Review of 2013 Herbicide Treatment

Based on the recommendation of Lycott, Inc., and with the concurrence of State scientists this year we treated approximately 35 acres of the lake with Renovate OTF.  We were able to devise a strategy that accommodated the rare proserpinaca palustris growing near the mouth of Middle Brook.  The application was delayed by equipment malfunction, but a plan was quickly developed which allowed the procedure to progress the next day.  We are grateful to the State, and particularly to Matthew Probasco, for being flexible under difficult circumstances in the field.  Details of the treatment, including locations, concentrations, and problems are covered thoroughly in in Lycott’s “Final Report for Year Four of Myriophyllum spicatum Management” which has been separately submitted to DEC.

The treatment was not as successful as we had hoped.  Our only other experience with triclopyr in the lake (2010) was a resounding success.  Then nearly all of the E. milfoil growing in the lake was soon decaying on the bottom.  In 2013 only the treated areas along the northwestern shore remained milfoil free at the end of the summer.  Most of the rest of the perimeter of the lake showed growth in the September survey.  In particular, the bed at the mouth of Middle Brook that was a primary focus of our efforts, was growing robustly.  

Some good news . . . and some bad

We have receive the results of tests run on samples taken from the lake on June 17th.  We tested the same five locations, and none contained more than 15  ppb (parts per billion) of triclopyr.  Therefore the “voluntary” restriction on drinking and cooking with water from the lake has been lifted.  Again we remind you that we recommend that you never drink lake water without treatment or filtration.

At the same time we have been informed that, because triclopyr was found at detectable levels at the downstream testing site, we are required to extend the restriction (again, voluntary) on irrigation an additional 1.5 miles downstream. In accordance with the terms of our permit, certified letters have been sent to property owners downstream as far as 621 Barker Road.

[the following is the opinion of the author, who is not an expert]  We believe that the State’s restriction on irrigation is overly broad.  Triclopyr is an effective herbicide for dicots.  It is not toxic to monocots (e.g. grasses) or Gymnosperms (e.g. conifers).  There is no danger from irrigation of lawns.  In addition, the requirement that the concentration of triclopyr be less than one ppb (part per billion) Before the restriction is lifted seems unnecessarily low.  We would welcome some quantitatidata justification.


Results from First Post-Treatment Water Testing

We are required by our State permit to analyze water samples from the lake periodically after the herbicide treatment to determine the concentration of triclopyr present.  The removal of various restrictions on lake use depend on the concentration declining below certain levels.

Sampling Locations

The first samples were taken on Saturday, June 2nd, approximately 48 hours after the treatment.  They were collected from four locations around the lake where the herbicide was applied, and one downstream, as directed by the State.  Samples were obtained using a Van Doren collector, a device that allows collection from a specified depth in the water column.  We took samples from four feet from the bottom, or less in shallow locations.

The samples were refrigerated until Monday morning, when they were dispatched via FedEx overnight in their own little cooler to the SePro lab in North Carolina.  This is the company that manufactures the Renovate OTF formulation of triclopyr that we used.  They have a GCMS which can measure the concentration of triclopyr down to less than 1 part per billion.

A few days later the results came back.  The herbicide was applied at 2.0 parts per million (ppm), which is 2000 parts per billion (ppb).  The concentrations measured two days later in the areas treated ranged from 36 ppb to 370 ppb.

      number location concentration
1 North end 56.8
2 Aloha Hive 370.2
3 Middlebrook cove 36.2
4 Lochearn cove 130.2
5 1 mile downstream 32.8

This tenfold difference between the lowest and highest concentrations measured is unexplained, but repeats our experience three years ago LINK.

The restriction on use of the lake for swimming, fishing, and boating was lifted on Sunday, June 2nd.  The restriction on using the water from the lake for drinking or food preparation will be lifted once the herbicide concentration is less than 75 ppb.  Based on our earlier experience we are hopeful that this will occur two weeks or so after the treatment.  Therefore we plan to test again the week of June 17th.


So, we finally got the herbicide in the lake . . .

On Thursday morning the crew arrived and the boat arrived and the truck laden with pallets of triclopyr arrived. Will Stevenson, from Lycott Environmental  took his skiff out to warn a fishing boat of the impending herbicide treatment.  The pontoon boat was launched, and motored down to Aloha hive’s shore, where the herbicide was being unloaded from the truck.  That was the last thing that went well for a while.

Matthew and Will

It would take about seven trips with the pontoon boat to distribute the required amount of chemical.  The first load was onboard, but the motor would not start.  They tried everything, from drying the spark plug to a fresh fuel filter to a new battery.  Ultimately it was determined that there was water in the gas tanks.  New tanks with fresh gasoline were brought, and the motor was still nonresponsive.   The motor was taken to the local marine store, and diagnosed with a broken flywheel (later determined to be a broken flywheel key, no less debilitating).  No replacement boat nor motor could be found.  Finally – about four hours later – a new motor was purchased, to be installed overnight.

