Final Triclopyr Test Results

September 1st, 2010

Earlier this week we sampled two locations in the lake and submitted them to the lab.  The concentration of triclopyr in the lake is now about 10 parts per billion.  The warning signs around the lake will have to stay up for the full 120 days, until the end of September.

The following table shows these results, as well as those for all of the other tests this summer.  The concentrations are expressed in parts per billion.

Applied June 3rd June 9th June 15 June 21 June 28 July 28 Aug. 30
0 days 1 day 7 days 13 days 19 days 26 days 56 days 89 days
Site 1 1500 202 121 38
Site 2 1500 930 127 66 13 11
Site 3 1500 510 113 98 59 50
Site 4 2000 85 47
Site 5 2000 160 39
Site 6 2000 145 42
Site 7 2000 123 93 65 42 17 10
Site 8 2000 332 88 40
Site 9 0.0 15 30
Site 10 0.0 31 0.0

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The Lake Fairlee Dam

August 26th, 2010

Lake Fairlee owes its present size and shape to a dam that was first constructed over two centuries ago.  There was a lake here before the dam, but it was only about 80% of its present volume.   The lake is owned by the State, but the dam is privately owned.  If the dam were to fail, the water level in the lake would be considerably lower.  Instead of their beautiful lakeshore many property owners would look out on an expanse of mud, silt, and decaying plants.  The Lake Fairlee Association has long wanted to learn as much as we can about the condition of the dam, what should be done to preserve it, and what plans might be needed in the longer term.

The dam extends from left to right under the green house. North is to the right.

Ancient History

In 1797 the Vermont Legislature passed an act enabling the construction of a dam a the southwest corner of Lake Fairlee “in order to supply with water several mills standing on the stream which empties out of said lake and the supplying said mills with a sufficiency of water to be of great public utility . . . .” [note]  Eldad Post, perhaps with his son Aaron, built the original dam shortly thereafter.  In 1831 the lake level was raised, and again in 1904 or 1905.  At various times the rights of property owners abutting the lake have been considered, and at least once the dam owner “purchased flowage rights” from them.  The saw mill that originally was located right at the dam was removed to another dam 1-2 miles downstream in 1891 (just above Route 113 in Post Mills).

By 1939 the dam needed repairs, and “was rebuilt at the expense of the littoral owners [the Lake Fairlee Association] , with the consent and under the direction of the [then owner Walter A. Malmquist].”  [note]  That repair necessitated lowering the level of the lake by six feet, about which the Lake Fairlee Association had no complaint.  In the summer of 1941 Malmquist claimed the right to raise or lower the lake level whenever he pleased, and offered to sell to the Lake Fairlee Association “his water rights” for $20,000.  When they declined the offer, he then opened the gate in the dam for two months, and “large areas of mud banks were exposed, a mephitic odor was generated by the decaying aquatic vegetation, and the littoral owners were impeded in their access to the lake from their cottages and boat houses.” (mephitic means a foul smelling or putrid stench)

As a result of this dispute, and presumably at the urging of the Lake Fairlee Association, the State of Vermont brought suit against Malmquist to enjoin him “from unreasonably and arbitrarily drawing down the waters of the lake.”  Malmquist appealed on procedural grounds, claiming that the State did not have standing (was not a party in interest) so could not bring the suit.  He also claimed that lowering the lake could not be considered wrongful, as he only returned the lake to its historical level (before 1797).  Finally, grasping at a legal straw here, he argued that the original Act enabling the dam was unconstitutional.

The Vermont Supreme Court found Malmquist’s arguments unpersuasive, and granted the requested injunction.  Along the way they said a lot of other things that might be of interest to the reader, who can read the whole opinion HERE.

More recently . . .

Jurisdiction over the dam now resides in the Dam Safety Section, a small office within the Facilities Engineering Division of the Department of Environmental Conservation.  They are charged by Chapter 43 of Title 10 of the Vermont Statutes with periodically inspecting non-federal dams to ensure that they don’t “pose a potential or actual threat to life and property.”  If they find a dam to be unsafe, they “shall issue an order directing reconstruction, repair, removal, breaching, draining or other action it considers necessary to make the dam safe.”  The law authorizes further enforcement, even allowing the State to take the dam by eminent domain if the property owner does not remedy the unsafe situation.  You can find the relevant laws HERE.  I direct your attention especially to sections 1095 and 1105.

