Conservation Commission approves alum treatment expansion for Sewataro swim pond

SUDBURY — October 2, 2023 — Conservation Commission grants Camp Sewataro alum treatment expansion in 4-2 vote. The commission amended an order of conditions for the camp at 1 Liberty Ledge to allow aluminum sulfate treatments of the swim pond when turbidity exceeds 4 NTUs or Secchi disc readings drop below 4 feet, in addition to the existing 20 ppb phosphorus trigger. Vice-Chair Kenneth Holtz and member Kathleen Rogers opposed, with Holtz arguing the commission should defer to the Board of Health, which cited a 48-hour post-treatment use restriction. The amended order requires a 48-hour pond closure after any alum application. SOLitude's Dominic Moringolo framed the change as a swimmer-safety measure; Camp Sewataro performed zero alum treatments in 2022 or 2023 despite turbidity readings around 4.2 NTU. The commission also approved a one-time vacuuming of roughly 100 by 100 feet of accumulated sediment, last done about 10 years ago.