Ottawa River drainage basin
The Ottawa River drainage basin is the drainage basin in northern North America where surface water empties into the Ottawa River and adjoining waters. Spanning an area of about , it is the 12th largest drainage basin in Canada, occupying the Canadian provinces of Ontario and Quebec. It accounts for about 11% of the total Saint Lawrence River drainage area.
Drainage basin
The five largest river basins (by area), from largest to smallest, are the basins of the Amazon (7M km), the Congo (4M km), the Nile (3.4M km), the Río de la Plata (3.2M km), and the Mississippi (3M km). The three rivers that drain the most water, from most to least, are the Amazon, Ganga, and Congo rivers.