Black Lake Aquatic Plant and Lake Management Plan
Located in the Town of Oswegatchie, NY, Black Lake is a large, natural, glacier lake. The lake’s shallow depths over 11,000 acres (stretching almost 20 miles) make it susceptible to excessive aquatic plant growth. Several aquatic invasive species (AIS) have been discovered in Black Lake, including Eurasian watermilfoil (Myriophyllum spicatum), curly leaf pondweed (Potamogeton crispus), water chestnut (Trapa natans), zebra mussels (Dreissena polymorpha), and common carp (Cyprinus carpio). These invasive species have degraded Black Lake’s native ecosystem and biodiversity.
The Town of Oswegatchie brought the GEI team onboard to examine the invasive aquatic plants and macrophytes within the lake and create recommendations for management strategies. The town’s goal was to gain a better understanding of both the aquatic plant community within Black Lake and of impairments to the waterbody. With that knowledge, GEI was able to provide the town with a realistic and feasible management plan with understandable goals and objectives. As part of this work, we conducted two separate week-long field visits approximately one week apart in late July to early/mid-August of 2021. During each visit, our staff recorded key water quality data, including dissolved oxygen, water temperature, pH, conductivity, turbidity, and nutrient concentrations to create lake profiles in specific areas.
GEI also conducted invasive and native aquatic plant surveys to further understand the extent of the invasions and potential loss of native plant life. With Blake Lake being so large (almost 4 miles across at its widest point) and having time constraints, the survey was conducted through visual inspection and the rake toss method as appropriate to inform management strategies. We used GPS and GIS to develop field maps that detailed the project site and survey points, showing the data we collected in a digestible form. While conducting the plant surveys, our teams also performed a BioBase sonar scan for vegetation volume. The results helped validate our observations and provided additional data to inform the management plan.
Our teams included the combined lake water quality data and plant survey information in the final lake management plan on strategies to reduce or eliminate invasive species and enhance overall lake health. GEI also aided the Town of Oswegatchie by doing research into permits, coordinating with regulatory agencies, and providing coordination and management of stakeholder meetings. Stakeholders are still involved with ongoing management of the lake and have completed follow-up invasive species monitoring events and removals of water chestnut.
