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200 Years of Water Quality History on Muskrat Lake

Just recently, the Muskrat Watershed Council received a study from the Ministry of Environment, Conservation and Parks (MECP) centering around the 200 year history of water quality on Muskrat Lake and the impact it could have on current lake trout populations.

Lake trout are native to Muskrat Lake and are considered a water quality sensitive species. In order for them to thrive in their surrounding environment they require cool (<10C) and well oxygenated waters (>6mg/L). These factors are currently at risk on Muskrat Lake due to several reasons. The two most prominent being competition for available dissolved oxygen with the excess growth of algae and higher average summer water temperatures.

The study was conducted in June 2017 in partnership with Queen's University. Using a Glew gravity corer, scientists extracted a 36cm-long core sample from Muskrat Lake at a depth of 33m. The core was then sectioned on site into smaller intervals using a Glew extruder.

Core intervals were analysed for a array of parameters. Some of these included lead, cesium, radium, chlorophyll a, diatom (algae) remnants and fossilized chironomids(aquatic insects). The later three parameters provide insight on the progression of eutrophication and blue-green algae blooms on Muskrat Lake and what the lake may have looked like prior to European settlement and colonization.

Sediment core analysis indicates that Muskrat Lake was as a mesotrophic lake prior to the arrival of Europeans. Mesotrophic lakes are classified as being a commonly clear water lake with beds of submerged aquatic plants and medium levels of nutrients. it is noted in the study that lake conditions worsened around 1920, during the time of European land clearance and the development of agriculture.

Scientists noted that segments of the sample that covered the last decade of water quality history showed signs of a decrease in chlorophyll a and higher levels of deep-water oxygen level. They suggested that these changes may be evidence of the recent community effort to improve water quality within the Muskrat Watershed.

The sediment sample also revealed something long suspected, that climate change may have a large role to play in the annual occurrence of blue-green algae blooms on Muskrat Lake. The study states "Given that the purported increased algal bloom intensity in the past decade does not appear to be linked to a recent deterioration of Muskrat Lake water quality (nutrient and oxygen conditions), it is possible that regional warming is playing a role. Increased reports of algal blooms on Muskrat Lake have occurred during some of the highest temperatures recorded from nearby Killaloe, Ontario." This idea continues into the study's conclusions and implications of lake management where it states "While reducing nutrient inputs could help improve water quality, this study demonstrates that recent warming and associated climatic changes must also be considered in the management of lakes with sensitive cold-water taxa experiencing nuisance algal blooms, in conjunction with nutrient management or abatement."

This study and process of analysis conducted by the MECP and Queen's University helps turn back the clocks on the lake's water quality history. This record of water quality is invaluable for organizations, like the Muskrat Watershed Council and governing authorities to better understand the current impacts to water quality and where we might refocus our efforts moving forward. If you have any further questions or concerns about this study feel free to contact us.


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