Carol Doré has been volunteering as the Association water tester for years. Thank her when you see her! She collects and delivers the water samples on a regular basis for phosphorus, nitrogen and also for e-coli bacterial contamination. Your association membership fees pay for the water testing.
2017 water testing results summary
Phosphate run-off from fertilizers, detergents and waste can act as a fertilizer for plants and algae in the lake, and can reduce the oxygen content. Target levels for Phosphorus in an uncontaminated lake are below .005 mg/L. Our lakes have so far been relatively uncontaminated, although levels occasionally creep up above the target.
- 2017 Phosphorus levels in August: 0.006 to 0.017 mg/L - fairly close to the target range.
Nitrogen and nitrates occur naturally in soil and water, but lawn and garden fertilizers leaching into the water can make it unsafe for drinking and upset the natural ecosystem. Target levels for nitrogen in drinking water are 0.02 mg/L. Levels in our lakes are higher than those targets.
- 2017 Nitrogen levels in August: ranged from 0.19 to 0.52 mg/L.
E.coli bacterium that can cause severe illness. The presence of E. coli in water is a strong indication of recent sewage or animal waste contamination. The safety target for e-coli in drinking water is a level of 4 CFU or below (CFU = Colony Forming Units in 100 ml of water).
- 2017 E-coli levels in Lac Notre Dame were good - at or below 4 CFU/100ml
- In Usher Lake in late August, there was evidence of contamination. Levels ranged from 15 to 25 - well above the target range of less than 4 CFU/100 ml.
Transparency/Clarity is an indicator of lake health - clear, more transparent water is a sign of a healthy lake. Water transparency is tested with a Secchi disk. Poor transparency of less than 3 meters can be a warning sign of eutrophication. In the dry summer of 2015 (only 40mm of rain), an excellent 7m measurement was recorded.
- 2017 water transparency tests in July recorded near location 13 were 3.75 meters. A similar reading of 3.75 was measured in late September. Water levels in the lake were very high in 2017 due to record-level rainfall (249.8mm). The rain brought in a lot of sediment, and high water levels eroded the shoreline as well.
Detailed water testing results for all years
Association volunteer Carol Doré collects water samples at specific locations where water enters and exits the lakes, as marked on the map. Note these locations are not the same as the Municipality of La Peche’s test locations referenced in the ABV-7 report.
Map of numbered locations where water samples are collected View all results for E-coli, phosphates and salts from 2005 to 2017 by test location (Google Sheet)
2014 ABV-7 Report and recommendations
In 2014, the Municipality of La Pêche, with the Association, worked with ABV-7 to produce a report on the shoreline and water of Lac Notre Dame. A translated summary is provided below - the report is in French.
ABV-7 was mandated in June 2014 by the Municipality of La Pêche to characterize the shoreline of Lake Notre-Dame, assess the physico-chemical quality of the water and delimit the milfoil meadows on the lake. This information provided a picture of the current situation in order to slow down the eutrophication of the lake and combat its invasion by Eurasian water milfoil.
Eutrophication is the gradual process of a lake becoming too rich in nutrients like nitrogen and phosphorus. The nutrients feed the cycle of plant and algae growth, which over time, can result in oxygen depletion.
The protocol of the Ministry of Sustainable Development, Environment and Parks (MDDEP) (currently MDDELCC) and the Laurentian Regional Environment Council (CRE Laurentides) (2007) was used to characterize the riparian strip. With respect to the assessment of water quality, ABV des 7 collected and analyzed data on total phosphorus and Escherichia coli (E. coli) provided by the Notre-Dame Lakes Association. and Usher (2005 to 2011 and 2013) as well as by the municipality (2008 to 2013). In addition, ABV des 7 collected and analyzed data on the concentration and dissolved oxygen saturation, pH, depth and conductivity of water acquired during field visits on 17 July 2014. L ABV des 7 subsequently identified and mapped the water-milfoil meadows on 3 September 2014.
Detailed reports including other minerals, alkalinity and nitrites
To understand the in-depth results, these Canadian Water Quality Guidelines for the Protection of Aquatic Life provide some target levels.