Ottawa RiverThis is about the river in Canada. For other uses, see Ottawa River (disambiguation) The Ottawa River (rivière des Outaouais) is a Canadian river which for most of its length defines the border between the provinces of Ontario and Quebec. It rises in western Quebec, reaches the Ontario border at Lake Timiskaming, flowing southeast to Ottawa, where it tumbles over the Chaudière Falls and further takes in the Rideau River and Gatineau River. Between the Chaudière Falls and Rideau Falls lies Parliament Hill perched atop a steep and militarily strategic gorge. The Ottawa River drains into the Saint Lawrence River at Montreal, forming Lac Saint-Louis. The length of the river is 1,130 km.\n
Major tributaries include the:\n* Bonnechere River\n* Coulonge River\n* Gatineau River\n* Kipawa River\n* du Lièvre River\n* Madawaska River\n* Mississippi River\n* Montreal River\n* Petawawa River\n* Rideau River\n* Rouge River\n* South Nation River
Following the retreat of the glaciers from this area at the end of the last ice age, the Ottawa River valley was flooded by an arm of the Atlantic Ocean known as the Champlain Sea. Fossil remains of marine life have been found in marine clay formed during that time. Sediment deposits from this period have resulted in areas of poor drainage and the presence of large bogs in some ancient channels of this river. Another consequence was the formations of large deposits of a material commonly known as "Leda clay"; these deposits become highly unstable after heavy rains. A number of landslides have occurred as a result. The former site of the town of Lemieux, Ontario collapsed into the South Nation River in 1993; fortunately, the residents had already been relocated due to the suspected instability of the earth in that location.
Large numbers of Canada Geese, ducks, gulls and shorebirds take advantage of spring flooding and wetlands in the Ottawa River valley during migration. Ducks also overwinter in sections of the river that do not freeze over.
![]() \nThe Ottawa River flows southeast across the image,\njoining the Saint Lawrence River which flows east.\nLake Ontario appears at the bottom of the image.\n
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"I am become death, shatterer of worlds." - Robert J. Oppenheimer (1904-1967) (citing from the Bhagavad Gita, after witnessing the world's first nuclear explosion) |

\nCommunities along the Ottawa River include:\n* 