Pursuant to this authority, the State has inspected the dam from time to time, most recently in November of 2009.  The engineer found the overall condition of the dam to be “fair.”  They classified our dam as to its potential for downstream hazard as Class 3 (“low hazard”).  This classification means that failure of the dam will only damage farm buildings, agricultural land, or country roads.  It is possible that an examination of recent construction downstream might lead to reclassification.  Class 2 (“significant hazard”) applies when there are a small number of habitable structures or appreciable agricultural structures in the potentially affected area.

The report included various recommendations for the owner, which involve monitoring, inspecting, testing, and planning for repair.  Although it details numerous specifics in which the dam is less than optimal, we understand that previous inspections resulted in similar findings.  So far the owner’s policy of benign neglect has been sufficient.  You can download a copy of the report HERE. (pdf)

Map and pictures

Water leaves the lake from the west end and flows under Robinson Hill Road into a small cove, then over (and through) the dam about 300 feet downstream.  As can be seen in the photo at the beginning of this post, a house sits in the middle of the dam.  To the south (to the left in the photo above) there is a 30 foot section of dam, where a spillway flows over the top.  To the north the dam extends about 120 feet. 

The dam is visible, and the house straddling it, in the photo below.  It is the bright line in the forest near the middle of the picture.  The dark area to its right is the outlet of the lake, and the outlet stream can be discerned as an upside down “U” to the left.  HERE is the surrounding area in google maps as an aid in orientation.

Satellite photo of the dam (nearly vertical line near center)

I was able to see the dam from downstrean by walking in the streambed.  The day I took these pictures no water was flowing over the spillway, as it had been relatively dry and the lake level was low.  There was lots of water flowing through the dam, however.  The following two photos were taken from below the dam, looking back up at the long (northern) portion.

Water flowing through (not over) the dam.

Water coming through the dam

The ladder and the railing give an indication of the relative dimensions of this part of the dam.  Water is not seeping, but flowing freely through the dam at several locations.

Water coming through the dam under the house

This photo was taken from the same location, looking just a little to the right.  Here you can see quite a lot of water coming from the portion of the dam under the house.  Note also the cinderblocks stacked up to support the walkway where the dam has eroded.

Where do we go from here?

We are grateful to the Town of Thetford for calling for the recent inspection.  It suggests the possibility of seeking to have the dam reclassified, which would at least get it inspected more frequently.  The Lake Fairlee Association can educate ourselves and our neighbors about the condition of the dam, and its economic importance.  We can partner with the Town, offering volunteer help where requested, and at some point financial help.  We can continue to study the confusing statutory and jurisdictional situation that might arise should the dam give indications of impending failure.

We do not expect any significant action or change in the dam in the short term, but feel that clear communication and greater understanding can only help in the long run.

[ our dam's State Identification Number is 206.01 ]

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An Open Letter to Lake Residents

August 14th, 2010

Dear Neighbor,

I too have property on the lake.  We have a common interest in preserving the health and beauty of our wonderful lake.

Are you planning any construction or landscaping on your property?  You may not be aware of the possible adverse impact that soil runoff into the lake can cause, and of beneficial choices available to you as you plan your finished lakeshore.

Lake Fairlee is becoming increasingly nutrient rich, which is accelerating its eutrophication.  [EXPLANATION] While this is a natural process in all lakes, ours is beginning to show signs of algal blooms and other symptoms of its over-rich diet.  Nutrients such as nitrogen and phosphorous enter the lake as runoff from lawn fertilizer and farm manure far up in the watershed.  Also every time the earth is disturbed (even for road maintenance) there is soil runoff that finds its way into the lake, and this soil contains nitrogen fixed by plants and in decomposing plant matter.

We hope that those who build around the lake are aware of this process and take steps to minimize the impact of their activity.  The silt fence that contractors are supposed to put downhill from their work probably helps a little.  Please encourage your builder to consider the health of the lake as he proceeds, and be careful as he digs and grades.  Protecting the health of the lake is the right thing to do, AND it protects our property values.

One of the best and easiest things a lakeshore property owner can do is to create and maintain a shoreline buffer.  Leaving an area of natural growth by the lake will both secure the shore against premature erosion and act as a filter for runoff from farther up the hill. [MORE INFORMATION]

The worst thing for a lakeshore – from the perspective of lake health – is a beautiful green lawn stretching down to the lake.  Usually this means fertilizer to promote growth and weed killer to keep down crabgrass etc.  Each of these is harmful to the lake.  And both can be ameliorated by planting a un-manicured buffer along the shore.  Simply electing not to mow down to the shore will allow useful growth to take over.

