Sampling continued in the same schedule as with our past Director, Ian Mackenzie. This involved DO / temp readings approx. monthly and collecting chemistry sampling in mid to late August. See the section LWCA Water Monitoring Program further down this page for more information.
Detailed graphs outlining the dissolved oxygen and temperature readings for June to August of 2022 can be
found in the final report. (Scroll down to find the .pdf) Notably, there has been an increase in water temperatures closer to the surface depths across the majority of sites compared to previous years (Appendix H).
Both phosphorous and E.coli results have been relatively stable over recent years, with a downward trend this
year. The results this year are well below this range, there is no health concern for swimming in Lake Weslemkoon. It should be noted that the South end inflow typically has the highest levels of E. coli (30 cfu/100mL) (Appendix J of the report), likely to its densely populated nature.
The results for total coliforms for this sampling season were very high as you can see in the chart to the right. Total coliforms are bacteria that are found naturally in an environment through soil, surface water and animals. Total coliforms are not always bacteria that can make an individual sick, instead E. coli, a fecal coliform is used to determine sanitary conditions of a waterbody. In the case of Weslemkoon, E. coli levels were extremely low and did not indicate any health concern for cottage owners. Since E. coli is used to determine sanitary conditions, PWQO recommends against using total coliforms as a sanitary measure, but indicated 1000 cfu/100 mL is acceptable in freshwater systems.
There are a number of reasons that the results for total coliforms were so high this year, it could be due to temperature increases within the upper column of the lake (Appendix H), rainfall or storm events (there were several significant ones this year), which allow soil erosion into the lake, or even upstream events which we are unaware of. Most importantly, these high results are not an immediate health concern. These results will need to be compared to next year’s results to gather more sufficient information.
Maintaining the high quality of our Weslemkoon water is the highest priority of the LWCA. Key values being safety for swimming, visual/clarity of water, and the health of fish populations.
At left Liam and Will earn volunteer hours while they assist with water sampling.
Nutrients (nitrogen and phosphorus) originate from sources such as erosion, poor sewage treatment, fertilizer, detergents, or natural sources, and enter the lake in runoff. Nitrogen can also reach the lake from atmospheric deposition.
Nutrients and light allow the growth of microscopic algae, which supports the food web, including small fish that are eaten by trout. When algae die they sink to the bottom of the lake where they decay (are broken down by bacteria). The decay process uses oxygen, which leads to low levels of dissolved oxygen in the bottom of the lake in summer and fall.
If nutrient concentrations are too high, excessive growth of algae can occur, leading to the layer of low dissolved oxygen taking up more of the lower levels of the lake. Solar radiation and arm air warm the surface of the lake, while the deeper waters stay cool throughout the summer. If solar radiation levels and air temperatures are too high, more of the surface waters of the lake may become too warm for lake trout.
Note that bass are more tolerant than trout of warm water temperatures and lower dissolved oxygen levels.
This image shows the ideal zone where fish thrive. We need to maintain this zone for our lake trout!
Various water testing has been done over the years. The current program has been influenced by what we know to be important to swimming, clarity & fish, and within the constraints of our budget (lab testing is expensive). Currently we do two types of tests:
Chemistry and Bacteria We monitor 21 locations around the lake. Up until 2019 we did these test every three years. In order to better monitor trends which may be changing quickly, the LWCA membership approved annual testing beginning in 2019. Measurements of Nitrogen, Phosphorus, E-Coli and total Coliforms are taken.
Deep water sampling Water is samples in order to measure the temperature and dissolved oxygen (DO). We’ve been monitoring two deep water locations. We take a measurement of temperature and DO every metre. The LWCA expanded the number of deep water test locations to 5 in the summer of 2018 which has provided interesting comparison data.
The chart is representative of what we find when deep water sampling. The "blue zone" between about 10 meters and 36 meters deep represents a 'sweet spot' for lake trout, where temperature and oxygen meet their requirements. The crosshatched area below 36 meters contains too little oxygen to sustain fish.
Deep water test data has been compiled since 1989. Dissolved oxygen trends are relatively stable across data taken from 1989 to June 2020. You can take a look a this data by opening the files below.
a) an overview of samples taken over time: "Temp-DO Water Quality Testing Data 2014 to June 2020
b) a closer look at two sets of data: "Temp-Dissolved Oxygen sample comparing Feb 2014 with Feb 2019"
Chemistry test results show a generally worsening water quality trend, particularly in the 4 south end sampling locations. Nitrogen levels are well above the target range at all test locations while Phosphorus levels are within the target range at all locations. E-Coli only appears in any significant level in the south end locations. Total Coliforms are generally above the target level at all locations, and significantly higher at south end location where creeks flow into the lake. It should be noted that we have not yet taken a reading higher than the upper ‘safe for swimming’ limit established by Ontario for e-coli or total coliform levels. A full analysis of chemistry tests over the years can be is available in the file below: "Water quality analysis LWCA 2019".
Lake Weslemkoon is classified as a highly sensitive lake trout lake. Tests show dissolved oxygen remains above the survival minimum of 6 mg/litre, but below their preferred range of 9.6-11.7 mg/l. It’s important to keep our lake trout, and important to keep our ‘highly sensitive lake trout lake’ classification, as the level of further human development on the lake is constrained by having this classification.
Nitrogen and Phosphorus levels influence growth of aquatic plants and algae. The levels are significantly higher at the south end of the lake due to the higher level of development both on the shore and upstream of the creeks flowing into the lake.
What we can do to Influence
Do you ever wonder how, or why the water in the lake turns over? Read this interesting article by the International Institute for Sustainable Development to learn more...