Final Triclopyr Test Results

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

Testing Results After Two Months

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.

Milfoil in Lake Fairlee – July 2010 Update

[ 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.

Testing Results from Fifth Round

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.”

Results from the Fourth Round of Tests

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]

The Milfoil is Dying

June 18th.

It has been sixteen days since the lake was treated.  This morning Will Stevenson from Lycott Environmental took me for a brief tour around the lake.  We looked for milfoil, and found no healthy plants. We saw plenty of very sick looking stalks with their leaves mostly missing, and quite a few floating plants and stem fragments, clearly dead.

This is not to say that there may not be some surviving milfoil plants in the lake, nor that some may return later.  Also this informal turn around the lake can not substitute for a comprehensive scientific survey, which will be performed in September.  It is far too early to declare victory.

We have been told that the effects of the triclopyr will be seen in the first four to six weeks.  It is taken in by the plants right away, in the first hours and days while its concentration is high.  Then over time, like a slow acting poison, it takes effect.  Hopefully, this is what we are seeing now.

We have spoken with some people around the lake who have said that they thought that the milfoil was dying.  Many more have asked us whether the treatment was working, and we have tried to sound hopeful.  It has seemed to us that there was no milfoil in places where it had been plentiful before.  We are glad to have Will come and share his informed observations.  Lycott manages aquatic nuisances in more than 300 lakes.  Will was clearly pleased.  I trust his educated and experienced opinion.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Where is the Milfoil?

Results from Third Test

On Tuesday, June 15th, we collected four more samples, and sent them off for analysis. Today we received the results from the lab. They appear in the table below.

location Applied concentration June 3rd June 9th June 15th (future)
Site 1 1.5 ppm 0.202 ppm 0.121 ppm n/a
Site 2 1.5 ppm 0.930 ppm 0.127 ppm n/a
Site 3 1.5 ppm 0.510 ppm 0.113 ppm 0.098 ppm
Site 4 2.0 ppm 0.085 ppm n/a n/a
Site 5 2.0 ppm 0.160 ppm n/a n/a
Site 6 2.0 ppm 0.145 ppm n/a n/a
Site 7 2.0 ppm 0.123 ppm n/a 0.093 ppm
Site 8 2.0 ppm 0.332 ppm n/a 0.088 ppm
Site 9 0.0 0.015 ppm n/a n/a
Site 10 0.0 n/a n/a 0.031 ppm

The concentrations have not decreased as rapidly as we would like.  We had hoped that the they might be down to 0.075 ppm, so that the next restriction might be lifted.   The average concentration of triclopyr in the lake on Tuesday was 0.093 ppm, which is about 25%  above this level.

The three results from the lake are all within a narrow range, which provides an internal indicator of reliability.  The downstream concentration is low, less than half of the 0.075 ppm set by the State as “safe for drinking.”

We will decide soon when the next samples will be taken, and keep you informed here.

The Effects of Triclopyr

The following report and photos were submitted by a friend of the lake who is a lifelong naturalist and a trained observer.  To better understand his comments, we first offer this simplified explanation of how triclopyr actually works.

Triclpoyr is a synthetic chemical called an auxin. Auxins are a class of chemicals found in plants that help regulate their growth. For example, phototropism is caused by inhibition of auxins by sunlight, so that the shaded underside of the plant grows more than the sunny part, causing the plant to ‘grow toward the sun.’  Abnormal amounts of these auxins can disrupt the normal growth of a plant, even kill it, so auxins are also used as herbicides.  Also, different species of plants respond differently to auxins, making them useful for weed control. Finally, triclopyr is an effective herbicide for dicots (flowering plants and trees) but not for monocots (grasses and conifers).  More information HERE.

June 9th, one week after treatment

I rowed out yesterday to review post therapy effects.   In the Middle brook cove the Eurasian watermilfoil is already dark grey and on the bottom.   I did not look for Eurasian watermilfoil in deeper areas.  As would be predicted there was a “side effect” of the treatment.   The triclopyr mimicked the growth hormone and accelerated the growth in other dicots.

Water Lily Stems Elongated Three Times their Normal Length

a

Nymphea

The white water lily (Nymphaea) showed the most effect with lengthening of the stem to three times normal.   Thus the leaves are overturned and the stems lie in a tangle of the surface.  There were areas near the water inlet of Middle brook that were not affected.  All plants at our end (southwest) of the lake showed these changes.

a

Nuphar

a

The Cow Lily (yellow water lily) (Nuphar)  was less affected in the large beds at Middle brook with the leaf stems only being twice lengthened.  The leaves looked healthy.    In other areas the whole cow lily plant looked fine with well formed flowers.

a

White Water Lily Root

a

Here is a photo of the white water lily root.    As you can see, the leaves and flower buds come right out of the root (which is under the mud on the floor of the lake).   So my conclusion is that even if the water lily looses some leaves from the triclopyr the whole plant will recover and continue to thrive.

a

These monocots were not affected in the Middle brook cove nor at our end of the lake: Elodea, Potamogeton, Typha, Vallisneria, or Najas.

Potamogeton (Pondweed) is a monocot which seems to be doing fine

Third Round of Water Samples Taken

Tuesday morning (6/15) we took three samples from around the lake, from locations numbered 3, 7, and 8 (MAP). We also took our first sample from the Ompompanoosuc, about 1/2 mile south of the Post Mills bridge, designated site #10.

These samples were sent in a cooler via overnight express to the SePRO lab in North Carolina that does our testing. We should have the results back Thursday afternoon (6/17). They will be posted here.

Results From Second Tests

On Wednesday, June 9th, before we had received the results from the first tests, we took samples from three locations in the north end of the lake and sent them for testing.  We took only three, as each test costs over $100, and we intended to get only a preliminary indication of how quickly the triclopyr levels are declining.

We took samples at locations one, two, and three (see MAP), put them in a small cooler with “blue ice” and sent them by FedEx to the lab in North Carolina.  This morning we received the results.  Unlike the results from the June 3rd test, these results showed normal variation and the expected rate of decrease in concentration.

location Applied concentration June 3rd June 9th (future)
Site 1 1.5 ppm 0.202 ppm 0.121 ppm
Site 2 1.5 ppm 0.930 ppm 0.127 ppm
Site 3 1.5 ppm 0.510 ppm 0.113 ppm
Site 4 2.0 ppm 0.085 ppm n/a
Site 5 2.0 ppm 0.160 ppm n/a
Site 6 2.0 ppm 0.145 ppm n/a
Site 7 2.0 ppm 0.123 ppm n/a
Site 8 2.0 ppm 0.332 ppm n/a
Site 9 0.0 0.015 ppm n/a
Site 10 0.0 n/a n/a


We are working with Lycott, our consultant, to determine when next to test, and how many sites we should sample.  We will need to have samples from all ten locations showing less than 0.075 ppm for the State to lift the restriction onthe use of lake and river water for drinking and cooking.

[note: we do not recommend drinking the water in any case, for a variety of reasons]