The Lake Maspenock Weed Management and Control Advisory Group at its Oct. 2 meeting shared information about the planned extended drawdown of the lake and the use of herbicides to control weed growth.
Joe Baldiga, the chair of the Citizens Input Group (CIG), led the meeting. The CIG has been studying the lake over the past decade, making recommendations to the Department of Public Works about how to control both native and invasive weed species. Annual weed surveys have been performed by the CIG since 2016.
Lake Maspenock is due for an extended drawdown this winter, noted DPW Director Kerry Reed. The Conservation Commission recently approved this action, as it occurs regularly every three years.
Last year’s drawdown, treatment results shared
Baldiga noted that the weeds were “noticeably diminished” after the targeted use of two herbicides last summer in the northern basin — Tribune (diquat) and Aquathol-K (endothall). There also were “decent drawdown conditions” this winter because of the low temperatures.
“Unfortunately, the weeds have come back with a vengeance,” he said.
Sabine St. Pierre, president of the Lake Maspenock Preservation Association (LMPA), added that the treatment had targeted variable milfoil and pondweed. While there was a “noticeable difference” with those two species, “pretty dense areas of Eurasian milfoil” grew in their place.
“The herbicide treatment worked for what we were hoping for,” she said. “We feel like if we hadn’t, we would be seeing even more dense populations of the Eurasian milfoil.”
CIG secretary Drew Logan said that the most recent survey also showed “a lot of naiad as well” in the lake’s lower levels.
“The point is not to eradicate everything,” stressed St. Pierre, noting that naiad is a native species and good for fish.
Reed noted that last year’s drawdown was a little lower than usual because of repair work to the dam. An extended drawdown typically is 8 feet, while an annual drawdown lowers the water by 3-5 feet. Last year’s was 5-7 feet.
“We are going to be very cautious, though,” she said. “We have significant concerns about the ability of the lake to rebound if we don’t get the rain.”
Residents fear ‘herbicide treadmill’
Donald Sutherland, a member of the Sustainable Green Committee (SGC) and the Water & Sewer Advisory Board (WSAB), expressed concern about chemical use impacting the lake.
“It sounds like this is an herbicide treadmill,” he said. “It comes with a price tag. It also comes with more extensive use exponentially as things get moved around.”
Don Keiser, who lives adjacent to Lake Maspenock, suggested doing a dry dredge of the lake’s bottom to aerate the soil.
He also lamented that some lakeside residents are using lawn fertilizer up to their property lines, which can infiltrate the lake.
Keiser suggested getting the Conservation Commission involved with enforcing fertilizer use violations within the 100-foot buffer zone. He also asked that the LMPA educate residents about the harmful effects of fertilizer use.
St. Pierre said the LMPA just completed a September educational campaign on ways to control lake weeds. This included email blasts, signs, Facebook posts and links on the LMPA website.
“We can’t police,” she stressed. “We can only try to educate and recommend to people what to use on their lawns.”
St. Pierre added that she will reach out to Health Department Director Shaun McAuliffe to see if lake sediment testing can be performed during the extended drawdown period.
An herbicide treatment likely will be necessary in the spring to control the weed growth, even with the extended drawdown, according to Baldiga.
“I think without herbicide treatment, the lake is going to be a real mess next summer and the summer after that,” he said.
Members voted 4-0 for having the herbicide treatment “in the event that optimal extended drawdown conditions have not been met.”
Reed said she will request $40,000 to the DPW budget request for the treatment, plus another $15,000 for a limnologist’s services. She also recommended that the group make its recommendation for the treatment directly to the Select Board. If approved, the group will need to appear before the Conservation Commission to explain whether the herbicide application is necessary.
Sutherland pushed back, noting that there has been no environmental impact assessment of the chemicals. Although it is not required by law, he questioned the “cost-benefit analysis and a budgetary attachment to the endless use of these toxins.”
Keiser added that there has been no analysis about how the herbicides affect microorganisms living in the water.