I hope you find this information helpful.  And that you take my letter in the neighborly spirit in which I intend.  Those of us who are lucky enough to own property on the lake have a special responsibility that comes with our delightful home sites.  The future health of the lake depends on us.

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A Primer on Lake Health

August 13th, 2010

The Natural Evolution of a Lake

Lakes in nature evolve.  A young lake has very clear water and is usually surrounded by rocks.  As time passes, erosion brings soil and organic matter into the lake, and it gradually becomes richer in nutrients.  It supports a rich diversity of aquatic plants and the fish that feed on them.  The runoff contains sand and clay and soil, some of which is not washed downstream and settles on the bottom as silt. It also contains increasing amounts of organic content, decayed plants and animals and animal waste.  Eventually – after many thousands of years – this sediment will fill in the lake, and it will become a marsh then a swamp then a field or forest.

One way that scientists classify lakes is by their trophic states [LINK].  A lake’s trophic classification is determined by the amount of nutrients in the lake, which in turn determine the amount of plant growth the lake can support. Lake Fairlee is in its mesotrophic phase, a mature lake growing into middle age. As additional nutrients run into the lake it will naturally become eutrophic, a state characterized by dense plant growth and algal blooms. While this is an excellent habitat for waterfowl, swimmers and boaters find it less enjoyable.

A eutrophic lake, characterized by algal blooms

Nutrients: Nitrogen and Phosphorous

Nitrogen (nitrates) and phosphorous (phosphates) are the primary nutrients needed by all plants to flourish.  Increased levels of these nutrients accelerate the natural process of maturation/degradation of a lake.

Of course nitrogen and phosphorous are found in fertilizer and plant food, which are used for their beneficial effect on lawns, gardens, and farms.  When excess is washed into the lake, it fertilizes plant growth there.  Every type of aquatic plant is affected, from single celled algae to beautiful water lilies.  Fast growing weeds, like Eurasian milfoil, absorb these nutrients rapidly with corresponding growth.

These nutrients are also found in all plant matter.  So trees, leaves, and needles that fall in the lake contribute to its nutrient load. More importantly, plants die and decompose on land, and become the rich soil in our forests and fields.  These plants have spent their lives (literally) pulling nitrogen out of the air and binding it in their cells.  When the land is disturbed, by natural erosion or human disturbance, this soil most often ends up in the lake, and increases its nutrient level.

These nutrients are also found in animal waste.  Farmers and gardeners have long taken advantage of this.  Manure that is spread on fields can run off to the lake, especially after a heavy rain.  An aging or poorly constructed septic system might also leak into the lake.

Pollutants: Oils, Chemicals, and Drugs

While excess nutrients can be too much of a good thing for our lake, other substances are just plain noxious.  Among the most problematic are oil, paint, and solvents.  This includes nail polish remover!  Unused pharmaceuticals or over-the-counter medications can also cause real problems.  Fortunately a properly constructed and maintained septic system will keep most of these from the lake.

But wait!  Because paint and oils can be ruinous for a septic system, some people would rather dispose of them by pouring them in the woods behind the garage.  Eventually some of this waste will find its way into the lake.  (Our problems are actually less than municipalities with community waste processing.  People throw just about anything down a garbage disposal . . . )

Because of the nature of drugs and hydrophobic (oily) contaminants, just a very small amount can have a detrimental effect on plants and animals in the lake.  We will probably never know just what human waste is in the lake.

The Whole Watershed

Lake Fairlee itself covers about 450 acres, but its watershed is more than 25 times as large.  All the runoff from within this 20 square mile area eventually finds its way into Lake Fairlee.  This means that when a farmer up Middlebrook Road spreads manure, some will flow down to the lake. (and that is good, nutrient rich, fertilizer)  It means that when a home builder half way to Bradford breaks ground for a new building, the soil unearthed will find its way into the lake.  Likewise, when the road maintenance crew of one of our three towns does routine grading on one of our many gravel roads it will likely affect our lake.

It may be helpful to think of the watershed as being like a sponge, just soaking up nutrients and pollutants.  The more slowly they are released into the lake, the better (from our point of view).  So let’s do what we can to avoid forest fires, earthquakes, clear cutting, and massive excavation.  And when we must disturb the earth anywhere near the lake, lets do so in such a way as to minimize the inevitable runoff.

