In 2020, Lewisboro received a grant for engineering studies for three lakes in town. Their purpose was to evaluate the sources of phosphorus pollution in these lakes and to recommend solutions. These studies were completed in 2021. While not every lake in town was studied, the results across the three lakes were similar and indicate that the same issues probably apply to all of our town’s lakes.
Lake Waccabuc was one of the lakes in the study. Unfortunately, the study did not include Lakes Oscaleta and Rippowam, so an assessment and recommendation for the entire watershed was not completed. However, the assessment of Lake Waccabuc is instructive. The final report is linked here: Waccabuc septic study.
Barton & Loguidice, the engineering firm that did the Waccabuc study, informative gave community presentations. The first was to introduce the study and and a survey to garner community information. The April 7, 2021 meeting slides are linked here: Initial meeting. The second meeting was on July 28, 2021 and had preliminary study results, linked here: Update meeting. Note that the links to the survey and information pages included in these slides were only active during the study period. In addition, the Town Board held a work session on November 15, 2021 to review the results of the studies of the three lakes. The Waccabuc slides from that session are here: Waccabuc Town Board and the YouTube presentation of the meeting is here: Town Board meeting.
The study showed that the soils around our lakes are poorly suited to protect the lakes against phosphorus pollution from our septic systems. The combination of poor soils, steep slopes, limited depth to bedrock, and close proximity to groundwater indicates that many of the septic systems around Lake Waccabuc are likely to be contributing phosphorus pollution to the lake. Combined with septic systems in tributary and lake buffer areas, and aged systems, the majority of the septic systems around Lake Waccabuc are problematic.
The report recommends solutions that range in scope and cost. The best solution but most expensive and difficult is a full sewer district and a wastewater treatment plant. Community systems were evaluated and are appropriate for targeted locations. Septic replacements, with new technology septic systems, are also a good choice, but the effect on phosphorus pollution depends on the number of systems that are upgraded.
The next steps are highly dependent upon community wishes and grant availability.
Bonus: Kellard Sessons’ 2016 assessment of a community septic system for the 30 homes in South Shore Waccabuc Association is available here.
The 2021 presentations and septic engineering studies of Truesdale and Kitchawan, which were completed at the same time as the Waccabuc study, are available at the bottom of the Town of Lewisboro Lakes page.