Eurasian Watermilfoil2023-11-10T13:56:33-05:00

Eurasian Watermilfoil

Zebra mussels, A. Benson, USGS

What is Eurasian Watermilfoil (EWM, milfoil)?

Eurasian WatermilfoilEurasian watermilfoil is a non-native aquatic plant that is present in most U.S. states and much of Canada. This plant is known for its rapid growth and ability to spread, which can lead to significant problems within a lake. Milfoil forms dense beds that can seriously impair the recreational use of a lake, reduce the availability of fish spawning grounds, outcompete beneficial native plants, and otherwise alter a lake’s natural environment.

The growth and spread of Eurasian watermilfoil is a threat to all our lakes and ponds. Once Eurasian watermilfoil has infested a lake and becomes established, it can be impossible to eradicate it. Lake managers can only seek to control it by integrating the most effective, economically feasible, and environmentally sound methods available.

Of note, Shadow Lake, which discovered milfoil plants in 2011, was able to eradicate an incipient population after eight years of intense efforts. Prevention and early detection of milfoil introduction to a lake through programs like the Vermont Public Access Greeter Program and the Vermont Invasive Patrollers (VIP) Program are critically important to prevent the spread. After milfoil was newly discovered in Shadow Lake, their lake association got to work using numerous methods over many years to eradicate their small population of milfoil before it became established and spread throughout the lake.

Currently, approximately 99 of the 800+ lakes and ponds in Vermont are infested with milfoil. A list of confirmed aquatic invasive species in Vermont lakes can be viewed here (updated May 2021).

Eurasian watermilfoil is listed on the Vermont Noxious Weed Quarantine list.

What is the Impact of Milfoil on a Lake?

Eurasian watermilfoil is not native to North America but originates from Europe, Asia and northern Africa. As an introduced aquatic plant species to this continent, Eurasian watermilfoil has no natural controls (insects, bacteria, fungi) to keep its growth in check. Milfoil stems can reach the surface in up to 20 feet of water, growing up from the lake bottom each year from a fibrous root system. Milfoil grows and spreads extremely quickly, forming dense surface mats. Eurasian watermilfoil will grow readily in many types of water bodies, as well as in almost any bottom type: silty, sandy, or rocky.

The presence of Eurasian watermilfoil often brings a change in the natural lake environment. Over time, it outcompetes and suppresses beneficial native aquatic plants, severely reducing natural plant diversity within a lake. Since its growth is typically dense, milfoil beds are poor spawning areas for fish. Although many aquatic plants serve as valuable food sources for wildlife, waterfowl, fish, and insects, Eurasian watermilfoil is rarely used for food. Dense surface mats of milfoil can also impede recreational activities like fishing, boating, kayaking, and swimming.

A bed of milfoil
Eurasian watermilfoil reproduces almost exclusively by the breaking off of stem pieces which can drift away, sink, develop roots, and grow into new plants. A stem fragment just a few inches long can start a new plant. This fragmentation occurs both naturally and as a result of human activity. Within a lake, wind and waves may break plants loose, allowing them to drift into new locations and become established. Boating activity through dense milfoil beds also contributes to the fragmenting and spread of milfoil plants.


“Eurasian water-milfoil competes aggressively to displace and reduce the diversity of native aquatic plants. It elongates from shoots initiated in the fall, beginning spring growth earlier than other aquatic plants. Tolerant of low water temperatures, it quickly grows to the surface, forming dense canopies that overtop and shade the surrounding vegetation (Madsen et al. 1991). Canopy formation and light reduction, are significant factors in the decline of native plant abundance and diversity observed when Eurasian water-milfoil invades healthy plant communities (Smith and Barko 1990; Madsen 1994).

Eurasian water-milfoil has less value as a food source for waterfowl than the native plants it replaces (Aiken et al. 1979). And although fish may initially experience a favorable edge effect, the characteristics of Eurasian water-milfoil’s overabundant growth negate any short-term benefits it may provide fish in healthy waters. At high densities, its foliage supports a lower abundance and diversity of invertebrates, organisms that serve as fish food (Keast 1984). Dense cover allows high survival rates of young fish, however, larger predator fish lose foraging space and are less efficient at obtaining their prey (Lillie and Budd 1992; Engel 1995). Madsen et al. (1995) found growth and vigor of a warm-water fishery reduced by dense Eurasian water-milfoil cover.

The growth and senescence of thick vegetation degrades water quality and depletes dissolved oxygen levels (Honnell 1992; Engel 1995). Typical dense beds restrict swimming, fishing and boating, clog water intakes and result in decaying mats that foul lakeside beaches.”

