Lake Boon Town Beach Closure
Submitted by David Gray, Lake Boon Association
The past two issues of the Stow Independent contained page 2 headlines, “Lake Boon Closed to Swimming.” This is not quite correct. The Pine Bluffs Town Beach was closed to swimming. However, the rest of the lake is not officially closed, though residents should make carefully informed decisions about whether to swim.
Pine Bluffs Town Beach is a public beach and the Stow Board of Health, advised by the Nashoba Consolidated Boards of Health, must comply with the regulations of the Mass. Department of Public Health. The algae blooms seen at the Town Beach and a few other locations around the lake must be taken seriously as they often contain the cyanotoxins that are a serious health threat, especially to small children and dogs that may ingest the water. A Mass DPH info sheet on hazardous algae blooms is available at https://www.mass.gov/doc/harmful-algae-blooms-in-fresh-water-bodies-english-0/download
Rescinding a no-swim advisory for a public beach takes a substantial period of a time as lab testing cannot be done quickly:
“Cyanobacteria cells can release cyanotoxins into the water when they die. Therefore, algal toxins may be present when a visible scum or mat is no longer evident. DPH recommends the rescinding of a public health advisory after two successive samples, collected a week apart, demonstrate cell counts or toxin levels below the quantitative guideline values.” (sic, should read cell counts and toxin levels) https://www.mass.gov/info-details/guidelines-for-cyanobacteria-at-recreational-freshwater-locations#issuing-a-public-health-advisory-
The Town Beach is in a vulnerable location for algae blooms. Although it is a nice cove with wonderful sunset views facing west, it is also a shoreline that tends to collect surface algae with the prevailing west and southwest winds on the lake. For the same reasons, algae blooms can be slow to disperse there.
For the rest of the lake, residents should avoid swimming wherever they see algae, and wait a few days more after algae has cleared from that location. Experts at the DPH have stated that lakes that have complex configurations with somewhat isolated basins and coves can experience very different algae conditions throughout its waters. Lake Boon has many basins and coves and very little flow between them, especially under these drought conditions. For these reasons residents on the lake are making their own informed-risk decisions about engaging in water recreation and swimming, supplemented by recording algae observations sent to email@example.com for future reference.