Report on the health of the Lake (2005)

By popular demand of survey we did last year, we decided to go ahead with the physicochemical analysis of the health of the lake. This analysis was made by Daniel Nero Hemisphere Consultant with the help of Julien Couture and myself.

Thank you in today brings the results. I will summarize and outline the report that you can see more detail on our website. But before you start, it is important to understand one thing:

Assessing the health of the lake is in terms of aging. All our lakes are called to die, that is to say, no longer exist or if one wants to be overgrown in the longer term. It is on the evolution of this invasion that will determine the age of our lake and its health. So an old lake is a lake increasingly overgrown with vegetation and a lake a lake that is young is not, and whose transparency and oxygenation are maximized.

It is in this understanding that we can capture some factors that inhibit or precipitate this change. Factors such as morphometry, the renewal of the lake water and the influence of watershed rush or slow down aging. Then I will talk briefly about the status indicators of age such as transparency, oxygenation, the amount of nutrients that supports vegetation in the lake as phosphorus and nitrogen. A bacteriological survey was conducted to verify the purification of wastewater. Finally I will give the conclusions and recommendations of our consultant.

Question morphometry:
The irregular shape of the lake no longer supports the development of pollution and deforestation as possible. Is a negative for the health of our lake.

It consists of several large lakes in the wilderness (Park Papineau Labelle) and the lakes act as settling of nutrients before the water reaches the lake. Excellent point. Excellent point.

Renewal of water:
The complete renewal of the lake is over two years, which is positive as the water remains long enough for lake act as a clarifier but not too much to stand still and keep chemicals such as salts de-icing roads for example.

Water Capacity:
The volume of water is very high (350 p at its deepest) makes it retains its freshness and its large size meant that its surface is strongly agitated by the winds, which gives an oxygen important lake.

Oxygen is brought into effect by stirring at the surface due to winds but also two times a year in spring and fall, when water reaches 4 degrees, there is a reversal that distributes oxygen evenly across the lake when we did the analysis July 20, 2004, there was 8 mg / l at the surface (the water was so saturated surface) and below the thermocline is lowered to 4 mg / l 50m depth (in terms of saturation, the water contains more than one third of the oxygen it may contain). One could extrapolate that there is more oxygen at the bottom, which constitutes a threat to the survival of lake trout (lake trout). Why this lack of oxygen?  The micro-organisms in sediments in the lake bottom using oxygen for their decomposition. Without oxygen, these sediments become in a state of anoxia. This produces a release of nutrients that is 1000 times faster than the rate of retention. So here we touch a very important point for the precipitation of the aging of the lake.

The water clarity is fairly good. In this chapter, we classify a lake''Young''if the visibility is greater than 6 m and we set at 7.7 m.

The lakes in our region are generally more acidic because of a share of granitic rocks of the Laurentians (which favor the acidic nature) and of course also due to acid rain. The fapel had even said that washing boats prevention of zebra mussels was useless because it does not live in acidic media. Off Lake Simon has a very high pH (7.8) of the likely presence of biological activity intense alkalinized water. Zebra mussels can live very well and prevention is necessary.

Phosphorus is the nutrient that still sorely lacking algae and aquatic plants, said it limits the growth of our plants. This is one of the major enemies of our lakes because it helps to accelerate the aging of our lakes by encouraging algae growth in water and deprived the lake of its oxygen when they decay. DENV was set at 10 g / L the maximum acceptable rate considering the protection of sensitive environments. Our Simon Lake is classified in this category because of the presence of trout. Nos analyses ont montré un taux de 8 μg/L. Our analysis showed a rate of 8 mg / L.

Record bacteriological 
We conducted surveys from 25 sites around the lake and in the Petite Nation north and the quality is excellent although a little worse at the public beach at the Camping and Camper's Paradise. Other tests on other components do not pose a significant problem.

The positive report of water quality is clouded by the observation of some disturbing points:

  1. Phosphorus will likely approach the criterion for the protection of sensitive habitats that demand to remain lower than 10μg / L.
  2. The oxygen runs out below 50m.
  3. A significant portion of sediment is in a state of anoxia and the release is surely underway.
  4. Periphyton is growing as residents.

We believe that Simon Lake is at the junction point between the young and moderately young. Often lakes subjected to rapidly changing stage resorts because a lack of oxygen at depth causes a dramatic change in the phosphorus cycle: the release of evidence against prisoners since the end of the Ice Age. The lake sediments subject to the period of anoxia will reject the phosphorus in the body of water at a rate 1000 times higher than the rate of retention. This mechanism may cause a runaway of the ecosystem and gives rise to the famous''bloom''of microscopic algae.

It's better then trying to stabilize the state of the lake by concerted action. Daniel Nero made several suggestions on this subject which the most important:

  • Prohibit the application of chemical fertilizer in forest management of the lake.
  • Urge residents to use phosphate-free soaps for our filter cleaning systems do not even 50% of phosphates.
  • Restore the banks that are themselves elements scrubbers land bordering the lake.
  • Undertake an inventory of the quality of surface runoff associated with the road network in order to reduce sediment inputs to Lake
  • Repeat the analysis to two or three years, including the extent of phosphorus in spring roll.

You can access the full study in PDF format

This post is also available in: French

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