SWCA Lake Warner Plant Assessment Report
A Plant Assessment of Lake Warner conducted in late summer by SWCA environmental consultants provided a detailed report of the findings in December. The report describes vegetation types by highest prevalence and percentage of cover by quadrat. Each quadrat is 200 feet by 200 feet in size (40,000 square feet) and a total of 85 quadrats were defined to encompass the entirety of the lake. The study identified over 30 species of aquatic and emergent wetland vegetation. The vast majority of these plants were native; only two invasive submerged aquatic plants were observed, curly-leaf pondweed (Potamogeton crispus) and water chestnut (Trapa natans). Three additional invasive emergent/wetland plants were identified on the banks and shallow waters surrounding the lake. This density of plants has been the historic condition within Lake Warner for many years. Achieving this density and diversity of aquatic plants with largely native plants (only two species of aquatic submerged or floating invasive plants were found) is not common in the Northeast. While this diversity is important, and not often the case within freshwater lakes and ponds of Massachusetts, the plants are also very dense throughout the lake. This density results in a number of water quality and habitat quality issues. With almost no open water areas, there is not a very high diversity of wildlife habitat within the water column.
Two surface water and two deep water samples were taken to determine water quality characteristics. Water quality measurements supported, as in previous studies of the pond, that the pond is eutrophic to hypereutrophic based on phosphorus concentrations in all four samples.
Two composite surficial sediment samples from the bottom of Lake Warner. The first composite sediment sample was collected from the eastern end of the lake near the inflow of the Mill River and a smaller tributary. The second composite sediment sample was collected at the western end of the lake near the boat ramp. The purpose of this surficial sediment sampling is to identify the accumulated sediment type and to determine whether there is a high content of phosphorus in the accumulated sediment in the lake. The results indicate that elevated concentrations of total phosphorus were detected in the surficial sediments at both ends of Lake Warner.
The Friends goal is to improve overall habitat value and water quality within Lake Warner. Some measures to achieve these goals are managing invasive plant species, thinning submerged and floating aquatic vegetation in portions of the waterbody, and attempting to reduce nutrient loading within the lake. The report is being used to develop a vegetative management plan that can reduce the overall volume of vegetation while protecting the high diversity and ecosystem being supported by it. Water quality monitoring, strategically working to support best management practices and stormwater improvements throughout the watershed are ongoing goals of the Friends.
Read the Lake Warner Aquatic Plant Assessment report in full: Lake Warner 2023 Assessment Report