New survey area explored
Baldiga said a new possible survey and treatment location would be in the area he described as “the swampy part north of the causeway.” His reasoning was that weeds and sediment there could migrate to the main water body.
Said St. Pierre: “It was basically a salad of greens over there.”
Reed said she would be “supportive” of having the limnologist “extend the scope of their work.” But she would not support dredging that part of the lake.
Baldiga asked for the termination of early season surveys, seeing them as an unnecessary expense. They have not been effective, he said, because they occur before weed growth starts. Surveys at the end of the summer demonstrate “the efficacy of whatever treatment that’s taken place that year” so that a treatment plan for the following year can be developed.
Members voted 4-0 to stop the early season surveys.
Triploid carp genetically engineered to be sterile. They eat vegitation. Less $ and no chemicals.
As someone who has been fishing the lake for over 50 yrs and has lived within view of the lake for 42 years, I have noticed a substantial decrease in the quality and quantity of Bass in the last few years. From our viewpoint on the lake it looked like last years drawdown was greater than the average. The big drawdown this year I believe will impact fish and wildlife.
Just my unscientific experience.
To: Conservation Commission / Board / Selectmen / LPMPA / Town Residents Interested Parties
Dear Members of the Commission et al,
I write in my capacity as a former Chair of the Hopkinton Conservation Commission and as someone who has participated in limnological management work (notably the Metcalf & Eddy studies on Lake Maspenock), and has had a family home on Lake Maspenock for decades, to voice strong objections to the proposed continued use of aquatic herbicide treatment in our local lake.
Having raised these concerns in a previous Conservation Commission meeting, I believe it is critical to restate them now in light of renewed interest in chemical approaches.
Key Objections to Aquatic Herbicide Treatment
Acceleration of Eutrophication via Internal Loading
When aquatic plants or algae are killed by herbicides, their biomass decays, releasing trapped nutrients (notably phosphorus and nitrogen) back into the water column, which fuels subsequent algal blooms, setting up a cyclical feedback loop. (2015 International Institute for Sustainable Development)
This phenomenon is well documented in lake-management literature: chemical control often suppresses symptoms temporarily but fails to arrest the underlying nutrient cycling dynamics. (Terence P. Boyle,Effects of the aquatic herbicide 2,4-D DMA on the ecology of experimental ponds,Environmental Pollution Series A, Ecological and Biological,
Volume 21, Issue 1,
1980)
Introduction of Toxic, Persistent, or Disruptive Chemicals
Herbicides such as 2,4-D and other aquatic algaecides/algicides pose risks to non-target species (macroinvertebrates, zooplankton, fish, amphibians) and may persist in sediments.
The Washington State Aquatic Plant Management SEIS emphasizes that chemical treatments often generate “significant adverse environmental impacts,” and that reliance strictly on chemical control is discouraged in favor of integrated management strategies.
(Supplemental Environmental Impact Statement Assessments of Aquatic Herbicides, Washington State Department of Ecology
Water Quality Program)
In-lake chemical methods may also disrupt sediment chemistry, benthic fauna, and dissolved oxygen regimes (especially if overused or misapplied).
(Illinois Environmental Protection Agency,LAKE RESTORATION METHODS AND FEASIBILITY OF WATER QUALITY MANAGEMENT IN LAKE OF THE WOODS, Krishan P. Singh, Ph.D., Principal Scientist)
Temporary Efficacy and the Need for Repeated Applications
Because chemical treatments do not physically remove nutrient-rich sediments, repeated dosing is often required. Over time, this increases costs and ecological stress without achieving durable improvement.
IISD
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Mass.gov
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The Massachusetts “Eutrophication & Aquatic Plant Management” report likewise warns that chemical control methods tend to treat symptoms not causes, and that long-term lake health depends on controlling nutrient loading and sediment dynamics.
