Truesdale Lake  

South Salem, New York

Truesdale Lake, Blue Green Algae and What to Expect

July 30, 2013

Truesdale Lake, Blue Green Algae and What to Expect

Greetings on this absolutely beautiful late July afternoon. It is simply amazing outside today – with wonderful temperature, and humidity and neat summer sounds. That is the good news.

But, our beloved lake is having its challenges. The extended heat wave has clearly harmed our lake – and we are still trying to figure out how. We have more blue-green algae than many of us remember and last week the lake had a low oxygen level so they could NOT treat it. Yesterday, we had air bubbles rising from the bottom of the lake, so they were only able to treat it with half of the usual amount of copper sulfate. We have spoken with Allied Biological many many times during the past few weeks – they are as puzzled as we are about what is going on. We have to abide by New York State rules about when and how to treat the lake, even though these are unusual circumstances. So, that means that even though they were only able to put in one-half of the usual amount of copper sulfate, we must still wait two more weeks (!) before we can treat again.

Here is what we were told when we asked about blue-green algae (which, by the way, is NOT a problem – but the toxic form is…)

One cannot tell by just the number of blue-green algae in the water if they are producing toxins or will produce them. Many factors affect a blue-green algae’s ability to produce toxins and apparently, those factors are poorly understood.

So NYSDEC has moved to a visual assessment of blue green blooms and the possible presence of toxins. See this website:

While the algae analysis Allied performs does not tell you if the toxins are present or if the blue-green algae have the potential for creating toxins, it does confirm the presence or absence of blue-greens and therefore if you see the scum you can be sure what is causing it.

All of us are frustrated about this. Allied Biological manages many lakes in Westchester County as well as other parts of New York and New Jersey. They are puzzled by what they see going on. New York State rules are the ones that we have to adhere to, even when unusual things happen.

So, my best advice is:

  1. Be patient
  2. Use your own good judgment. If the lake looks ok, then feel free to swim in it. If the lake looks yucky, then avoid those locations.
  3. Be patient. The weather will change, we will have some rain, and things will improve.
  4. Be patient.
David Sachs
Phone: (914) 763-8165

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