The ongoing battle against invasive water chestnut

September 21, 2023| Environment, People

By: Donna Macalle-Holly

Ten years ago, the Lake Hopatcong Foundation took charge of the Lake Hopatcong Water Scouts program, which was previously managed by the Knee Deep Club. Each summer, volunteer Water Scouts help protect the lake environment by locating and removing invasive water chestnut from the lake. 

Throughout the summer of 2023, our team of Water Scouts paddled along their designated area of shoreline looking for water chestnut and hand-pulled 78 water chestnut plants (containing 96 rosettes) in the cove south of Liffy Island in the Woodport section of the lake.

Water chestnut is a highly invasive aquatic plant known for its rapid growth and ability to spread quickly in freshwater environments. When these plants decompose, they deplete oxygen in the water, disrupting the delicate balance of the aquatic environment. They also outcompete native aquatic plants, and their thick mats can hinder recreational activities on the lake.

Each water chestnut plant can have multiple rosettes and each rosette can produce up to 20 seeds that drop to the lakebed and can remain viable for up to 12 years, which makes eradication challenging and why the dedication of the Water Scout volunteers is so critical to managing the spread of this aggressive invasive species in Lake Hopatcong. 

It is best to find and remove the plants early in their season before the hard seeds form and drop in the lakebed to fuel future growth. But Water Scouts do continue to search for water chestnut through the end of the season. This year, a water chestnut plant measuring 12 inches in diameter, found and removed late in the season, still had 15 of its 18 seeds still attached (see video HERE). 

You can help prevent the spread of water chestnut and other aquatic invasive species by remembering to Clean, Drain, and Dry your boat, fishing equipment, and other gear… in every waterbody, every time. You can also join our team of volunteer Water Scouts! Click HERE for more information.