(Eutrophication and Aquatic Plant Management in Massachusetts
Final Generic Environmental Impact Report, Executive Office of Environmental Affairs, Commonwealth of Massachusetts)
Misalignment with Past Limnological Findings in Our Region
In my prior work with Metcalf & Eddy (Lake Maspenock studies), chemical treatment was evaluated and rejected as a viable long-term strategy. The hydrodynamics, sediment nutrient profiles, and ecological resilience in our lakes render chemical control ineffective or only marginally beneficial.
The Commission’s earlier meeting, at which I made this case, reflects that these concerns have not been new or speculative but grounded in prior local study and precedent.
A Feasible, Long-Term Alternative: Drawdown & Dredging
Given the shortcomings of chemical control, the only sustainable path to long-term improvement is a controlled drawdown combined with targeted physical dredging, especially in the north basin and the shallow southern margins. This approach offers:
Removal of nutrient-rich sediments rather than mere suppression of vegetation
Restoration of deeper basins that discourage macrophyte overgrowth
A more stable baseline for long-term aquatic ecology
The possibility to reprofile bottom topography, improve mixing, and reduce internal nutrient recycling
National Academy reference data on lake restoration methods highlights that dredging (removal of contaminated sediments) is one of the few approaches capable of genuinely resetting benthic nutrient loads.
(Restoration of Aquatic Ecosystems: Science, Technology, and Public Policy
National Academies of Sciences, Engineering, and Medicine. 1992. Restoration of Aquatic Ecosystems: Science, Technology, and Public Policy. Washington, DC: The National Academies Press. https://doi.org/10.17226/1807.)
Moreover, the “Eutrophication & Aquatic Plant Management in Massachusetts” report itself describes physical interventions as more durable and ecologically sound when properly designed.
In conclusion, aquatic herbicide treatment is neither environmentally responsible nor scientifically justified in our context. It risks perpetuating eutrophication and chemical harm rather than resolving the core issues. I strongly urge the Commission to reject chemical options and commit to a restoration strategy grounded in drawdown and dredging, supplemented by nutrient-control measures in the watershed.
I am available to assist further—or to review proposed plans—to ensure they align with sound limnological principles.
Sincerely,
Peter Cholakis
Former Chair, Hopkinton Conservation Commission
Degrees in both Biology and Chemistry
Eutrophication occurs as well if the weeds grow, and worsen, and die, right? If we don’t treat, and that results in even MORE weed growth year after year, isn’t the Eutrophication even worse? At least treatment LESSENS the aggregate weed eutrophication. Why is that point being ignored by those in opposition?
Dredging would be great, if lake bed wasn’t full of stones and we had million plus and place to put all the dredged material. This was looked at and rejected. To suggest dredging without addressing those impediments shows a lack of seriousness in suggesting that option.
LMPA is actively working to address what goes into the lake. And no one loves the idea of using herbicides. But even worse would be for the weed growth to continue unabated resulting in shrinkage of the lake and even more weed sediment on the bottom.
Herbicide treatment in lakes accelerates eutrophication because it kills aquatic vegetation, causing the rapid decay of organic matter that releases nutrients—particularly nitrogen and phosphorus—back into the water column. This nutrient surge promotes algal blooms, depletes oxygen, and further degrades water quality. Additionally, repeated chemical treatments increase sediment contamination and organic accumulation, making future restoration options like dredging more difficult, costly, and environmentally disruptive.
The impediments to dressing can be addressed and were discussed with the Con Com years ago. It is the only “serious” consideration, if the Town is serious about maintaining it’s natural resources.
The LMPA and Con Com should be aware that herbicide treatment in lakes accelerates eutrophication because it kills aquatic vegetation, causing the rapid decay of organic matter that releases nutrients—particularly nitrogen and phosphorus—back into the water column. This nutrient surge promotes algal blooms, depletes oxygen, and further degrades water quality. Additionally, repeated chemical treatments increase sediment contamination and organic accumulation, making future restoration options like dredging more difficult, costly, and environmentally disruptive.