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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The study by the U’s Minnesota Aquatic Invasive Species Research Center looked at 13 years of vegetation survey data collected from about 1,100 lakes by the Department of Natural Resources.

The surprising results: Researchers found no evidence that having a diverse plant community somehow keeps invaders such as curly-leaf pondweed or Eurasian milfoil from taking hold.

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Fishermen certainly appreciate a good balance of both milfoil and hydrilla for bass populations. Less vegetation and it doesn’t provide enough cover for juveniles, and too much makes it too difficult for the fish to navigate – and for the fisherman to locate them. Too much vegetation also causes difficulties for swimmers, skiers and boaters, as well as clogging powerplant intakes and municipal water systems.

Another definite drawback to a lot of milfoil is low oxygen content and increased eutrophication caused by the decaying of the plant.

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Indian Lake Watershed Project Received New Weed Harvester

Aquatic Invasive Species: Eurasian Watermilfoil

Definition of “Waters of U.S.”

The Importance of Restoring Your Shoreline

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The aquatic weed harvesters are used for establishing things like navigation lanes and clearing out areas of varied plant growth, like impacted boating or swimming areas and the weed harvester can remove a lot of plant material.  Alternatives would be more time consuming and expensive!

Funding for the 18-year old program is now in question as concerns were raised whether the harvesters are contributing to the spread of Eurasian watermilfoil by fragmentation in Lake Champlain.

However, an environmental analyst with the state’s Department of Environmental Conservation said that there’s no hard scientific evidence outside of anecdotal observation to suggest that harvesting is causing the spread of the milfoil.  There are no data sets to answer whether the two lake weed harvesters are the major spreaders of the invasive plant species when there is plenty of boat traffic making waves and cutting through the invasive vegetation.

As part of a summer-long effort to cut a channel in Black Lake (New York), the Black Lake Association used an aquatic weed harvester to cut and remove invasive Eurasian watermilfoil.  On one September afternoon, the Black Lake Association harvested roughly 6,000 pounds of invasive wet weeds in less than two hours.

The harvested vegetation was taken to a local dairy farm to be used as fertilizer.

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Green Lake Township has for years collected a special assessment tax to pay for Eurasian watermilfoil treatments in Duck Lake, an effort to keep the species’s signature mats of floating vegetation from building up. But not every lakeshore resident thinks it’s worth the trade-off, given other plant species are now gone and certain algae have appeared.

The Lake Pewaukee Sanitary District is in charge of lake management and its program consists of many pieces of aquatic weed harvesting equipment. It is apparent that an autumn harvest cuts back the milfoil, which is flourishing under the ice, to allow native plants an opportunity to grow.

Pewaukee Lake is about 5 miles long and 1 mile wide and covers 2437 acres. It has a maximum depth of 45 feet and is known for its inland sailing races and abundance of fish. It is a premier lake for Musky, Walleye, Northern Pike, and Largemouth Bass.

Pewaukee Lake’s aquatic plants have been monitored since 1988 in an effort to aid in lake management. The lake has a diverse plant community that is dominated by Eurasian watermilfoil but has many native species including Pondweed, Coontail, and Muskgrass.

300 feet out on January 9th, 2013 the Eurasian milfoil is quite healthy and seems to be flourishing under the surface of the frozen lake. This portion of the lake remains untouched by the aquatic weed harvester and the District does not apply aquatic herbicides.

The effective management of the lake has kept the milfoil in check and allowed native species to survive An autumn harvest helps to cut back the dominant milfoil and provides the native plants an opportunity to grow.

75 feet out in 4.5—5 feet of water the crews were able to perform a “deep cut” cutting near the lake bottom. As you can see, there is very little milfoil growth. During the 2011 harvesting program, 11,412 cubic yards of plant material was removed from Pewaukee Lake.

Tennessee Valley Authority is a corporate agency of the United States that provides electricity for business customers and local power distributors serving 9 million people in parts of seven southeastern states.  TVA maintains 29 power generating dams with reservoirs in addition to another 17 non-power dams that are used solely for flood control and recreation.  TVA is certainly no stranger to invasive species.

Management of invasive plants is necessary to keep the right balance between the diversity and density of plant growth. TVA has been managing invasive plants since the late 1950s, when it began to address the problem of milfoil. In the 1960s, TVA began to use helicopters to chemically eradicate weeds.

One of TVA’s management options is prevention. In some communities the spread of invasive plants have been prevented by quarantining boats on specific bodies of water to prevent transfer.

• Physical management including the use of mechanical weed harvesters or barriers such as plastic to prevent sunlight from reaching the plants.

• Biological methods include the introduction of grass carp to eat the weeds.

• Chemical management includes the use of herbicides to kill the weeds.

• Mother Nature is perhaps the most effective force in managing invasive plant growth. Many of the invasive weeds are susceptible to cold. The past few mild winters in the region might explain the increase of invasive plants on TVA waters.

In a recent workshop on the issue of aquatic invasive species, over 200 people turned out to not only voice their concerns on the growing weed problem, but to learn how they can help in the management.