One way we keep a close eye on water quality and lake health is by helping researchers dig in the mud, called “benthic sampling”.
HHLPOA has been financially supporting the work of U-Links Centre for Community-based Research to monitor water quality through benthic sampling in our lakes for the past six years.
What do the reports tell us this year? It’s time to do more, because water quality on Big Hawk Lake and Little Hawk Lake is declining.
We’ve included some quotes from the reports for the Hawk Lakes and for Halls Lakes below, and have attached the reports below. This kind of data and analyses help inform our lake plan and direct the activities we can take to reduce organic pollution (like from septic systems), nutrient loading (from use of fertilizers), habitat stress (can be addressed in part by shoreline and property re-naturalization), disturbance of lake bottom sediments from boat motors and wakes and to minimize invasive species.
In 2023 the fifth (and for now concluding benthic research report) on Halls Lake indicated:
…the overall water quality of Halls Lake was fair, but there was a significant amount of organic pollution in the lake. This was reflected in the moderate biodiversity of the benthos found in the lake.
Little Hawk and Big Hawk have now also completed their five year benthic sampling and have a baseline for future periodic comparisons. Here are some of the conclusions from the 2024 reports completed by 3 groups of students:
From the interpretations of the data laid out in this report, the Hawk Lakes seem to be in a state of fair health for the time being. Abundance of pollution-tolerant species has remained in normal ranges and there is relatively high amount of diversity in the makeup of the benthic communities. However, the HBI scores suggest fairly poor water quality and the presence of some organic pollution, while the %EOT scores have begun to show a slight decrease overall. Both of these things indicate that the quality of water in the Hawk Lakes is very gradually declining.
There has also been a considerable increase in the number of Chironomidae present in the lakes, which suggests that the disturbances faced by the lakes are beginning to take a toll on the benthic communities.
The water chemistry baseline is also stable right now, but it also shows the beginnings of decline. Increased water temperatures and lower DO are a concern, however continued monitoring is recommended to better understand how these parameters are changing over time. Otherwise, our findings suggest that the water quality in the lakes has remained mostly stable. The lakes do not show an excess of algae or macrophytes, meaning that eutrophication is likely not related to the slight decline we are seeing. Overall, it is recommended to continue monitoring the lakes as use of them continues to ensure the health and safety of not only the lakes, but also the humans and animals that depend on them.
Over the course of the five year data collection, there is a noticeable decline of ephemeroptera indicating environmental changes and suggests an increase in water pollutants.
Overall, the purpose of this project was to survey the benthic communities and assess water quality to determine the state of Big Hawk and Little Hawk Lake. This is based off concerns by the lake association, who are worried about issues including increased algal growth, acidification, water clarity, phosphorus loading and fluctuating water levels. As such our partnership with the Halls and Hawk Lake Association will contribute to long-term benthic biomonitoring, data records and provide recommendations to the lake association to improve lake quality.
This led to the conclusions that both Big Hawk and Little Hawk Lake are in a state of decline, based on data available from both this year and the previous four (for five years total). This was due to declining water temperatures over five years, lower pH levels for three of the five and lower dissolved oxygen levels for three of five years. Additionally, benthic sampling shows that values are within the expected ranges for the Haliburton area, however water quality was determined to be fair with significant levels of organic pollution in both lakes.
Read the full reports below: