Invasive Water Chestnut

Water ChestnutThe water chestnut is an invasive plant species that can quickly wreak havoc on the Lake Hopatcong ecosystem. As outbreaks occur in lakes throughout the region, including just downstream on Lake Musconetcong, the community has to be vigilant.

The water chestnut itself is fairly distinctive in appearance. 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 two inches wide, serrated with an arrowhead shape. 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.

Water Chestnut 2Plants that are discovered at an early stage can be removed before going to seed. Therefore, 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 may have dropped seeds, so removing them doesn’t guarantee that a larger colony won’t appear in subsequent years.

The Lake Hopatcong Foundation, the Knee Deep Club, the Lake Hopatcong Commission, and the N.J. Department of Environmental Protection encourage residents to be on the lookout for this very damaging invasive species.

To become more familiar with the species, download our Water Chestnut Brochure or check out the following links:

U.S. EPA Blog: Invasion of the European Water Chestnut

U.S. Fish and Wildlife Water Chestnut Fact Sheet

National Parks Service Water Chestnut Information Page

New Jersey Water Chestnut Task Force Water Chestnut Presentation