What Can We Do?

We cannot stop the gradual maturation and filling-in of our lake.  We can, however, take steps to reduce our contribution to the process.  We can also stop allowing the introduction of hazardous chemicals.

To minimize the increase in nutrient levels:

  • When doing farming, construction, landscaping, road repair: MINIMIZE disturbance (to the extent possible, NO DIGGING)
  • Do not use chemical fertilizer nor herbicides
  • Plant a buffer zone — this prevents erosion and filters pollution from runoff
  • Work with your builder, architect, and town to make decisions that are healthy for the lake.  Little changes.
  • Road maintenance matters.  Work with town road departments.

To protect against other pollutants:

  • Dispose of paint, solvents, drugs, and the like properly
  • Inspect and maintain your septic systems
  • Educate the community

Remember, even clearing a lot three miles upstream has an impact.  Think of the whole watershed!

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

links for more information:

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Showing that our Greeter Program Works!

August 10th, 2010

[following is an email dated August 6th, 2010, that speaks for itself]

Hi Libby,

I just received the sample you submitted that came from a boat inspected by your access area greeter, Liza.  The plant specimen is not Eurasian watermilfoil.  In fact, the specimen is fanwort (Cabomba caroliniana), an invasive plant not known to occur in Vermont, although there are known populations in neighboring states – including Massachusetts, from where the boat apparently came.

The only known populations of this plant in northern New England are in southern NH, but it has been introduced fairly widely in southern New England (MA, Conn, RI) and southern NY.  If the boat did not come from a waterbody with a known infestation it could indicate a new infestation that has not previously been detected.  It would be good to find out the specific waterbody this boat came from so that I can alert my colleagues in Massachusetts in case they aren’t aware of the infestation, and to let them know there may be a spread prevention issue for them as well.  If you could find that out for me I’d much appreciate it – or feel free to have Liza contact me directly.  Also, if this is a boat that makes frequent trips back and forth between Fairlee and an infested water in Massachusetts, it would be good to be sure that the boater is well educated about the importance of careful spread prevention.  Perhaps Liza will know whether this boat is a frequent visitor to Fairlee, or whether this was a one-time visit, and how receptive the boater was to her spread prevention information.

Hats off to Liza! This was a really important “save”!!!  It would be a shame to see this invasive plant (fanwort) become established in Fairlee or anywhere else in Vermont.  Although the plant was a little bit dried out when I received it, I believe it could have been sufficiently “alive” when Liza collected it to have been viable, and this plant fragment could have conceivably introduced this species into Fairlee.  This is what greeter programs and spread prevention are all about!  Well done!

[ . . . ]

Once again, congratulations on your successful greeter program, and thanks for all your efforts to protect Vermont’s waters!

Best regards,

Leslie J. Matthews, Ph.D.
Environmental Scientist
Water Quality Division
Department of Environmental Conservation

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Testing Results After Two Months

August 1st, 2010

Even though the State does not require it, we are continuing to measure the herbicide residue after it was measured as less than 75 parts per billion, and the State declared the lakewater to be “safe to drink*.”  We only sampled from two locations, because the cost of analyzing each sample is in excess of $100.00.  We chose the two locations where we had found the highest concentrations of triclopyr in earlier tests, one from each end of the lake.

As expected, the concentration has declined significantly.  Although the sites tested are where the chemical was applied, we believe that by this time the chemical has diffused throughout the lake, and that concentrations measured anywhere would be similar.

Location Applied June 3rd June 9th June 15 June 21 June 28 July 28
0 days 1 day 7 days 13 days 19 days 26 days 56 days
Site 1 1.5 ppm 202 ppb 121 ppb n/a n/a 38 ppb n/a
Site 2 1.5 ppm 930 ppb 127 ppb n/a n/a 66 ppb 13 ppb
Site 3 1.5 ppm 510 ppb 113 ppb 98 ppb 59 ppb 50 ppb n/a
Site 4 2.0 ppm 85 ppb n/a n/a n/a 47 ppb n/a
Site 5 2.0 ppm 160 ppb n/a n/a n/a 39 ppb n/a
Site 6 2.0 ppm 145 ppb n/a n/a n/a 42 ppb n/a
Site 7 2.0 ppm 123 ppb n/a 93 ppb 65 ppb 42 ppb 17 ppb
Site 8 2.0 ppm 332 ppb n/a 88 ppb n/a 40 ppb n/a
Site 9 0.0 15 ppb n/a n/a n/a 30 ppb n/a
Site 10 0.0 n/a n/a 31 ppb n/a 0.0 ppb n/a

We plan to test the water at least once more, in late August, around 12 weeks after the chemical application.

