New Herbicide Resource Page

In the summer of 2009 the Lake Fairlee Association first seriously considered the use of an herbicide to control our milfoil.  To help us decide how best to care for the lake we collected the best information we could find about what we called “the chemical alternative.”  Links to various sources are scattered through this blog, and appear in numerous posts.

To make it easier to find this information we have created a new resource page, where we will collect these links.  You can find this page at the top of the right column of this blog, under ‘Pages,’ where it is called Herbicide Resource, or you get there by clicking HERE.

In addition we have recently added a new “Category,” also in the column on the right, under “Milfoil Erradication,” called “Herbicide.”  Click that link to see an archive of every page related to the question of chemicals in the lake.

A (very relevant) Science Lesson

As we grapple with the difficult decision whether to use chemicals in Lake Fairlee, we are confronted by more than a few complicated questions.  Much of the information is not easy to understand.  We are grateful when we find one that clarifies the issues.

Here is a web-based presentation, in which aquatic herbicides are used to demonstrate scientific concepts regarding herbicide toxicity, persistence in the environment, dosage, mode-of-action, carcinogenicity, bioaccumulation and other public concerns.  It is called:

Why Aquatic Herbicides Affect Aquatic Plants and Not You!

The video was made by Professor Carole A. Lembi, of the Department of Botany and Plant Pathology at Purdue University.  Her laboratory has studied a number of issues integral to aquatic plant management, particularly those that deal with finding more ecologically-friendly alternatives to herbicides/algicides.

Please do not be deterred by the length (30 minutes) and academic tone of this presentation.  Make time to watch it.  Your understanding of the issues we face will certainly be increased.

Making sense of difficult information

On August 31 we held an informational meeting to discuss our board’s decision to proceed towards herbicide treatment of Lake Fairlee next summer (2010).  We reminded all attending that we take seriously our role as stewards of the lake, and that the decision to hire an outside consultant to conduct an initial survey was made reluctantly and after considerable discussion.  We emphasized that we (board members) are not scientists, and are struggling to learn all we can about chemical treatments and alternatives.

There is an abundance of information available about the herbicide triclopyr.  (Ann Bove would remind me here that we are not assured of getting a permit for herbicide application, and we don’t even know which herbicide will be recommended)  Only a little of it is original research – most simply summarizes scientific data collected by others.  This information is available from a various different sources, and often reaches a variety of conclusions.

Most of the published scientific research on triclopyr was conducted by the manufacturer (Dow Agrosciences) pursuant to their EPA registration.  This is unfortunate, but typical.  Research is expensive, and most easily funded by a large company with an expectation of future profits.  Most of the information about triclopyr found on the web is based on this original data, digested and explained for non-scientists.

One contributor to the meeting suggested that we look at a website called “,” which contains a factsheet about the herbicide triclopyr, and that we include a link to it in this blog.  As promised, I include the link HERE.  I feel compelled to add few words of caution.

The website is maintained by the Northwest Coalition for Alternatives to Pesticides [NCAP].  This is an outfit dedicated to reducing pesticide use, and “keeping [us] informed about pesticide hazards . . . .”  We applaud their mission, and agree that pesticides are overused and sometimes dangerous.  Nonetheless their “factsheet” on triclopyr seems selective in its choice of facts, and slanted in its conclusions.  The facts it includes are true, but they are chosen selectively.

The factsheet was written in 2000.  The formulation of triclopyr we are considering was not released until later, and arguably is a safer formulation.  Renovate 3 contains the triethylamine salt of triclopyr, and references to the butoxyethyl ester of triclopyr in the factsheet may not be applicable.

In this blog I have tried to include links to sources that are understandable and reliable.  I have also looked for sites that are balanced.  The “Triclopyr Questions and Answers” from the State of Washington (LINK) is a good example. I can understand how someone who is vehemently against all use of chemicals might see this as slanted in favor of chemical use, just because it does not conclude that using triclopyr is always bad.

