POTSDAM - During the summer of 2012, the presence of Eurasian watermilfoil, an invasive aquatic plant, was detected in Norwood Lake, a fluvial lake created by a dam on the Raquette River in Norwood.
Eurasian watermilfoil is one of the nations most widespread invasive aquatic plants and has already invaded more than 50 lakes in New Yorks Adirondack State Park.
Proliferation of the plant in lakes tends to choke out native aquatic plant species and thereby reduce optimal game fish habitat. It also can interfere with boating and swimming activities.
This plant is very capable of spreading rapidly due to its range of tolerances, its rapid growth rate, and ability to easily spread by growth of plant fragments, Clarkson University Biology Professor Michael Twiss said.
Upon the urging of Norwood lakeside residents, Mr. Twiss and his students of limnology (freshwater oceanography) tasked themselves with examining the case for invasion in Norwood Lake with the aim of recommending sustainable management practices to control the plant.
The students used their technical skills to evaluate key factors that would allow Eurasian watermilfoil to spread in Norwood Lake. Measurements were made of the key nutrient (phosphorus), the light climate, and the area of the lake suitable for the plant to spread. Phosphorus concentrations were able to support growth and the degree of light penetration revealed that 80 percent of the lake area is suitable for Eurasian watermilfoil spread.
This plant is here to stay,according tos Mr. Twiss. However, various options are available to manage this invasive species.
Our students have looked carefully into various techniques used elsewhere and have discounted some based on high cost or those ill-suited for use in this system, such as use of herbicides. For example, mechanical harvesting is too costly and can cause increased spread by fragments downstream. Hand harvesting is equally expensive. Moreover, it has cost hundreds of thousands of dollars to control this plant in Upper Saranac Lake, and it remains there.
Sustainable options will likely require coordination among the local government, residents, and Brookfield Power, the company controlling the dam at Norwood Lake, concluded the students at a brief presentation at the Norwood Municipal Building on Dec. 6.
Winter drawdown of water levels has been used to kill Eurasian watermilfoil in other water-level regulated lakes. However, this action also kills native aquatic plants and would require a deviation from the Federal Energy Relicensing Commission to deviate from the agreed water level regulation and approval from the NYSDEC.
Allowing the plants to spread naturally will eventually lead to self-control as natural pests would increase and serve to reduce the population. However, this can take as long as 10 years to come to equilibrium and may not be feasible, owing to the detrimental impact the plant has on recreational value in this lake, a focal point in the community.
Lake stewards that can assist in educating the public and help prevent spread of the plant could be involved with environmental monitoring in the lake to determine the rate of Eurasian watermilfoil spread, so that any management plan decided upon can have the information needed to determine the best solution for all stakeholders.
Control efforts have to be sustained from year to year to set up management projects for success, says Mr. Twiss. Discussion needs to take place now so that the community can be prepared for making decisions on the choice of a sustainable management plan to maintain the value of this important regional water resource.
Given the value that Clarkson University places on the natural environment and the social wellbeing of its students, employees and the broader Northern New York community, the University mission, vision and values statements were recently revised to truly integrate sustainability principles and practices into all of its activities. This investigation of a pressing issue regarding an invasive aquatic species in a local community is one example of this.