At the Lake Archer Association (LAA), we believe in sharing the results of our hands-on efforts to manage invasive species. Through three years of active management, we have found that a methodical, manual approach allows us to contain milfoil while protecting the lake’s vital natural biodiversity.
Through field observations and data collection, we have developed a strategy based on several key experiences:
The "Garden" Philosophy: We have found that milfoil management is more like weeding a garden than shaving a beard. If you stay ahead of it with frequent visits (every 4–6 weeks), the work of keeping it contained is significantly smaller than the work of taming a full-scale infestation.
The Power of Manual Harvesting: We have found that a combination of hand-harvesting divers and DASH (Diver Assisted Suction Harvesting) is highly effective. Other lakes have seen similar success; for example, the 1,000-acre Otis Reservoir reduced milfoil from 50 buckets to just 1 bucket in three years using these manual methods [1].
Solving the Search Bottleneck: We have found that the biggest expense in management is "search time." By using our MilfoilMapper sonar technology to identify weed beds before divers enter the water, we ensure that their time is spent pulling weeds rather than searching for them.
While chemical treatments like ProcellaCOR are a common consideration, our review of the data and local conditions led us to prioritize manual removal. We have found several compelling reasons for this choice:
Cost Realities: While a manual dive program is a significant investment—costing approximately $20,000 annually (based on $7,500 for 5 days of hand-harvesting and $13,749 for 5 days of DASH)—we found it to be more efficient than herbicides for our current state. An herbicide treatment for 17 acres would cost between **$32k–$38k**, and because ProcellaCOR is milfoil-specific, it would not address other invasives like Brazilian Waterweed, still requiring manual diving afterward.
Protection of Native "Good" Weeds: We have found that native plants like Coontail are essential to Lake Archer, making up nearly 40% of our ecosystem [2]. Research indicates ProcellaCOR can cause a 60–70% reduction in Coontail in treated areas, and up to a 30% reduction in untreated areas [3]. This removes the natural competition that prevents harmful algal blooms.
Health and Environmental Observations: Our research highlighted studies showing potential impacts on freshwater wildlife, including neurological development issues in fish [4] and harmful negative impacts on invertebrates, insects, and trout at all treatment levels [5]. Furthermore, we noted evidence of harmful mouse and rat side effects in laboratory settings [6].Â
Preserving Tool Efficacy: We have found evidence that milfoil can develop resistance to ProcellaCOR [7]. We prefer to maintain a manual program and save chemical options as a last resort to prevent the development of resistant "super-weeds."
We don’t profess that this is the only way to manage a lake, but we have found it to be the most responsible and effective path for Lake Archer. We are working on a way to share access to the MilfoilMapper software and our "Scout & Mark" workflow so that other associations can see how we turned technology into a tool for environmental stewardship.
The information shared on this site is an account of the findings and results experienced by the Lake Archer Association. These results are specific to our weed density, water chemistry, and volunteer efforts. We recommend all lake associations consult with aquatic experts and local regulatory bodies.
[1] Otis Reservoir Management Success: From 2021 to 2023, Otis Reservoir (1,000+ acres) went from 50 five-gallon buckets to 6, and finally to just 1 bucket using DCR-recommended hand-harvesting.
[2] Native Vegetation Density: Native "good" weeds make up 21% to 40% of Lake Archer's ecosystem.
[3] Impact on Coontail: VT 11 Lake Post-Treatment Survey showing significant reduction in native plants following herbicide use.
[4] Fish Neurological Impact: Toxicity Study on Freshwater Fish (Video) showing developmental impacts.
[5] Impact on Non-Target Species: Beyond Pesticides Report (2025) regarding threats to biodiversity and aquatic species.
[6] Mammalian Lab Studies: Evidence of mouse/rat side effects including mammary gland tumors and organ weight reduction (Reference #42-45 in LAA Draft).
[7] Herbicide Resistance: Documented evidence that Milfoil develops resistance to ProcellaCOR (Reference #58 in LAA Draft).
[8] Lake George Persistence Case Study: Environmental Persistence Video showing chemical tracers persisting longer than initial assumptions.