With the Ministry of the Environment, Conservation and Parks (MECP) predicting above-normal temperatures for the summer of 2021, and 19 algae blooms confirmed in Muskoka by the Ministry between the summer and fall of 2019 and 2020, the District of Muskoka and has retained two consultants to conduct causation studies in five lakes.
The studies will attempt to discover what is causing algae blooms and/or elevated phosphorous levels in those lakes.
Hutchinson Environmental Sciences Ltd. (HESL) and RiverStone Environmental Solutions Inc. were selected through a competitive process to conduct concurrent studies of five lakes identified as vulnerable in Muskoka’s Official Plan (MOP) at an estimated cost of $213,000 according to a June 24, 2021 staff report.
Bass Lake in the Town of Gravenhurst, Echo Lake in the Township of Lake of Bays, Leonard Lake in the Township of Muskoka Lakes, Three Mile Lake in the Township of Muskoka Lakes, and Stewart Lake located in both the townships of Georgian Bay and Muskoka Lakes have been selected.
HESL will be conducting causation studies for Bass, Echo, Stewart, and Three Mile lakes, while RiverStone was awarded the contract for Leonard Lake, according to District staff.
Out of the five lakes identified for causation studies, four experienced one or more blue-green algae blooms in the past two years, while Bass Lake has been listed as vulnerable in Muskoka’s Official Plan due to elevated phosphorous levels.
Staff uses several factors to identify vulnerable lakes. They include phosphorous levels, blue-green algae blooms, the size of the lake, the lot sizes allowed around a particular lake, the amount of current development around a lake, stakeholder participation, and the potential for further development.
“Until such time as a causation study is completed, enhanced protection policies apply to development on vulnerable lakes. Policies in the MOP may be updated pending the results of a causation study to ensure that water quality of the lake continues to be protected,” noted an April 15, 2020 report compiled by District planner Emily Crowder and director of planning Summer Valentine for Muskoka’s community and planning services committee.
District planning staff were back before the committee on June 24, 2021, asking for an additional $50,000 for total funding of $262,875 for the projects, noting that lakes being studied may experience algae blooms during the course of the studies, which may require additional fieldwork to collect water samples for analysis.
“Through stakeholder consultations and meetings with the consultants, staff have become aware of the need to respond quickly should an algae bloom take place on any of the five lakes being studied to minimize the risk of it dissipating before the consultant’s field crew can attend the lake for sample collection. This budget amendment is being proactively proposed, given the already warmer-than-average seasonal temperatures, early bloom observations reported this year, and the Ministry’s seasonal forecasts,” states the report by Jacquie Evans, planning policy and programs coordinator, and Christy Doyle, director of environmental and watershed programs.
“The consultants have advised that the additional cost for sampling and data collection per bloom event would be approximately $5,000, which is consistent with fees paid for on-demand sampling and analysis of the algae bloom in Stewart Lake in fall 2020. The requested budget amendment would cover costs to collect and analyze water samples for up to ten algae blooms, or an average of two for each of the five lakes participating in the causation studies,” adds the report.
The first causation pilot project was conducted by HESL in Peninsula Lake in 2019 to try and identify the cause of algal blooms observed in the 1990s and 2017. Although the report did not provide conclusive findings regarding the blooms, consideration was given to low winds and warm climate as the perfect conditions associated with such blooms as well as the possibility of runoff from developed lands.
“Based on the lines of evidence considered and our analysis of the available data, we concluded that the most likely cause of the 2017 bloom in Peninsula Lake was a combination of climate factors including a period of prolonged high air temperature and low wind speed, which created ideal conditions for cyanobacterial dominance and proliferation. Periods of sustained low wind and high temperature were noted in all three bloom years in either August or September. The lake may also be predisposed to Gloeotrichia blooms by inputs of sediments in runoff from developed lands, but the link was not conclusive,” states the report. You can find it here.
The pilot helped set the parameters for causation studies moving forward.
The following lakes have been listed as vulnerable for recreational water quality in Muskoka’s latest Official Plan amendment, found on the District of Muskoka’s website:
If you spot a blue-green algal bloom, the Simcoe Muskoka District Health Unit recommends that you take a cautious approach as some varieties of the algae can produce toxins harmful to both humans and animals. If you suspect a blue-green algal bloom, they recommend that you:
- assume toxins are present;
- avoid using, drinking, bathing or swimming in the water;
- restrict pet and livestock access to the water; and
- call your local health unit
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