Middleborough conservation panel votes to seek funding to treat invasive plants in Tispaquin Pond

The Middleborough Conservation Commission on Feb. 6 authorized staff to pursue funding and to contact the state representative after hearing results of an aquatic-plant survey showing widespread invasive growth in Tispaquin Pond.

The commission heard a presentation on a September 2024 point-intercept survey of Tispaquin Pond, roughly a 94-acre waterbody, that sampled 58 locations across the littoral zone. Presenter Matt, who organized the survey materials for the commission, said the results show invasive submerged aquatic vegetation dominating much of the pond’s nearshore area and causing ecological decline. “This large volume of plants and algae die back every summer, leaving an equally large volume of organic materials on the pond bottom to decay,” Matt said, describing the process that can reduce oxygen and harm fish and other wildlife.

Why it matters: Commission members were told the dominant invasive is fanwort, which the surveyor reported occupied roughly two‑thirds of sampled locations, with variable (invasive) milfoil present in smaller patches and a small amount of a protected native milfoil appearing only in trace amounts. Presenters warned that without management the vegetation will continue to proliferate, clog recreational access at the boat ramp and spread via boats and campers, and contribute organic buildup that can degrade water quality and habitat connected to the town’s regional drinking-water system.

Survey and treatment options: The survey was performed by On Point Aquatic Consulting (the field work credited to “Brie” in the meeting packet). Presenters described the point‑intercept method (58 sample points, about 1.22 acres represented per point) and showed maps indicating dense patches in the north portion of the pond and near the boat ramp. Consultants evaluated possible controls and recommended pivoting from Procellacor to a fluridone product (commonly sold as Sonar) because fluridone controls fanwort (the dominant species identified) while Procellacor would be less effective against it.

Matt summarized consultant guidance on timing and monitoring: maintaining an average fluridone concentration of roughly 8 parts per billion for about 45–60 days, accomplished through multiple applications in spring (typically late April–early May), plus pre‑ and post‑treatment monitoring and residue sampling. He said that the whole‑lake approach would likely provide “2 to 3 seasons of nuisance‑level control” of fanwort, and that natural‑heritage review will be required because the survey found trace occurrences of a protected milfoil species.

Costs and funding limits: Commission presenters and commenters emphasized a steep price tag. The consultant ballpark for a whole‑lake Sonar treatment was presented at about $85,000, a figure that includes application and monitoring but not all permitting fees. Presenters also cited typical per‑acre herbicide application ranges ($300–$1,000 per acre) to illustrate that targeted hotspot treatment could be less costly but might not achieve the same level of control.

Grant prospects and next steps: Commission staff and speakers said they had explored grants and other sources. The Taunton River Stewardship Council and the town grant writer are among groups previously engaged; the commission learned some state and discretionary grants have been limited for the town recently because of noncompliance issues related to MBTA obligations. The presenter noted that some regional programs are offering smaller awards (for example, a $25,000 cap on certain project grants) and that a phased or hotspot approach could be used while additional funds are pursued.

Action taken: Commissioner Diane moved and Commissioner Bart seconded a motion authorizing the conservation agent, Trish, to seek funding opportunities for treatment of Tispaquin Pond and to contact the state representative for the area to seek additional support. The commission voted in favor of the motion.

Background and community impact: Speakers emphasized that the pond is actively used year‑round—by campers and day users via a popular state boat ramp—and that boats and wind action help spread plant fragments. Camp and youth program representatives at the meeting said camps use the pond for swimming and boating and had been included in communications. Presenters and commissioners flagged that any treatment plan will require formal permitting (MassDEP and likely Natural Heritage review) and careful public communication about timing and expected short‑term die‑off effects.

The commission also acknowledged costs already borne: the aquatic survey itself was paid for with commission‑approved funds and cost about $9,000, information the presenter thanked the commission for funding. The commission’s authorization directs staff to continue pursuing a mix of grant, municipal and partner funding and to report back as permitting, cost estimates and potential phased treatment plans are refined.