‘They’re Back’—Pesky Fawn Lake Water Lilies will be Treated with Herbicide this Autumn

September 28, 2021
Heron at Fawn Lake, with ‘patchy vegetation’ ~ Image (c) Mike Rosenberg, 2021 all rights reserved


A band of “patchy vegetation” on the surface of Fawn Lake will be attacked by an herbicide sometime this fall, according to the Department of Public Works.

The application, approved by the Conservation Commission last month, was recommended by the town’s environmental consultant to the $1.8 million Fawn Lake reclamation project, which was undertaken in 2020.

Bob Hartzel, a principal scientist with the project’s consulting firm, Comprehensive Environmental, Inc. (CEI), said the vegetation was noted by town staff during the height of summer, eight months after the dredging was completed.

“It appears that dredging operations may have been sub-optimal in that area, leaving some portions of water lily rhizomes intact in the pond sediments and allowing for the observed patchy re-growth,” he said in a memorandum.

Hartzel stressed, “Despite the moderate re-growth, conditions in the dredged area are generally as expected – open water in areas that had been almost entirely covered in very dense growth of water lilies and other aquatic plants prior to dredging.”

The herbicide applied will be glyphosate, described by the consultant as “one of the most commonly used and effective herbicides for control of floating leaf species.” As recommended to maximize effectiveness, there will be a follow-up treatment next spring.

The goal of the reclamation was “to restore pond depth and provide control of aquatic vegetation in approximately 60 percent of the pond.”

Hartzel, in an email Monday, pointed out, “The remaining 40 percent along the southern shoreline was left undisturbed to provide a balance between open water and habitat provided by a natural vegetated littoral zone – an area of rooted aquatic plant growth.”

“This is important, as there may be a misperception that the dredging operation was intended to remove all vegetation from the pond,” he wrote.

CEI estimated that the cost for treatment of a one-acre area of “water lilies and other floating-leaf species” with glyphosate would range from $1,400 to $1,700, plus permitting under state law. “A more precise treatment area estimate could be provided either by GPS mapping from a boat or from drone imagery,” he told the DPW.

Mike Rosenberg can be reached at [email protected], or 781-983-1763

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DAgmar Meissner
October 10, 2021 10:15 am

There are reasons to be concerned about this application of glyphosphate. This pond is the habitat to various animals from frogs, fish, turtles, snakes, beavers and a range of insects. According to material data safety sheet (MSDS) glyphosate “may be slightly toxic” to some invertebra. The toxicological studies only evaluate few species and do not include the types of animals found In the lake. Also, fawn lake is not a closed system but with a Brook f lowing into the lake at Sweetwater Ave and one creek flowing out near springs rd. How will BPW account for the dilution and distribution of the poison account for? Also if the goal is not to kill all the vegetation how is BPW planning to ensure that a habitat and food source remains for the creatures in the lake?? http://www.fmccrop.com.au/download/herbicides/msds/glyder_450_msds_0912.pdf

Looking at the MSDS (material safety data sheet) the following is listed.
Source: https://www.lakerestoration.com/pdf/glyphosatemsds.pdf
ENVIRONMENTAL DATA: Do not contaminate water when cleaning equipment or disposing of equipment washwaters. Treatment of aquatic weeds can result in oxygen depletion due to decomposition of dead plants. This oxygen loss can cause fish suffocation.

96 hour LC50, Rainbow trout – 8.2 μg/L (technical) 96 hour LC50, Bluegill – 5.8 μg/L (technical)

Source: http://www.fmccrop.com.au/download/herbicides/msds/glyder_450_msds_0912.pdf

(…) Technical glyphosate acid is practically nontoxic to fish and may be slightly toxic to aquatic invertebrates. (…) The 48-hour LC50 for glyphosate in Daphnia (water flea), an important food source for freshwater fish, is 780 mg/L. Some formulations may be more toxic to fish and aquatic species due to the surfactants used in the formulation. (…)
Environmental Properties: Glyphosate is moderately persistent in soil, with an estimated average half-life of 47 days. Reported field half-live’s range from 1 to 174 days. It is strongly adsorbed to most soils, even those with lower organic and clay content. In water, glyphosate is strongly adsorbed to suspended organic and mineral matter and is broken down primarily by microorganisms. Its half-life in pond water ranges from 12 days to 10 weeks. Glyphosate may be translocated throughout the plant, including to the roots. It is extensively metabolized in some plants, while remaining intact in others.

October 3, 2021 9:29 am

this is what I found when I looked gkyphosphate:
“Glyphosate is being banned because of its potential link to cancer in humans, as well as potentially causing the death of important insects, such as bees. … In addition, scientists warn that these glyphosate and other similar products damage ecosystems by disrupting the natural food chains and plant pollination.”
And how about the ground water?
We are messing too much with nature. Let Nature take its course. What is wrong with waterlilies taking over Fawn lake. Let Fawn Lake find its own balance.
What is the reason for our interference? Is it important enough?
As for the loss of ice skating:
The fire department – years ago- used to fill up part of Page Field in the winter for iceskating. Let’s revisit this. A big tarp, a border and our trusty fire department would take care of that once a year for much less money the dredging probably cost us.

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