Water Chestnut Management

Water Chestnut (Trapa natans) is a major nuisance in the Concord and Sudbury Rivers; smaller infestations are found in the mainstem of the Assabet River as well. It is also in many local ponds and lakes.

In 2017, OARS released its "Water Chestnut Management Guidance & Five-Year Management Plan for the Sudbury, Assabet, and Concord River Watershed." The Guidance compiles the most recent research on the lifecycle and control of water chestnut, provides guidance on permitting of control efforts (for both permittees and Conservation Commissions), and lays out a management plan for the Sudbury, Assabet and Concord Rivers. You can download the Guidance and its Appendices here:

Full Guidance (3.8 MB)
1. Background (taxonomy, history, biology, impacts, management options, funding, permitting for control efforts, model permitting language) (2.9 MB)
2. Water Chestnut in the SuAsCo Watershed (distribution, management history)
3. Water Chestnut Management Plan (goals, Action Plan)
4. References
Appendix I: Responses to OARS/MACC survey
Appendix II: Sample Wetlands Protection Act permitting (RDA, NOI, OOC)
Appendix III: Water Chestnut Maps: OARS' 2014 survey index and on-line maps

The project was supported through the Natural Resource Damage Assessment and Restoration Programs of the U.S. Fish and Wildlife Service, National Oceanic and Atmospheric Administration, and Massachusetts Department of Environmental Protection, using funding via the Nyanza Trustee Council, to restore natural resources that were injured by the release of mercury and other contaminants from or at the Nyanza Chemical Waste Dump Site in Ashland, Massachusetts. We are grateful to the Nyanza NRD Trustees for their support.

You can help!

By hand-pulling these small patches on the river, we can control it before it becomes a major nuisance here. Read more about invasives in our rivers.

Volunteer this summer! Water chestnut pulling on the Assabet River will take place in June and July (dates-to-be-determined). Please let us know if you are interested in helping.

Help us track water chestnut: If you are heading out on our rivers, please print our ID and Reporting Card and take it with you on your trip. Don't forget to mail it back or report via email!

In July and August 2016, volunteers hand-pulled truckloads of water chestnut from the Sudbury and Assabet River. But the work needs to continue!

Hand-pulling efforts by OARS volunteers and staff since 2008 have made a visible a visible difference in the Assabet River. Volunteers in canoes need to return every year to pull water chestnut because the spiny "chestnuts" (seeds) are viable in the sediments for up to 10-12 years. The goal each year is to hand-pull the new plants before they reproduce and drop another generation of chestnuts. If this is done year after year until no more plants appear, an infestation can be eradicated and then only a small amount of effort can control any new populations.

Thanks: A big hand to all our volunteers from Stow, Framingham and surrounding towns! OARS would like to thank Rob Albright, Bob Collings, Bob and Mary Cutler and George Simpson for giving us access to the river to launch our canoes. Many thanks to Stow Acres Country Club, Bob Collings, Honey Pot Hill Orchard, and the Assabet River National Wildlife Refuge for composting the weeds. Special thanks to Tom Largy and Dick Lawrence for hauling the weeds in their pickup trucks and to Laurence Ullman, the Acton Boy Scouts, Pat Conaway and the Charles River Canoe and Kayak Service for supplying canoes.