Blue-green algae (cyanobacteria) are microscopic, plant-like organisms that grow naturally in ponds, rivers, lakes, and streams. Most of the time they are blue-green in colour, they can also be olive-green, or red. Blue-green algae blooms are more common where the water is shallow, slow moving, and warm, but can also happen in deeper, cooler water. Fresh blooms can smell like newly mown grass, while older blooms may smell like rotting garbage.
If the surface of the local stormwater pond is covered in a bluish-green film, like pea soup or turquoise paint, this could be a sign of a blue-green algae bloom. Blue-green algae can become a problem if the stormwater pond receives too much phosphorous from fertilizers or animal waste.
Blue-green algae can produce toxins that affect the health of fish, animals, and humans that encounter the water. If you suspect a blue-green algal bloom in the local stormwater pond, call the:
Ontario Spills Action Centre
If it is the first blue-green algae bloom of the season on that pond, the Ministry will take a sample of the algae to confirm whether it contains cyanobacteria.