YOU can control Water Chestnut!

Invasive water chestnut is a fast-growing annual and, if left unattended, will easily cover an entire waterbody. YOU can prevent it from clogging our rivers—become a Weed Warrior.

Learn how to identify, remove, and report water chestnut infestations on our rivers, using our new App. We recommend you watch our training video. Whether you prefer working alone or with a team, your help is needed.

Water chestnut (Trapa natans) is a rooted, floating aquatic plant that is easily identified.

1. Floating leaves form a rosette
2. The diamond-shaped leaves are toothed on two sides and connect to the stem by a long, flexible submerged stalk
3. Submerged leaves are featherlike, whorled around a stem
4. Sharp four-pointed nuts may be attached at the bottom of the root and new nuts are formed under the rosette

Hand-pulling infested areas repeatedly is the most effective way to achieve long-term control

1. The best time is when the plants first appear at the water surface in early May. They are small, and you should gently pull up the whole plant, including its roots.
2. As the rosettes get larger (up to 15”), grip the stem firmly and pull, breaking off the stem below the submerged leaves just above the roots. This will prevent them from re-sprouting and keep mud out of your boat.
3. By August, the nuts are maturing, so carefully flip over the rosette and break it off to avoid nuts dropping off.
4. Place what you pull into your boat in a laundry basket or other container with holes, draining out the water and keeping rosettes and nuts from escaping and starting new infestations.

Any disposal method must ensure that there is no possibility for viable plants or seeds to be re-released into the river.

• Composting is the best, but the plants must be away from the water and above the floodplain
• Bag and take home for disposal or composting
• Remember: you are not finished until you clean your boat carefully to avoid carrying invasive plants to other water bodies. No Aquatic Hitchhikers!

Use our reporting App to share with us and other river users where you have seen or pulled water chestnut.

Reporting App Instructions:

1. Zoom in on the map to where you have seen or pulled water chestnut and click once to drop a pin
2. Select icon for seen or pulled
3. Enter your name and email so we can follow up with you if needed
4. Estimate how many rosettes you saw or pulled
5. Attach a photo if possible
6. Do this on or near the river or when you get home

Visit the OARS Water Chestnut Reporting App


When you are on the water:

• Wear a life jacket
• We recommend your work with a partner
• Wear gloves and shoes that can get wet (the nuts can be sharp!)
• Bring a bailer. A boat full of water is tippy.
• Stay hydrated. Bring water!


Invasives on our rivers
Mapping and managing invasive water chestnut
Weed Warriors

OARS and other organizations hold volunteer-pulling events. If you or your employer are interested in joining these fun and rewarding service opportunities, email OARS or call 978-369-3956.