McKenzie Lake Scoped Management and Monitoring Plan
Plain Language Summary
Hutchinson Environmental Sciences Ltd. were hired by the McKenzie Lake Property Owners Association to assess the water quality of McKenzie Lake. Water quality was assessed through a review of historical data and reports, and water samples which were collected in August 2022.
The water quality of McKenzie Lake is good with low concentrations of nutrients, bacteria and algae, although blue-green algae was observed in the lake on August 16, 2022. The majority of development on McKenzie Lake is true “cottage” development, large homes with manicured lawns to the water’s edge are largely absent. The development character of McKenzie Lake, such as naturally vegetated shorelines, will help to maintain water quality.
A number of recommendations were developed through the study:
-
1) The Spills Action Centre should be called at 1-866-MOETIPS (663-8477) if a blue-green algae bloom is suspected in the future. If a bloom is present, MECP will collect samples to determine if it is blue-green algae and will complete additional sampling to determine if toxins are greater than drinking water or swimming guidelines.
-
2) Water quality sampling of McKenzie Lake has been completed through the Lake Partner Program which is coordinated by the Ministry of Environment, Conservation and Parks. It is recommended that two sites are routinely monitored (instead of one) and that samples are also assessed for calcium and chloride (instead of just total phosphorus).
-
3) The development capacity of McKenzie Lake is uncertain because oxygen concentrations have fluctuated above and below the development threshold. Temperature and dissolved oxygen measurements should be collected in the late summer (September 1 – 15) to determine if the lake has additional development capacity.
-
4) The development capacity of lakes in Ontario is typically determined through a model that predicts total phosphorus. The total phosphorus model should be completed for McKenzie Lake to determine the development capacity of the lake.
Executive Summary
The McKenzie Lake Property Owners Association (McKLPOA) retained Hutchinson Environmental Sciences Ltd. (HESL) in 2022 to conduct a background review and field investigation with the goals of characterizing the lake’s water quality and shoreline development, reviewing shoreline development policies, and providing recommendations for future monitoring and management of McKenzie Lake. Historical data were obtained from the McKLPOA archives and the Ministry of Environment, Conservation, and Parks (MECP). The lake was surveyed by HESL on 16 August 2022.
The water quality of McKenzie Lake is generally good, with relatively low concentrations of nutrients, chloride, metals, E. coli, and phytoplankton. Clarity is relatively low for an oligotrophic lake due to the export of dissolved organic carbon (DOC) from the lake’s forested catchment. Clarity has decreased over time which could be the result of increasing DOC concentrations, consistent with trends in south-central Ontario lakes over a similar timeframe (Palmer et al. 2011).
There is good habitat for cold-water fish in the lake’s relatively well-oxygenated hypolimnion. Internal phosphorus loading appears to be of limited magnitude based on available data. The only two water quality guideline exceedances were for iron (just above the sediments) and nitrite (on a single date in 2004; possibly an erroneous value).
Climate change, brownification (i.e., increased DOC), and changes to hydrology have resulted in conditions conducive to the proliferation of nuisance and harmful algal blooms. In Central Ontario, this includes a marked recent increase in algal blooms in low-nutrient lakes. The observation of aggregations of a potentially toxic, bloom-forming cyanobacterium of the genus Planktothrix is of some concern, but toxic blooms have not been reported (to our knowledge) and this genus is known to thrive in low-light environments, which may explain its presence in the relatively brown waters of McKenzie Lake.
The majority of existing development on McKenzie Lake is typical of true “cottage” development and is well- buffered; intense waterfront development (e.g., large homes, vast impermeable surfaces, wake-surfing boats, and manicured lawns) is largely absent. Responsible waterfront development often requires the enforcement of appropriate planning policies such as those present in the Official Plan, and stewardship/education initiatives implemented by volunteer groups such as McKLPOA. The development character on McKenzie Lake, including intact vegetated shoreline buffers, will help to maintain water quality. Protective Official Plan policies are in place which will help to mitigate development-related impacts if the policies are implemented through education and/or enforcement.
HESL has four recommendations based on the results of this study:
5) The Spills Action Centre should be called at 1-866-MOETIPS (663-8477) if a cyanobacteria (“blue- green algae”) bloom is suspected in the future. If a bloom is present, MECP will collect samples to determine if cyanobacteria are present and if there is potential for toxins to be produced based on the particular genus or species identified. If it is confirmed that harmful cyanobacteria are present, additional analyses are completed to determine microcystin concentrations and compare concentrations to the drinking water limit of 1.5 μg/L and recreational limit of 10 μg/L.
-
6) The Lake Partner Program (LPP), coordinated by MECP provides the best possible entry point to lake monitoring for lake associations with limited resources. The stated goal of the LPP is to protect and understand the water quality of Ontario’s inland lakes. This is accomplished by involving citizens in a volunteer-based monitoring program. Total phosphorus (TP) concentrations (2002– 2004, 2006, 2010, 2019, 2020, 2021) and water clarity measurements (i.e., Secchi depth; 2001 and 2002) have been collected in McKenzie Lake through the LPP but sampling has been somewhat sporadic and primarily focused on one parameter (TP) and one sampling location. It is recommended that two sites (LPP #2 and ML-3) are routinely monitored following LPP instructions and that samples are also assessed for calcium and chloride.
-
7) The development capacity of McKenzie Lake is uncertain because mean volume-weighted hypolimnetic dissolved oxygen (MVWHDO) concentrations have fluctuated above and below the threshold of 7 mg/L and a Lakeshore Capacity Assessment has not been completed. Temperature and dissolved oxygen measurements should be collected in the latter half of the allowable August 15 – September 15 time period and the calculated MVWHDO concentration should be compared to the threshold of 7 mg/L. Sampling in 2022 was completed on August 16th and sampling later in the time period could result in lower MVWHDO concentrations because the lake will have been thermally stratified for a longer period allowing for greater depletion of oxygen in the hypolimnion.