I remind all concerned that none of us wants to introduce an herbicide into the lake.  We agree that it would be preferable to find a non chemical alternative.  We believe that we have exhausted all other available alternatives, and that doing nothing would be unacceptable.  We examine each choice asking, “What is best for the lake?”  The wishes of our members and donors can be taken into account, but the welfare of the lake is our first concern.

I urge each reader to scrutinize these resources, and others, and to come to her own conclusions.

What Can Happen . . .

. . . if milfoil is allowed to take over.


This is a lake in Idaho, a portion of which was rendered unusable by the unchecked growth of milfoil.  Click on the image above for a larger view.

While this is not Lake Fairlee, we are afraid that it represents what could happen to Lake Fairlee.

Milfoil at ‘tipping point’ in Lake Fairlee

More news coverage of our July 23rd meeting

by Lillian Gahagan, Journal Opinion

WEST FAIRLEE—A group of about 50 people turned out for an informational meeting at Horizons Day Camp on the evening of July 23 to discuss strategy and options for controlling an invasive weed in the waters of Lake Fairlee. The 457-acre lake is spread out across the towns of Fairlee, West Fairlee and Thetford. Eurasian milfoil, a non-native weed, has reached a “moderate” level of infestation there on a scale used by the state that goes from light to moderate to heavy.

Lakeshore users and homeowners are now contemplating what to do next since the milfoil is growing faster than it can be removed using manual and mechanical means. It is estimated that milfoil affects between 10% and 20% of the lake. Milfoil spreads by seeding itself, through root propagation and by fragmentation such as when boats churn through the weeds. The harvesting operation itself spreads the weeds, but the association has continued to remove as much as possible this way. Ten to 15% of the milfoil is removed each season, according to a fact sheet distributed at the meeting, but lake temperature, sunlight and phosphate levels all contribute to the weed’s growth.

The chair of the Lake Fairlee Association, Skip Brown, moderated the meeting that brought together representatives from the Vermont Agency of Natural Resources’ Department of Environmental Conservation, divers who have been pulling the milfoil from the lake, people who have coordinated the treatment of milfoil in neighboring Lake Morey and others from the area who have a connection to Lake Fairlee. Brown assured the group that no decision had been yet been made about what to do and he did not expect the group to arrive at an outcome at that meeting.

“Everyone here has a love for Lake Fairlee,” said Brown in his introduction of the various parties present. He said as chair of the Lake Fairlee Association, he had the “dubious honor” of running the current milfoil program for the lake. The meeting was held to provide an opportunity to hear from everybody concerned about the lake and to try to build a consensus about what to do in the future. To date, there has been a “no chemical” approach to treatment.

Brown described the status of Lake Fairlee as at a “tipping point” with the weed infestation as current efforts to control the milfoil are not enough. The milfoil grows in waters up to about 15 feet in depth, when severe, can form dense mats at the surface that “umbrella” out, making boating and swimming extremely difficult as the tangle of weeds becomes impassable.
Continue reading

Information Requested at our July 21 Meeting

I will post a summary of the meeting and the topics discussed soon.  If you were not there, you should know that about sixty lake residents and users attended, and that we had a spirited discussion about the future of Lake Fairlee.

The experts from the State were able to answer many questions in summary fashion.  But the issues are complex, and the information often inconclusive.  As promised, we are making some of the original data available on this blog, so that those interested can form their own conclusions.

Lake  Quality – Lay Monitoring Data For 30 years volunteers have measured phosphates and underwater visibility several times each summer in the lake.

  • Raw annual data for Lake Fairlee may be found HERE
  • A so called “Summary Report” for Lake Fairlee can be found: HERE
    There is a “key” which will help in its understanding: HERE

Triclopyr – the herbicide used in Lake Morey.  Look in these articles for citations to the original scientific research.

