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Lake Water Monitoring

The beauty of Muskoka's lakes and rivers has drawn people to its shores to live and work for generations. 

  • There are over 679 lakes 8 hectares in size or larger within the District of Muskoka 
  • 70-75 lakes are sampled each year through the District’s Recreational Water Quality Monitoring Program

Learn more about lake water monitoring initiatives below:

 Muskoka Water Strategy
The Muskoka Water Strategy is a framework of integrated and strategic initiatives for the protection of Muskoka's water resources.

The purpose of the strategy is to guide and minimize the impact of human activities on water resources; ensure human and environmental health; and preserve the quality of life in Muskoka.

The District spearheads Muskoka's Water Strategy to protect Muskoka's water resources in collaboration with the Muskoka Watershed Council and other stakeholders.   

The strategy emphasizes relationship building, community involvement and resource sharing with other organizations.

As the strategy evolves, new issues or concerns for Muskoka's water resources will be addressed and provide structure for future initiatives.

The strategy consists of four components.

1. The Lake System Health Program

Lake and watershed monitoring, volunteer-based benthic monitoring, stewardship and outreach programs.

2. Communication and Community Involvement Initiatives  

Provide presentations on water quality, ecology, and the natural environment to local schools, lake associations, and at public events.

3. The Muskoka Watershed Council

4. Watershed Initiatives

 Lake System Health

The Lake System Health Program incorporates the best available science and responds to emerging water quality issues guiding the District policies to achieve a holistic and balanced approach to managing Muskoka’s watershed health and shoreline development.

The District undertakes several monitoring programs to assess chemical, biological and physical aspects of Lake System Health:

Chemical: The recreational water quality monitoring program collects data on phosphorus, calcium, chloride, pH, and several other chemical parameters, as well as dissolved oxygen and temperature.

Biological: The benthic monitoring program collects data on the aquatic communities that form the basis of the food web. Support is available for lake associations and volunteers interested in collecting data on other biological communities, such as algae, amphibians and reptiles, and birds, etc.

Physical: Shoreline land use surveys map the physical characteristics of shorelines across Muskoka and shoreline assessment programs provide relevant stewardship information at a property level.

 Recreational Water Quality Monitoring Program

The recreational water quality monitoring program is a field-based program that monitors approximately 165 lakes across Muskoka on a rotating basis (80-85 sites/year) depending on development pressures and the specific characteristics of the lake.  The purpose of the program is to establish a long-term record of key water quality parameters to identify water quality trends and has been in operation for over 40 years.

Reports and Data:

Annual Reports

Lake Data Sheets

Sampling Schedule:

View the 2024 Sampling Schedule for lakes scheduled to be monitored for clarity, temperature, dissolved oxygen, phosphorus and other chemical parameters.

 Phosphorus Monitoring

The District of Muskoka reports annually on phosphorus levels in lakes across the watershed and the Muskoka Watershed Council includes phosphorus as an environmental health indicator through the Muskoka Watershed Report Card. Visit the links below to learn more:

Lake System Health Water Quality Monitoring Program 2023 Annual Report

More about phosphorus in Muskoka...

 Biological Monitoring Program

The District provides training for lake associations interested in undertaking volunteer monitoring programs. The program focuses on benthic monitoring and contributes data to the Ontario Benthos Biomonitoring Network.

Reports and Data:

Aquatic Invertebrate Data Sheets

 Shoreline Land Use Surveys

Shoreline land use surveys document all constructed structures, the condition of the shoreline and general land uses adjacent to a lake. This information is mapped and made available for municipal planning programs, lake associations, Area Municipalities, and other interested parties. Visit the Muskoka Water Web website to view 

Shoreline Land Use Survey Maps for Muskoka.

 Causation Studies

The Muskoka Official Plan outlines that a Causation Study may be undertaken on a lake identified as Vulnerable.  Lakes are determined to be Vulnerable based on a set of water quality parameters (i.e., algae blooms, increasing phosphorus levels); when Vulnerable, a causation study may be conducted based on defined criteria to understand why. The effects on water quality could be due to natural processes or human activities, and determining the cause is essential to protecting Muskoka’s lakes.

Visit the Causation Studies project page on Engage Muskoka to learn more.
 Reporting Erosion - Erode Survey

Soil erosion can cause many issues like loss of land, property, and vegetation; increased pollution in streams and lakes; and reduced recreational water quality and drinking water.

The District’s Erosion survey, called Erode, allows citizens to collect and submit erosion information for lakes and waterways throughout the Muskoka River Watershed using a digital reporting system accessible on a laptop, desktop, or mobile phone. Its easy to use simply, take a picture, note the location and share it with the District using the Erode survey.

The goal is to create an inventory of eroding sites to enhance the river and lake quality habitat.

You can complete the Erosion Survey at the following link: Erode Survey


 Stewardship and Education

The District works closely with the Muskoka Watershed Council to implement several stewardship initiatives:

  • Love Your Lake shoreline assessment and stewardship program.
  • The Natural Edge shoreline re-naturalization program.
  • Workshops for school groups and summer camps.
  • Activity centres at water festivals.
Presentations on species at risk, invasive species, and other stewardship topics
 Blue-Green Algae Blooms
Blue-green algae (cyanobacteria) blooms may impact waterbodies in the District of Muskoka during the summer and fall months. Recent studies show an increase in the number of blue-green algae blooms across Ontario, which is consistent with what is being seen locally. This increase may be attributed to public awareness and increased reporting, but climate change is also making the conditions more favourable for bloom formation.

Many species of cyanobacteria have the potential to produce toxins that are harmful to the health of humans and animals when exposed to high concentrations.

The Simcoe Muskoka District Health Unit (SMDHU) works collaboratively with the Ministry of Environment, Conservation and Parks (MECP) to respond to reports of blue-green algae blooms. Municipalities also play an important role by monitoring and reporting suspect blooms, sharing information with residents and lake associations, and posting water quality advisory signage, when necessary.

When blue-green algae are visible, residents and visitors should exercise care and take the following measures:

  • Do not use the lake water for the preparation of infant formula.
  • Do not allow pets or livestock to drink or swim in the water.
  • Be cautious about eating fish.
  • Do not use herbicides, copper sulphate or other algaecides that may break open algae cells and release toxins into the water.
  • Avoid swimming and other water sport activities.

Roles and Responsibilities:

  • Ministry of the Environment Conservation and Parks: The MECP’s role is to gather, assess and provide basic scientific and technical information with which the health unit can use to assess the risks to humans. They are the lead agency for field response. They will gather information, conduct field visits, as necessary, and facilitate testing to confirm if a blue-green algae bloom is present.
  • Simcoe Muskoka District Health Unit: The SMDHU is the leading agency for assessing human health risks and providing health education when potential risks are identified. SMDHU will notify municipal partners through email and provide public notification through social media and on their website. Their website contains a list of impacted waterbodies, information about the potential risks and precautions to take (
  • Municipalities: Area Municipalities use their knowledge of the area and best practices to communicate with residents. This may include the use of mass notification systems (e.g., email, phone, SMS), website and social media. Municipalities are also responsible for posting water quality advisory signage at public access points, if necessary.

Learn More About Blue-Green Algae Blooms

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