-
8) The development capacity of lakes in Ontario is typically determined via Lakeshore Capacity Assessment. A Lakeshore Capacity Assessment should be completed for McKenzie Lake to determine the development capacity on the lake based on modelled TP concentrations.
Summary and Recommendations
4.1 Water Quality Summary
The water quality of McKenzie Lake is generally good, with relatively low concentrations of nutrients, chloride, metals, E. coli, and phytoplankton. Clarity is relatively low for an oligotrophic lake due to the moderate DOC concentration of the water caused by export of organic carbon from the lake’s forested catchment. Clarity has decreased over time which could be the result of increasing DOC concentrations which have increased in south-central Ontario lakes over a similar timeframe (Palmer et al. 2011).
There is good habitat for cold-water fish in the lake’s relatively well-oxygenated hypolimnion. Internal phosphorus loading appears to be of limited magnitude based on available data. The only two water quality guideline exceedances were for iron (when measured just above the sediments) and nitrite (on a single date in 2004; possibly an erroneous value).
Climate change, brownification (i.e., increased DOC) and changes to hydrology have resulted in conditions conducive to the proliferation of nuisance and harmful algal blooms. In Central Ontario, this includes a marked recent increase in algal blooms in low nutrient lakes. The existing scientific body of literature suggests that the conventional understanding and management of algal blooms, that is based on controlling phosphorus concentrations in the water column, is not adequate to manage the development of oligotrophic blooms in nutrient-poor lakes (Reinl et al. 2021). The observation of aggregations of a potentially toxic, bloom-forming cyanobacterium of the genus Planktothrix is of some concern, but toxic blooms have not been reported (to our knowledge) and this genus is known to thrive in low-light environments (Kurmayer et al. 2016), which, with its relatively brown waters, may explain its presence in McKenzie Lake.
4.2 Shoreline Development Summary
The majority of existing development on McKenzie Lake is typical of true “cottage” development and is well- buffered; more intense waterfront development (e.g., large homes, vast impermeable surfaces, wake- surfing boats, and manicured lawns), which would place greater stress on McKenzie Lake, appears to be largely absent. Responsible waterfront development often requires the enforcement of appropriate planning policies such as those present in the Official Plan, and stewardship/education initiatives implemented by volunteer groups such as McKLPOA.
4.3 Recommendations
Water quality data in McKenzie Lake is generally good. Water clarity has declined over the years and blue- green algae was observed, both of which are likely driven by changes in climate and DOC concentrations. The development character on McKenzie Lake, complete with intact vegetated shoreline buffers will help to maintain water quality and protective Official Plan policies are in place which will help to mitigate development-related impacts if they are implemented through education and/or enforcement.
HESL has four recommendations based on the results of this study:
(1) The Spills Action Centre should be called at 1-866-MOETIPS (663-8477) if a cyanobacteria (“blue- green algae”) bloom is suspected in the future. If a bloom is present, MECP will collect samples to determine if cyanobacteria are present and if there is potential for toxins to be produced based on the particular genus or species identified. If it is confirmed that harmful cyanobacteria are present, additional analyses are completed to determine microcystin concentrations and compare concentrations to the drinking water limit of 1.5 μg/L and recreational limit of 10 μg/L.
(2) The Lake Partner Program (LPP), coordinated by MECP provides the best possible entry point to lake monitoring for lake associations with limited resources. The stated goal of the LPP is to protect and understand the water quality of Ontario’s inland lakes. This is accomplished by involving citizens in a volunteer-based monitoring program. TP concentrations (2002–2004, 2006, 2010, 2019, 2020, 2021) and water clarity measurements (i.e., Secchi depth; 2001 and 2002) have been collected in McKenzie Lake through the LPP but sampling has been somewhat sporadic and primarily focused on one parameter (TP) and one sampling location. It is recommended that two sites, LPP #2 (45.3711°N, 78.0136°W) and ML-3 (45.3540°N, 78.0329°W), are routinely monitored following LPP instructions and samples are also assessed for calcium and chloride. The MECP provides sampling instructions and the equipment needed to participate in the LPP (https://www.ontario.ca/page/lake-partner- program-sampling-instructions). This includes a basic sampling bottle, plastic funnel with Nitex mesh (to screen out large particles), Secchi disk, pre-paid Canada Post labels for sample return, sample containers and instructions. Water samples are collected once annually, at least 2 weeks following ice off (i.e., in April or May), and water clarity measurements with a Secchi disk are performed 1–2 times per month during the ice-free period. Lake associations interested in participating in the Lake
Partner Program should contact the Program Coordinator at
(3) The development capacity of McKenzie Lake is uncertain because MVWHDO concentrations have fluctuated above and below the threshold of 7 mg/L and a Lakeshore Capacity Assessment has not been completed. Temperature and dissolved oxygen measurements should be collected in the latter half of the allowable August 15 – September 15 period and the calculated MVWHDO concentration should be compared to the threshold of 7 mg/L. Sampling in 2022 was completed on August 16th and sampling later in the time period could result in lower MVWHDO concentrations because the lake will have been thermally stratified for a longer period allowing for greater depletion of oxygen in the hypolimnion.
(4) The development capacity of lakes in Ontario is typically determined via Lakeshore Capacity Assessment. A Lakeshore Capacity Assessment should be completed on McKenzie Lake to determine the development capacity on the lake based on modelled TP concentrations.
PDF Viewable