  • Triclopyr Questions and Answers. LINK These questions were submitted by the public, and answered by a team of experts for the Washington State Department of Ecology.  This 12 page document is an excellent good starting place.
  • A summary LINK from EXTOXNET, A Pesticide Information Project of Cooperative Extension Offices of Cornell University, Oregon State University, the University of Idaho, and the University of California at Davis and the Institute for Environmental Toxicology, Michigan State University:
  • From National Pesticide Information Center, a cooperative agreement between Oregon State University and the U.S. Environmental Protection Agency, with source citations: LINK
  • Lake Morey’s 2009 application for herbicide application LINK – 34 pages but there is LOTS of information buried here, particularly about how Vermont approaches the treatment of lakes with chemicals:

Other pages of interest

  • Vermont DEC’s main page on Aquatic Invasive Species HERE
  • About Vermont’s issuance of Aquatic Nuisance Control Permits HERE

Materials for the Informational Meeting

This is the sheet that was handed out at the meeting.  It is reproduced here for the benefit of those who could not attend.

Lake Fairlee Informational Meeting
Thursday July 23, 2009

Goals for this meeting:

  • To bring together lake users
  • To share information about the condition of the lake
  • To learn what LFA has been doing about milfoil, and to what effect
  • To hear from constituents
  • To learn from each other
  • To work towards understanding how best to care for the lake

Each of us should:

  • Try to keep an open mind, and to LISTEN to other speakers
  • Respect whoever has the floor, as you would hope that s/he would respect you
  • Identify yourself by name and connection(s) to the lake
  • Try to plan your questions or remarks so as to be brief


  • Skip Brown (LFA) will act as moderator
  • First he will give preliminary remarks, summarizing where we are and how we got here
  • Then will introduce the representatives from the State
  • They may make a few observations, but are present primarily to answer our questions
  • Everyone who wants to speak will be afforded an opportunity. This means that you may not get a second chance until others have had theirs.


  • Directors of the Lake Fairlee Association
  • Divers – employees of LFA who know the condition of the lake better than anyone
  • Representative of the Vermont Agency of Natural Resources, Department of Environmental conservation. These are the folks who license and help fund our milfoil program, AND who are charged with licensing and monitoring chemical applications such as in Lake Morey

– – – – – – – – – – – –

Fact, Surmise, and Opinion

1.    Milfoil has been growing in Lake Fairlee for at least 15 years.
2.    LFA has been removing it for almost that long.  Until recently we used only hand pulling. Now we also use suction harvesting and bottom barriers
3.    LFA has been spending in excess of $100,000 per year to remove milfoil — about 40% from the State, 10% from the towns, and 50% from donations.   (thank you all)
4.    Milfoil spreads three ways: by seeding, by root propagation, and by fragmentation.  Yes, we know that harvesting also spreads it.  But at this point we are resigned to removing as much as we can each season.
5.    Other factors affect the amount of milfoil in the lake as much as or more than our eradication efforts.  These include lake temperature, sunlight, and phosphate levels.
6.    The milfoil is growing and spreading faster than we can remove it.  Our divers remove an estimated 10 to 15 percent of the milfoil each season. IF we had two or three full time dive crews we might be able to get ahead of it.
7.    Membership and donations in support of our dive program are declining.  Again this year we will likely have to stop our dive program early due to lack of funding.
8.    Some members believe that we should follow Lake Morey’s lead and use a herbicide to kill the milfoil.  Even if we did this and it removed all or most of the milfoil we would have to continue a (more modest) dive program to ensure that the milfoil not become widespread again.
9.    Other members are adamantly opposed to the use of ANY chemicals in the lake, fearful of unknown consequences and mindful of the many examples of man’s disastrous intervention with nature.
10.    To date we have put NO chemicals in the lake, nor have we spent one dollar on planning for chemical treatment.  We have, however, invited two companies to inspect the lake and advise us on possible courses of action, including chemicals.

