Environmentalists Seek Local Volunteers to Pull Invasive Water Chestnuts on the Connecticut River

A carpet of water chestnut plants covering the northern section of Selden Cove in July 2019 before removal by volunteers organized by Friends of Whalebone Cove (Credit: FOWC)


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Summer is the season for pulling out water chestnuts along the Connecticut River, and groups concerned with the prolific invasive plant are getting ready and organizing volunteers. 

The Connecticut River Conservancy aims to promote and coordinate removal of the invasive European water chestnut from the river’s source in northern New Hampshire, down to the Long Island Sound.

The conservancy works with local groups like Friends of Whalebone Cove, which has taken on the task of removing invasive plants from Whalebone Cove, Selden Cove and Selden Creek, near Hadlyme.

“What we’re doing is a small part of what they’re trying to do,” explained Humphrey Tyler, a board member of the Whalebone Cove group.

Along with out-competing native aquatic plant and animal life, the 2-4 inch canvas that chestnuts develop on the surface of the water makes it harder for boats to pass through, and impossible to cast a fishing line. The plants also cause water to stagnate, creating a breeding ground for mosquitoes that carry diseases dangerous to people, said Tyler.

“From an ecological point of view, it can be pretty devastating,” said River Steward Kelsey Wentling for the Connecticut River Conservancy. “There are coves along the river, and in other places, that in some sense have already been lost to the plant. So it’s really important that we’re doing this consistently throughout the entire river.”

There is a short window each year to pull as many plants as possible before seeds begin to drop and spread around mid-August. When its seeds drop, water chestnut plants can move easily down the river, and even upriver in tidal areas, said Wentling.

According to Tyler, the water chestnut is mostly limited to freshwater, so it’s not common on the river below Hamburg Cove, but it has been been discovered at the northern end of the Lieutenant River in Old Lyme as well, and volunteers will be monitoring that stretch of water again this year.

Fiske said they haven’t seen much of the water chestnuts in Whalebone Cove this year – volunteers pulled about 75 plants out of the cove last year.

Last year, water chestnuts covered 5,000 to 7,000 square feet of Selden Cove, but volunteers got a late start and couldn’t pull all the plants before late August, so more seeds likely dropped and will grow new plants this year, said Tyler, and they expect a large infestation in Selden Cove again this year.

An earlier start this year will mean a much smaller infestation next year.

The group will start monitoring for water chestnuts in the coming weeks, as they typically start to appear in late June. As soon as they spot the plants, they’ll organize volunteers to start pulling them out. 

Seeking volunteers

Friends of Whalebone Cove needs volunteers for two tasks. The first is scouting for plants in the coming weeks. If anyone is out on Selden Cove or Creek, or Whalebone Cove, they should let the group know if they see any water chestnuts. 

The second step will be actually pulling the plants in July and August. Pulling is organized around high tide, when it’s easiest to get in and out of Selden Cove. People with canoes or kayaks can go in and pull the plants out of the water, and they need volunteers with small motorboats to bring the plants to shore before they’re taken to dry land to compost.

Anyone can reach out on Facebook or by email to get involved, or to report any water chestnut sightings on Selden or Whalebone coves. There may be some extra canoes and kayaks available for people who want to help, but don’t have a boat of their own.

It’s not difficult to practice social distancing on the water, said Fiske, and pulling chestnuts is a good way to get out on the water while also making a positive impact on the environment.

Most years, the conservancy also organizes events of large groups of volunteers to pull chestnut plants. This year, there will still be organized group pulls, but they’ll be kept smaller and with more precautions in place to prevent the spread of COVID-19, said Wentling. That includes staggering boat launches to avoid congestion, asking people to bring their own boats, sanitizing rentals, providing masks and hand sanitizer, and requiring people sharing a boat to be from the same household.

The conservancy is beginningt to use the Water Reporter app this year to try to streamline the process of locating water chestnut infestations and organizing removal. Anyone who wants to report infestations for the conservancy can make an account, and when they find an infestation, take a picture and tag its location to the conservancy’s map.

“It’s giving people the chance to be citizen scientists and collect that data, which is really, really useful for us,” Wentling said.