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Cyanobacteria and public health notices!

Cyanobacteria can produce toxins, called cyanotoxins. When there is a flower bloom with sludge, the quantity of cyanotoxins is likely to be problematical. There are three types of toxins:

  • dermatotoxins (affects skin and mucous)
  • hepatotoxins (affects the liver)
  • neurotoxins (affects the brain)

The most frequent problem to emerge is skin irritation following bathing. The ingestion of contaminated water can, in the long run, affect the liver or the brain. That is the reason for which the public health authorities, when faced with a situation of large quantities of cyanobacteria, issue their public warnings. 

Following a report by a citizen, a beach operator or a municipality, the MDDEP quickly dispatches a technician to take water samples for laboratory analysis. If it involves a beach the operator must, if he or she observes a bloom, close the beach or the affected sector immediately, including a safety zone of 3 metres from the bloom or sludge area.  He or she must also advise the MDDEP. The beach operator may also independently open the beach 24 hours after the bloom has disappeared. If the situation persists for more than 72 hours however, he or she must recontact the MDDEP.

Most of the time the lab results will confirm the degree of cyanobacteris present and its toxicity level within 48 hours. In these situations, the public health directorate, on recommendation of the MDDEP, will issue a public health advisory establishing the level of restricted use (boating activities, fishing, drinking water, etc.) for a particular sector or for the entire lake. The citizens will be immediately informed via a written notice from the municipality. 

It will be up to the public health directorate to lift the advisory notice in the following days, weeks or months, all of this following subsequent water analysis.

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