Northern Lake Frog-bit and Water Chestnut Control and Mapping Project

Lake Champlain Committee (2016). Northern Lake Frog-bit and Water Chestnut Control and Mapping Project (Final Report). Grand Isle, VT: Lake Champlain Basin Program.

• Dataset 1
• Dataset 2

Arrowwood Environmental, LLC and the Lake Champlain Committee collaborated on a project to conduct an inventory of frog-bit and water chestnut in northern Lake Champlain. The Northern Lake Frog-bit and Water Chestnut Control and Mapping Project was undertaken with the following objectives: 1) remotely identify frog-bit and water chestnut habitat; 2) conduct field inventories in these habitat areas to identify new infestations; 3) initiate control on any new, small infestations; and 4) continue control on known populations in the northern lake.
The study area consisted of the lake and its adjacent marshes from Colchester Point and Ausable Marsh north to the Canadian border. Two types of remotely identified Habitat Areas were identified: Water Lily Habitat Areas and Marsh Habitat Areas. To identify populations of invasive plants, point-intercept and visual survey methods were used in the Water Lily Habitat Areas, and visual surveys in the Marsh Habitat Areas. Though absent in most Water Lily Habitat Areas, frog-bit was found to be widespread and abundant throughout the study area in many Marsh Habitat Areas. Over 100 pounds of frog-bit were harvested from these communities, but it was determined that these populations were too large and dispersed to be effectively controlled. The impact that frog-bit is having on these marsh communities is unknown.
Unlike frog-bit, water chestnut was found to be absent from most of the northern lake. This species has been found only in Missisquoi Bay, in the vicinity of the Missisquoi National Wildlife Refuge (MNWR). There is only one site where it was documented outside of the MNWR borders, where 24 rosettes were pulled by MNWR contractors. Continued monitoring in the northern lake for these two species is recommended.