Managing Eurasian watermilfoil often requires a long-term commitment and a combination of management techniques. Mechanical harvesting, hand removal, bottom barriers, biological controls, and aquatic herbicides are all commonly used to reduce infestations and improve waterway access. Each method offers advantages and limitations, and many lake managers rely on integrated management programs that combine multiple approaches to achieve their goals.

One herbicide that has gained significant attention in recent years is ProcellaCOR®, a selective aquatic herbicide designed to target invasive plants while minimizing impacts on many native species. Lake associations and resource managers across the country have used ProcellaCOR to combat persistent milfoil infestations, often reporting successful control of invasive growth and improved conditions for recreation and native plant recovery.

However, as with any management tool, questions remain about potential long-term effects and environmental persistence.

Findings from Lake George

Following a ProcellaCOR treatment in Lake George, New York, researchers conducted independent sampling of water, sediment, and aquatic plants to better understand how the herbicide behaved within the ecosystem after application.

According to the study, degradants associated with the herbicide were detected in the upper layer of sediment five months after treatment. Researchers also reported finding the herbicide’s active ingredient, florpyrauxifen benzyl, in deeper sediment layers more than a year after application.

These findings have generated discussion among lake residents, scientists, and resource managers regarding how herbicide compounds interact with lake sediments and whether long-term accumulation may occur under certain conditions.

Balancing Benefits and Concerns

For many lake communities, ProcellaCOR has become an important tool in the ongoing effort to control invasive milfoil. Dense infestations can significantly impact recreation, property values, water flow, and native aquatic plant communities. Effective control methods can provide substantial benefits when invasive species threaten the health and usability of a lake.

At the same time, some residents and environmental advocates have expressed concerns about possible unintended consequences of repeated herbicide use. Questions have been raised regarding sediment persistence, impacts on non-target organisms, and the long-term effects on lake ecology. While current research continues to evaluate these issues, many stakeholders are calling for additional monitoring and independent studies to better understand the full environmental picture.

The Importance of Integrated Aquatic Plant Management

The debate surrounding Eurasian watermilfoil management highlights the complexity of aquatic ecosystem stewardship. There is rarely a single solution that works for every lake or waterway. Factors such as infestation size, waterbody characteristics, management goals, budget, and environmental considerations all influence the selection of appropriate control methods.

Mechanical harvesting continues to play an important role in many aquatic plant management programs by physically removing plant biomass from the waterway without introducing chemicals into the ecosystem. Harvesting can improve navigation, reduce nuisance growth, and remove nutrients contained within the harvested vegetation. In many cases, harvesting is used alongside other management strategies as part of a comprehensive aquatic plant management plan.

As research continues and new information becomes available, lake managers, regulators, and stakeholders will need to evaluate all available tools carefully. Ongoing monitoring, transparent reporting, and science-based decision making remain essential for protecting both recreational access and long-term ecosystem health.

The conversation surrounding ProcellaCOR and Eurasian watermilfoil management is likely to continue as additional studies are completed. For lake associations and water resource managers, understanding both the benefits and potential tradeoffs of available management options remains a critical part of maintaining healthy and usable waterways.

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That connection does not stop on land. It continues below the surface of our lakes, rivers, and wetlands. Aquatic plants play a critical role in maintaining water quality and supporting life. They produce oxygen, stabilize sediments, absorb nutrients, and provide essential habitat for fish, waterfowl, and invertebrates. In many ways, they are the foundation of a healthy aquatic ecosystem. Without them, water bodies can quickly lose balance.

However, like any natural system, balance is key. Too little vegetation can lead to erosion, poor habitat, and declining water quality. Too much growth can restrict water flow, limit recreation, and contribute to issues like low oxygen levels and algae blooms as plants die and decompose. Excess nutrients from runoff, changing weather patterns, and other environmental pressures can all shift that balance in the wrong direction.

Managing aquatic plants is not about removing them entirely. It is about maintaining a healthy, functional system. Mechanical harvesting and targeted removal can control excessive growth while preserving beneficial vegetation. Aquarius Systems has worked with lake managers, municipalities, and contractors to remove overgrowth in a way that improves water flow, supports recreation, and helps maintain overall water quality.

Healthy aquatic plant communities lead to clearer water, stronger ecosystems, and better recreational opportunities. Whether you are managing a lake, river, or pond, understanding the role of aquatic plants is an important step toward long term water health.

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Glyphosate is one of the most heavily used herbicides in the world. Regulatory decisions surrounding its approval have relied on research evaluating toxicity, exposure limits, and environmental impact. When a study that helped shape public confidence is pulled back, it naturally raises broader questions. Science is meant to evolve. That’s not a flaw — it’s the process. But it does highlight the importance of independent review, long-term data, and open disclosure of funding and methodology.

The same framework applies to aquatic herbicides used in lakes, ponds, and reservoirs. These products are also deemed safe when applied according to label directions, based on studies measuring water concentration levels, species sensitivity, and breakdown rates. Yet water systems are complex. Variables such as temperature, oxygen levels, sediment composition, and nutrient loading all influence outcomes in real-world conditions. Ongoing evaluation matters.

For communities managing aquatic vegetation, the discussion often comes down to balancing effectiveness, cost, and environmental impact. Mechanical harvesting, for example, physically removes vegetation from the water body — along with the nutrients contained in that plant material. Left in place, excessive vegetation eventually dies and decomposes, releasing nutrients that can contribute to algae blooms and reduced oxygen levels. Different management tools bring different trade-offs.

What the glyphosate retraction ultimately reinforces is this: sound environmental decisions depend on sound science. That science must be transparent, repeatable, and open to scrutiny. Whether addressing agricultural weeds or aquatic vegetation, long-term ecosystem health depends on continually testing assumptions and being willing to re-examine conclusions when new information emerges.

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Eurasian water milfoil grows aggressively, uprooting native vegetation, disrupting aquatic habitats, and interfering with recreation. By 2013, the Commission was spending up to $250,000 per year on herbicide treatments to control approximately 300 acres of milfoil. Grants helped fund these efforts, but by the mid-2010s, funding had dwindled to around $50,000 annually.

After a decade of chemical treatment, the Commission made a bold decision to stop using herbicides altogether. The results? Within a few years, the milfoil population began rebounding. According to the aquatic ecologist who has monitored these lakes for 18 years, the plant is “too big, it’s too much” for manual removal alone, which costs roughly $2,500 per day.

The lesson is clear: eradication with herbicides is expensive, temporary, and environmentally damaging. Even if chemicals were used without regard for ecological impacts, controlling the entire population long-term is not practical.

Instead, a management-focused approach should to taken to target plants that interfere with navigation and recreation rather than attempting total eradication. Mechanical harvesting offers a solution; it doesn’t attempt to eliminate every plant but efficiently manages growth, maintains recreational access, and avoids repeated herbicide costs.

After more than a decade of observation, the evidence is in: spending hundreds of thousands of dollars chasing eradication with chemicals is far less effective than strategic, mechanical management. It’s time for a shift in mindset: toleration and control, rather than endless eradication efforts, may be the only sustainable way forward for our lakes.

Read more about the Lower Eagle River Chain of Lakes Commission’s milfoil efforts

The piles of weed surfaced two weeks ago after strong winds disturbed the lakebed. The Bay of Plenty Regional Council began removal on 14 November, with Rotorua Lakes Council handling disposal. Ongoing weather fluctuations have worsened the smell, prompting calls for increased investment in preventative weed management to protect both the lake and Rotorua’s visitor experience.

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