Water Chestnut Information Page
The water chestnut (trapas natans) is an invasive species that could wreak havoc on the Lake Hopatcong ecosystem (and no, it’s not the same as the water chestnut you get on your Chinese food). Thus far, it has been found on Lake Hopatcong in Landing Channel in 2010 and in Woodport and the Jefferson Canals in 2014 and 2015, all of which had a quick response and removal effort because of the Water Scouts program. As outbreaks occur at lakes throughout the region, including just downstream on Lake Musconetcong, the community has to be vigilant.
Thankfully, in 2010 the Knee Deep Club established the Water Scout program, which enlisted dozens of volunteers to scour the shoreline to find and remove any instances of the water chestnut. In fact, the one discovered colony was found because of this program. In 2013, the Lake Hopatcong Foundation took over the management of the Water Scout program.
The lake’s shallower, more stagnant waters are most at risk of water chestnut infestation, and since the plant multiplies so quickly, it could damage the natural environment and the recreational opportunities in short order.
The water chestnut itself is pretty distinctive: it starts with a seed that has four barb-like prongs, which can be transmitted to the lake by boaters or by sticking to the feathers of geese, ducks, and other birds. Once the seed embeds itself in the lake bottom (particularly shallow areas without much turbulence), a stringy plant grows toward the surface, creating clusters of leaves called rosettes. Each leaf is about 2 inches wide, serrated with an arrowhead shape, and the rosettes can multiply quickly, with each producing up to 20 seeds (which can remain dormant for more than a decade). The result is a lake surface covered in green, and a body of water deprived of sunlight and, therefore, aquatic life.
Plants that are discovered at an early stage can be removed before going to seed. Because of that, the bulk of the search for the water chestnut takes place in June (when the first signs of rosettes appear) and July. By August, the plants might have dropped seeds, and removing the plants doesn’t guarantee that a larger colony won’t appear the following year.
So the Lake Hopatcong Foundation, the Knee Deep Club, the Lake Hopatcong Commission, and the N.J. Department of Environmental Protection all encourage residents to be on the lookout for this very damaging invasive species. To become even more familiar with the species, download our Water Chestnut Brochure or check out the following links: