Archive for May, 2012

No Herbicide in the Lake This Summer

Tuesday, May 22nd, 2012

In 2008 Proserpinaca palustris (Marsh Mermaid Weed) was found in Lake Fairlee.  Its presence was recorded, but was not considered when our application to use the herbicide triclopyr in the lake was considered and granted in 2010.Early this year we proposed to treat a much smaller area of the lake with the same product.  In March we were advised that the presence of the rare species Proserpinaca palustris would “trigger further review”.


Mermaid Weed

The concern was that the mermaid weed might be susceptible to the triclopyr, as it is in the class of plants (dicots) that are affected by this class of chemical.  The other plant in this category commonly found in the lake is the pond lily.  These were somewhat affected by the 2010 application (link), but survived and have completely recovered.  Scientists from SePRO, the company that manufactures the herbicide we use, had no experience with mermaid weed and their product.  They had never been asked, probably because P. Palustris is widespread and abundant in other states.

In April the Department of Environmental Conservation made it clear that our chemical treatment was conditioned on somehow ensuring that the mermaid weed would not be harmed, and detailed how we might do this.  In mid May scientists from Lycott and from the State visited the lake and mapped the locations where milfoil and mermaid weed are growing (link).

Since then we have been gathering information and determining how to proceed.  In addition to the cost of the herbicide and its application, we now have to fabricate two custom 400 foot sections of plastic barrier to isolate the area where the mermaid weed is growing.  They will have to be installed the day before the herbicide, and then removed two days later.  In part because of how quickly we need them, they will be very pricey.  As we added up the costs it became apparent that protecting the mermaid weed would almost double the original cost of killing off a relatively small area of milfoil.

Therefore we have decided that we will not use chemicals in the lake this year.  We will pay instead for divers to hand pull the milfoil, and probably to deploy our bottom barriers in areas where the plants are growing densely.  Herbicide treatment remains a possibility for future years.  This year we will measure the efficacy of mechanical control, and will have more data about our ability to control the milfoil by non-chemical means.

At the same time we plan to work on two fronts to open the possibility to treating without special protection for the mermaid weed next summer.  Now that we know where and how P. palustris likes to grow, we can look in other Vermont lakes, and invite residents of other lakes to join us.  If we can demonstrate that it is not as “rare” as previously thought it will not require special treatment.  Also we will gather data on how tolerant the mermaid weed is to triclopyr.  We will engage SePRO to conduct controlled experiments with P. palustris in measured concentrations of the herbicide.

It is our belief that the careful use of triclopyr is safe, and that is is a cost effective way to control dense growths of Eurasian milfoil.  It is likely that in future years we will employ it again.

Mermaid Weed – A Correction

Tuesday, May 22nd, 2012

In an earlier post we mistakenly stated that Proserpinaca palustris is categorized “S1” by the State of Vermont.  This would mean that it is “Very rare (Critically imperiled): At very high risk of extinction or extirpation due to extreme rarity (often 5 or fewer populations or occurrences), very steep declines, or other factors.”

In fact P. palustris is listed as “S2”, a slightly less extreme category, meaning “Rare (Imperiled): At high risk of extinction or extirpation due to very restricted range, very few populations (often 20 or fewer), steep declines, or other factors.”

The source for this information is the Natural Heritage Information Project of the Vermont Department of Fish and Wildlife.  You can find it on the 13th page of their document Rare and Uncommon Native Vascular Plants of Vermont.  An explanation of the status codes and their legal implication s can be found here.

Taking Care of the Mermaid Weed

Friday, May 18th, 2012

On Wednesday, May 16th, scientists from the State and from Lycott visited Lake Fairlee to inspect the area near the mouth of Middle Brook where the milfoil was growing densely at the lend of last season.  They were looking in particular for the presence of mermaid weed, which was identified in that area in 2008, and which is designated a rare plant in Vermont.

The red dots in the picture below show where E. milfoil was found this week.  The red line delineates the area proposed to be treated on June 6th.

click above for larger image

Mermaid weed was found in abundance, which is evidence that it survived the triclopyr treatment in 2010.  The green dots in the aerial view above indicate where it was found this week.  The red dots show where E. milfoil is growing.  To protect the mermaid weed from the effects of the herbicide we are planning to install a plastic barrier (yellow lines above) extending the full height of the water column — only about 12″ to 18″ here.

Lake Restrictions for Herbicide Treatment

Friday, May 18th, 2012

A small 10 acre area of Lake Fairlee will be treated with the herbicide triclopyr in early June, hopefully on the morning of the 6th.  The treatment area will be near the mouth of Middle Brook, off to the right as you look at the lake from the boat launch ramp.  Much of the lake will be closed to ALL use for two days, and water use from the lake will be restricted  until the herbicide concentration has diminished.

Here are the details:

  • There shall be NO USE of Lake Fairlee, south of the intersection of Burma Road and Route 244, and the outlet stream downstream to its confluence with the Ompompanoosuc River (as indicated in the attached map) FOR ANY PURPOSE, including boating, fishing, swimming, domestic (household) use or irrigation, on the day of and the entire day after the treatment.
  • Swimming/wading, boating, fishing and domestic use (except drinking or for food or drink preparation) may resume the beginning of the second day following treatment.
  • Use of water from Lake Fairlee, south of the intersection of Burma Road and Route 244, and the outlet stream downstream to its confluence with the Ompompanoosuc River (as indicated in the attached map) for drinking or for food or drink preparation shall not resume until water sample analyses reveal that the active ingredient in Renovate OTF (triclopyr) is at or below 75 parts per billion by laboratory analysis.
  • Use of water from Lake Fairlee, south of Idle Pine Drive, and the outlet stream downstream to its confluence with the Ompompanoosuc River (as indicated in the attached map) for irrigation, including use for watering lawns, trees, shrubs or plants, shall not resume for 120 days or until water sample analyses reveal that triclopyr is at or below 1.0 part per billion by laboratory analysis, whichever comes first.

Treatment Date Set for June 6th

Friday, May 18th, 2012

If all goes well, we plan to treat the dense patch of E. milfoil near the mouth of Middle Brook on the morning of June 6th.  There are lots of things that might cause a postponement, but our fingers are crossed.

Watch this blog for updates and more information.

Lake Fairlee Association – The Case for Support

Thursday, May 3rd, 2012

[Around this time of year we mail a spring fundraising letter to our membership.  This is not that letter, but it contains substantially the same points.]

The chemical treatment of the lake for milfoil in 2010 was a success.  The vast majority of the E. milfoil fell to the bottom of the lake and rotted.  As predicted, some milfoil has continues to grow in the lake.  This may be from rootstock that survived the earlier treatment or, in some cases, from reintroduction.

As part of our five-year treatment permit, this year we are planning to aggressively pursue the surviving plants.  There are isolated sparse growths in a dozen locations around the lake (based on the survey last September) and a dense patch near the mouth of Middle Brook.  This summer we plan to treat the latter area with a local application of triclopyr early in the summer.  We will use hand pulling to remove the stragglers in other locations and locate any others.

We have operated a greeter program to educate the lake-using public about invasive aquatic plants and animals and to prevent the further spread of milfoil into and our of our lake.  This summer we intend to double the amount of coverage we provide, so that most lake boaters will be exposed to our message.

We continue to work for the health of the lake with programs designed to reduce the runoff of nutrients into the lake.  In the past two years we have been awarded three grants to plant riparian buffers and restore shorelines.  These grants are part of our effort to educate residents and others about lake health issues.

We continue to be concerned about the dam that maintains Lake Fairlee’s level.  We are working with representatives from the three towns and the Aloha Foundation to obtain a proper engineering analysis of the present dam and explore options for repair or reconstruction of the dam, if necessary.  We are thinking about how this might be funded.

This past winter the selectboards of the three towns met together twice (for the first time in recent memory) to collaborate on Lake Fairlee issues.  The selectboards agreed to form a working group to consider the dam and other concerns related to Lake Fairlee.  We consider this a major step forward, and are working to help advance the process.

The Lake Fairlee Association Board is suffering from declining participation.  We have managed to raise the money we need to run our programs, but the work is being done buy a dwindling few volunteers.  Our unpaid jobs include negotiating with the state and with Lycott on the milfoil control program, writing grants, evaluating, hiring and managing employees for the greeter program, fundraising, running the annual dinner/meeting event, preparing reports, bookkeeping and correspondence.  The few carrying the load are getting burned out.

Our membership numbers have declined in recent years, from a recent high over 100 to about 60.  We need to reach out and engage every owner and others nearby who use and love our lake.

We continue to need your financial support.  We also need some of you to volunteer to do some small jobs – and some big ones.  Please help.