From the Vermont Department of Fish and Wildlife:

“Despite a variety of treatment methods, Eurasian watermilfoil is nearly impossible to eradicate once it has invaded. Current control efforts include benthic barriers, mechanical harvesting, diver-operated suction harvesting, biological control using watermilfoil weevils, and chemical treatment. Due to the high costs and continuous effort required, the best management option for milfoil is spread prevention. Eurasian watermilfoil was originally brought to North America through the aquarium trade and was introduced to lakes and ponds through aquarium dumping. The plant species is on the Vermont Noxious Weed Quarantine list, making it illegal to buy, plant, or transport milfoil in the state.

Because milfoil fragments can easily hitch a ride on boats and equipment, practicing the Clean, Drain, Dry spread prevention methods is very important. Drain all water from your boat, canoe, kayak, and other vessels and any equipment used in the water. Clean vessels and gear and remove all plant fragments and dispose of properly. Dry all damp areas of boats and vessels, such as livewells and bilges, with a towel and let air dry in the sun for at least five days before using in another waterbody. If this is not possible, rinse equipment with hot, high-pressure water.”

According to the Lake Champlain Basin Program (LCBP), milfoil can:

  • Decrease native plant diversity by out-competing native aquatic plants
  • Decrease light penetration, habitat complexity and oxygenation
  • Increase sedimentation, nutrient loading, and accelerate eutrophication
  • Affect pH and temperature levels

Prevention and Early Detection Are Extremely Important

Lakes that are milfoil-free should participate in Vermont DEC early detection programs like the Vermont Public Access Greeter Program and the Vermont Invasive Patrollers (VIP) program. The costs to prevent new infestations of aquatic invasive species (AIS), and to detect them early, are significantly less than what it costs to control an established milfoil population.

From the Vermont DEC, about the Vermont Public Access Greeter Program:

“Aquatic invasive species are spread by overland transport of watercraft, trailers, and fishing and recreational equipment. The most effective way to prevent spread is through education and equipment inspections designed to catch invasive species ‘hitching a ride’ from one waterbody to another. Preventing the spread of aquatic invasive species is far more effective and economically sensible than eradicating invasive species once they are established. With support from Vermont DEC, Public Access Greeters educate lake visitors about invasive species, provide courtesy watercraft inspections, and STOP introductions.

Since 2002, the Vermont Public Access Greeter Program has expanded operation to access points at 32 lakes and ponds statewide, and those numbers are increasing annually. The total number of inspected watercrafts has increased since the program’s inception, with 404 inspected in 2002 to 31,052 in 2022. In 2022, Greeters intercepted and removed 530 instances of aquatic invasive species. Of these AIS intercepts, 451 were Eurasian watermilfoil.”

From the Vermont DEC, about the Vermont Invasive Patrollers (VIP) Program:

“The Vermont Invasive Patrollers (VIP) program was established by the Vermont Department of Environmental Conservation in 2007 to focus on early detection of all known and potential aquatic invasive species (AIS). VIPs are trained to identify both aquatic invasive plants and animals that are either established in Vermont or in nearby states and pose the greatest threat to Vermont’s water bodies.

Through hands-on workshops, lakeshore residents and lake users learn what aquatic invasive species are, how to prevent the spread of AIS, and how to identify the species that pose the greatest threats to Vermont lakes and ponds. By enlisting the help of a trained network of volunteers, Vermont DEC staff are much more likely to learn of new AIS infestations early and as a result, may have more management options at their disposal.”

Milfoil Control Methods

Lakes with established populations of milfoil have several tools available to keep it under control. Some of these options require an Aquatic Nuisance Control (ANC) permit from the Vermont Department of Environmental Conservation. When dealing with a well-established infestation of milfoil, the goal is control. While eradication is possible (see Shadow Lake above), it is certainly not a high possibility unless it is detected early and acted upon immediately, and adequate resources exist for long-term control.

Hand-pull milfoilHand-Pulling & Fragment Cleanup: Milfoil can be hand-pulled at any time during the season and does not require a permit as long as no mechanical methods are used. When hand-pulling, it is very important to be sure to remove the whole plant, including the roots, and to also remove any plant fragments that may occur during the removal. While fragments can occur any time, milfoil plants naturally become brittle in the fall and fragment more easily. If diving or snorkeling when hand-pulling, a mesh bag should be used to collect the milfoil to be able to bring it to the surface, remove it from the lake and reduce escaping fragments. It is also beneficial to remove floating milfoil fragments from the waterbody so they do not grow into new plants.

Diver-Assisted Suction Harvesting (DASH): DASH crews hand-pull milfoil by the roots from the lakebed and place the plant into a suction tube. This tube pulls the plant up to the surface to a boat with a collection basin where a team member will load the milfoil into buckets for transport from the lake. In areas where milfoil is present among native plants, divers are selective and only remove the milfoil while leaving native plants alone. DASH require a permit from the Vermont DEC and typically can’t begin before July 1st to protect fish spawning.

