The river divides the Grande-Île and the Island of Salaberry, which are located approximately 50 km east of Montreal.

Deep, arable soils lie across this flat plain, which rarely exceeds 200m above sea level.

[3] The municipal government of Valleyfield recently purchased a portion of the river, and has halted development on it for the time being.

Because of extensive damming of the Saint Lawrence, several fish species are left without sufficient areas to migrate up and downstream.

Before industrial development, the river and surrounding areas were used mostly as agricultural land by the Iroquois and European colonists.

In the mid 19th century, the river was recognised for its hydroelectric potential and factories began to be built in the region.

Thus, because of its hydroelectric potential, there is a long history of factory placement along the Saint Charles River and the old Beauharnois Canal.

Several studies have shown that the water quality of the river is low, and much lower, in fact, than that of the Saint Lawrence in general.

Sailing and motorized boating is popular on Lake Saint Francis, and there is a world class whitewater kayak course on the rivière Saint-Charles.