Blue -Green Algae

In August a blue-green algae bloom was confirmed on Paint Lake—read the Health Unit notice. To date, there has not been a confirmed bloom on Lake of Bays, although there have been sightings of potential blooms, each of which has subsequently dissipated.

If you spot a possible bloom, immediately report it to the Spills Action Centre at 800-268-6060.

Blue-green algae or Cyanobacteria (Pronounced “sigh-an’-oh-bacteria”) are microscopic, plant-like organisms that occur naturally in our lakes, ponds, rivers and streams. While blue-green algae are not normally visible in the water, when conditions are favourable, populations can rapidly increase to form a large mass or scum called a bloom. This most often occurs in late summer and early fall. What makes blue-green algae blooms problematic is their ability to produce dangerous toxins.

If a bloom is reported on Lake of Bays, the Simcoe Muskoka District Health Unit will put out warnings and advisories to everyone in the vicinity. As soon as LOBA becomes aware of a bloom we will put out a NewsFlash.

How to recognise a blue-green algae bloom
  • Most often blue-green or turquoise, but can also be olive-green or red.
  • Can look like green pea soup or turquoise paint has been poured in the water.
  • Very dense blooms may form solid-looking clumps.
  • There may be a green or brown scum on the surface of the water and/or along the shoreline.
  • A new bloom often smells like freshly cut grass while older blooms may smell like rotting garbage. 
If there is a blue-green algae bloom, be cautious and assume that toxins are present. Avoid using, drinking, bathing, or swimming in the water. Restrict pet and livestock access to the water.

  • Follow advice from the Health Unit on what water is safe to drink and where it is safe to swim.
  • Do not drink the water from the lake where there is a bloom.
  • Never mix infant formula with water that you suspect contains cyanobacteria.
  • Never cook, wash dishes or do laundry in water contaminated with cyanobacteria.
  • Filtering or treating the water does not remove the toxins.
  • The toxins can be fatal to pets so do not allow your them to swim in the lake as they tend to swallow the water.
  • Wear rubber gloves when washing a pet exposed to cyanobacteria. Use fresh water to wash hands well after cleaning your pet.

Take these simple steps to prevent the growth of blue-green algae:
  • Use phosphate-free detergents, personal care and household cleaning products.
  • Do not use fertilizers on your waterfront lawns or gardens.
  • Maintain a natural shoreline.
  • Do not disturb the lake bed by pulling weeds or using agitators to reduce weeds.
  • Check septic systems to ensure they do not leak into the water source.