Diver Assisted Suction Harvesting

Benthic barrier

Photo credit: NYS Parks Department

Benthic Barriers: Benthic barriers are mats (which can be made of various materials) that are weighted and placed on the lakebed to prevent sunlight from reaching covered plants. These bottom barriers can be effective but are not selective. All plants under the mat will die, and the mats can also have a negative impact on invertebrates and slow moving organisms like mussels. The use of benthic barriers requires a permit from the Vermont DEC, and they may be installed on July 1st and must be removed on October 1st.

Herbicides: Aquatic herbicides are another tool that can be used to control milfoil. Over the past several years, the herbicide ProcellaCOR has been successful in controlling milfoil in lakes in Vermont and around the country as part of an integrated control plan. Vermont DEC has a rigorous process for applicants seeking to obtain an Aquatic Nuisance Control (ANC) permit to use an herbicide in waters of Vermont.

Applications to use an herbicide must meet five criteria:

  • There is no reasonable non-chemical alternative available
  • There is acceptable risk to the non-target environment
  • There is negligible risk to public health
  • There is a long-range milfoil management plan that has been developed which incorporates a schedule of pesticide minimization
  • There is a public benefit to be achieved from the application of a pesticide

These five criteria are required by Vermont law, under statute 10 V.S.A. § 1455.

ProcellaCOR is highly selective to milfoil, but some native plants found in some Vermont lakes may be impacted by a treatment. A recent statistical analysis by the Vermont DEC of lakes treated with ProcellaCOR saw a statistically significant increase in frequency of occurrence of native plants, and a decrease in milfoil.

Recently, there has been a rash of misinformation in newspaper commentaries, and in online comments about the permitting process and ProcellaCOR. Please see the Milfoil FAQ section below for more information.

Other Control Methods: other techniques have been investigated but they have unfortunately not been successful in providing milfoil control. Some of these include:

  • Milfoil Weevils: These small aquatic beetles with snouts feed on milfoil, damaging stems. However, maintaining weevil populations at levels in lakes needed to have an impact has not been achieved, and has not resulted in control. Milfoil weevils (Euhrychiopsis lecontei) are native to North America.
  • Grass Carp: Sterile triploid grass carp have been stocked on some lakes (not Vermont) for their appetite for aquatic plants. However, they are not selective and will eat many native plants as well as milfoil. This has been an issue at Candlewood Lake in Connecticut where they are now trying to reduce the number of carp because they ate almost all of the lake’s submerged aquatic vegetation. Grass carp (Ctenopharyngodon idella) are native to China and the Soviet Union. In Vermont, it is illegal to stock grass carp in any waters of the state.
  • Aeration: Aeration is an in-lake management tool used to increase the concentration of dissolved oxygen in the water. From the DEC: “…there is no evidence to support the use of artificial circulation/aeration systems for the control of macrophyte (aquatic plants) populations in the scientific literature”. You can read more from the Vermont DEC in their report: “Aeration as a Lake Management Tool and its use in Vermont“.
  • Mechanical Harvesting: Mechanical harvesting machines have been used for decades in an attempt to control milfoil and nuisance aquatic plants. While this method provides temporary relief, it does not provide control, and can contribute to milfoil spread via fragmentation. From Vermont DEC: “…this method did not provide a satisfactory level of control and may have contributed to its spread via fragmentation. Experience with mechanical harvesting on Rutland County lakes in the 1980s and 1990s showed that harvesting resulted in dense beds of EWM since the aggressive plant is quickest to regrow after cutting.”

Watershed Management (Phosphorus Reduction): Aquatic plant growth is fueled by phosphorus in the water, so working to mitigate sources of phosphorus entering a lake can help to limit excessive plant growth, and improve water quality. Phosphorus can be carried into the lake by runoff from stormwater events and malfunctioning septic systems. Vermont DEC initiatives like Lake Wise, Stormwater Master Plans, Lake Watershed Action Plans, and Wastewater Workshops offer many phosphorus mitigation strategies. You can read more about phosphorus on “The Phosphorus Challenge” page on our website.

Education: Education of all lake users about milfoil can make a big difference in successfully keeping it under control.

Educational messages for lake users and lake property owners should include:

  • Before moving vessels between waterbodies, be sure to Clean, Drain, Dry.
  • As a general rule, get as much milfoil out of the lake as possible. Let it dry out on land and dispose of it as you would yard waste or use it as compost, well away from the water.
  • Avoid boating through milfoil patches which will create fragments.
  • If you have milfoil on your prop, don’t just reverse and drive away, remove it from the lake for proper disposal.
  • If you have milfoil growing around your dock or in your swimming area, pull it out by the roots and remove it from the lake for proper disposal.
  • If you see milfoil floating anywhere in the lake, near your dock, or along your shoreline, remove it from the lake for proper disposal.

