Lake water quality measurement 

 

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The lake water sampling protocol follows guidelines developed by the Lake Monitoring Network (RSVL). This approach is used to document water quality with regard to eutrophication.  The three variables analyzed within the framework of this program are: 

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• Total phosphorus (TP), this nutrient essential for the existence and growth of aquatic plants, is generally found in low concentrations in lakes.   However, this item has the highest need/availability ratio, around 80,000; this is why it is said to be a limiting factor in the growth of aquatic plants. This explains all the attention paid by lake protection associations to the control and reduction of phosphorus inputs. The phosphorus concentration of a young lake is 5 ug/l, for Brome Lake the readings we have are in the range of 12 ug/l to 18ug/l. 
   

• Chlorophyll is a green pigment that is found in the composition of plants.   By measuring the concentration of chlorophyll, we have a good indicator of the biomass of the algae present in the water column. Again, the more dissolved phosphorus there is in the water column, the more algae there is, and the higher the chlorophyll level will be.   Eutrophic lakes often struggle with an overabundance of algae.   The chlorophyll level measured at Brome Lake is 10 ug/l, which places it at the lower limit of the eutrophic zone. 
   

Dissolved organic carbon arises from the decomposition of organisms. The measurement of dissolved organic carbon makes it possible to have an appreciation of the color of the water, which also affects its transparency. Therefore, the presence of living algae, such as those that are decomposing, influences the transparency of the water.