The two current methods for water chestnut removal are hand-pulling and mechanical harvesting.

Water chestnuts are an invasive species native to Eurasia that was brought to the US in the 19th century. Water chestnuts are problematic because they grow in thick mats, blocking sunlight from reaching the water and absorbing dissolved oxygen. Water chestnuts out compete native vegetation and use up the oxygen for other aquatic life, such as fish. Moreover, when water chestnut growth becomes too thick, the river becomes unnavigable.

Water chestnuts generally starting growing in late June and drop their seeds into the river in August. The hand-pulling season, therefore, occurs between early June to mid-August.

For CRWA's Canoeing for Clean Water program, CRWA staff lead groups of 30 volunteers in kayaks onto the river to hand-pull water chestnuts. The events last 2-3 hours and generally occur in the morning to avoid extreme heat and severe weather events. CRWA and Boating in Boston provide all necessary equipment and training.

On average, CRWA leads 25 events and 500+ volunteers per season. In 2015, 40 tons or 80,000 pounds of water chestnuts were removed from the Charles.

Volunteers meet at the Newton Historic Boathouse at 2401 Commonwealth Avenue in Newton. Parking is available across the street at the end of Norumbega Road.

Sign up for a public event through CRWA's website www.crwa.org