Cyanobacteria (Blue-Green Algae)
What are cyanobacteria (blue-green algae) blooms?
Blue-green algae blooms (sometimes just called "pond scum") are large masses of a type of bacteria called cyanobacteria. There are actually no algae in blue-green "algae" blooms.
Cyanobacteria grow in warm, shallow or slow-moving water, especially if the water has been contaminated with fertilizer, sewage or phosphate soap. Even though cyanobacteria are often called blue-green algae, blooms can range in colour from green to red. New blooms smell like mown grass and older blooms smell like rotting garbage.
What are the health effects of cyanobacteria?
Some species of cyanobacteria produce toxins that can negatively affect health. It is impossible to tell which cyanobacterial blooms are producing toxins just by looking at them.
If you are exposed to high levels of these toxins, you might develop a headache, vision changes, an itchy rash, diarrhea, nausea and vomiting, or difficulty breathing. If you have any of these signs or symptoms, see your health care provider.
Recommendations
- Recreational water activities:
Avoid recreational water activities during cyanobacterial blooms. If you want to continue recreational water activities during a cyanobacterial bloom, try lower-exposure activities, like canoeing or sailing. Higher-exposure activities include swimming, water skiing, wind surfing, and other activities with a lot of water contact or splashing.
- Fishing:
Avoid eating fish from areas where a cyanobacterial bloom is visible. If you still want to continue eating fish, do not eat the organs because this is where most of the toxins accumulate. Cooking does not inactivate most cyanobacterial toxins.
- Drinking water:
Do not drink water that is contaminated with cyanobacteria. If you obtain water from a surface water source that might be contaminated with cyanobacteria, contact the Ontario Ministry of the Environment's Spills Action Centre at 1-800-268-6060 or 416-325-3000. Conventional water treatment and boiling are not effective at removing cyanobacterial toxins.
Want more information?
Visit Health Canada Blue-Green Algae (Cyanobacteria) and their Toxins or Ontario Ministry of the Environment Blue-green algae: Information for cottagers and home owners.
Contact a public health inspector at KFL&A Public Health by visiting our office or calling 613-549-1232, ext. 1231.