Bad News: Water Chestnuts Creeping South

A biologist, an environmental planner, and a naturalist trolled the lower Connecticut River last week in a small boat, looking for water chestnuts. About four hours in, a small clump of them came into view at the edge of Eustacia Island. The leaves had the telltale jagged edges and the brown seed pods revealed the classic sharp points.

The group had met their objective: they’d found water chestnuts, but this news was bad. “It’s the only project we’ve ever been on where the objective is not to be successful,” said Judy Preston, director of the Tidewater Institute, who is working with the U.S. Fish & Wildlife Service and the Connecticut River Estuary Regional Planning Agency on this project to search for the water chestnut before it can do damage.

Water chestnuts, once they take hold in quiet waters, grow so fast that they leave no room for other marine life. Their presence in the lower Connecticut is a reminder that this invasive plant has now worked its way south from Massachusetts. Fears are that it will spread elsewhere, including the Thames River.

A grant from the U.S. Fish & Wildlife Service funded their sleuthing and inventory making. Preston’s two colleagues are Margot Burns, the environmental planner for the Connecticut River Estuary Regional Planning Agency, and Andrew MacLachlan, a biologist for the U.S. Fish & Wildlife Service. They set aside half-days to conduct these searches when their schedules allow them. They patiently creep along the edges of the river and its tributaries in either a small USFWS motorboat, as they did last week, or smaller craft like kayaks.

Water chestnuts are easier to see at low tide because they root underwater. But navigation as the tide recedes requires careful maneuvers. More than once, Burns and Preston disembarked, standing on rocks or in the water. They used paddles, poles and their hands, guiding the craft around giant rocks or low water. I got out a few times to keep the boat light. At least twice, MacLachlan disentangled handfuls of weeds from around the propeller.

The project to locate the water chestnut is crucial because this plant can do so much damage. No one thought that possible in the 1800s, when this European plant immigrated to America.

“It was brought here intentionally by botanists, and people who had botanical gardens,” said Cynthia Boettner, who is the invasive plant control initiative coordinator for the U.S. Fish & Wildlife Service. “It is a kind of pretty plant in small quantities,” she added.

Typical of invasive plants that cause damage, the water chestnut took many, many years to stray beyond the few ponds where horticulturalists placed it so long ago. Then, once it got out, the spread intensified. To learn more, visit the Invasive Plant Atlas of New England.

A determined traveler           

The ability of the water chestnut to travel sounds a little like a horror movie. “There have been reports of seeds stuck to wild waterfowl,” Boettner said. “So we think that it might be moving around that way, as well. The seeds have a bunch of prickly spines on them that can attach to soft things.” And they do, to boat bumpers and ropes, and anything else they can find.

If it’s in the Connecticut River, it could easily be in other rivers and ponds here. Preston said that anyone who spends time on rivers and connected waterways ought to be on the lookout for the water chestnut.

Within the last few years, people found water chestnuts growing in Chapman Pond, a tidal inlet in East Haddam, and Hamburg Cove, on the eastern side of the river in Lyme. Volunteers and biologists pulled them out by the bottom-grabbing roots, the only method to keep them from taking over.

This season, again, citizens’ reports guided the search. Preston and her colleagues were acting on reports from boaters who thought they might have seen the plant.

Acting quickly matters. Last year, water chestnuts covered the entire surface of the Hockanum River, a small Connecticut River tributary in Massachusetts, before anyone noticed it. Groups went out in canoes to remove the plants.

If you think you have seen the water chestnut, take a photograph of it, note the location, and contact the U.S. Fish & Wildlife Service or Preston through the Tidewater Institute.