* The State has determined that 75 ppb is a safe amount of triclopyr in drinking water.  Nonetheless we do not recommend drinking from the lake – for a variety of other reasons.

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How to Keep the Milfoil from Returning

July 20th, 2010

The herbicide appears to have worked its magic, and our milfoil is lying on the bottom of the lake in decay.  We know that this situation is only temporary, that the milfoil will return, sooner of later.  There are several things we can do to slow its return.

One of these is to prevent the introduction of new plants and fragments into the lake.  This most commonly occurs when a boat enters Lake Fairlee, having recently visited another lake.  Unless the boater is careful to wash off his boat, his motor, and his gear, fragments of Eurasian milfoil can wash off in our lake and can take root.  That is how a new infestation starts.

Many states have laws requiring that every boat be washed before entering a new lake.  Still more have nearby wash stations for the convenience of boaters.  We support both of these ideas, and will work to bring them to Lake Fairlee.

Greeter Program

Over the past three summers we have introduced and expanded our Greeter Program.  Our goal was to have someone stationed at the boat ramp during prime access hours to inform boaters about the threat of milfoil to our lake and others.  In the first years it was staffed by volunteers, and more recently by part time employees.  This summer Liza McEvoy represented us every Friday, Saturday, and Sunday.

Our "Greeter," Liza, at her station by the lake

Unfortunately our greeter has no real authority, and cannot do more than advise boaters.  She asks each one if she can help them perform a “courtesy inspection,” and she shows them what to look for and where.  She explains about the threat and potential cost of new invasive species to our lake and to others.  She is our ambassador to the outside world, the only thing besides the ubiquitous “Warning” signs that many non-residents know about the Lake Fairlee Association.

The following is a handout that Liza has available for visitors:

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

AQUATIC INVASIVE SPECIES FACT SHEET

MOST COMMON PATHWAYS THAT INTRODUCE NEW SPECIES:

  1. Canals and waterways (shipping) – (e.g. From the Great Lakes on ship hull to Lake Champlain. From Lake Champlain to a boat trailer and then to a new body of water)
  2. Overland transport (trailers)
  3. Fishermen’s felt-soled gaters, boots, gear
  4. Introduced as ornamentals  (ex. Loosestrife)
  5. Aquariums (releasing aquarium fish, plants or water into lake, river, etc.)
  6. Ducks and geese
  7. Illegal stocking (e.g. “alewives”) Need to have a permit to release any fish into water.

THE BIG THREE AQUATIC INVASIVE SPECIES IN VERMONT:

1. Eurasian Milfoil (looks very similar to many native milfoils)

  • crowds out native spceies
  • can produce dense mats over the surface
  • reproduces rapidly through fragmentation
  • 64 lakes and ponds, and 25 other bodies of water in VT have Eurasian milfoil
  • 2-3 new infestations are reported each year

***NEW invasive milfoil found last year in one location -  Hall’s Pond, in Newbury, VT. “Variable-leaved Milfoil” is more difficult to control than Eurasian Milfoil.

2. Water Chestnut

  • floating clusters create a dense canopy on the surface which allows no light        through. This kills all the native plants beneath.
  • Spreads by seeds. It’s an annual plant, but one seed can live in the sediment for 10 years (!). The plants must be harvested BEFORE they go to seed for management to be effective.

3. Zebra Mussels

  • Native to the Caspian Sea. Came to U.S. via international shipping into through Lake Champlain Canal. Young zebra mussels are microscopic. They can be transported via water so bilges and bait buckets should be cleaned, and water in motor should be drained. They can get entangled in plant material, so remove all plants. If they attach to boat hulls, they may be invisible but can be felt if you run your hand across the surface.

OTHER AQUATIC THREATS:

1. Didymo (common name= “rock snot”)

  • Algae that prefers moving water and rocky bottoms, but could float down to our outlet stream where it could settle and multiply…then move to the Ompompanoosuc and into the CT River. Didymo is already in the White River and CT River – so boats traveling here after being in either river could bring it to the lake. Didymo is microscopic and is most often carried unknowingly on boat hulls and felt-soled fishing boots and waders. Cells will thrive in moist conditions for weeks unless boats and gear are washed thoroughly and dried in the sun for 5 days.

