Blue Algae
A blue-green algae bloom.

Algae Blooms

Green Algae

  • Typically light green to grass green
  • Colour can vary depending on the age of the algae
  • Found attached to surfaces of rocks and aquatic plants, floating in the water column or on the surface of the water
  • Often have hair like strands that can be found in clumps giving a cotton candy appearance while floating in the water

Blue-green Algae

  • Typically a blue-green to green pea soup in colour
  • It will appear as though someone has spilled paint on the surface of the water or in small green dots or globs
  • Float within the water column and you may observe it is present only during a certain times of the day
  • Some of these blooms can produce toxins that can make people and animals sick; so it is important to understand what blue green algae looks like as use of the water should be avoided until the bloom is gone
  • If you notice a blue green algae bloom please call the Ministry of Environment and Climate Change’s Spills Action Center 1-800-268-6060.

Algae or something else?

  • Algae do not have roots, stems or leaves while aquatic plants do.
  • Pollen will most often appear in a yellow colour where a blue green algal bloom will be a pea green to blue green colour. Pollen occurs in spring and early summer and blue green algae are more likely to bloom in late summer to early fall.
Blue Algae

Report any details about how it was growing, colour, odour, and substrate (in water, sand, rock, wood, vascular plants).