The Case for an Accessible Path for Vermont Lake Associations to Use ProcellaCOR To Control Invasive Milfoil

As you may be aware, the Vermont legislature has created an Aquatic Nuisance Control Study Committee with the passing of Act 57 (H.31). From the Act 57 Committee’s website:

“The Aquatic Nuisance Control Study Committee was created to assess the environmental and public health effects of the use of pesticides, chemicals other than pesticides, biological controls, and other controls in comparison to the efficacy of their use in controlling aquatic nuisances recommendations regarding whether and when pesticides, chemicals other than pesticides, or biological controls should be used to control aquatic nuisances in Vermont in a report to the VT General Assembly on or before December 15, 2023.”

FOVLAP has been monitoring and attending the public meetings of the committee, and felt it was necessary to provide the committee with this paper to outline the need for continued access to regulated, safe, and effective use of herbicides as a tool to maintain control of Eurasian watermilfoil in infested waterbodies.

Click here to read the white paper: “The Case for an Accessible Path for Vermont Lake Associations to Use ProcellaCOR to Control Invasive Milfoil

Milfoil FAQ

In this section, we’ll provide general milfoil-related information, and also address some recent, specific misinformation that we have encountered in a Q & A format.

It was previously mentioned that there has been misinformation about the herbicide ProcellaCOR and the Aquatic Nuisance Control (ANC) permitting process. What is this in reference to?2023-11-01T15:38:45-04:00

In early 2022, the Lake Bomoseen Association applied for an ANC permit to use ProcellaCOR which resulted in misinformation being spread online and in newspaper commentaries.

To help combat this misinformation, and to provide fact-based information on ProcellaCOR, the Vermont Department of Environmental Conservation (DEC), published a document in October of 2022 entitled “Permitting Aquatic Herbicide Projects in Vermont”.

The Vermont DEC describes that the purpose of this document is to:

  1. Provide background information about DEC’s Aquatic Nuisance Control (ANC) permitting program, with a specific focus on aquatic herbicide projects;
  2. Identify some of the recent findings related to ProcellaCOR; and
  3. Provide a Q&A section on this topic reflecting common questions that DEC receives about our ANC permitting program

The document details Vermont statutes, the permitting application and technical review process, and the departments and agencies involved in the permitting process.

It also discusses key findings on ProcellaCOR EC, including:

  • a pre- and post-treatment statistical analysis of the aquatic plant survey data from Vermont treated waterbodies (showing increases in native plants, and decreases in milfoil)
  • an aquatic toxicity review memorandum performed by a Vermont DEC Environmental Scientist (concluding that “the potential for acute and chronic risks to fish, aquatic invertebrates, amphibians and other aquatic animals is considered low”)
  • a macroinvertebrate survey conducted by New York DEC, finding that “No significant changes to the macroinvertebrate community assemblage were observed when comparing survey results pre- and post-herbicide treatment.”
  • a review of ProcellaCOR’s confidential statement of formulation memorandum, performed by a Vermont State Toxicologist from the Vermont Department of Health concluding: “Based on a review of the confidential statement of formulation, it is reasonable to conclude that human exposure to the inert compounds contained in ProcellaCOR at the concentrations that would result under the conditions proposed by the applicants, is not likely to result in an increase in the level of concern for public health. Thus, the proposed treatment of Lake Bomoseen with ProcellaCOR is expected to result in negligible risk to public health, from both the active and inert compounds in ProcellaCOR.”)
  • an acknowledgement from the Vermont DEC’s Drinking Water & Groundwater Protection Division,“DWGWPD does not have concerns with the use of ProcellaCOR provided the conclusions from VDH have not changed and that treatment concentrations do not exceed 5 PDUs.”

Finally, the document contains 16 frequently asked questions posed to the Vermont DEC about these topics with their answers.

This document can be viewed here: Permitting Aquatic Herbicide Projects in Vermont

We also highly recommend reviewing this presentation by the Vermont DEC entitled “ANC Permitting 101” which goes into great detail about the permitting process.

Milfoil has been present in Vermont for over 60 years, hasn’t ‘Mother Nature’ adapted?2023-11-01T15:41:02-04:00

Vermont waterbodies have not “adapted” to milfoil, which is why tremendous effort – including at a significant cost – goes into controlling current infestations and preventing new ones. Milfoil has no natural controls to keep it in check as it does in its native regions. The US Department of Agriculture National Invasive Species Information Center lists Eurasian watermilfoil as an invasive species, the Vermont Agency of Agriculture, Food and Markets also designates Eurasian watermilfoil as a Class B Noxious Weed on their Noxious Weeds Quarantine Rule.

We’d encourage you to watch this documentary by the New York DEC: “Uninvited: The Spread of Invasive Species,” which you can view on YouTube. While the 53-minute documentary is worth watching in its entirety, if you fast-forward to the 38 minute mark, you’ll learn a lot about ‘Mother Nature’ and invasive species.

