Virtual Museum of Canada




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Satellite photograph of Lake Saint-Pierre

Satellite photograph highlighting the south shore waters of Lake Saint-Pierre.

Source of the water masses

Richelieu River at the junction of the St. Lawrence River

Richelieu River at the junction of the St. Lawrence River

The southern water mass is fed by the Richelieu, Yamaska and Saint-François Rivers.

Yamaska and Saint-François Rivers joining at the St. Lawrence River

Yamaska and Saint-François Rivers joining before the St. Lawrence River

Put together, these rivers contribute 10 % of Lake Saint-Pierre’s water flow; however, their water is spread over 20 % to 30 % of the lake’s surface area.

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Physical characteristics

Colors of waters near the archipelago

The waters near the south shore are much browner and more turbid than the waters of the waterway. This aerial photo shows the brown waters of the north shore (on the right) and south shore (on the left). In the centre, you can see the green waters of the waterway.

Arrowheads in a marsh

Arrowheads in a marsh

Water flows very slowly near the banks. During the summer, the water becomes stagnant in certain areas.

Erosion of the bank

This part of the lake has the highest concentration of nutrients and suspended matter.

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Trees bent over the water in De Lavallière Bay.

Lavallière Bay

The south shore receives very high nutrient loads (phosphorus and nitrogen) from the tributaries that feed it.

Cows in the field

A large proportion of the land in these rivers’ watersheds is dedicated to agricultural use.

Cyanobacteria on the shore

This superabundance of nutrients, along with the stagnant waters, leads to an excessive growth of plants and algae, including cyanobacteria.

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Aquatic plants and algae on south shore

Vast areas are colonized by dense mats of algae and vegetation.

Feathers of ducks among aquatic plants

Furthermore, the south shore is sheltered from prevailing winds; this promotes the growth of abundant vegetation.

Aquatic plants reflecting on the water.

By taking up nutrients, the plants increase water transparency. However, when there are too many plants, they impede water activities.

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Great Black-backed Gull on a buoy

Great Black-backed Gull

From 1952 to 2000, the lake south of the navigation channel was used as a shooting range by the Canadian army base in Nicolet.

Nine ducks paddling in the bay.

Nearly 300,000 projectiles, some of which are potentially explosive, lie on the lake bottom. This part of the lake is therefore off limits to pleasure boaters, hunters and fishers. However, it serves as a refuge for wildlife.

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