Lac Notre-Dame and Usher Lake Association

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Water testing results

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.

2018 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.

  • 2018 Phosphorus levels in August: Lac Notre Dame is at 0.005 to 0.009 mg/L - fairly close to the target range and slightly better than 2017. Usher Lake is a little higher at the inlets - around 0.01 fairly consistently but lower at Usher out.

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. Our water testing reports measure Total Kjeldahl Nitrogen (TKN) - the sum of nitrogen in bound in organic substances, nitrogen in ammonia (NH3-N) and in ammonium (NH4+-N). Guidelines suggest levels between 0.100 to 0.500.

  • 2018 TKN Nitrogen levels in August: ranged from 0.25 to 0.39 on Lac Notre Dame which is fairly normal for the lake. In Usher Lake, levels are 0.36 to 0.51, again consistent with previous years.

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). For swimming, the safety limit is 100 - 200 CFU.

  • 2018 E-coli levels in Lac Notre Dame on August 13th were normal or slightly above in a few locations and very high in one sample (370) at location 6 (in front of Ch. des Generations). E-coli results were back to normal a few days later when a new set of six samples were tested from a range of points around that location.
  • In Usher Lake, there is continuing evidence of contamination at the culvert and the associated inlet at location 11 (50 CFU), although the good news is the sample at the outlet was within the target range (less than 10 CFU). By late October, the contamination at location 11 had fallen to 20 CFU, but that level is still higher than the target of less than 10 CFU.

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.

  • 2018: water transparency tests on August 10 were measured at 5 meters. Water levels are high. This is an improvement over 2017’s measurements of 3.75 meters with record-level rainfall (249.8mm). The rain brought in a lot of sediment, and high water levels eroded the shoreline as well.

Eurasian Milfoil Suprisingly low levels of Eurasian Milfoil in the lake in early August. The area marked by buoys had almost no milfoil at all - native plants re-established themselves there. By late August, with continuing warmer temperatures and lower water levels, milfoil plants started growing more rapidly. Even by mid September, there was less overall milfoil density than usual, with greater density of native plants. We continue to encourage people to cut milfoil near your shore and remove the cuttings.

All detailed water testing results

Association volunteers collect water samples at specific locations where water enters and exits the lakes. Note these locations are not the same as the Municipality of La Peche’s test locations referenced in the ABV-7 report.

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.

Old 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.