The Ottawa River (, ) is a river in the Canadian provinces of Ontario and Quebec. It is named after the Algonquin word "to trade", as it was the major trade route of Eastern Canada at the time. For most of its length, it defines the border between these two provinces. It is a major tributary of the St. Lawrence River and the longest river in Quebec.
Geography
The river rises at Lac des Outaouais, north of the Laurentian Mountains of central Quebec, and flows west to Lake Timiskaming. From there its route has been used to define the interprovincial border with Ontario.
From Lake Timiskaming, the river flows southeast to Ottawa and Gatineau, where it tumbles over Chaudière Falls and further takes in the Rideau and Gatineau rivers.
The Ottawa River drains into the Lake of Two Mountains and the St. Lawrence River at Montreal. The river is long; it drains an area of , 65 per cent in Quebec and the rest in Ontario, with a mean discharge of . It has a maximum depth of at the Carillon Reservoir and is wide at its widest part.
The average annual mean waterflow measured at Carillon dam, near the Lake of Two Mountains, is , with average annual extremes of . Record historic levels since 1964 are a low of in 2010 and a high of in 2017.
The river flows through large areas of deciduous and coniferous forest formed over thousands of years as trees recolonized the Ottawa Valley after the ice age.Anderson, T.W. 1989. Vegetation changes over 12000 years. Geos (3) 39-47. Generally, the coniferous forests and blueberry bogs occur on old sand plains left by retreating glaciers, or in wetter areas with clay substrate. The deciduous forests, dominated by birch, maple, beech, oak and ash occur in more mesic areas with better soil, generally around the boundary with the La Varendrye Park.Braun, E.L. 1950. Deciduous Forests of Eastern North America. The Blakiston Co., Philadelphia, PA.Keddy, P.A. 2008. Earth, Water, Fire. An Ecological Profile of Lanark County. General Store Publishing House, Renfrew, Ontario. (revised from first edition 1999). These primeval forests were occasionally affected by natural fire, mostly started by lightning, which led to increased reproduction by pine and oak, as well as fire barrens and their associated species. The vast areas of pine were exploited by early loggers.Hughson, J.W. and C.C. J. Bond. 1965. Hurling Down the Pine. The Historical Society of the Gatineau, Old Chelsea, Quebec. First edition 1964, Revised second edition 1965. Later generations of logging removed hemlock for use in tanning leather, leaving a permanent deficit of hemlock in most forests.Keddy, C.J. 1993. Forest History of Eastern Ontario. Prepared for the Eastern Ontario Model Forest Group, Kemptville Associated with the logging and early settlement were vast wild fires which not only removed the forests, but led to soil erosion.Howe, C.D. 1915. The effect of repeated forest fires upon the reproduction of commercial species in Peterborough County, Ontario. Pages 116-211 in Forest Protection in Canada, 1913 1914, Commission of Conservation of Canada, William Briggs, Toronto. Consequently, nearly all the forests show varying degrees of human disturbance. Tracts of older forest are uncommon, and hence they are considered of considerable importance for conservation.Henry, M. and P. Quinby. 2009. Ontario Old Growth Forests. Fitzhenry and Whiteside, Markham, Ontario
