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Massawippi Lake NAM-49

Riparian Nation(s) Canada
Lat. 45°12' N Lng. 72°00' W Alt. 160.8 m
Surface Area 17.9 km2 Mean Depth 41.6 m Volume 0.74 km3
Shoreline 38.3 km Catchment Area 586 km2 Residence Time 1.5 yr
Frozen Period Dec-Apr   Mixing Type Dimictic   Morphogenesis/Dam  
Related Info/Site  

Description

From the morphometric point of view, Lake Massawippi is a lake of which the maximum and average depth are very large. The dissolved mineral content is high compared to other Quebec lakes and even elevated compared to lakes of the Eastern Townships. The specific conductivity, for example, ranges from 120 to 230 micro S cm-1 and the waters are dominated by HCO3- (64-72 mg l-1) and Ca (26-35 mg l-1). The general geology of the Lake Massawippi watershed consists of two lithology groups. Calcareous fine to coarse-grained clastic sedimentary rocks are found on the southwest of the lake, while non-calcareous siliceous sedimentary rocks characterize the northwest portion of the watershed. It is a dimictic lake. The temporal variations in the percentage saturation of dissolved oxygen at the bottom of the lake (deep zone) are characteristic of a mesotrophic lake. One notes in effect, a percentage of oxygen saturation at the bottom of the order of 50% in August. The concentrations of phosphorus and nitrogen are elevated and it could be assumed that these waters are productive. The parameters of the primary production are high at the south end of the lake and show medium values in the zone of the outlet of the lake. In addition, the transparency of the water of this lake is in the mesotrophic range (4-6 m).

In the immediate environment, 71% of the perimeter of the lake have been strongly affected, above all by the following criteria: cottages too close to the lake, railway bordering the beach of the lake and excessive clearing of trees. 21% of the perimeter of the lake have not yet been touched.

The catchment basin of the lake is only 46% wooded and agriculture occupies a bit more than 44% of the area of the basin. The rest is in a zone of leisure and urban development.

The amount of phosphorus received annually by Lake Massawippi surpasses theoretically the dangerous limit, above which accelerated eutrophication can be expected. Of all the total input more than 54% comes from the animal population. Agricultural husbandry contributes enormously to the eutrophication of the lake. The spreading of chemical fertilizers as well as the animal population contribute more than 75% of the total input to the lake. The natural input constitutes only 16% of all the total input. The effect of this input seems to make itself felt in the southwest section of the lake receiving the principal load of phosphorus.

Eutrophication of the southwest part of Massawippi Lake has been accelerating for the past several years due to various human activities in the environment near the lake and in a developing sector of its drainage basin (1, Q).

Photo of Massawippi Lake
Photo: J. Dupont