Stewardship - Concord Land Conservation Trust

Controlling the Invasive Water Chestnut

A pile of water chestnuts

July 22, 2010 - The Concord Journal covers the water chestnut control effort with an excellent article and many pictures online.

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Water chestnuts (Trapa natans L.) are native to parts of Eurasia and Africa. In these areas the seeds have been harvested for thousands of years because of their nutritional value (though they should not be confused with the white "Chinese water chestnut" found in many Chinese dishes). In North America, however, they are considered an invasive species.

Introduced here in the mid-1800s, the water chestnuts grow very thickly in lakes, rivers and fresh-water tidal habitats. As a result they push out native plants. Their dense growth also means the oxygen level in the water below them is reduced which effects the fish populations. Another reason for their outlaw status is they impede recreational swimming and boating.

The Concord Land Conservation Trust has been doing battle with the water chestnut in the Sudbury River for many years now. We have organized volunteer groups to hand pull them as well as used a harvesting machine owned by Great Meadows National Wildlife Refuge. We share the costs of operating the harvester with the Town of Lincoln and the Town of Concord.

Nat Marden, our property manager, is very encouraged by the harvesting we did this year and hopes to see a much reduced number next year. Eradicating them completely is probably not realistic, but with continued perseverence we should be able to keep the population way down which will allow the native plants to flourish.

The following are pictures from the water chestnut harvesting this year. Our thanks to Alan and Ruth Bragg, John Schalow and David Witherbee for sending us these. Our thanks also to all the other many volunteers who helped out in August and September.


	Trucks are gathered on the Sudbury Bridge preparing for the launch of the harvester. Photo by John Schalow
	The harvester being lowered into the water by a crane on the Sudbury Bridge. Photo by John Schalow
	Nat Marden, the CLCT Property Manager, driving the harvester down the river. Photo by David Witherbee
	View of the cutterhead before it is lowered into the water. It has three sets of teeth that cut the root of the plant. Photo by John Schalow
	A view of the thick growth of the water chestnuts along the Sudbury River. Photo by John Schalow
	The harvester on its first pass through a bed of water chestnuts. Photo by John Schalow
	Martha's Point during the harvesting. Photo by David Witherbee
	Martha's Point after the harvesting. Photo by David Witherbee
	A close-up of the water chestnut seed. Photo by John Schalow
	Hand pulling of water chestnuts is also done using volunteers in kayaks with bins strapped to the front. Photo by Ruth and Alan Bragg
	The pile of water chestnuts from hand pulling. The kayakers fill a bin, take it to shore, dump it and go back for more. Photo by Ruth and Alan Bragg
	A view of Conantum during the harvesting. Photo by David Witherbee
	A view of Conantum after the harvesting. Photo by David Witherbee
	The shore conveyor moves the water chestnuts from the harvester into a dump truck. Photo by John Schalow
	The water chestnuts are left at Brigham Farm where they will dry out and can be used for compost. Photo by David Witherbee

CLCT, P.O. Box 141, Concord, MA 01742
Tel. (978) 369-6526
info@concordland.org