Taking Care of the Mermaid Weed

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.

Mermaid Weed in our Lake – a Mixed Blessing

Last November we reported that there is a dense patch of E. milfoil growing near the mouth of Middle Brook, which our consultant (Lycott, Inc.) is recommending that we treat with a local application of triclopyr [LINK].  We are planning such a treatment, and the State has indicated its approval.  The affected area covers about eight acres, and is located in shallow water just offshore.

click for factsheet

But wait!  In late June of 2008 Leslie Matthews, a State biologist, took a group of us on a “field trip” in that location as part of a workshop to teach us how to recognize invasive plants (and others).  One of the participants pointed out a plant that Leslie could not name.  So she took a sample for later identification. She soon emailed that “it is a native plant called “marsh mermaidweed” – Proserpinaca palustris.  This plant is in the same family as the milfoils (Haloragaceae) but it is not in the “water milfoil” genus (Myriophyllum).”

Prior to the issuance of our herbicide permit in 2010 Lycott conducted an extensive audit of plant species in the lake.  The mermaid weed was not found.  Nor was it noticed in subsequent inspections by Lycott and by the State.  This might have been because it is growing in such shallow water that it is hard to get to even with a kayak.  Or its small incidence just escaped notice.

But P. palustris has “S1” status in Vermont, meaning that it is “very rare, generally 1 to 5 occurrences believed to be extant and/or some factor(s) making it especially vulnerable to extirpation from the state.”  So in the course of a routine review of our proposal the Department of Fish and Wildlife noted the presence of the rare mermaid weed in the same area.  To protect the rare weed from the effects of the herbicide we will be required to install a barrier between it and the treatment area.  And we will pay special attention to this species in the post application plant survey.

Just how this will play out is unknown.  The water is less than a foot deep in the area where the barrier will be placed, which poses problems.  And while the mermaid weed has this rare plant status, the State botanist reported:

“Overall, likely thousands of genets, but hard to tell number of individuals. Very vigorous growth of plants; nearly all in fruit. Two areas, one 10×10 feet and another 15×15 feet which were colonized completely by this species with 100% cover. Another large area 40×50 feet had about 90% cover. Many plants were emergent from the water.”

Little is known about how susceptible the mermaid weed is to the herbicide tricolpyr.  It is a perennial dicot, the class of plants affected by this auxin.  Besides milfoil, the only aquatic dicot widely found in the lake are the water lilies.  They suffered some effect from the triclopyr in 2010, but they quickly recovered.

One bit of irony: marsh mermaidweed is widely advertised as a desirable aquarium plant.  Many believe that Eurasian milfoil found its way into this country’s waterways when it was discarded by aquarium enthusiasts who had purchased it for the same purpose!

2011 Final Report to the State

Pursuant to our herbicide application permit from the State our consultant/contractor is required to file annual reports detailing milfoil management activities undertaken this year and recommendations for next year.  The complete report may be downloaded by clicking on the image above.  CAUTION: this is 32 page pdf file which is 3.6Mb in size.

Spot Treatment with Herbicide Proposed for 2012

In a prior post we reported on the low incidence of E. milfoil found in the September 2011 survey, but noted that “we are very cautious about the low incidence of milfoil reported here.”  Based on anecdotal information we expected that considerably more milfoil has returned to the lake.  Now we have received a report from Lycott titled  Summary of 2011 Eurasian Milfoil Observations & 2012 Management Recommendations which confirms our fears.

You can download the three page document ay clicking this link, but here are the high points:

  • Milfoil was observed at fourteen locations around the lake this summer.
  • Ten of these exhibit only “sparse” growth.  We believe that these can be managed with hand pulling next summer.
  • Three areas have “moderate” growth.  In these locatirons we will employ either hand pulling or install bottom barriers, as the situation warrants.
  • At the mouth of Middle Brook there is an eight acre patch with heavy milfoil growth.  Lycott recommends that we again apply the herbicide triclopyr to this area for three reasons:
    • The existence of native species in moderate to heavy densities makes finding E. Milfoil difficult
    • Wide distribution of E. Milfoil over 8+ acres will be difficult to target with bottom-barrier
    • Sediment deposits in this area can greatly reduce visibility during hand-pulling and therefore increase the chance that plants will be missed

The report includes maps showing the locations where milfoil was found.

This comes as somewhat of a surprise to us, as we had come to believe that the 2010 herbicide treatment might last a few years. Apparently this is not the case. We are learning that milfoil is a pernicious weed (alright, we already knew that), and that its roots can survive in the ground under the lake for years. We do not know whether the newly grown milfoil is growth from submerged rootstock, if it is newly seeded from introduced plant fragments, or if some if it is coming into the lake down Middle Brook.

Based on this information we are beginning to explore just what this will mean for Lake Fairlee and for the Association.  We will be meeting with representatives of the State DEC to discuss premitting, notifications, testing, and funding.  As we know more it will be posted here.

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In related news, we have learned that our sister Lake Morey intends to apply an herbicide treatment next summer as well.  They treated portions of their lake in the summers of 2007, 2008, and 2009.  Now the area they treated in 2007 is again densely infested with E. milfoil.

Year Two Aquatic Vegetation Survey Report

Lycott Environmental has submitted their Aquatic Vegetation Survey Report to the State.  Jumping to the chase, here is the conclusion of their report:

The surveys conducted in 2011, the year following herbicide treatment of 120 acres of E. Milfoil in the littoral zone of Lake Fairlee, show that the treatment both significantly reduced the distribution of E. Milfoil and allowed for continued growth of non-target, native species. Of the thirteen (13) species observed during the 2009 pre-management survey, more than half were observed at the same or greater densities during the September 2011 survey.

Although E. Milfoil was documented at only one of the data points surveyed during September 2011, growth of this invasive species extends beyond this single point. Additional work conducted by Lycott as part of the Lake Fairlee Association’s management efforts, including diver surveys and hand-pulling efforts, have further mapped distribution of E. Milfoil. The details of these surveys and additional management efforts conducted under 2009-C08 HB will be provided with the forthcoming ‘Final Report for Year Two of Eurasian Milfoil Management in Lake Fairlee’.

The entire report is available HERE.  It is a 23 page pdf file with color graphs and maps.

PLEASE NOTE: We are very cautious about the low incidence of milfoil reported here.  This survey collected data only at predefined locations.  We have reason to believe that the “Final Report” mentioned above will show more milfoil.  In addition, we are watching closely the experience of our sister Lake Morey, which will again be treating portions of their lake with tricopyr next summer, as milfoil is regrowing vigorously in the north end of the lake.

Click above to download the entire report

Some Bottom Barriers Will Be Used this Year

On july 23rd and 24th weekend divers from Lycott came to remove the milfoil growth that had been identified in June.  They located and hand pulled individual plants from locations near Camp Aloha Hive and Camp Lochearn.  They also identified an area or about 2500 square feet near where Middle Brook flows into the lake where the milfoil growth is dense enough to warrant using bottom barriers.  After determining that this would be the most cost effective way to proceed,  we engaged Lycott to install bottom barriers to completely cover this patch.

Lycott has prepared and submitted a permit application to the State, and will send notifications to abutting landowners as required.  Once we receive approval from the State, Lycott’s divers will perform the work, probably in the first half of August.  We are still planning to have them return again nearer the end of the summer.  Then they will swim the entire perimeter looking for milfoil and removing any they find.

The following satellite photo shows the portion of the lake near the mouth of Middle Brook.

The area of milfoil to be treated is indicated in red.  Above it you can see the mouth of Middle Brook, which meanders down from the top of the photo.  Camp Billings is at the lower left, the Horizons docks stick into the lake right of center, and the state fishing access is at the wide part of the paved road to the right.  Click on the photo for a larger image.

[if you look closely you can see that Camp Billings has mowed their initials into their field on the northwest side of the road — perhaps for the benefit of the frequent balloons that fly over from the Post Mills Airport]

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The following enlargement shows the shape and extent of the milfoil patch more clearly.  It is about 33 feet by 80 feet.  The Lycott divers use software which collects their GPS locations and maps them onto Google Earth, which then shows the area in context.  If you are so inclined you can download the KML data here.

2009 Grant Report

[what follows is a portion of the report we file each year with the Vermont DEC as a condition of their grant in support of Lake Fairlee’s milfoil program]

Summary of Program Activities

Even from our first look at the lake in the late spring, the milfoil grew aggressively this year.  We continued to employ the same methods we have used for the past several years, but were able to remove less milfoil this year than last.  This was primarily caused by two factors.  First, we faced declining funding from both private donors and from our State grant, which allowed us to employ the divers for three weeks less than last year.  Second, more than half of our 2008 dive crew did not return, and our progress was impeded by the need to replace several crewmembers during the season.

During the summer it became apparent to many of us that this year the milfoil seemed to be out of control to an extent not previously seen.  We are aware that this can be due to numerous factors, including cyclical population fluctuations, variation in sun and water temperature from year to year, as well as the effects of our harvesting program.  We began a series of meetings with owners and other interested parties to consider the possibility of using an herbicide to treat the milfoil in Lake Fairlee.  After consultation with the State, we invited two companies licensed to chemically treat Vermont lakes to come look at our problem and give us their recommendations.  This led to our decision to employ Lycott Environmental, Inc., to conduct a comprehensive survey of aquatic species in the lake.  At the time of this report we are working with Lycott to prepare an application for a permit to use triclopyr in Lake Fairlee late next spring.

The attached map shows the lake, and areas where we employed the following methods this year.

Hand pulling was employed at many locations around the lake.  A total of 361 divers’ “catch” bags were filled and removed.  Each bag holds slightly more than one cubic foot, but they are filled under water, and not packed as densely as the material which is suction harvested.  In any case, this amounts to more than 13 cubic yards of milfoil removed.

Suction harvesting was also employed at several locations.  A total of about 1230 cubic feet, or about 45½ cubic yards, was removed.  See the section titled “Amount of Milfoil Harvested” for discussion of how this was calculated.

Bottom barriers were moved in late August this year.  Again this year limited resources required us to lay off our divers before we wanted to, leaving some barriers in place for a second season.

Disposal:  This year one of our divers had written a business plan and received a mini-grant to demonstrate of how harvested milfoil might profitably be composted and sold as fertilizer.  For most of the summer he hauled the milfoil three miles to a field where it was allowed to compost.  After work he would tend the compost piles, checking their internal temperature and turning them.  He had intended to package the product in 50 lb. bags, but in the end he sold the entire quantity to a local farmer for use on his fields.  For the first few days and last few weeks of the season we disposed of the milfoil as we had in previous years, by piling it across State Route 244 from the boat ramp.  As usual, local gardeners and farmers removed it for use in their gardens almost as fast as it accumulated.

Program detail

This year the dive crew worked from May 18th through September 3rd.  They worked Monday through Thursday every week, including Memorial Day.  Only occasionally did the weather or their equipment keep them from their primary activities, and they took advantage of those opportunities to perform maintenance and catch up with other support tasks.

Volunteers provide the administrative backbone of our operation.  Members of the Board of Trustees have taken on significant operational responsibilities, in addition to their management role.  The Treasurer did hours of office work including handling incoming mail, making deposits, managing the payroll, and filing tax and employment records.  The Milfoil Program Director met with the divers several times each week to review progress and plan strategy.  He drafted the grant application and the requests for permit modifications required by the State.  He also created the educational “blog” on the Association’s website.  Another trustee took responsibility for the Greeter program, which educates boaters entering and leaving the lake at the State boat ramp.  Some undertook the significant fundraising required to support our effort. This requires letter writing, stuffing, and mailing, and individual solicitations.  Finally other trustees managed an annual membership dinner and a benefactors’ cocktail party to thank and cultivate our supporters.  In the face of the controversial decision to explore the “chemical option,” trustees stepped up and  took leadership roles in the ensuing discussions.

This year funding from the state decreased, as did support from local residents and friends.  This might be attributed in part to the economy.  It is also certainly due to the disaffection of those members who have decided that we ought to be seeking to use chemicals because our present methods are not doing the job.

Many people donated in-kind services, including the use of boats, equipment storage, and office equipment.  These are detailed in a later section.

Our equipment inventory can mostly be best described as “well used.”  Fortunately the dive crew is experienced and competent with field repairs, and seems to be able to keep the aluminum boats afloat with duct tape and epoxy, and the outboards running without the help of outside mechanics.  We continued to have trouble with our outboards this year, which slowed down our operation on more than one occasion.  This ought not be a surprise, considering their age and condition. We made improvements to the pontoon boat, which we use for both suction harvesting and bottom barrier operations.  Our bottom barriers and silt screen are still serviceable.

Our supplies consisted mostly of air tank refills for the divers and gas and oil for the boats.  There were also a few trips to the hardware store and the marine supply for hardware and rope and repair parts.

A much more detailed explanation of many of our program activities can be found on our blog at http://lakefairlee.org.  There one can find greater detail about the mechanics of our suction harvesting and bottom barrier operation as well as photographs of the lake and of the divers at work.

Consultant’s Report Now Available

Click here to download report

Click above to download report

The Lake Fairlee Association Board has received the Aquatic Vegetation Report prepared by Lycott Environmental, Inc., and has begun to discuss its implications.  This report will be the subject of our third public meeting, to be held on Wednesday, October 14th. (details here)  You can download the whole report HERE.  It is a pdf file and is eighteen pages long.  We invite you to read it so that you will better understand our deliberations.

This report is the result of several surveys of the lake conducted this summer.  It includes scientifically collected data from over 200 locations around the lake, including the kinds and density of various species, and particularly of Eurasian milfoil.   It concludes that “approximately 120 acres, or about 26% of the lake’s surface area is infested” with Eurasian milfoil.

What this report does NOT include are recommendations about what we should do.  In private conversations the consultant has said that our lake is a good candidate for herbicide treatment.  But the decision is ours.  If we decide to apply for a permit for next summer the details of our proposal will be hammered out with the State regulators.  We will be continuing to explore this possibility, gathering information about what the treatment would consist of, how long it might take, and what it would cost.

Please read the report and come to one of our public meetings.  The lake may be “owned” by the State of Vermont, but it is our lake, and it needs our care.

How Grows the Milfoil This Year?

On Tuesday, May 26th, I joined the dive crew for a thorough survey of the lake.  We spent about two hours circumnavigating the lake on the pontoon boat, occasionally with a diver in the water for closer inspection.

This year, even though the ice went out mid April as usual, we had a week or two of unusually warm weather in early May.  Consequently the milfoil seems to have gotten an early start.  During the winter it “lies down” and goes dormant.  In the spring when the sunlight reaches it on the bottom it begins to grow.

A patch of milfoil

A patch of milfoil

It is hard to get a good photo of milfoil from above the surface. For that matter it is not easy underwater either. In a future post I will try to include some underwater shots.

As usual the milfoil has some surprises for us. In some locations where we have wiped out whole patches using bottom bottom barriers or suction harvesting the milfoil has not returned, and the local pondweed and other species are returning. In others the milfoil has taken root again. The purpose if today’s tour is to gather information so that we can plan this summer’s activities intelligently.