Ottawa River falls into Saint Lawrence River at Montreal. The river is 1,271 km long with a catchment area of 146,000 sq. kilometer out of which 65% lies in Quebec and rest in Ontario. The tributaries of Ottawa River include Montreal River, Mississippi River, Coulonge River, Gatineau River, du Lievre River, Madawaska River, Kipawa River, Petawawa River, Rouge River, Bonnechere River, Riviere du Nord, Rideau River, Mattawa River and South Nation River.
River Ottawa owes its origin to the glaciers that melted towards the end of the last Ice Age. During this time the whole of Ottawa River valley was engulfed by a part of Atlantic Ocean. This part was named as Champlain Sea. Traces of pre-historic marine life are evident in marine clay found in this valley. The enormous sediment deposit during this period resulted in the creation of large marshland or bogs. These large deposits are popularly known as Leda Clay.
The Ottawa River has played a major role in the development of Ottawa city. The River serves as the main source of sustenance for the people of this region. Both agriculture and industry are dependant on the waters of River Ottawa. The Ottawa River, thus, shaped the growth of the city, helping it to develop from a lumbering outpost to becoming the capital of Canada.
