The Citizens Input Group (CIG) met on February 11 to review how Hopkinton should manage aggressive weed growth in Lake Maspenock. They focused on the North Basin, as that is where invasive weeds primarily grow. The discussion centered on three things:

• Effectiveness of this winter’s deep drawdown
• Return of invasive weeds after the 2024 herbicide treatment
• Whether non-chemical options can realistically replace herbicides

The Lake Maspenock Weed Management & Control Advisory Group, commonly referred to as the CIG, or the “weed committee,” is a resident-led committee that advises the town (DPW, Select Board & Conservation Committee) on controlling aquatic weeds.

Drawdown Helped, But Conditions Not Ideal

Committee members opened the meeting by assessing the extended winter drawdown. The purpose is to expose and freeze weeds along the shoreline. Several members noted that early ice formed on the lake before the water reached the desired low level. This created a layer of ice with water still flowing underneath. That raised safety concerns and forced the town to stop the drawdown. It was about half a foot to a foot higher than planned.

Members said the cold temperatures and the duration of freezing this winter were better than in recent years, but the ice and snow cover may have limited weed kill. One member described ice as “the enemy,” because water under the ice remained too warm to effectively kill plants. The group agreed the drawdown was probably more effective than in the past few years, but that its impact will not be clear until late spring and summer.

Consultant Report Shows Invasive Weeds Have Returned

The committee reviewed a December 2025 report from the lake consultant, Aquatic Restoration Consulting (ARC). ARC documented five key non-native invasive species in Lake Maspenock: fanwort, variable water milfoil, Eurasian water milfoil, curly-leaf pondweed, and brittle naiad.

A post-treatment survey conducted by the vendor Solitude in 2024 found that invasive weeds were essentially absent in the treatment area, with only sparse fanwort present. By August 2025, however, ARC’s survey of roughly 70 stations found that non-native invasive weeds had returned in strong numbers in the North Basin and again required control.

ARC also concluded that a single annual survey is sufficient and in line with typical practice across the state. The consultant further reported that neither the extended drawdown nor the 2024 herbicide application appeared to cause a negative impact on the overall lake ecosystem.

Sustainable Green Committee Presses for Non-Chemical Solution

Representatives from the Sustainable Green Committee (SGC) addressed the meeting. Both committees share the same first choice: non-chemical solutions. SGC members cited federal and state research indicating that herbicides offer short-term control and can lead to a “herbicide treadmill,” where repeated applications are needed year after year.

HopNews did some research on the aquatic “herbicide treadmill” and how to prevent it. It turns out that we are already doing many of the right things.

• Don’t use herbicides every year. We don’t. We’ve done it once.
• Mix things up, adjust water levels if possible—we do that every year.
• Use herbicides sparingly and focus on trouble spots. In 2024, we treated only the north basin with one gallon of herbicide per acre.
• Rotate the herbicides used to prevent resistance from building. We discussed that, and we plan to investigate changing the herbicide next time.
• Add shoreline buffers and reduce nutrient inputs directly into the water when possible. That is now part of ConComm’s requirements.
• Track plant growth and water quality every season. We’ve done that for many years.
• Use what you learn to fine-tune your approach, so over time, you need fewer treatments—and the ones you do use hit the mark. That’s why the CIG was formed.

Lake Association Focuses on Prevention and Water Quality

Leaders from the Lake Maspenock Preservation Association (LMPA) described work underway to reduce nutrient and weed inputs into the lake. Water testing in Lake Maspenock (since 2015) has consistently shown that high phosphorus levels are not a problem. In fact, they never have been a problem.

But to be on the safe side, LMPA has included public campaigns against phosphorus-heavy lawn fertilizers throughout the lake and watershed. This is in coordination with the Conservation Commission. They are also looking to enforce and possibly expand existing fertilizer buffer zones near the water. They’re reaching out to landscapers and lakefront homeowners to ensure everyone understands the rules on runoff and fertilizer use. The focus is clear: keep the lake clean, start with what goes into it.

LMPA and Sustainable Green Committee (SGC) Working Together

The two groups are exploring strategies to reduce weed introductions from boats arriving from other lakes. Most lakes in New Hampshire require boats to be washed before launching. This would be difficult to implement here as the runoff would go directly back into the lake.

Residents Describe Summer Weed Impacts

Several North Basin residents spoke about how weeds affected recreation last summer. A homeowner on Downey Street said that early in the summer, there were almost no weeds. He could easily swim with his young daughter. But by late summer, they “really couldn’t swim at all” due to dense growth.

One neighbor said his kids could only swim comfortably near their house the year the herbicide treatment happened.

People living along Lakeshore Drive and tucked away in the coves agreed—they saw a real drop in weeds and a better place to swim and boat after the 2024 treatment.

A fisherman who’s spent nearly thirty summers on the lake put it simply: the treatment made things much better, and fishing or wildlife didn’t suffer.

Another homeowner pointed out that, even though the 2024 treatment focused mostly on the North Basin, weeds also pulled back in the middle basin near his place.

