Hudson Bay drainage basin
The Hudson Bay drainage basin is the drainage basin in northern North America where surface water empties into Hudson Bay and adjoining waters. Spanning an area of about , the basin is almost totally in Canada (spanning parts of the Prairies, central and northern Canada), with a small portion in the United States (in Montana, the Dakotas, and Minnesota). The watershed's headwaters are in part on the Continental Divide of the Americas, and the watershed's connection to the Labrador Sea is at the Hudson Strait's mouth between Resolution Island in the Qikiqtaaluk Region and Cape Chidley on the Labrador Peninsula. On the Continental Divide the basin is bounded at Triple Divide Peak to the south, and Snow Dome to the north.
Water supply and sanitation in Canada
The water supply of Montréal is taken from lac Saint-Louis, lac des Deux-Montagnes, Rivière des Prairies and the St. Lawrence River. This water is then treated in seven plants with a daily capacity of 2,917,000 m³ for 1.8 million residents and industries, businesses and institutions. The river receives untreated liquid waste from metropolitan Montreal and the newly developed suburbs by way of over 150 discharge outlets. Whenever there is significant rainfall on the island of Montreal, household sewage is mixed with the city street rainwater and discharged untreated into the river.
The Rivière des Prairies used to receive massive discharges of untreated waste water from the city, turning it into essentially an open sewer; however, ecological intervention and modern waste water treatment mostly reversed the damage and the river is often considered clean by the RSMA(Réseau de suivi du milieu aquatique), and suitable for swimming. A CAN$10 billion investment program is underway in Montreal to upgrade water treatment plants, to replace ageing water pipes and to install roughly 23,000 meters for industries, businesses and institutions until 2013.