2. Baitfish

  • VHS is a coldwater fish virus that causes bleeding and large scale mortality in fish and 36 other aquatic species. Once it is found in a lake, you cannot get rid of it. The virus can be carried in a live well from one body of water to another. Emptying and cleaning live wells will help keep the virus from spreading.

IF FISH ARE TRANSFERRED FROM ONE BODY OF WATER TO ANOTHER, THEY CAN SPREAD VHS WHILE SHOWING NO EXTERNAL SYMPTOMS. Buy baitfish ONLY at certified dealers:

The Vermont Fish and Wildlife web site lists certified baitfish dealers: http://www.vtfishandwildlife.com/fish_baitdealers.cfm

  • Fisherman are allowed to harvest baitfish ONLY on the lake in which they fish in. Do not transport baitfish to another body of water.
  • Alewives have been responsible for huge fishkills on Lake Champlain and elsewhere.
  • Rusty Crayfish (red spot on side) are harmful. They have been found in Lake Morey. Native crayfish are okay. Buying baitfish at a state-approved distributor will help ensure the right kind of crayfish.

CLEANING INSTRUCTIONS (WHEN MOVING BOAT TO NEW BODY OF WATER):

1. Always remove debris and plants from:

  • propeller
  • trolling motor (check shaft)
  • transom
  • trailer lights and license plates
  • behind wheel wells
  • hitch and auto bumper
  • bunks on trailer
  • axle
  • chains
  • fishing gear
  • anchors

2. Always drain the bilge and live wells.

3. If possible, rinse boat with hose or dry in sun for 5 days.

4. Even better, power wash with soapy water at a car wash or at home.

ABOUT THE LAKE FAIRLEE ASSOCIATION

The LFA has used the traditional 3-weapon offense against Eurasian milfoil in the past: hand-pulling by divers, bottom barriers, and use of a suction harvester. However, these methods could not keep pace with the exponential spread of milfoil. The decision was made this year to treat the lake with an herbicide which targets milfoil specifically. You can learn more about the research that led to this new strategy, and about the permit issued by the state DEC Water Quality Division, by going to our blog via our website (www.lakefairlee.org). Based on the post-treatments assessments on Lake Morey after they used the same herbicide, we are hopeful that Lake Fairlee will experience similar success.

The lake does NOT have zebra mussels or other invasive species yet, but that is why it is so important to wash your boat and trailer before coming on to this lake from another body of water. Lake Champlain has many more invasive species than milfoil and we want to keep Lake Fairlee free of other nuisance plants/animals.

Join The Lake Fairlee Association and become involved in preserving the lake.

If you are interested in joining or learning more about the lake association, write your name and address on the sign up sheet with the Greeter and go to www.lakefairlee.org. There will be a link to our blog that will have updated information about upcoming events, some history, education, and more.        

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Milfoil in Lake Fairlee – July 2010 Update

July 9th, 2010

[ We were asked to provide a brief statement on the milfoil in Lake Fairlee to be used by the guides on the boat tours of the lake offered as part of LAKEFEST 2010. We include it here, as it provides a concise summary. ]

Eurasian Milfoil is a floating aquatic plant native to Europe, Asia, and northern Africa. It was imported and sold in the United States as a decorative aquarium plant. It has become a problem in many northern lakes, and has been in our lake for over fifteen years. It grows faster than many native lake plants, and tends to crowd out the native plants and can drastically alter a lake’s ecology.

Because it roots in the lake bottom and reaches for the sunlight at the surface, it grows primarily in water less than 15 feet deep. Even a small fragment can take root, so it spreads easily within a water body and from lake to lake, traveling on boat bottoms and trailers. In the spring it is frail and brittle, and easily fragmented. In the summer it grows strong and thick. If allowed to spread unchecked it threatens to clog the lake with dense mats of plant material. Parts of the lake can become inhospitable to boaters and swimmers, and ultimately property values and tax revenues may suffer.

The Lake Fairlee Association recognized the threat posed by Eurasian Milfoil fifteen years ago, and began a series of escalating responses intended to eliminate or at least control it.  Initially we used hand pulling of the plants and their roots.  In 2002 we began using bottom barriers for some of the most problematic areas.  In 2004 we built and deployed a suction harvester to make the hand pulling much more efficient.