The documentary explains that nature cannot take care of itself after the balance is upset, typically a result of human activity. They offer a good example in the documentary of a reed (common reed or Phragmites) that was used as packing material 400 years ago on ships traveling from Europe. The reeds were thrown on shore and took root here in the US. This invasive reed is now destroying native plant species in wetlands, marshes and along lake shores.

In its native land, Phragmites has 170 different insects that feed on it, which keeps it in check, and that ecosystem is in balance. Here in North America, this plant only has five insects that eat it or have adapted to eat it. This imbalance allows common reed to grow uncontrollably, outcompeting native plant species. So, in over 400 years, nature has not adapted. In fact, the speaker says it would take thousands to hundreds of thousands of years for this reed to act like the plants it has displaced.

Unfortunately, we (humans) interfere with ‘Mother Nature’ all the time by introducing invasive species – knowingly or unknowingly. It is our responsibility to work to control or eradicate invasive species to protect the native species and the ecosystems they have unbalanced.

As was previously mentioned, tremendous cost and effort goes into milfoil control, 99 Vermont lakes are currently infested, and only 1 lake is known to have eradicated it. Isn’t all this time, effort, and money wasted since milfoil ‘keeps coming back’?2023-11-01T15:44:19-04:00

The goal of milfoil management programs is control, not eradication.

Left unchecked, milfoil will spread throughout the littoral zone (the area where light penetrates) of a lake, can form dense beds, and outcompete and suppress native plants, including rare, threatened and endangered species.

Unmanaged milfoil can also:

  • Impede recreational activities like fishing, boating, kayaking, and swimming
  • Decrease light penetration – limits photosynthesis and can cause algae blooms
  • Decrease habitat complexity – reduces species biodiversity and impacts the food web
  • Decrease oxygenation – lower oxygen can lead to algae blooms
  • Increase sedimentation – a buildup of ‘muck’ and loss of water depth
  • Increase nutrient loading – a release of phosphorus from the sediments causing algae blooms
  • Accelerate eutrophication – enriching the lake with nutrients (phosphorus) which can lead to excessive plant and algae growth
  • Affect pH and temperature levels – many aquatic organisms have a preferred pH and temperature range

As a perennial invasive aquatic plant, milfoil ‘keeps coming back.’ Whether an area was cleared of milfoil by hand-pulling, DASH, benthic barriers, or spot treatments of ProcellaCOR, milfoil is prolific, aggressive, and has the ability to grow in a wide range of environmental conditions. Uncontrolled milfoil can lead to fragments that can easily reseed newly controlled areas. By no means does this mean that the time, effort, and cost put into these control efforts is wasted, as the goal of these programs is to keep milfoil at manageable levels so that it’s not impacting lake health or recreational use.

A recent newspaper article contained this quote attributed to a university professor with previous work experience at the EPA: “ProcellaCOR is not selective at all. It will not just target the milfoil. It will target indiscriminately every plant in the lake. ProcellaCOR will decimate pretty much all the plants in the treatment areas.” Is this true?2023-10-30T12:11:15-04:00

Absolutely not. ProcellaCOR is highly selective to milfoil. The specimen label does list a few plants native to Vermont that can be impacted by ProcellaCOR, for example, coontail and watershield. When spot ProcellaCOR treatments are permitted for control milfoil in a lake, permit conditons take into consideration impacts to non-target plants and treatments, e.g.,  avoiding populations of these sensitive native species, use of low ProcellaCOR concentrations.

Vermont DEC performed a statistical analysis of ProcellaCOR use in Vermont lakes, and this analysis showed statistically significant decreases in milfoil, and statistically significant increases in native plants. These results reflect a successful treament regime –  when the invasive plant species is controlled, the native plants will take back that space. This analysis was completed using data from permit-required aquatic plant surveys from Vermont lakes treated with ProcellaCOR.

A recent commentary that appeared in the newspaper written by a university professor with previous work experience at the EPA stated: “…the idea that there is one person in the [Vermont] DEC with sole power to allow or disallow the addition of toxic chemicals into our lakes and streams, is appalling. One person can submit a permit request and another person can grant it? At a minimum, the Vermont Fish and Wildlife Department and the Vermont Department of Environmental Conservation should be in agreement on any pesticide approval.” Is it true that one person has the sole power to allow herbicide use, and no other departments are involved?2023-10-30T12:11:47-04:00

No, this is a gross distortion of the permitting process. This commentary was written in response to the Lake Bomoseen Association (LBA) submitting a permit application to use ProcellaCOR. All herbicide permit applications go through a rigorous process, involving numerous departments and scientists.

