Protecting Muskoka’s Vulnerable Lakes: Causation Studies

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In order to protect one of Muskoka’s most valuable assets, the District undertakes a comprehensive recreational water quality monitoring program each year. The data collected from this program is used to identify lakes that are considered vulnerable based on specific water quality indicators such as confirmed blue-green algae blooms or increasing phosphorus levels.

When a lake is listed as vulnerable, one of the first steps outlined in the Muskoka Official Plan (MOP) is to initiate a waterbody-wide causation study to determine the causes and relative contributing factors to the identified water quality indicator(s).

Although the overall framework for undertaking a causation study is outlined in the MOP, studies are to be tailored to respond to the unique situations and contexts of individual lakes. Additionally, because the causation study approach is a new methodology, the approach and process is best initiated through a pilot project. Every causation study undertaken will be evidence-based through the use of the best available science.

In 2019, the District of Muskoka retained an environmental sciences consultant to undertake a Causation Study Pilot Project and Peninsula Lake was selected to be studied first. That study has now concluded, and five additional studies are underway on Stewart, Three Mile, Leonard, Bass, and Echo Lakes. The complete list of vulnerable lakes can be found in Schedule E2 of the MOP.

STAY INFORMED:

To receive general causation study updates and to stay informed of future causation studies being undertaken by the District, please subscribe to our courtesy notice list by entering your email address in the "Stay Informed" tool (located at the top right-hand corner of this page on your desktop, or scroll down on your mobile device) and click the subscribe button.

To follow a specific causation study, please select one of the current studies below and subscribe using the "Stay Informed" tool on the respective page.


In order to protect one of Muskoka’s most valuable assets, the District undertakes a comprehensive recreational water quality monitoring program each year. The data collected from this program is used to identify lakes that are considered vulnerable based on specific water quality indicators such as confirmed blue-green algae blooms or increasing phosphorus levels.

When a lake is listed as vulnerable, one of the first steps outlined in the Muskoka Official Plan (MOP) is to initiate a waterbody-wide causation study to determine the causes and relative contributing factors to the identified water quality indicator(s).

Although the overall framework for undertaking a causation study is outlined in the MOP, studies are to be tailored to respond to the unique situations and contexts of individual lakes. Additionally, because the causation study approach is a new methodology, the approach and process is best initiated through a pilot project. Every causation study undertaken will be evidence-based through the use of the best available science.

In 2019, the District of Muskoka retained an environmental sciences consultant to undertake a Causation Study Pilot Project and Peninsula Lake was selected to be studied first. That study has now concluded, and five additional studies are underway on Stewart, Three Mile, Leonard, Bass, and Echo Lakes. The complete list of vulnerable lakes can be found in Schedule E2 of the MOP.

STAY INFORMED:

To receive general causation study updates and to stay informed of future causation studies being undertaken by the District, please subscribe to our courtesy notice list by entering your email address in the "Stay Informed" tool (located at the top right-hand corner of this page on your desktop, or scroll down on your mobile device) and click the subscribe button.

To follow a specific causation study, please select one of the current studies below and subscribe using the "Stay Informed" tool on the respective page.


  • Causation Study Update for Leonard Lake

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    The District Municipality of Muskoka and project consultants have now completed the Leonard Lake Causation Study initiated in 2021 at the direction of Muskoka District Council. The final report is available for review here:

    Leonard Lake Final Report

    Below are answers to some common questions:

    Is my lake still subject to Enhanced Protection Policies?

    No. The Causation Studies have confirmed that development was not the cause of the reported water quality indicators on these five waterbodies. As such, all five waterbodies are now considered to be removed from Schedule E2 and are not subject to the Enhanced Protection Policies, as outlined in Section C2.6.6. of the Muskoka Official Plan (MOP).

    What happens if my lake experiences another blue-green algae bloom this summer?

    The scope of each Causation Study is to determine the cause of one specific blue-green algae bloom and are intended to provide an in-depth review of a snapshot in time to determine why a bloom occurred. However, the results of each report indicate that the primary cause of the reported bloom is climate change.

    If you suspect a blue-green algae bloom, call the Pollution Hotline at 1-866-663-8477.

    If my lake experiences another blue-green algae bloom, will another Causation Study be initiated?

    While the Muskoka Official Plan currently envisions causation studies to be undertaken on all lakes that experience a confirmed blue-green algae bloom, the District is currently embarking on a follow-up study to determine the effectiveness of the existing lake system health policy set and the value in conducting future causation studies.

    I have additional feedback I want to provide – is it possible to do so?

    While we welcome additional feedback, the reports are now final and no further amendments/revisions will be occurring. The District is undertaking a review of the applicable policies contained in the MOP, and a public consultation process will occur through that initiative, which all are welcome to contribute to.

    What are your next steps?

    The District is in the process of retaining a consultant to conduct a follow-up study to determine the effectiveness of the existing lake system health policies contained in the MOP, and the value of conducting future causation studies. Any changes to the existing policies will be undertaken as a public process and anyone who is interested in contributing their comments/concerns will be able to do so through the public meeting process that will be initiated – likely in the fall.

    I have more questions. Who do I contact?

    Please feel free to reach out to Elizabeth Purcell, Manager of Planning, if you have any questions about the Causation Studies. You can email her at Elizabeth.purcell@muskoka.on.ca.

