Invasive water chestnuts present a significant threat to the Nashua River’s biodiversity and recreational value. These plants form dense mats of vegetation that degrade water quality, reduce oxygen levels in the water impacting aquatic life, compete with native plant species, and make boating difficult to impossible.
Plants emerge in May and develop up to 20 seed pods each; and each pod can contain 10 to 15 seeds. By early fall, the seed pods drop to the river bottom where they remain viable for 12 or more years. The key to protecting the river from water chestnuts is to remove the plants from the river before they can drop their annual seed pods.
Historically, the Nashua River Watershed Association (NRWA) has worked with the MA Department of Conservation and Recreation, the Town of Pepperell, and the Nashua River Regional Aquatic Invasives Alliance, to address the large infestation in Pepperell Pond. That area, which covered over 130 acres in 2018, is now greatly reduced. To address water chestnut in areas beyond Pepperell Pond (both up and downstream), ongoing scouting and hand-pulling of the plants is required. Many volunteers have assisted with these efforts under the guidance of the NRWA.
Funded by the Stewardship Council, in 2025, the Adopt-a-River Program was initiated as a pilot project, to be managed by the NRWA. The program enlists volunteers to adopt specific stretches of river and commit to scouting and removing water chestnuts from their section throughout the summer and fall seasons. Training, equipment (except for boats), and management is provided through the partnership of the NRWA and the Council. With a first-year success story, the Adopt-a-River Program is being continued and expanded going forward.