In the specific case of the LBA’s application, we have learned from the Vermont DEC that when this application was received, these 15 internal experts, along with additional scientists in the Vermont DEC, reviewed, and provided comments and input on this permit application:

  • two scientists from the Vermont Department of Fish and Wildlife (DFW) Wildlife Division
  • three scientists from the DFW Fish Division
  • the DFW Public Access Area manager
  • two DFW staff that oversee the Keho Camp
  • two scientists from the Vermont Department of Health
  • one scientist from the Vermont DEC Drinking Water Groundwater Protection Division
  • the Vermont Department of Forests, Parks and Recreation regional State Parks manager
  • two scientists from the Vermont DEC Wetlands Program
  • one scientist from the Vermont DEC Monitoring and Assessment Program who is an aquatic toxicologist and member of the Vermont Pesticide Advisory Council

The Vermont DEC and DFW created a framework in 2018 for permitting both herbicide and non-herbicide milfoil control efforts. This framework has been in place since that time, and was used for all ProcellaCOR permits issued, for which both departments determined that all the projects presented an acceptable risk to the non-target environment.

The Vermont DEC also engages the Vermont Department of Health to review submitted pesticide applications to determine if a finding of negligible risk to public health can be made for the pesticide project proposed. In the memorandum for this review, the State Toxicologist determined that the use of ProcellaCOR “…is not likely to result in an increase in the level of concern for public health.”

Finally, in late March of 2023, all three departments: Vermont Department of Environmental Conservation, Vermont Department of Fish and Wildlife, and Vermont Department of Health officially formalized the agreed upon framework which you can see here: “Aquatic Nuisance Control (ANC) Individual Permit Application Internal Review Procedure”.

For a thorough explanation of the Aquatic Nuisance Control permitting process, see this presentation by the Vermont DEC entitled “ANC Permitting 101”.

In recent online postings and newspaper commentaries, statements are made claiming that the Vermont Department of Fish and Wildlife (DFW) had ‘weighed in’ and opposed the Lake Bomoseen Association’s permit application, and that Vermont DEC and the Vermont DFW are in conflict. Is this true?2023-10-28T17:29:56-04:00

No. As you can hear in his testimony to the House Committee on Environment and Energy on March 15th, 2023, Lakes and Ponds Program Manager Oliver Pierson dispels the myth that the two departments don’t work together, and that the Vermont DFW opposed the Lake Bomoseen permit application:

“This process which we’ve developed which we call the aquatic nuisance control internal review procedure is unique. I’m not aware of any other examples in our own permit issuing where the authority to issue the permits voluntarily seeks out the input of other State departments who may have slightly different missions and mandates, but we’re all in this for similar long-term outcomes and does our best to incorporate those into our permitting decisions. And I think it’s worth noting that since we’ve issued the ProcellaCOR permit on Lake Iroquois, and with all of our ProcellaCOR applications since then, as I’ve said, we’ve received input from Fish and Wildlife. With that input, you’ve established permit conditions you may prohibit certain parts of the lake from being treated because there’s rare, threatened, or endangered species. You may say that this part of the lake doesn’t need herbicide because they haven’t demonstrated that the invasive is interfering with aquatic habitat because we’ve taken that feedback from our sister department into consideration, and that’s influenced our permitting decisions. Most recently, for the Lake Bomoseen permit application, we received feedback from Fish and Wildlife, saying that with a few conditions, such as not treating north of the Grady bridge, and a few other conditions, that as long as we implement those conditions, in the permit, they do not object to this application. Again, I’ll let them speak for themselves tomorrow, but I think that is an important point to make that all this division that’s being portrayed between DEC and Fish and Wildlife, when you look at the facts, isn’t as divisive as it might appear to be. We are really working together to issue these permits in a collaborative manner where their feedback is taken into consideration.”

Earlier in his testimony, before this detailed explanation, Oliver stated:

“I can’t speak to what happened prior to 2018, but what I can say, since 2018, there has not been an example of Fish and Wildlife objecting to an herbicide permit issued in Vermont.”

We’d also like to note a response from Secretary Julie Moore on March 20th, 2023 to an individual who made misrepresentations and false accusations about the relationship between the departments, and ‘clandestine’ groups and meetings to the House Environment and Energy Committee:

“I received a copy of the email message you sent to members of the House Environment and Energy Committee last week; I am deeply concerned with the misrepresentations made in your message. Staff at the Agency are dedicated to working in collaboration with other agencies and the public to protect Vermont’s environment and the accusations in your letter represent either an unwillingness to conduct basic due diligence or a willful disregard for the facts.

The Agency’s Lakes and Ponds Program has organized an Aquatic Nuisance Control Pre‐Rulemaking Focus Group to foster discussion and solicit input to a rulemaking on the ANC rulemaking process. Information on this focus group, including participating entities, proposed timeline, and minutes, is available at ponds/permit/control/aquatic-nuisance-control/anc-pre-rulemaking-focus-group. Given the emotional and sometimes accusatory discussion on this topic, the group collectively agreed to abide by the “Chatham House Rules,” which simply states that group participants “are free to use the information received, but neither the identity nor the affiliation of the speaker(s), nor that of any other participant, may be revealed.” This agreement and process allows for robust discussion and constructive disagreement, without resulting in polarizing public exchanges that stifle genuine progress.

