LandTech Consultants: Lake Terramuggus testing finds isolated E. coli spikes; drawdown not recommended

Tom Ryder, a consultant with LandTech Consultants, presented the Lake Terramuggus 2025 water‑quality report to the Town of Marlborough Lake Advisory Commission on April 14, 2026. Ryder said the testing recorded two high E. coli readings at the Town Beach — 290 in June and 480 in July — which exceeded the 235-count limit used in the report, but that none of the geometric means reported for the season exceeded the 126-count threshold the presentation cited.

Ryder also reported a high total Kjeldahl nitrogen (TKN) result of 910 µg/L at the Cheney Road inlet from the August 14, 2025 sample and a center-of-lake TKN of 580 µg/L at the same time. He noted center-lake total nitrogen fell to about 520 µg/L in September and recommended that next year’s sampling be used to determine whether the August spike was an isolated event or a continuing trend.

On trophic status, Ryder said all 2025 Trophic State Index (TSI) scores fell solidly within the mesotrophic range. Using DEEP rankings cited in the report, the lake was classified as Oligotrophic for Secchi depth and Mesotrophic for Total Nitrogen, Total Phosphorus and Chlorophyll‑a.

After concerns were raised about dogs getting sick, additional algal/toxin analysis was performed; Ryder reported those results were “well below acceptable levels” as presented to the commission. When Chair Dan Dupre asked about vegetative control, Ryder said pockets of native aquatic plants are important habitat that produces oxygen and supports healthy dissolved-oxygen conditions, and he urged caution before removing native growth.

P. Hughes, a meeting participant, said a weed survey is planned for July–August 2026. Ryder described the survey’s two goals: (1) identify and remove invasive species before they spread and (2) document native-plant presence, dominance and change compared with previous years. He advised residents who want help distinguishing native from invasive plants to contact LandTech for identification assistance.

Commissioners reviewed a 2026 budget proposal similar to prior years; the proposal includes funding for the planned weed survey. On the topic of a lake draw down, Ryder told the commission he does not recommend a draw down; Chair Dan Dupre said he would like to explore whether and how a draw down could be done to gather information, but that recovery time after a draw down is unknown.

Procedural actions during the meeting included a unanimous vote to approve the January 2026 minutes (motion by Louise Concodello; seconded by J. Boston) and a unanimous motion to adjourn at 8:05 PM (motion by J. Planeta; seconded by J. Boston).

Next steps listed by the commission: conduct the July–August 2026 weed survey and continue sampling during the next season to monitor nutrient concentrations and verify whether the August 2025 nitrogen/TKN spike was anomalous.