Columbia River
The Columbia drains an area of about . Its drainage basin covers nearly all of Idaho, large portions of British Columbia, Oregon, and Washington, ultimately all of Montana west of the Continental Divide, and small portions of Wyoming, Utah, and Nevada; the total area is similar to the size of France. Roughly of the river's length and 85 percent of its drainage basin are in the US. The Columbia is the twelfth-longest river and has the sixth-largest drainage basin in the United States. In Canada, where the Columbia flows for and drains , the river ranks 23rd in length, and the Canadian part of its basin ranks 13th in size among Canadian basins. 
The Columbia shares its name with nearby places, such as British Columbia, as well as with landforms and bodies of water.
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.