In addition, your continued attempts to suggest a schism between the scientists in the Fish and Wildlife Department and those in the Department of Environmental Conservation reveals a basic lack of understanding regarding the collaborative and consultative process involved in management of the public trust and the importance of scientists’ ability to discuss and sometimes disagree with one another. FWD has been included in and engaged in every meeting of the Pre‐Rulemaking Focus Group and all substantive meetings with the Lake Bomoseen Association. The idea that DEC is actively undermining their colleagues is a fiction that does a disservice not only to DEC but also to FWD, and would seem to suggest you believe I am failing in my capacity as the leader responsible for overseeing both departments in ensuring all concerns are being heard and being given equal consideration.

I recognize your passion on this subject but disagree with your divisive approach. Rather than casting aspersions on the dedicated staff in DEC and FWD, I suggest that you focus your time and energy on the substantive issues under consideration before the legislature.”

So, why are these claims still being made? It may be that they are misinterpreting, whether intentionally or unintentionally, a memo dated April 8th, 2022 from an individual biologist in the Fish Division of Fish and Wildlife to the DEC Lakes and Ponds department opposing the permit after comments were solicited on the Lake Bomoseen application. As you can hear from Oliver’s testimony, this lone biologist expressed an opinion that was not shared by the Vermont Department of Fish and Wildlife. Fish and Wildlife did not oppose the treatment under the conditions they shared with the DEC. It’s important to distinguish comments from an individual and the leadership of the department.

We’ll again suggest that you read the framework / procedure agreed upon by the Vermont Department of Environmental Conservation, Vermont Department of Fish and Wildlife, and Vermont Department of Health to collaboratively review permit applications: “Aquatic Nuisance Control (ANC) Individual Permit Application Internal Review Procedure”.

In recent online postings, newspaper commentaries, and in legislative committee testimony, aquatic plant management in Lake St. Catherine was described as ‘nothing short of a disaster for warmwater fish populations’ and attributed to the Vermont Department of Fish and Wildlife. Is this true, and what is it referring to?2023-11-28T12:07:47-05:00

No. This quote is from email correspondence between an individual biologist from the Fish Division of the Vermont Department of Fish and Wildlife and Misha Cetner from the Vermont DEC, and has been repeated numerous times, and in numerous mediums.

Lakes and Ponds Program Manager Oliver Pierson addressed this statement directly in his March 15th, 2023 testimony to the House Committee on Environment and Energy, saying this:

“The example that has been read twice today about the Lake St. Catherine situation where it’s been quoted twice by a [Vermont DFW] fisheries biologist that Lake St. Catherine’s aquatic plant management has been quote “nothing short of a disaster.” That’s one individual in Fish and Wildlife. We’ve heard from others in Fish and Wildlife that it has not been a disaster, it has simply led to a change from a decrease in largemouth bass, but an increase in smallmouth bass. Fish and Wildlife will be here tomorrow, I’ll let them speak for themselves, but I think it’s fair to say that we don’t agree, nor does Fish and Wildlife’s leadership, with the statement that aquatic plant management has been quote unquote, ‘nothing short of a disaster at Lake St. Catherine’.”

It should also be noted that the DEC took this claim very seriously, leading to the following reply from Vermont DEC Lake & Shoreland Ecologist Misha Cetner later that day:

“I take your comments on the St. Catherine warmwater fish populations quite seriously as that is not a casual statement. Do you have data that supports this? If so, that needs to be incorporated into the overall discussion. Is this observation in St. Catherine only or is it seen in the other lakes with EWM control?”

There was no response from the biologist to this direct questioning from the DEC.

Often cited along with this comment is a report entitled “2021 Bass Inventory and Management – District 2”, which was compiled by the fish biologist referenced above. This report contains data on electrofishing surveys performed on Lake St. Catherine from 1988 – 2021, with the data showing a decrease in largemouth bass, and an increase in smallmouth bass populations. It should be noted that this report does not contain bass data prior to 1988, so there can be no comparison between bass population data from 1988 to 2021 to the pre-milfoil era of Lake St. Catherine (prior to the early 1970s).

In the ‘Discussion’ section of this report, the author notes:

“Following a 15-year study of the black bass population in Lake Morey, VT, Kirn (1996) concluded that the introduction and rapid expansion of Eurasian watermilfoil (Myriophyllum spicatum) (EWM) in the lake was a major factor that lead to the development of a high-quality Largemouth Bass fishery there. Similar observations have been made in other Vermont lakes with established EWM populations (Good 2019).”

The author is citing a study, and his own observations, that milfoil infestations in lakes have a positive impact on largemouth bass populations.