These methods were not sufficient.  In fact, the milfoil has continued to spread in spite of our best efforts.  Scientific surveys we had conducted last summer found moderate or dense milfoil growth in 26% of the lake.  Late this spring we obtained a permit from the State to treat the lake with an herbicide, triclopyr, to which the milfoil is particularly susceptible.  In early June Lycott Environmental, Inc., a firm licensed to do this kind of work in Vermont, applied triclopyr to the areas of heavy milfoil growth.

The chemical has had its effect, and the milfoil in the lake is now dead or dying.  Most of the plants can be seen decaying on the bottom of the lake.  There has been negligible effect on other species of plants, and no observed effects on fish, birds, or other animals in the lake.  We have been testing the lake water in ten locations since the treatment, and the State has declared the lake’s water safe for drinking – at least as far as the herbicide concentration is concerned!

Late this summer another detailed survey will ascertain just how successful our treatment has been.  Until then we will enjoy swimming and boating in the open water of the lake.  And we will redouble our efforts at educating boaters how to wash their boats and equipment to curtail the further spread of milfoil and other aquatic nuisances from lake to lake.

Posted in Herbicide, Milfoil Eradication, Mlfoil Education | No Comments »

Testing Results from Fifth Round

June 30th, 2010

Here are the cumulative testing results.  The most recent samples are on the right*.

Location Applied June 3rd June 9th June 15th June 21st June 28th
Site 1 1.5 ppm 202 ppb 121 ppb n/a n/a 38 ppb
Site 2 1.5 ppm 930 ppb 127 ppb n/a n/a 66 ppb
Site 3 1.5 ppm 510 ppb 113 ppb 98 ppb 59 ppb 50 ppb
Site 4 2.0 ppm 85 ppb n/a n/a n/a 47 ppb
Site 5 2.0 ppm 160 ppb n/a n/a n/a 39 ppb
Site 6 2.0 ppm 145 ppb n/a n/a n/a 42 ppb
Site 7 2.0 ppm 123 ppb n/a 93 ppb 65 ppb 42 ppb
Site 8 2.0 ppm 332 ppb n/a 88 ppb n/a 40 ppb
Site 9 0.0 15 ppb n/a n/a n/a 30 ppb
Site 10 0.0 n/a n/a 31 ppb n/a 0.0 ppb

This is as we had expected, and it is very good news. It means that the State should remove the penultimate restriction on use of the lake, maybe as soon as tomorrow. You might recall that once all of the locations in the lake test below 75 ppb the lake water is no longer unsafe for drinking. Well, actually, we believe that it is still unsafe for drinking, but the level of residual triclopyr is now considered safe.

The presence of no triclopyr at all at site 10 might seem anomalous at first, but it bears noting that these samples were taken the morning after a long hard rain.  Site 10 is on the Ompompanoosuc River well below where the lake empties into it.  The river was well above its normal level, and flowing extremely fast.  There was a lot of water there, and most of it had come from sources other than Lake Fairlee.  It is possible that if the river been lower when we sampled some triclopyr might have been detected.

* “ppm” means “parts per million,” and “ppb” means “parts per billion.”

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Results from the Fourth Round of Tests

June 24th, 2010

On Monday, June 21st, we collected two more samples, and sent them off for analysis. Today we received the results from the lab. They appear in the table below.

Location Applied June 3rd June 9th June 15th June 21st
Site 1 1.5 ppm 0.202 ppm 0.121 ppm n/a n/a
Site 2 1.5 ppm 0.930 ppm 0.127 ppm n/a n/a
Site 3 1.5 ppm 0.510 ppm 0.113 ppm 0.098 ppm 0.059 ppm
Site 4 2.0 ppm 0.085 ppm n/a n/a n/a
Site 5 2.0 ppm 0.160 ppm n/a n/a n/a
Site 6 2.0 ppm 0.145 ppm n/a n/a n/a
Site 7 2.0 ppm 0.123 ppm n/a 0.093 ppm 0.065
Site 8 2.0 ppm 0.332 ppm n/a 0.088 ppm n/a
Site 9 0.0 0.015 ppm n/a n/a n/a
Site 10 0.0 n/a n/a 0.031 ppm n/a

We took only two samples this time, just to confirm the continuing decrease in concentration. Based on these results we will take samples at all 10 locations next Monday, and hope to have the State lift the next restriction (drinking lake water) later next week.

[note: we still do not recommend drinking from the lake, for a variety of other reasons]

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