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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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

A Message from Our Leader: Looking Back, Planning Ahead for Our Lakes

As the Leaves Fall, Harvesting Winds Down

When Communities and Harvesters Work Hand in Hand

What’s Really Happening Beneath the Water?

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The cleanup effort aimed to improve water quality and restore the lake’s ecosystem, which had been impacted by excessive vegetation. This significant environmental effort highlights the importance of preserving natural water bodies and ensuring sustainable ecosystems. Unlike chemical treatments, harvesters provide an eco-friendly method of managing vegetation with immediate results.

Aquatic weed harvesters play a crucial role in maintaining healthy water ecosystems by removing excessive vegetation. Without intervention, this vegetation eventually dies and decomposes, releasing nutrients into the water that can fuel harmful algae blooms. These blooms deplete oxygen levels, harm aquatic life, and diminish water quality, making weed harvesters an effective, environmentally-safe solution to prevent such environmental issues.

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The harvester and operators were on lease from the White River Flowage Lake Management District. The harvester, by the end of work on June 27, harvested an estimated 50,000 pounds of aquatic vegetation currently choking out the waterway.

A very positive impact on the millpond can be seen from the Highway 73 bridge. The channels cut are  extremely obvious and show what a clean body of water can look like. A healthy millpond remains the focus of most Friends members. If the millpond is not maintained, impacts on other parts of the White River will be noticed in years to come.

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“I know how important the water is to residents who live adjacent to it and all residents of Chestermere. Weed harvesting and weed control are an uppermost issue in most people’s minds,” interim CAO Pat Vincent said.

Chestermere Community Operations removed 132.5 harvester loads of weeds in 2023. Compared to 2022, when they removed 254.5 loads.

“We have been dealing with a flowering rush infestation, and it seems were enjoying some success in 2023 with the amount of flowering rush being removed from the lake is significantly lower than 2022, which to me is a good sign that we have been dealing with this issue effectively,” Vincent said.

The vegetation is then composted and used throughout the community.

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Save Minnewawa Association was formed in 1977 and they purchased their first aquatic vegetation harvester in 1982. Since the harvester has been in use, not only have the amount of weeds decreased, but the water clarity has significantly increased.

A big reason for this is because there are fewer weeds dying in the lake and decomposing in the bottom of the lake. Also, the weeds contain a huge amount of phosphorous which is being removed along with the weeds. The more phosphorous in a lake, the more algae growth, therefore the lower the water clarity.

The board has heard the suggestion of controlling the weeds by using chemicals instead of the weed harvester. The cost of the chemicals is very prohibitive though. It was $250,000 dollars and the lake had to be treated twice a year for the first 5 years; a price tag of a half million dollars. Compared to approximately $25,000 a year it takes to run the weed harvester.

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Harvester operators volunteer their time and currently have 2 primary and 2 backup operators that received training from Aquarius Systems. There are several volunteers lined up for next year already too. According to Richardson, each load of harvested vegetation is approximately 275 cubic feet and weighs about 4,480 lbs.

The aquatic vegetation had been so bad the past few years that some did not even attempt to get their boats and pontoons in the water. After the second day of cutting, fishermen and recreational boaters were taking advantage of the open water to enjoy some of their favorite past times. The cut vegetation will be of great use to many as well, Dragonfly Nursery will use the vegetation as compost and farmer Brad Fougner will use the material as fertilizer next year.

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