  • Causation Study Update for Leonard Lake, Three Mile Lake, Echo Lake, Bass Lake and Stewart Lake

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    The District Municipality of Muskoka and project consultants have now completed four (4) of the five (5) Causation Studies initiated in 2021 at the direction of Muskoka District Council. The final reports are available for review here:

    Three Mile Lake Final Report

    Echo Lake Final Report

    Bass Lake Final Report

    Steward Lake Final Report

    The final report for Leonard Lake is forthcoming, and will be posted to this page once complete.

    Below are answers to some common questions:

    Is my lake still subject to Enhanced Protection Policies?

    No. The Causation Studies have confirmed that development was not the cause of the reported water quality indicators on these five waterbodies. As such, all five waterbodies are now considered to be removed from Schedule E2 and are not subject to the Enhanced Protection Policies, as outlined in Section C2.6.6. of the Muskoka Official Plan (MOP).

    What happens if my lake experiences another blue-green algae bloom this summer?

    The scope of each Causation Study is to determine the cause of one specific blue-green algae bloom and are intended to provide an in-depth review of a snapshot in time to determine why a bloom occurred. However, the results of each report indicate that the primary cause of the reported bloom is climate change.

    If you suspect a blue-green algae bloom, call the Pollution Hotline at 1-866-663-8477.

    If my lake experiences another blue-green algae bloom, will another Causation Study be initiated?

    While the Muskoka Official Plan currently envisions causation studies to be undertaken on all lakes that experience a confirmed blue-green algae bloom, the District is currently embarking on a follow-up study to determine the effectiveness of the existing lake system health policy set and the value in conducting future causation studies.

    I have additional feedback I want to provide – is it possible to do so?

    While we welcome additional feedback, the reports are now final and no further amendments/revisions will be occurring. The District is undertaking a review of the applicable policies contained in the MOP, and a public consultation process will occur through that initiative, which all are welcome to contribute to.

    What are your next steps?

    The District is in the process of retaining a consultant to conduct a follow-up study to determine the effectiveness of the existing lake system health policies contained in the MOP, and the value of conducting future causation studies. Any changes to the existing policies will be undertaken as a public process and anyone who is interested in contributing their comments/concerns will be able to do so through the public meeting process that will be initiated – likely in the fall.

    I have more questions. Who do I contact?

    Please feel free to reach out to Elizabeth Purcell, Manager of Planning, if you have any questions about the Causation Studies. You can email her at Elizabeth.purcell@muskoka.on.ca.

  • Causation Study Update for Leonard Lake, Three Mile Lake, Echo Lake, Bass Lake, and Stewart Lake

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    Posted on August 24, 2022

    The District Municipality of Muskoka and project consultants have experienced unexpected delays with respect to external data collection required for these projects. This has resulted in an overall delay for all causation studies.

    The required data has recently become available, and the analysis portion of the studies is now underway.

    When will the next stakeholder meetings be?

    The next stakeholder meetings will occur in late Fall 2022. At these meetings, the draft report for each subject lake, including project results, will be shared and discussed. Stakeholder and public comments are welcome and encouraged. You can stay informed on the future meeting dates by subscribing to the Engage Muskoka Page (see links below). To subscribe, enter your email address in the “Stay Informed” tool.

    Click here for the Leonard Lake Causation Study

    Click here for the Three Mile Lake Causation Study

    Click here for the Echo Lake Causation Study

    Click here for the Bass Lake Causation Study

    Click here for the Stewart Lake Causation Study

    When will the final report be published?

    Following the public consultation on the draft report in late Fall 2022, the final report is anticipated to be published in late 2022 and brought forward to the District’s Community Services and Planning Committee in early 2023.

    Is my lake still subject to Enhanced Protection Policies?

    Yes. Until a causation study is completed and any recommendations adopted by Muskoka District Council, the enhanced protection policies will continue to apply to development on vulnerable lakes, as outlined in Section C2.6.6. of the Muskoka Official Plan (MOP).

    What happens if my lake experiences another blue-green algae bloom this summer?

    The scope of each Causation Study is to determine the cause of one specific blue-green algae bloom and are intended to provide an in-depth review of a snapshot in time to determine why a bloom occurred. For that reason, blue-green algae blooms in subsequent years will not be a part of the current/underway Causation Study. Further, if current Causation Studies did include new blooms, the project would be delayed due to more data collection and analysis requirements.

    If you suspect a blue-green algae bloom, call the Pollution Hotline at 1-866-663-8477.

    If my lake experiences another blue-green algae bloom, will another Causation Study be initiated?

    Currently, there are 9 lakes in Muskoka on Schedule E2 of the Muskoka Official Plan as a result of a confirmed blue-green algae bloom. While the Muskoka Offical Plan envisions causation studies to be undertaken on all lakes that experience a confirmed blue-green algae bloom, it does not provide guidance on a priority order for the vulnerable lakes to be studied. For the current lakes undergoing a Causation Study, they were recommended by staff to District Council based on development potential, historical water monitoring and stewardship activities, stakeholder impact, and engagement between the District and the lake association.

    Once the current causation studies are complete, District staff will once again review the vulnerable lakes and provide optionsfor the consideration of District Council..

    I have more questions. Who do I contact?

    Please feel free to reach out to Cassie Emms, Planner, if you have any questions about the Causation Studies. You can email her at cassie.emms@muskoka.on.ca.

  • Leonard Lake, Township of Muskoka Lakes

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  • Three Mile Lake, Township of Muskoka Lakes

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  • Echo Lake, Township of Lake of Bays

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  • Bass Lake, Town of Gravenhurst

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  • Stewart Lake, Township of Georgian Bay and Township of Muskoka Lakes

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  • Peninsula Lake - (Concluded)

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Page last updated: 18 Jul 2023, 07:14 AM