Also known as phytoplankton, pond scum, watermelon snow. Icon showing a green, cartoon representation of algae

What is it?

Algae is a general term for microscopic plants that live in the water. There are many different types of algae and they can grow and multiply very quickly. Like land plants, they photosynthesize (they absorb carbon dioxide and release oxygen) and they absorb nutrients from the water. 

There is a wide variety of algae in Alberta. Their appearance in water can range from murkiness; to green pea soup; to mats of green, brown or reddish material. Some types of algae float in the water, while others attach to something. Sometimes, the same type of algae can appear differently if the environmental conditions change. 

Blue green algae/cyanobacteria

Blue green algae are not algae at all. They are a group of many different bacteria that have similar traits to algae. Cyanobacteria usually form long strands of single bacteria cells all linked together and living cooperatively. They have unique pigments and some (but not all) look blue green in colour. 

Cyanobacteria are often referred to as algae because they photosynthesize, form blooms, absorb nutrients, and look similar to algae.

Are algae in the water regulated in Alberta?

Yes, there are guidelines for quantities of algae in surface water for purposes of environmental protection, human health and recreation. There are also regulations on some activities that can indirectly cause algae blooms (e.g., fertilization of crops).  

The toxins produced by algae are regulated by federal guidelines. The Canadian guideline for the cyanobacterial toxin microcystin is 1.5 micro-grams per litre. More information can be found here

Are algae in my water?

Source Water

Algae are in surface water across Alberta. In addition to lakes, ponds and rivers, algae are also found on snow and ice, in the soil, and paired up with fungi to make lichens. Natural algae in surface water are an essential part of the ecosystem, despite their reputation as problematic for water quality. See our page on concerns about blue-green algae for more information.

Tap Water

There are no algae in tap water because they are easily filtered out. Certain toxins released by algae can end up in tap water, but the health authority will have issued a health advisory for any residents whose source water may be contaminated with these toxins.

When there are any health risks from a toxic algae bloom, Alberta Health Services posts public health advisories on signs at the water itself, over the media, and online

What are the impacts on human health?

When there is an abundance of all the things algae need to grow (e.g. nutrients, sunlight, and carbon dioxide) they can multiply so quickly that they form a bloom. 

Some types of algae produce strong toxins that are released into the water. When these types of algae form blooms, they are called toxic algal blooms and are damaging for the environment and people. During a toxic algal bloom, people and their pets are warned to avoid drinking the water or playing in or near it. People are advised not to fish and farmers are advised not to let their livestock drink it.

Water treatment plants can have a difficult time removing algal toxins from drinking water, so in some cases people are advised to drink bottled water rather than tap water if their source water has an algae bloom.

Although they are not true algae, cyanobacteria are the most common cause of toxic algal blooms.

What are the impacts on the environment?

Algae are an essential part of aquatic ecosystems. They provide food for many other organisms, help recycle nutrients, and help absorb some contaminants from water.

An algae bloom can damage an ecosystem because it can smother other plants and, when all the algae die and start to decompose, oxygen is depleted. Without enough oxygen in the water fish and other animals can die. Toxic algal blooms also lead to fish and other animals dying from the toxicity of the water.

How do algae get into the water?

Algae are naturally occurring. Algal blooms are triggered when there are more nutrients than typical for a certain body of water. The more relevant question is, “How do extra nutrients enter surface water?”

What can we do about algae in the water?

The Bow River Basin the Phosphorus Management Plan has been put in place to reduce the amount of phosphorus getting into the water. This is a positive step to preventing algae blooms.

Restricting the use of non-essential fertilizers can help prevent nutrients from entering the water.

Where can I find more information?

Public Health Advisories in Alberta

Quick facts about blue green algae in Alberta

Cyanobacteria blooms and toxicity

Environment and Climate Change Canada – Phosphorus and excess algal growth