Mechanical Harvester Proposal Sparks Debate

Lake resident Don Kaiser proposed using a mechanical weed harvester instead of herbicides. He said traditional harvesters cut weeds like a lawnmower, which is ineffective. But newer designs, such as an “Eco Harvester,” pull plants out by the roots.

Kaiser argued that, by investing once in equipment the town could reduce reliance on herbicides. He suggested temporarily placing harvested weeds on a rocky island area in the lake to dry and reduce hauling costs. CIG members responded that harvesting has always been part of their “toolbox” discussions, but that it comes with significant challenges.

• Need for staging the large volumes of plant biomass to dry
• Cost and logistics of removal
• The likelihood that weeds would regrow more quickly than with herbicides (for harvesters that cut the weeds)
• Concern about the North Basin’s extensive rock fields that would make harvester operation difficult and potentially damaging.

Committee Chair Joe Balidga added that, unlike boaters seeking a simple navigation channel, the committee’s concern is the long-term health of the lake and preventing the North Basin from turning into a “grown-in swamp.”

LMPA and other residents raised additional questions about whether placing weed piles on small rock islands would truly remove the material from the system, given that runoff and birds would spread fragments back into the water.

Eco Harvester

HopNews was intrigued, so we did a little research. The Eco Harvester is made by Silver Mist Aquatics in Wisconsin. They are sold through distributors such as Weeders Digest. A setup for the north basin (60ish acres) would cost ~$150-100K for the harvester and a trailer. Then there is the need for a dumping spot for the biomass to dry, away from homes, due to the “stink” factor. The equipment would need a place to be stored when not in use.

Herbicides Just One Tool in the Toolbox

Throughout the meeting, CIG members emphasized that herbicides are just one tool in a broader management plan. They noted that the committee intentionally did not pursue a lake-wide broadcast treatment. This is despite pressure from some residents to treat the entire lake. Instead, they focused on targeted applications in the North Basin combined with drawdowns, monitoring, and prevention measures.

The town skipped herbicide treatment in 2025 after determining the 2024 application was highly effective. This confirms that the committee does not support automatic annual treatments.

The CIG disagreed with characterizing herbicide use as “irresponsible” or ineffective. They argued that the 2024 treatment successfully reduced invasive weeds and reduced plant biomass. (The biomass dies back into the sediment and fuels future growth.)

Public Outreach and Boat Education

The conversation turned to ways to limit new weed introductions, especially from visiting boats. LMPA members are coordinating with the Conservation Commission on signage and education at the town boat ramp. LMPA President Sabine St. Pierre recently completed the state boating safety course noted that while the class mentions nuisance weeds, it does not clearly explain that boaters are legally required to clean their boats before launching.

St Pierre plans to ask the Department of Environmental Protection to include stronger messaging about this legal requirement in course materials and handouts. “This is a missed opportunity, given that hundreds of boaters will undergo certification between now and 2028,” said St.Pierre.

Funding and Permitting Path for 2026 Treatment

Department of Public Works (DPW) Director Kerry Reed outlined the process and timeline for a potential 2026 herbicide treatment. Funding for the treatment is already proposed in the town’s Fiscal Year 2027 budget, which runs through June 30, 2027, and includes the summer of 2026. That budget will go before the Select Board in early March and then to Town Meeting on May 2.

On the permitting side, Hopkinton already holds an Order of Conditions from the Conservation Commission that authorizes the full suite of management tools, including herbicides. Each year, CIG must present its proposed treatment plan to the commission, but this is now handled as a work session rather than a new public hearing.

Reed said she will first move through the town’s procurement process to select a vendor, likely through competitive bidding that could include Solitude or other firms.

Once a vendor is on board, the town and ARC will refine technical details such as which herbicide to use, dosage rates, and treatment areas, then present that information to the Conservation Commission in late March or early April. ARC’s recent report referenced potential alternative products, but Reed said the previous product remains the most common and cost-effective, and that final choices will be based on the pre-treatment weed survey.

The vendor will conduct a pre-treatment survey in late spring to confirm which species are present and where, and must also complete a post-treatment survey, as required under the existing permit. The timing of any treatment will seek a “sweet spot” when plants have grown enough biomass to absorb the herbicide but before they reach peak density, which last time was around mid-June.

No New Public Hearing, But Dialogue Will Continue

Reed clarified that because the Conservation Commission and Select Board have already granted the core approvals, there will be no new formal public hearings or abutter notifications specifically on herbicide use.

Future Conservation Commission discussions will not be required to include public comment, and the Select Board will not take another up-or-down vote on treatment each year.

Residents can still speak at Select Board public forums, and LMPA is committed to keeping lake residents informed.

CIG members stressed that they view meetings like this as important opportunities for residents and town committees to be heard.

CIG and SGC leaders both want to collaborate

• Fertilizer rules
• Boat-cleaning rules
• Exploration of feasible non-chemical options

Both groups share the same goal

• Preserving the health of Lake Maspenock
• Protecting its ecosystem
• Keeping it usable for swimming, boating, and fishing
• Protecting wildlife for years to come