So, this would lead you to the logical conclusion that lakes which experienced increases in their largemouth bass populations because of their milfoil infestation would also see a reversal of those unnatural largemouth bass population increases when they began milfoil control programs. Meaning, if the rapid expansion of milfoil was a major factor in increasing largemouth bass populations, the control of that milfoil would bring the population back down to its natural level that had been previously supported by the lake’s native aquatic plants.

As you have read previously, this logical conclusion has been described by the author as ‘nothing short of a disaster’. It certainly appears that the author is advocating for lakes to remain heavily infested with milfoil to support “high-quality Largemouth Bass fisheries”, without regard for the overall long-term health of the lake.

Finally, see this excerpt from the document “Rapid Response Plan for Eurasian Watermilfoil in Massachusetts” developed for the Massachusetts Department of Conservation and Recreation by ENSR International which discusses how intermediate densities of aquatic plants (including milfoil) can be beneficial for fish, but dominance of milfoil can result in replacement of native plants, alter the food web, and decrease fish and macroinvertebrate abundance.

“Aquatic macrophytes [aquatic plants] can provide food, shelter and spawning habitat for a wide variety of fishes (Lillie and Bud 1992). Intermediate densities of aquatic macrophytes, even including EWM, enhance fish diversity, feeding, growth and reproduction (Dibble et al. 1996). However, dominance by EWM tends to replace native macrophytes, altering the food web and creating food shortages for many fishes (Engel 1995). Beds of EWM can also impede predation, shelter overly dense assemblages of panfishes, and cover spawning areas, leading to potential decreases in sportfish abundance (Engel 1995). Large piscivorous fishes spend more time foraging for prey as plant density increases, thus reducing growth rates through unfavorable energetics (Savino and Stein 1982). EWM beds have been shown to decrease fish abundance compared to native vegetation, and Keast (1983) found that beds of native vegetation supported up to four times as many fish and up to seven times as many macroinvertebrates. Decreases in macroinvertebrate abundance were observed as EWM coverage increased in a Michigan study examining six lakes (Cheruvelil et al. 2001). In another Michigan study involving 13 lakes (Schneider 2000), EWM was implicated in undesirable population features for centrarchid fishes (bass and sunfish). The depletion of oxygen in waterbodies with dense milfoil coverage can also result in fish avoidance, and, in extreme, cases fish kills (Holland and Huston 1984, Lillie and Bud 1992, Engel 1995).”

In recent online postings and newspaper commentaries the phrase ‘spraying toxic chemicals’ appears frequently. Is ProcellaCOR sprayed on the lake?2023-10-28T17:34:40-04:00

No. ProcellaCOR is injected by hoses at subsurface depths of the lake from a boat.

A term like spraying may be purposefully used to evoke an image of applicators in hazmat suits using aerosol spray wands around a lake, which is not how ProcellaCOR is applied. Other scaremongering terms like poison, toxic, and chemicals may also be used purposefully to influence those who are not fully informed on the topic of this herbicide to steer away from a rational discussion of their use, safety, and effectiveness.

Note: There are no recreational or household restrictions for lake water usage after a ProcellaCOR application, but the State of Vermont recommends that the lake not be used for recreation or household use on the day of the treatment.

Some postings and commentaries have suggested that there is a link between herbicide applications and the occurrence of cyanobacteria blooms. Do herbicide applications lead to cyanobacteria blooms?2023-11-01T07:25:51-04:00

No, it’s not likely that herbicide applications lead to cyanobacteria blooms. Herbicides work by targeting specific aspects of a plant’s internal cellular processes. This allows them to kill one kind of plant, but not another. Freshwater algae and cyanobacteria do share many cellular processes with terrestrial plants. A number of recent papers indicate that both algae and cyanobacteria are sensitive to many different herbicides (for example, Gomes and Juneau 2017, Singh et al. 2016, Hernadez-Garcia and Martinez-Jeronimo 2020). Just how much they are affected depends on the herbicide, when/how it is applied, and environmental conditions at the time of application. Applicators must take this into account and apply herbicides that target the nuisance plant primarily and limit effects on non-target species. Applied properly, herbicides should not change phytoplankton community structure to favor cyanobacteria.

Cyanobacteria grow in aquatic environments with many other inhabitants. Competition for light, nutrients, and space to grow has led many species to develop abilities that allow them to access what they need better than others can. When you look at the phytoplankton communities in lakes affected by cyanobacteria blooms, they are not conspicuous because of the lack of other algae like diatoms and green algae. On Carmi, St. Albans, and Missisquoi, there are major spring diatom blooms and masses of green algae in summer along the shorelines. They also support large communities of aquatic plants. This is true even during persistent bloom events and over many years despite persistent blooms. Cyanobacteria dominance at a certain time of the year is more likely connected to other characteristics like temperature and nutrients than to the use of herbicides. You can read more about cyanobacteria from retired aquatic biologist Angela Shambaugh in her FOVLAP website article here: “Cyanobacteria”.

Go to Top