blue-green algae

Blue-Green Algae Documented In Superior’s Canadian Waters – A First?

A picture of Lake Superior surface water some 35 km/21 mi. east of Thunder Bay on September 20th. (Photo:

Green Patches Stretch Offshore

On the evening of September 19th, a boater some 35 km/22 mi. east of Thunder Bay noticed green patches stretching far out into the open waters of the lake. The boater noted water temperature at 15 degrees Celsius or 59 degrees Fahrenheit. The next morning marked the third day of unusually calm conditions on Lake Superior and a kayaker in the same area, noted the same unfamiliar sight: patches of green on the surface of Superior’s waters. 

The kayaker first observed the green patches in a small bay, which area residents refer to as “East Bay.” The green patches continued out into the open waters of Lake Superior to a distance of at least a couple of miles from shore. In the early afternoon of the same day, green patches covered more of this same area. They were also observed in an adjacent small bay, referred to by locals as “North Bay.” By late afternoon, green patche coverage had also increased in the open waters of Superior.

In the late afternoon on September 20th a scum covered the inshore area of “North Bay” to a distance of approximately 50 meters, or 54 yards, from shore. (Photo:

The late afternoon situation in North Bay was intense, with several extensive green patches. Additionally, a surface scum covered the entire inshore area of the bay, out to approximately 50 m/54 yd. from shore. A thick line of dark scum, perhaps a foot in width and less than a foot from the water’s edge, ran along the sand on the bay’s shoreline.

Algae sample collected from Lake Superior on September 20th. Photo taken under the microscope. (Photo:

Testing Confirms Cyanobacteria (Blue-green Algae)

The kayaker collected a sample of the green material which was sent to Lakehead University for identification. Testing determined that the material was dominated by a genus of cyanobacteria (also known as blue-green algae) called Dolichiospermum. 

Next, the sample was tested for toxicity. An enzyme-linked immunosorbent assay (ELISA) test showed microcystin toxin levels were lower than the drinking water threshold. In lay terms, test one came back positive for cyanobacteria, test two came back negative for toxicity. 

To the best of Infosuperior’s knowledge, this event is the first documented incident of a cyanobacteria bloom in the Canadian waters of Lake Superior. Government environment and health agencies were notified about the situation.

Algae extended into the open waters of Lake Superior, even into unprotected waters well beyond the island in the distance, which is approximately 2 km. / 1 mi. from shore. (Photo:

Clear Water Returns

The next morning, on September 21st, waters in the area, including East Bay, North Bay and the open lake, were relatively calm and extremely clear. Beach sand was clean and there was no sign of the scum, which had lined the shoreline the previous day.

Material from the surface of Lake Superior – September 20th. (Photo:

Algae Briefly

Algae are simple aquatic plants without roots, stems or leaves and with primitive reproduction methods. Algae ranges in size from microscopic, or microalgae, to macroalgae, large seaweed that can be over 30 m./100 ft. in length. Cyanobacteria fall within the microalgae size. Most microalgae flourish by harvesting sunlight and a few nutrients, like phosphorous and nitrogen. 

Algae are a natural part of the ecosystem and the foundation of the aquatic food chain. They are primary producers that support fisheries in both inland waters and oceans; however, Cyanobacteria (blue-green algae) are not generally eaten by other aquatic organisms.

Algae blooms usually occur in late summer or fall. Blooms can occur naturally in the absence of any human influences and are even noted in the journals of early explorers. Alexander MacKenzie noted such an occurrence in the seventeen hundreds on Lake of the Woods; however, today’s large-scale nuisance algae blooms like those experienced on Lake Erie and Lake Winnipeg are not “natural.” Nutrient enrichment from humans contributes significantly to these types of algae growth. Phosphorus and Nitrogen are the primary nutrients contributing to increased blooms, and they can enter waterways in surface runoff from sources such as lawn and agriculture fertilizers, soap, and sewage.

Algae blooms are a complex subject. A bloom can include many species and even variants within species. Cyanobacteria blooms, are of particular concern due to their ability to produce several toxins. These toxins can damage liver tissue and/or the brain and can be lethal to animals, including pets and humans. Cyanobacteria can also cause skin irritation, along with taste and odour issues.

A green patch in the Canadian waters of Lake Superior on a hazy September 20th morning. A sample was collected and examined under the microscope and determined to be blue-green algae. Algae coverage in this area expanded throughout the day. (Photo:

Algae in the U.S. Waters of Superior

Algae blooms in Lake Superior are rare, and until recently, were almost unknown. In the last few years however, algae blooms have been observed in the U.S. waters of Superior. The New York Times link below provides an overview of this situation. Other links provide information about algae blooms in lakes large and small, including Lake Baikal in Russia. Like Superior, Lake Baikal is known for its clear waters and holds an almost spiritual significance to Russians. Due to its extreme depth, Lake Baikal holds more water than all of the Great Lakes combined.

Reporting Blue-green Algae in Ontario

If you observe blue-green algae in Ontario call the Spills Action Centre, 1-866-MOETIPS (6638477), TTY: 1-855-889-5775.

Local Algae Information:

After reporting any suspected algae blooms to the Ontario Ministry of the Environment, Conservation and Parks, through the Spills Action Centre, local residents looking for additional information on blooms are encouraged to contact us. Our research team offers a wide range of expertise including phytoplankton identification.

Lake Superior Research Center (contact via – offering educational information on phytoplankton blooms in Northwestern Ontario. 

U.S. Algae Information:

More Photos:

View More Pictures of the September 20th Situation Described in this Article.

After reporting any suspected algae blooms residents looking for additional information on blooms are encouraged to contact us. Our research team offers a wide range of expertise including phytoplankton identification.


August 29, 2018 NYTimes Article: Lake Superior Algae Raises Concerns

June 3, 2019 Infosuperior Article by Nathan Wilson: Classifying Lakes: Eutrophication in the Boreal Forest Ecozone

November 29, 2016 Infosuperior Article: It Could Never Happen Here

Province of Ontario Information About Blue-green Algae

Learn About Research Carried Out By Lakehead University Doctoral Student Nathan Wilson at Cloud Lake Near Thunder Bay

Globe and Mail Article Updated April 3, 2018: Algae and Property Values

September 10th, 2019 Waukesha Patch Article: Invasive Algae Found in Two Wisconsin Lakes

Environment and Climate Change Canada Algae Identification Field Guide

Northern Kentucky University Algae Field Guide

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