Healthy Lake Boon update

A lot has been going on with lake water quality recently.

Brown algae
The proliferation of a brown algae in the last 2 weeks has raised concern. It appears to be mostly in the top foot of the water column and blows with the wind to different areas of the lake. Photos of it were sent to the Mass Dept of Public Health, Nashoba Boards of Health, and Solitude Lake Management, our weed treatment contractor. All responded that it doesn’t look like any kind of cyanobacteria. Solitude indicated that it appears to be dead fragments of filamentous algae that have broken off from the bottom or an actual brown algae that has nearly circular clumps. In either case it should be harmless though a nuisance. In recent days it seems to be declining.

Water clarity
Perhaps due to the agglomeration of these particles, water clarity has been exceptionally good recently. A 20 cm diameter Secchi disk is now visible down to 12 ft in the first basin–representing much better clarity than typical for this time of year. Get out your mask and snorkel and take a look at the fish or find your long lost anchor!

Stow Pine Bluffs Town Beach
Although the town beach is not officially permitted and has no lifeguards during this pandemic, the Board of Health is still having the usual weekly tests for eColi bacteria done and all results thus far have been acceptable. The LBA has agreed that if a positive result comes up there, it will have a test done in the second basin.

Healthy Lake Boon volunteer actions
In addition to water clarity, we have been recording level/flow over the dam, rainfall and evaporative data to develop hydrological modeling to help understand how phosphorus enters, accumulates and leaves the lake. We have also been measuring dissolved oxygen and temperature profiles in deep areas to understand the amount of stratification in the lake and its effect on sediment at the bottom. Samples for phosphorus analysis are also being taken.

We have not heard anything yet on our application for a Mass. Municipal Vulnerability Preparedness grant to fund more “in-depth” study of the lake and the effects on it anticipated with climate change in the future.

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