The Lorette River sub-basin occupies the southwest portion of the
Saint-Charles River watershed. The main tributaries of the Lorette river are the Friches stream (also called Sainte-Geneviève stream or Martres stream), Mont-Châtel stream originating in
Val-Bélair and another tributary (without toponym, but locally called Souvenance stream) which rises at
mont Bélair. The other tributaries are mainly agricultural drainage ditches. Land use essentially divides them into three distinct occupations: cultivated land, woodlands and urbanized areas. The Lorette river is in length and its watershed covers an area of . The course of the Lorette river descends on , with a drop of , according to the following segments: • northeasterly in a straight line in the agricultural zone, crossing rang des Beaumont and route Jean-Gauvin, to
route 358 (avenue Notre-Dame), either in the hamlet Les Grands-Déserts; • towards the northeast along the west side of
route 358, ie passing on the west side of Jean-Lesage international airport, collecting two streams (coming from the north), then winding up to the airport road; • towards the north-east by crossing the Étienne-Lessard street, by collecting the Friches stream (coming from the north), up to the boulevard Chauveau Ouest. • towards the east entering
Quebec City and collecting Ruisseau du Mont Châtel (coming from the north-west) at the start of the segment, then by forming a big curve towards the south in an
urban forest area, until at a bend in the river; • towards the south by forming a large loop towards the west in an urban park, by winding by cutting the rue Saint-Jean-Baptiste, by bifurcating towards the east while continuing to wind, by collecting a stream (coming from the southwest), up to
route 138 (boulevard Wilfrid-Hamel); • to the east, forming a large hook to the north, passing through the Carrefour-Du-Commerce industrial zone, to the
autoroute 73 (Autoroute Henri-IV) • towards the north by forming a loop towards the west and another towards the east and crossing the boulevard du Parc Technologique, the
route 138 (boulevard Wilfrid-Hamel) and boulevard Masson, to its mouth. The Lorette river flows in a river curve on the southwest shore of the
Saint-Charles River, in the Les Saules sector, district of Quebec city. From this confluence, the current descends on generally towards the northeast, following the course of the Saint-Charles river. == Hydrography ==