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Lake Memphremagog Water Quality

Summary 

Lake Memphremagog is the largest body of water in the Estrie region. Its water quality is a major regional concern due to the fact that this lake is the source of drinking water for nearly half of the region’s population and offers a unique potential for recreational and vacationing use in Québec. Recognizing the international importance of this lake, the governments of Vermont and Québec, signed an Environmental Cooperation Agreement on Managing the Waters of Lake Memphremagog in September 1989. In the wake of the agreement, a Vermont/Québec Working Group tabled in 1993 a report that summarizes the current situation and makes several recommendations to protect and improve the water quality of the lake and its watershed (Québec/Vermont Working Group on Managing Lake Memphremagog and its Environment, 1993).

In December 2003, Vermont's Governor and Québec's Premier signed a new Cooperation Agreement on Managing Lake Memphremagog and its Watershed. Improving the knowledge of the water quality of the lake and its watershed is one of the objectives of this agreement which replaces the one signed in 1989.

As early as 1993 the need to establish a permanent and comprehensive program to monitor the water quality of Lake Memphremagog was clear. While several research organizations have done studies on the lake over the years, it was not until 1996 that the Direction du suivi de l’état de l’environnement (DSEE, formerly the Direction des écosystèmes aquatiques) of the ministère de l’Environnement du Québec (MENV) implemented a summer program to monitor the lake’s water quality in collaboration with Memphremagog Conservation Inc. (MCI).

 Whether phosphorus, chlorophyll a or water transparency measurements are used, we find that a majority of Lake Memphremagog‘s sampling sites show a biological state that is characteristic of a mesotrophic body of water. The most obvious signs of the accelerated aging of the lake are observed in the lake’s shallowest sectors, namely the northeastern part of Fitch Bay and the southern basin. However, the analysis of the data collected since the beginning of the sampling program in 1996 reveals no significant trend in the results of the three water quality variables.


Reference: Simoneau, M., 2004. Lake Memphremagog Water Quality, 1996-2002, Québec, ministère de l’Environnement, Direction du suivi de l’état de l’environnement, envirodoq no ENV/2004/0265/A, report no QE/149/A, 17 p.

Report, PDF format,  216 ko


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