Triclopyr is the chemical used to kill milfoil in Lake Morey

It is an herbicide that mimics a plant growth hormone.  It affects certain grasses.  In the doses used (2.5 parts per million) it is not toxic to humans, animals or fish.  It has no known reproductive toxicity, teratogenic effects, nor carcinogenic effects.
It has been in use since 1979.  (DDT was used for more than 30 years before being banned)
Over 70,000 lbs are used annually in the USA.  (I am not claiming this is a good thing)
It breaks down rapidly in water.  Renovate OTF (the triclopyr formulation used in Lake Morey) is a triethylamine salt, which dissolves in water and breaks down with a half life of 2.8 to 14.1 hours, depending on season and depth. (photolysis needs sunlight)
A toxic dose of triclopyr (LD/50) for a 120 pound person would be ingesting about an ounce of the raw chemical before it is applied, or drinking more than 3800 gallons of water to which it has been added. It is not readily absorbed through the skin.  It can cause burning of the eyes (hence the no swimming rule).

Informational Meeting Notice – July 23rd

What follows was circulated and posted around Lake Fairlee in the weeks before July 23rd under the banner,  Chemicals in Lake Fairlee? This headline was intended more to attract peoples’ attention than to frame the discussion.  We have reached a tipping point, where our efforts to control Eurasian Milfoil are not keeping up with its growth in our lake.  We need to come together as a lake community and take ownership of this problem, and begin to work to address it.  The Lake Fairlee Association has called this meeting to begin the process.

– – – – – – – – – –

All Interested Parties Please Attend
An Informational Meeting and Discussion
Concerning the Future of Lake Fairlee


For over a decade Lake Fairlee has been dealing with an invasive weed called Eurasian milfoil.  The Lake Fairlee Association has developed an extensive program using scuba divers every summer to clear patches of milfoil using hand picking, suction harvesting, and bottom barriers. This has been funded by donations from residents, from the three adjoining towns, and by grants from the State of Vermont.  Even though our dive program has been called a model program by the state, our resources are limited, and the milfoil continues to thrive in Lake Fairlee.

Meanwhile our neighbor Lake Morey has been combating milfoil for even longer.  Three summers ago they received permission to use an herbicide to kill milfoil in the lake.  They appear to have had good results, and the milfoil in their lake is greatly reduced.  Some Lake Fairlee people have suggested that we ought to do the same.  They have serious concerns that that our dive program is not the most efficient use of our resources.  Others are disinclined to allow the use of any chemicals in our lake.  The LFA Board has determined to be open-minded and cautiously consider the issue.  We have begun to gather information, and invite all interested parties to participate in the discussion.

Assertions – which the LFA Board wants to examine and understand

•    Even if all the milfoil is killed or removed from the lake, it will likely return.
•    Our dive program, at the level at which we can afford to maintain it, is not gaining ground on the milfoil problem.
•    Vermont, which regulates all of our milfoil activities, is among the most restrictive of all states about approving the use of chemicals.
•    The chemical triclopyr (used in Lake Morey) acts on a growth hormone in a certain class of plants.  It does not “poison” people or animals.
•    Triclopyr has been around for 30 years, and its toxicity has been exhaustively studied.
•    Triclopyr, and its chief metabolite TCP1, have known and measured levels at which it poses a danger to humans and animals, which is many times higher than the levels at which it would be introduced into the lake.

Please join us at 7:00 pm Thursday, July 23rd, at Horizons Day Camp, on Route 244 at Middlebrook Road.  Representatives from the Vermont Agency of Natural Resources will be on hand to answer questions.  Bring your issues and concerns, and see if we can develop a consensus on how to proceed.

Greeter Program Grows in Second Season

2008 was the second summer of our ‘Greeter’ program.  We believe that educating lake users is an important part of combating the spread of milfoil.  Our volunteers teach boaters about milfoil and how it spreads so that they can take preventive measures such as cleaning and inspecting their boats and equipment.


Our goal was to have a trained volunteer stationed at the boat ramp every Saturday and Sunday during peak hours.  We had trouble getting enough volunteers to provide the coverage we wanted.   Providing adequate training was very labor intensive, as we often had to provide the training one at a time.  We are in contact with other lakes, and are learning from their experience.

In spite of these difficulties, the program is growing and is having a beneficial effect.  Many of the people the greeters speak to are surprised by some of what they learn and express their gratitude for the information.  Next year we hope to be able to find funds to hire a regular (part time) greeter so we won’t have to lean so heavily on our (small number of) volunteers.