Algal Bloom Alerts - Overview

Algae are simple, typically small aquatic organisms and range in structure from unicellular (a microscopic single cell) to multicellular and as they produce and grow, form colonies that appear on the surface or attached to various substrates. Algae are always present in lakes and rivers, and are at the base (primary) of most lake food webs, and as such, are critical components of a healthy aquatic environment. Without algae, zooplankton (small animals that feed on algae) would not survive, and this would impact the survival of fish and other animals further up the food chain.

When conditions are favourable, certain populations of algae can increase to levels that result in poor water quality and an algal bloom or scum may form. Bloom-forming conditions include:

  • sufficiently high levels of nutrients (phosphorus and to a lesser extent nitrogen)
  • calm weather and low water flow
  • strong sunlight
  • high air & surface water temperatures

As there is an abundance of relevant literature covering the identification, reporting and relevant health implications, this introductory material has been limited to the above general information on algal growth and a list of key findings relevant to Kahshe and Bass Lake property owners/guests or public users.  A more detailed report on the types of algae that may impact the health of Kahshe and Bass Lakes, on factors that play a role in algal bloom development and on the health symptoms and use restrictions has been developed and is appended. Also appended to this section are several excellent references to help readers better understand the health and aesthetic implications of a toxic algal bloom and how the presence of a bloom needs to be reported.

The key findings relevant to Kahshe and Bass Lake property owners/guests/users include:

  • To date, there have been no documented blue-green (toxic) algal blooms on Kahshe or Bass Lakes.
  • However, there have been an increasing number of toxic algal blooms detected in Northern Ontario, including lakes in Muskoka since the late 1990s.
  • This increase in impacted lakes appears to be associated primarily with increasing air and water temperatures associated with a changing climate but may also be due to a more informed public and reporting procedures.
  • In the event that a bloom is detected, it needs to be reported to the Spills Action Centre, Ontario Ministry of Environment, Conservation and Parks (MOECP). The phone number is: 1-800-268-6060.
  • If it is identified as a toxic blue-green or other type of toxic bloom, the Simcoe/Muskoka Health Unit will issue advisories regarding the health implications and conditions for use of the water for consumption and recreational purposes.

This section of the Lake Health tab will serve as a repository for any future algal bloom alerts and associated health advisories.

Ron Pearson

Kahshe and Bass Lake Steward


Kahshe Lake Ratepayers' Association (1994) Inc. (KLRA)
PO Box 1318, Gravenhurst, ON, Canada, P1P 1V5
Information: info@kahshelake.ca      Site Comments: webmaster@kahshelake.ca

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