The Saint Charles River is not a distinct river unto itself, it is in reality an arm of the Saint Lawrence River.
 The river originates at the end of Lake Saint Francis at Salaberry-de-Valleyfield and passes through the town of Saint-Timothée, before entering Lake Saint Louis to the east.
Originally, at the eastern end of Lake Saint Francis, there were two channels, northern channel and the Saint Charles River.
 Because of the presence of rapids, several canals have been built.
 The Old Beauharnois Canal and the Soulanges Canal, neither of which are still in use, and the Beauharnois Canal have contributed to changes in flow of the rivière Saint-Charles.
 Historically, it has been a significant source of hydroelectric power for factories in Salaberry-de-Valleyfield.
 Much of the river's banks are developed, but a portion of its banks remain undeveloped.

The Saint Charles River is in the physiographic region of the Saint Lawrence Lowlands.
 The bedrock of the region is a slightly dipping limestone, but glacial deposits define the landscape.
 Deep, arable soils lie across this flat plain, which rarely exceeds 200m above sea level.
 Before extensive logging and development, the Saint Lawrence Lowlands were a mix of mostly forest and wetlands.
However, they now remain primarily as isolated fragments.
 The region between Lake Saint Francis and Lake Saint Louis originally supported a diverse fluvial environment which has now been transformed into a slow-moving lacustrine one.
The Saint Charles River is one area that has not been significantly dammed but still has seen a large degradation of habitat.
 The Saint Lawrence Lowlands is also the most urbanized ecozone in Canada, holding most of Canada's population and manufacturing jobs.
 The Saint Charles River has developed considerably in terms of agriculture and industry.
A sizable portion of the river is residentially owned, which is typical of many rivers in the region.
 Only 15% of the natural shoreline in the area remains today.
 The municipal government of Valleyfield recently purchased a portion of the river, and has halted development on it for the time being.
The Saint Charles River is not a distinct river unto itself, it is in reality an arm of the Saint Lawrence River.  The river originates at the end of Lake Saint Francis at Salaberry-de-Valleyfield and passes through the town of Saint-Timothée, before entering Lake Saint Louis to the east. Originally, at the eastern end of Lake Saint Francis, there were two channels, northern channel and the Saint Charles River.  Because of the presence of rapids, several canals have been built.  The Old Beauharnois Canal and the Soulanges Canal, neither of which are still in use, and the Beauharnois Canal have contributed to changes in flow of the rivière Saint-Charles.  Historically, it has been a significant source of hydroelectric power for factories in Salaberry-de-Valleyfield.  Much of the river's banks are developed, but a portion of its banks remain undeveloped.
The Saint Charles River is in the physiographic region of the Saint Lawrence Lowlands.  The bedrock of the region is a slightly dipping limestone, but glacial deposits define the landscape.  Deep, arable soils lie across this flat plain, which rarely exceeds 200m above sea level.  Before extensive logging and development, the Saint Lawrence Lowlands were a mix of mostly forest and wetlands. However, they now remain primarily as isolated fragments.  The region between Lake Saint Francis and Lake Saint Louis originally supported a diverse fluvial environment which has now been transformed into a slow-moving lacustrine one. The Saint Charles River is one area that has not been significantly dammed but still has seen a large degradation of habitat.  The Saint Lawrence Lowlands is also the most urbanized ecozone in Canada, holding most of Canada's population and manufacturing jobs.  The Saint Charles River has developed considerably in terms of agriculture and industry. A sizable portion of the river is residentially owned, which is typical of many rivers in the region.  Only 15% of the natural shoreline in the area remains today.  The municipal government of Valleyfield recently purchased a portion of the river, and has halted development on it for the time being.
Saint Charles River (Valleyfield)