Understanding Recent Blue-Green Algae Advisory in Lake Scugog

As a result of questions from the Lake Stewards, Scugog Township, Durham Region Health, and the Ontario Ministry of the Environment and Climate Change (MOECC) have tested the waters adjacent to Palmer Park Beach and Joe Fowler Park, and found the presence of blue-green algae there. The Ministry is currently testing the water to determine whether the blue-green algae bloom is toxic. In the meantime, as a precaution, a public advisory has been issued. To help you understand this advisory better, we have put together a brief FAQ  on blue-green algae, and what they mean for the health of Lake Scugog.


What are Blue-Green Algae?

Blue green algae are not actually true algae, but a group of photosynthesizing bacteria. They are found in virtually every habitat, in freshwater, oceans, even in damp soils. They play a vital role in the health of ecosystems, but can quickly become a problem when they reach high densities (called “blooms”). This is because many species of cyanobacteria are capable of producing toxins. The most commonly reported cyanotoxins are called microcystins, which are a liver toxin as well as a skin, eye, and throat irritant.

What is a Bloom and How Can you Identify It?

There is no definitive scientific definition of an algal bloom, but it generally means an accumulation of algae that is readily visible with the naked eye. In the case of cyanobacteria, this has to be confirmed by looking at the algae under a microscope to determine which species are present. We are currently confirming with the MOECC what definition they used to define a “bloom” in the recent case of Lake Scugog.

Cyanobacteria blooms usually give the water a blue-green or pea-soup green colour, and commonly (but not always) presents as a slime that accumulates on the surface of the water near shorelines. Cyanobacteria will not be a stringy mass like much of the plant life in Lake Scugog. Although the characteristic colour associated with cyanobacteria is a pea-soup green, blooms of certain species can also appear as olive green or red. Please be aware that, to the untrained eye, it can be easy to confuse surface accumulations of pollen or free-floating macrophytes as a cyanobacteria bloom.

Is the Recent Reported Algal Bloom in Lake Scugog Toxic?

We do not know yet whether the recent bloom released toxins to the lake at concentrations above water quality guidelines. Testing is ongoing at the MOECC. Until the results are back, it is advisable to avoid swimming or consuming fish caught in the areas included under the advisory.  Children or pets should also not play or drink water in these areas until the advisory has been lifted.

What do I do if I suspect a bloom on my shoreline?

We hope our above description helps you to know what to look for. There are also numerous examples on the internet of what a blue-green algae bloom can look like. If you suspect a bloom, the safest thing to do is to assume toxins are present and avoid drinking, bathing, swimming, or otherwise using  the water in the vicinity of the suspected bloom.  You can report suspected blooms to the MOECC Spills Action Centre at 1-800-268-6060. If possible, take photos of the suspected bloom to share with the MOECC.

What are the Stewards doing about Blue-Green Algae in Lake Scugog?

In addition to acting as a liaison between the community and the township, Kawartha Conservation, Durham Region Health, and the MOECC, the Lake Stewards are also actively supporting ongoing research into algal and plant communities in Lake Scugog by Dr. Andrea Kirkwood’s lab at the University of Ontario Institute of Technology. This research is an important part of our 3-year Ontario Trillium Foundation Grow Grant, which began this summer. We will be sharing the results of our work as we go along, including a series of educational videos produced by Moko Media. We are committed to better understanding cyanobacteria in Lake Scugog, including identifying areas of risk, and the underlying causes of cyanobacteria blooms.

What can I do to combat Blue-Green Algae Blooms in Lake Scugog?

The best thing that you can do to combat cyanobacteria blooms in Lake Scugog is to help manage nutrient run-off into the lake. This includes using phosphate-free detergents, avoiding fertilizer use on lawns (especially those that contain phosphorus), picking up after your dog, and maintaining healthy shorelines and functioning septic systems. Keep an eye out for Kawartha Lakes Blue Canoe program for more information on shoreline management.

We at the Scugog Lake Stewards are always happy to answer questions from the community about the health of the lake, and will continue to serve as your “eyes and ears”.

Dr. Jennifer Korosi , Aquatic Ecologist

Assistant Professor , Department of Geography, York University

Director of Research and Monitoring, Scugog Lake Stewards


General inquiries: Info@scugoglakestewards.ca

Research and Monitoring: research.scugoglakestewards@gmail.com

Barbara Karthein, SLS President: bkarthein@yahoo.ca