BUT the permit allowing us to perform the treatment was for that day, Thursday May 30th.  Further, it specified that the lake could not be closed on Saturday or Sunday.  Delaying the application until Friday would mean that there could be no swimming, fishing, or boating in the lake through Saturday.  We explored the possibility of postponing the treatment until the next week, but could not.

     Herbicide secured overnight in the Aloha Hive boathouse

Fortunately Matthew Probasco, the Aquatic Nuisance Control and Pesticide General Permit Coordinator from the Vermont DEC, was at the lake to oversee the treatment.  After some discussion he agreed to allow us to proceed with the application on Friday, provided that we were able to provide actual notice of the change to the lake users and residents.  So early Friday morning volunteers from the Lake Fairlee Association posted signs on the three Town Halls, made changes on the 46 signs posted around the lake, and visited every one of the hundred or so houses and camps on the lake.  Where we found people at home we explained what was happening.  Otherwise we posted a notice where it would be seen by anyone entering with the same information.  In every case those we met were supportive of the treatment and wished us good luck.

Will picked up the pontoon boat with new motor installed and was on the lake by about 8am.  Shortly the crew arrived and the first batch of herbicide was loaded aboard.  The boat departed and disappeared around the corner headed to the north end of the lake.  An hour later it had not returned.  Now there was a problem with the chemical being so moist that it was clumping up and not flowing smoothly down into the eductor – which is the gadget that creates a suspension of the herbicide particles in water so that it can be sprayed out on the lake.  After several experiments Will figured out how to rig sire screens in the intale of the eductor which would catch and break up the offending clumps.  The treatment was finished by mid afternoon.

We are grateful to all who participated and helped overcome the various difficulties.  Many thanks to all.


Press Release from VT DEC

[The following was issued by the Vermont Department of Environmental Conservation on Friday, May 31]

Use Restrictions Recommended for Lake Fairlee Following Milfoil Treatment May 31, 2013

Fairlee, VT – The chemical herbicide triclopyr was selectively applied to Lake Fairlee on Friday, May 31, to control the aquatic invasive plant Eurasian watermilfoil, Myriophyllum spicatum in dense beds around the lakeshore.

Originally scheduled for Thursday, the application was delayed until Friday. Local residents were informed of the application, which was authorized by the Department of Environmental Conservation’s Aquatic Nuisance Control Program, before it was scheduled.

Lake Fairlee is not officially closed. However, as a precautionary measure, under advice from the Vermont Department of Health, the public is strongly encouraged to comply with the following voluntary use restrictions for Lake Fairlee and the waterway downstream to its confluence with the Ompompanoosuc River:

  • No use of the water for any purpose today (Friday, May 31) and tomorrow (Saturday, June 1)
  • No use of the water for drinking, or for food or drink preparation until further notice.
  • No use of the water for recreation (swimming, boating, fishing) until Sunday, June 2.
  • Other domestic uses, other than for drinking, or for food or drink preparation may resumeSunday, June 2
  • No use of water for irrigation for 120 days or until further notice.

Triclopyr is a highly effective broadleaf herbicide that is used to control a variety of nuisance and invasive aquatic plant species, and is very selective to Eurasian watermilfoil. Triclopyr is most effective when applied when Eurasian watermilfoil is actively growing, thus a late spring treatment is generally most effective.

The displacement of native aquatic plants in particular has been seen in lakes in Vermont where Eurasian watermilfoil has become widespread and dense. By using this herbicide selectively Eurasian watermilfoil growth can be controlled manually in other areas of the lake and improve habitat for the native aquatic plants in the lake. Uncontrolled, Eurasian watermilfoil will eventually out-compete the native plants. Native plants will not be significantly affected by this treatment.

Please contact the Lake Fairlee Association, via Skip Brown at 802-333-4541 or Suzy Kerr at 802-333-9079 for additional information.

Up to date information may also be obtained by visiting the Lake Fairlee Association webpage

Visit Vermont’s Aquatic Nuisance Control Program webpage at:

Lake Treatment Delayed One Day

Lake Will Be Closed Thru Saturday

We had planned to complete the chemical treatment of Lake Fairlee on Thursday.  Our permit requires that the lake be closed to all recreational uses until the second day after the treatment.  The lake would then have reopened on Saturday.

Due to mechanical difficulties we were unable to apply the herbicide on Thursday.  The motor on the only boat equipped to carry the required weight of dry chemical and the water sprayer developed a broken flywheel.  We explored every option to find another way of doing it, but to no avail.