The Ottawa River has large areas of wetlands. Some of the more biologically important wetland areas include (going downstream from Pembroke), the Westmeath sand dune/wetland complex, Mississippi Snye, Breckenridge Nature Reserve, Shirleys Bay, Ottawa Beach/Andrew Haydon Park, Petrie Island, the Duck IslandsDarbyshire, S.J. 1981. Upper Duck and Lower Duck Islands. Trail and Landscape 15:133-139. and Greens Creek.Brunton, D.F. 1992. Life Science Areas of Natural and Scientific Interest in Site District 6-12. A Review and Assessment of Significant Natural Areas. Report prepared for Ontario Ministry of Natural Resources, Kemptville, Ontario.Ecosystem Diversity . ottawariverkeeper.ca. Retrieved on 2013-07-12. The Westmeath sand dune/wetland complex is significant for its relatively pristine sand dunes, few of which remain along the Ottawa River, and the many associated rare plants. Shirleys Bay has a biologically diverse shoreline alvar, as well as one of the largest silver maple swamps along the river. Like all wetlands, these depend upon the seasonal fluctuations in the water level.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK High water levels help create and maintain silver maple swamps,Toner, M, and P. Keddy. 1997. River hydrology and riparian wetlands: a predictive model for ecological assembly. Ecological Applications 7: 236-246 while low water periods allow many rare wetland plants to grow on the emerged sand and clay flats.Brunton, D.F. and B.M. Di Labio. Diversity and ecological characteristics of emergent beach flora along the Ottawa River in the Ottawa-Hull region, Quebec and Ontario. Naturaliste canadien 116: 179-191. There are five principal wetland vegetation types. One is swamp, mostly silver maple. There are four herbaceous vegetation types, named for the dominant plant species in them: Scirpus, Eleocharis, Sparganium and Typha.Day, R., P.A. Keddy, J. McNeill and T. Carleton. 1988. Fertility and disturbance gradients: a summary model for riverine marsh vegetation. Ecology 69:1044-1054 Which type occurs in a particular location depends upon factors such as substrate type, water depth, ice-scour and fertility. Inland, and mostly south of the river, older river channels, which date back to the end of the ice age, and no longer have flowing water, have sometimes filled with a different wetland type, peat bog. Examples include Mer Bleue and Alfred Bog.
Tributaries Major tributaries include:
Bonnechere River Coulonge River Dumoine River Gatineau River Kipawa River du Lièvre River Madawaska River Mattawa River Mississippi River Montreal River Rivière du Nord Noire River Petawawa River Rideau River Rouge River South Nation River
Communities
Communities along the Ottawa River include (in down-stream order):
Kitcisakik Anicinape Community Long Point First Nation Moffet, Quebec Angliers, Quebec Notre-Dame-du-Nord, Quebec Timiskaming First Nation Temiskaming Shores, Ontario Ville-Marie, Quebec Témiscaming, Quebec Thorne, Ontario Mattawa, Ontario Deux Rivières, Ontario Rapides-des-Joachims, Quebec Rolphton, Ontario Deep River, Ontario Sheenboro, Quebec Petawawa, Ontario Pembroke, Ontario Westmeath, Ontario Waltham, Quebec Davidson, Quebec Fort-Coulonge, Quebec La Passe, Ontario Campbell's Bay, Quebec Bryson, Quebec Portage-du-Fort, Quebec Bristol, Quebec Norway Bay, Quebec Braeside, Ontario Arnprior, Ontario Fitzroy Harbour, Ontario Quyon, Quebec Constance Bay, Ontario Aylmer, Quebec Ottawa, Ontario Gatineau, Quebec Masson-Angers, Quebec Cumberland, Ontario Rockland, Ontario Thurso, Quebec Wendover, Ontario Plaisance, Quebec Papineauville, Quebec Montebello, Quebec Fassett, Quebec L'Orignal, Ontario Grenville, Quebec Hawkesbury, Ontario Carillon, Quebec Pointe-Fortune, Quebec Saint-André-Est, Quebec Rigaud, Quebec Saint-Placide, Quebec Kanesatake Hudson, Quebec Oka, Quebec Vaudreuil-sur-le-Lac, Quebec L'Île-Cadieux, Quebec Vaudreuil-Dorion, Quebec Terrasse-Vaudreuil, Quebec Pincourt, Quebec Pointe-des-Cascades, Quebec
