Chemicals in Lake Fairlee?

[ Editor’s Note: At the time this post was written in August of 2008 our understanding of the herbicide issue was incomplete.  In the ensuing year we have learned more about triclopyr use and about the permit application process.  Please rely on more recent posts for better information. ]

Last year our neighboring Lake Morey began treating its milfoil infestation with the herbicide Triclopyr.  Although they are only in the second year of a planned five year program, it is clear that the treatment is having the desired effect, and that milfoil populations have been greatly reduced where the chemical has been applied.  So far no adverse effects have been reported: native fish populations and plants species seem not to be suffering.  The chemical doesn’t work as well on strips along the shore as it does on large patches of milfoil, but Lake Morey is hoping to overcome this by using a higher concentration in future applications.  Finally it must be noted that nobody expects this to be a permanent solution to the problem.  The milfoil will come back, sooner or later.

Lake Morey’s success has prompted discussion among Lake Fairlee residents and the Association Board about whether we too ought to be using chemicals.   Some have suggested that we are wasting time and money on our program of suction harvesting, hand picking, and bottom barriers.  A few long time donors have told us that they would rather support treatment with chemicals than the seemingly ineffectual program of diver harvesting.  Others have spoken out strongly against putting chemicals of any sort in our lake, saying that the long term consequences cannot yet be forecast with certainty.

The Lake Fairlee Association board is evaluating every reasonable suggestion and giving serious consideration to each alternative.  This summer we have been gathering information, which is presented here, so that you will know what we know.  You will see that the situation is complicated by various factors, and that there is no easy answer.

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Preparation – Permits and Consultants

All milfoil control efforts are regulated by the State Department of Environmental Conservation.  Permits are required for suction harvesting, bottom barriers, chemical treatments, and biological controls.  Before a permit for herbicide application may be issued, the applicant must demonstrate that the nuisance species is not responding to other less drastic means of control, and that there are no reasonable non-chemical alternatives available. The applicant must contract with a licensed company that is approved by the State to develop and execute a comprehensive plan for milfoil control that includes the proposed herbicide application.

Lake Fairlee is successfully controlling its milfoil infestation.  After its discovery in 1993 milfoil was at first removed by hand picking.  Over the next decade the milfoil population grew steadily, and it spread to numerous parts of the lake in spite of our efforts to control it.  In 2002 we began using bottom barriers, which increased our effectiveness.  In 2005 we began suction harvesting, which allows a smaller crew of divers to remove much more milfoil than they might with hand pulling alone.  We cannot prove whether our efforts alone are responsible, but the milfoil population in Lake Fairlee seems to have stabilized over the past few years.

For whatever reason, Lake Morey’s milfoil problem got out of control.  By 2004, the north end of the lake was thickly infested with the plant, and other areas became too widespread to manage.  After a difficult application process, Lake Morey’s herbicide permit  was issued in 2007 to cover a five-year plan of treatment.  The plan approved included application of Renovate OTF (triclopyr) to the densest patches of milfoil in the first year, and the continued use of non-chemical means (harvesting and bottom barriers) in other area of the lake.  It anticipated subsequent applications for up to five years, with the exact areas and other requirements to be negotiated each year.  It must be understood that this “cure” is not permanent.  Even if 100% of the milfoil in Lake Morey could be eradicated, it seems likely to be reintroduced sooner or later.


If we were eligible for a permit, the tightly regulated application and herbicide treatment process is certain to be expensive.  Lake Morey’s annual milfoil costs increased by half the year they began using triclopyr.  The chemical treatment is expensive, in part because all work with it has to be done by an outside firm that does the application and conducts the extensive monitoring and pre- and post- testing.  In addition, we would have the expense of continuing conventional means in untreated areas.  We have had trouble raising enough money to pay for the program we run now. Lake Morey has “deeper pockets” than we do, for a number of reasons.  We would likely have to find an additional source of money for us to consider using chemicals.

Multiple Town Ownership

Lake Fairlee is bordered by three towns, any one of which might block a planned chemical application.  Unlike Lake Morey, which is completely within the Town of Fairlee, our lake is adjacent to Thetford, West Fairlee, and Fairlee.  Although only the Town of Thetford’s Selectboard would be directly involved as the permittee, the selectboards or citizens of any of the towns could object, with or without good reason. Because the herbicide can only be applied after the milfoil has started actively growing in the late spring and before the fish begin to spawn, there is a narrow window in which it can be used.  A lone citizen might therefore bring a lawsuit which could, by delaying the application, effectively block it even if the suit is unsuccessful,  We are cautioned by the experience of Lake Morey, whose earlier application was stymied by a court challenge, and whose recent attempt required a special election.  In our case these impediments could be compounded threefold.

Chemical Unknowns

These are all complicated realities. If we were eligible for a permit, and if we could come up with the extra money, we would still be compelled by the state to be in the business of divers, harvesting and bottom barriers. And all of this does not touch on the possible  long-term adverse effects to the ecosystem that might be caused by introducing this herbicide. We have learned a lot about triclopyr, how it works and that it is relatively safe. Nonetheless, the history of man’s intervention in nature is replete with tragic tales of unintended consequences. We are open to every reasonable approach, but want to be certain that concerned citizens know the issues and do not oversimplify the solution.

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