Because the company that is doing the application is obligated to do work on other lakes every day next week, and because we are committed to completing the process before the commercial camps on the lake begin their pre-camp training sessions, we were faced with a hard decision.  We could push back the treatment one day until Friday, which would mean that the lake would be closed until Sunday, or we could postpone the whole thing for another year.

On the one hand a Saturday closure will work a hardship on those who had planned to get in or on the lake this weekend.  On the other, we were stymied last year by the marsh mermaidweed and there is already more milfoil in the lake than can be controlled by hand pulling.  We made the decision that we feel serves the lake’s best interest.

Therefore the following permit conditions are changed:

  1. No use of the lake for any purpose on Friday, May 31, and Saturday, June 1.
  2. Recreational use of the lake may resume on Sunday, June 2.  This includes boating, fishing, and swimming.

The other conditions are unchanged.

We apologize for the inconvenience.

Herbicide Treatment Planned for May 30th

Sign to be posted around lake

We have received permission to use the herbicide triclopyr to treat the Eurasian milfoil in Lake Fairlee.  Although we will be treating only about 30 acres, less than 7% of the lake, for safety we are required to close the whole lake for two days.  Notices have been mailed to owners of lakeshore properties, and signs (above) will be erected around the lake to prevent accidental use.

The herbicide we will be using is toxic to certain plants, and particularly hard on the milfoil we want to get rid of.  HERE is how it works.  On the other hand, it is relatively benign in animals, which makes it a good choice for use in our lake. Before the first lake treatment in 2010 I pulled together this collection of articles [LINK] to help evaluate any risk of its use.  Lake water may not be used for irrigation for four months – or until the concentration of triclopyr is below 10 parts per billion.  If you are accustomed to watering your lawn with lake water, please make other arrangements.

Vermont is among the most restrictive states, imposing strict regulations on the use of any chemicals.  Even so you can see on the sign above that fishing, swimming, and washing in the lake are permitted after the second day.   According to their regulation one could drink from the lake (which we do not ever recommend, for a variety of other reasons) once the concentration of triclopyr falls below 75 ppb, which took less than four weeks in 2010.

So please forgive the inconvenience.  We have scheduled the treatment as early as we could, so as to minimize conflicts.  Bear with us and get ready to enjoy another glorious summer in a (more nearly) milfoil free lake.



Proposed Milfoil Treatment – Summer 2013

Our State permit requires that we make plans for next summer’s milfoil treatment while the lake is still covered with ice.   So in the end of January we met with representatives of Vermont’s Department of Environmental Conservation, including the Administrator of the Aquatic Nuisance Control Permit Program.  We talked about the condition of the lake, looking at last fall’s situation and speculating about the coming summer.

Also present at that meeting were representatives of Lycott Environmental, Inc., the company with whom we contract for milfoil control services.  The Lake Fairlee Association board believes that herbicide treatment is the most cost effective way to control the milfoil in our lake.  On the other hand, our State permit mandates that herbicide be used as an integrated part of a multi modal plan.

The State only allows the use of herbicide where the milfoil growth is moderate or dense.  So the program we presented to the State looked much like the previous map:

In 2012 our planned treatment was foiled by the last minute discovery of a rare plant near the mouth of Middle Brook.  See LINK.  We prepared this graphic to show the range and extent of both the mermaid weed and the milfoil.

In 2012 the State would have let us proceed with the herbicide treatment if we had erected an expensive and cumbersome barrier between the treatment area and the shallows where the mermaid weed grows. We wanted permission to proceed this year without a barrier, arguing that the mermaid weed survived the 2010 treatment and flourished.

Based on our conversations Lycott would prepare and submit a treatment plan.  Our answer would wait for the necessary review process.  Meanwhile we had other work to do.


The Condition of the Lake

Year Three Herbicide Report Available

Our herbicide treatment permit from the Vermont DEC requires that Lycott (the firm that does the herbicide treatment) prepare a report for the State at the end of each year during the five year term of the permit.  Lycott has released this report, and it details the milfoil control activities undertaken this year, and the results of the surveys done throughout the growing season which identified and assessed the areas of Eurasian milfoil growth.

As we reported earlier [LINK], our plan to treat the dense patch of milfoil near Middle Brook was stymied.  Instead we employed divers to do hand pulling in other areas where the plants were sparse, hoping to prevent further spread.  In all, over 11,000 plants were removed.  In addition, some bottom barriers which had long overstayed their welcome were removed.  The report includes several maps, one of which shows the location and density of our milfoil enfestation as of the last survey in September, 2012.

The most important part of the report, however, is the section titled Conclusion and Recommendations.  It concludes that despite our efforts this year the distribution of E. milfoil in Lake Fairlee has increased substantially.  It recommends another triclopyr application in areas where the milfoil grows thickly, and hand pulling or possibly bottom barriers in other areas.

You can download the complete report by clicking on the image below.  (pdf file, 8Mb)

Click to download complete report