Islands Ontario
Alexandra Island Aylmer Island Basil Island Bate Island Beacon Island Beckett Island Bell Island Big Island Big Elbow Island Bruyère Island Burnt Island Butternut Island Carl Island Cedar Island Chapman Island Chartrand Island Chenaux Island Christie Island Clarence Island Coreille Island Corinne Island Cornelius Island Cotnam Island Crab Islands Cunningam Island Cushing Island Daisy Island Davis Island Deep River Islet Demers Island Dow Island Dunlop Island Dupras Island Dutch Island Ellis Island Evelyn Island Farr Island Fish Island Fraser Island Fury Island Gibraltar Island Green Island Gutzman Island Hamilton Island Haycock Island Hazel Island Hazelton Island Hen Island Hog Island Houston Island Île Chénier Île du Chenail Île Ste-Rosalie Île Young Irving Island Jamieson Island John Joe Island Kate Island Kedey's Island King Edward Island Latour Island Lemieux Island Lillian Island Lorne Island Louise Island Lower Duck Island Lumpy Denommee's Island Mackie Island Man Island Meadow Island Merrill Island Metcalf Island Miller Island Morris Island Nichol's Island Oak Island O'Meara Island Parker Island Pearl Island Petrie Island Pink Island Poker Island Princess Island Ramsey Island Randolph Island Rempnouix Island Riopelle Island Rocher Capitaine Island Ruby Islet Sack's Island Sandbar Island Santa Island Sawlog Island Shoal Island Short Turn Island Steamer Island Snake Island Sullivan Island Upper Duck Island Victoria Island Wabewawa Island Willson Island Windsor Island
Quebec
L'Île Île Allen Île aux Allumettes Île Armstrong Île Avelle Bald Rock Île Béique Îles Benny Île Bernard Île Bernardin Île Berry Île à Bertrand Île Boom Île Bray Île Brisseau Île Brunet Île Bryson Île Cadieux Île Cobb Île de Carillon Île du Centre Île du Chef Île du Chenal Blind Île du Chicot Îles à Cole Île du Collège Île de la Compagnie Île à Cowley Île à Crépault Île D'Arcy Île Davidson Île Dog Île Dubé Île d'Edelman Île à Everill Île Fer à Cheval Île du Finlandais Îles Finlay Île Fitzpatrick Île au Foin Île Fox (Pontiac) Île Fox (Témiscamingue) Île French Île Frigon Île Gagnon Rocher à Gillis Rochers aux Goélands Île Graham Île du Grand Calumet Île Green Île Greene Île à Griffin Île Harbec Île Hemlock Île Henry Île Hiam Île Jacey Île John-Park Île Jones Îles Jumelles Île Kettle Île Lafleur Île Lafontaine Île Lasalle Île à Lawn Île Leblanc Île Lemoine Île Leroux Île Lighthouse (L'Isle-aux-Allumettes) Île Lighthouse (Bristol) Île Limerick Petite île Limerick Île Lorelei Île Mann Île Marcotte Île à Marion Île Mohr Île Morrison Île Mulligan Île O'Connor Île Oscar-Béchamp Île Oster Île Paquin Île à Payne Îles Pelley Île Philemon Île Pigs Île aux Pins Île des Quinze Île Rainville Île des Rapides Île du Refuge Île Reid (Clarendon) Île Reid (L'Isle-aux-Allumettes) Île Rita Île à Ritté Île du Rocher Fendu Île à Rouleau Île à Roussin Île de Sable Petite île Sèche La Semelle Île Smith Île Snake Île des Soeurs Île Soulier Île Squelette Île Submergée Île Sunset Île Todd Île à Tom Île à Tom-Simon Île aux Tourtes Île Verte Île Victoria Île Wickens Île Winneway Île Woods Île Wight Île Young (Pontiac) Île Young (Gatineau) Île Yvette-Naubert
Geology
The Ottawa River lies in the Ottawa-Bonnechere Graben, which is a Mesozoic rift valley that formed 175 million years ago. Much of the river flows through the Canadian Shield, although lower areas flow through limestone plains and glacial deposits.Chapman, L.J. and D.F. Putnam. 1984. The Physiography of Southern Ontario. Third edition. Ontario Geological Survey, Special Volume No.2. Government of Ontario, Toronto.