Lake Committee

Water Quality 2012

By John Van Couvering, Lake Committee 

In the face of a massive infestation of bladderwort – a native weed that until now had never been seen in the lake in any abundance – the Association voted in 2011 to try physical and biological control first, before resorting to chemical treatment. In the fall of 2011 we received delivery of a Weedo harvester, an all-electric skimmer craft with simple, low maintenance construction that can work easily in water as shallow as eight inches. We also restocked 170 grass carp in the spring of 2012, the maximum allowed after introducing 400 fish in April 2011.

Somewhat mysteriously, the bladderwort did not come back in the spring of 2012. Not only that, but the lake was remarkably free of any kind of soft weeds, and was reasonably clear as well. Our water quality consultants, Princeton Hydro, had been asked to add a survey of bottom conditions in their reports this year; in their spring survey, they found that plant growth was very limited, and in the late summer survey they reported that there was no trace of emergent weeds at all.  The immediate cause was obviously grazing by grass carp, but it is not clear why the carp could have no effect in 2011 but be completely dominant in 2012, even before the 170 new fish were added.  It may be that the just-amplified fish population was unable to get ahead of the bladderwort in the spring of 2011, but the next year was a different story. It is also possible that weather and nutrients that favored growth in 2010 and 2011 may not have been so favorable the following year. In any case, the Weedo awaits its first serious test, and most residents were happy that it was not needed.