of animals, other plants, and some boats, allowing them to get carried to new water bodies and begin their invasion there. The plants themselves can also get caught on boat trailers and props, spreading when that boat moves to a new waterbody that doesn’t already have water chestnut. People also sometimes still plant water chestnut in nearby water bodies, not realizing how quickly they can spread and the negative impacts they can have.