Water Quality Testing
Each year, GORA volunteers conduct transparency tests on the lakes using Secchi disks and the readings are submitted to the Government of Québec (Développement durable, Environnement et Lutte contre les changements climatiques). The aggregated longitudinal data are used to reveal general trends in water quality.
Despite the pandemic, we continued to do the lake water testing (in a safe manner). A big thank you goes out to Valerie Buchanan (Little Hughes), Nick Cushman (Hughes), John and Maggie Madden (McCuaig), and Stewart Wilson (Farm) for collecting the samples throughout the summer. The regular Secchi disk testing for water clarity was completed and data was sent to the Province for analysis. Final results should be available on the Province’s website by Spring 2021.
In addition, for the second consecutive year, separate sampling was done in July, August and September to determine the levels of phosphorus, chlorophyll, and dissolved organic carbon in the four lakes. As you may recall, these tests are done periodically (last done 2010-2012) and typically over a 2-3 year period in order to get a representative sample. The water samples were sent to the Province for analysis and we will let you know the results once they are made available.
We are grateful to the Municipal Council for their 50% contribution towards the cost of these special tests.
All four of our lakes scored very well in 2019. The province recommends our lakes “be protected” to preserve this status, which is why GORA worked together with the Municipality for the Fall 2020 By-Law on Mandatory Boat Washing.
Transparency - How we do Secchi Disk testing
A Secchi Disk is a black and white circular disk, 8" in diameter. The disc is mounted on a pole or line, and lowered slowly down in the water. The depth at which the disk is no longer visible is taken as a measure of the transparency of the water. While Secchi Disk readings do not provide an exact measure of transparency, they are an inexpensive and straightforward method of measuring water clarity.
It is important to test for phosphorus levels because too much phosphorus leads to algae growth which can choke a lake by using up all the oxygen. Phosphorus enters a lake from the run-off from land surrounding a lake. This is why pesticides or fertilizers should not be used on lakefront properties. Phosphate-based products (detergents and soaps) and deficient septic systems can also be detrimental to a healthy lake.
Testing for chlorophyll helps to determine the level of algae present in a lake. While some algae is normal, elevated levels of algae can be very harmful to a lake.
Dissolved Organic Carbon
The tests for dissolved organic carbon are done to determine the extent to which the lake is coloured by organic deposits (wood, etc.). The more “coloured” a lake is, the more likely that it will impact the transparency measurements done with the Secchi disks.
A note regarding interpretation of 2019 results for phosphorus, chlorophyll, and dissolved organic carbon compared to those from 2010-2012 – they only represent one year.