Large growths of algae are called algal blooms and they can severely reduce or eliminate oxygen in the water, leading to illnesses or the death of large numbers of fish. Some algal blooms, such as cyanobacteria, also known as blue-green algae, are harmful because they produce toxins that can make people and animals sick if they come into contact with the polluted water, consume tainted fish or shellfish, or drink contaminated water.

When in doubt, stay out!
Cyanobacteria Overview
Harmful algal blooms
Report an Algal Bloom
If you come across an algal bloom, report it
Health Information
Cyanobacteria can affect our health
Animal Health Information
Cyanobacteria can affect our pets and livestock
Cyanobacteria Blooms Photo Gallery
Photo examples of cyanobacteria blooms
Non-Cyanobacteria Blooms Photo Gallery
Photo examples of non-cyanobacteria blooms
Cyanobacteria Information and Resources
Where to get more information