What is a blue-green algae bloom?

Smoke on the water

A blue-green algae bloom forms a scum or slime on a lake’s surface, making the water look like pea soup. These blooms reduce oxygen in the water, block sunlight needed by aquatic plants, and are poisonous for fish, birds, amphibians, pets, and humans.

The surprising thing about blue-green algae, however, is that they are not actually algae. They are a type of bacteria known as cyanobacteria. Cyanobacteria are considered by some to be the oldest lifeforms on earth; they predate dinosaurs and are the force that turned dead plants into crude oil

Many factors contribute to a blue-green algae bloom (and blooms occur naturally), however, the presence of too much phosphorus or sediment is often the triggering event.

Not all blooms are easy to see, and toxins can still be present even if the water looks fine. They usually happen in late summer or early fall but can occur at any time of year. A bloom can last from a few days to a few months.

Natural shorelines prevent algae blooms, as they filter out nutrients and sediment before they get into the water.

Learn more in the full Lakes of Victoria, BC guidebook.

Cover of Lakes of Victoria, BC.

In the full guidebook, discover where to:

  • Walk: enjoy lakeside strolls & boardwalks.
  • Hike: discover single-track trails & scenic views.
  • Swim: find the best beaches to soak up the sun.
  • Fish: learn about stocking trends and piers.
  • Paddle: explore shorelines, and hidden bays.
  • Bike: plan your next route and hit the trails.

Along the way you will meet the animals and plants that call these lakes and watersheds home, unearth forgotten place names, and learn stories of days past.

The book is full of useful maps, access information, and local trivia to get you started on your next family day or great adventure.

From locals to visitors, everyone will learn something new about the freshwater lakes that bring Victoria to life.