Chicoutimi River

Used by the Montagnais of the Saguenay River before the arrival of Europeans, it was at that time the first portage from the main access road to Lac Saint-Jean. In the 20th century, it was developed from its source to its mouth for hydropower purposes. In addition to being the source of drinking water for the Chicoutimi and Jonquière boroughs, this river has six dams (including 2 hydroelectric power plants in operation). During the Saguenay flood in 1996, its surge caused significant damage to Laterrière and Chicoutimi.

Geography

Course and hydrogeology

The Chicoutimi River rises at Portage-des-Roches, in the Laterrière sector of the Chicoutimi borough at 150 m (490 ft) altitude and flows northeast towards Laterrière-Bassin where it is spanned by the Père-Honorat bridge. Leaving the rocky base and the steep relief of Portage-de-Roches, it then enters an alluvial and semi-alluvial plain up to dam de la Chute-Garneau where the landscapes on both banks alternate between residences and agricultural land for a little over ten kilometers.

The Chute-Garneau dam is a watercourse retaining structure located on a rock base. Half a kilometer further on, route 170 crosses the river which then enters a more urbanized sector of the Chicoutimi borough. After having bypassed Pointe du Chien, it passes under Autoroute 70 and enters the Haut-Saguenay industrial park. The river then crosses the Pont-Arnaud dam and begins its increasingly rapid descent towards the Saguenay as the relief becomes increasingly steep. After passing under the Ulric Blackburn bridge (boulevard Barette) it flows into Lac Dubuc; the reservoir of the Chute-Blanchette dam. This retaining structure dries up the original rock bed of the river to divert it towards an underground water intake which supplies the S.P.C. ( Elkem Métal). The river then re-emerges in the historic site of the Pulperie de Chicoutimi and continues to descend to the Chicoutimi dam basin. Finally, it flows into the Saguenay River.

The Chicoutimi River flows mainly in the Saguenay graben, a vast elevated valley that overlooks the lowlands surrounding the Saguenay River. The soils of this large depression are composed of Quaternary marine sediments, such as silt and clay, deposited at the end of the Pleistocene and during the beginning of the Holocene by the Laflamme Sea. During the last three kilometers when approaching the Saguenay river, opposite the landscape of the alluvial plain of Laterière, the river is encased in a series of gullies in which it sinks to 70 m (230 ft). The composition of the soils and the strong acceleration of the runoff caused by unevenness in this sector are the main causes causing the river to cut, through marine clay, an incision from 10 to 20 m (66 ft) until the parent rock giving it the appearance of a torrent.

Hydrography

The watershed of the Chicoutimi River occupies an area of 3,390 km² (1,310 sq mi), distributed mainly in the Laurentian Wildlife Reserve and shared between two administrative regions: Saguenay–Lac-Saint-Jean and Capitale-Nationale. The basin territory includes sections of 6 unorganized territories, the municipality in four MRCs.

Flowing from south to north, the Chicoutimi River rises east of Kenogami Lake via the Portage-des-Roches dam in the old town from Laterrière (today Chicoutimi borough to Saguenay (city)). This river is artificially controlled over 26.2 km (16.3 mi) in distance and 150 m (490 ft) in elevation for a century.

The first section, delimited by the dams of Portage-des-Roches and Pont-Arnaud, would represent a part in upstream of the river almost 20 km (12 mi) in length. Located in the plain of Laterrière, south of Chicoutimi, this section would have a drop of barely 17.3 m (57 ft) and would form a meander and a reservoir retained by the dams of Pont-Arnaud and Chute-Garneau.

Downstream from Pont-Arnaud, the second section has a drop of 132.7 m (435 ft) for about 5 km (3.1 mi) of distance. The Chute-Blanchette (Elkem Métal) and Chicoutimi (Abitibi-Consolidated) dams were built respectively on falls of 84.1 m (276 ft) and 21.3 m (70 ft) and largely explain this steep descent to the Saguenay. The erosion of the river, barely visible upstream, becomes very apparent downstream because it has been dug, over time, in the granite of fjord, a small valley up to Saguenay River. The river is influenced by the tide only downstream of the Chicoutimi dam where it forms a basin.

Watershed

Official designation of the basin

First, it is important to specify that the Chicoutimi river watershed includes that of Kenogami Lake since the Letellier judgment in 1911. This judgment designated the Chicoutimi River as the main outlet for the lake to the detriment of the Rivière aux Sables. The daily contributions of spills from Kenogami Lake into these rivers according to the following proportions: 2/3 go to the Chicoutimi river and 1/3 to the Sables river.

General description

The watershed of the Chicoutimi River, with an area of 3,390 km² (1,310 sq mi), holds, with those neighboring it, the Quebec record of precipitation on its territory (approximately 1.2 m (3 ft 11 in) of water per year). Located mainly in the mountainous region (40% of its surface is more than 650 m (2,130 ft) above sea level. Du Laurentides Wildlife Reserve, the basin follows, in several places, steep slopes. The latter would also include three sub-basins (rivers Pikauba, Cyriac and aux-Écorces), two reservoirs (Kenogami and Pikauba) and part of the territory of each of the 5 former cities of Chicoutimi, Laterrière, Lac-Kénogami, Arvida and Jonquière which are now part of city of Saguenay.

The Chicoutimi river basin is also a sub-basin of the Saguenay River, which in turn flows into the St. Lawrence River and ends up in the Atlantic Ocean which drains most of the eastern Quebec rivers.

Flow management

The Chicoutimi River, during the 20th century, saw its level rise significantly following the construction of numerous dams which made it pass from the stage of river to that of a succession of basins between Kénogami Lake and the Saguenay. In terms of flow control, four entities are involved in the management of dams:

• Quebec Department of Environment and Wildlife (Portage-des-roches Dam)
• City of Saguenay (Chute-Garneau and Pont-Arnaud)
• Elkem metal (Chute-Blanchette)
• Abitibi-Bowater (Chicoutimi)

Since the beginning of the 20th century, several works on the Kenogami Lake made it possible to regulate the flow of the Chicoutimi river and the Sables river which shared this same source. In order to ensure a constant supply to industries downstream from the rivers, water shares were supplied according to the demand, which differed between the cities of Chicoutimi and Jonquière. This approach triggered conflicts because the capacity to supply water to Kenogami Lake varied according to the seasons and the levels of the various structures did not allow an equitable sharing of flows. This situation was brought to court in 1911 resulting in the Letellier judgment which shared the contributions of the two main outlets from Kenogami Lake at 2/3 at the Chicoutimi river and 1/3 at the rivière-aux-Sables. Despite the changes in management, this rule is still in force today. The following year, in 1912, the construction of the Pont-Arnaud power station was completed.

The major enhancement of the waters of Kenogami Lake and the construction of retaining structures was envisaged in 1918. This mandate was given to the Commission des eaux running du Québec which plans to build the Portage-des-Roches dam which will be built with the Pibrac East and Pibrac West dams between 1923 and 1924.

Pro-riparian management versus pro-industry management

The flow management of the Chicoutimi River is dependent on two factors:

• The safety of local residents, protection against flooding and the recreational and tourist development of the Kenogami Lake and the Chicoutimi River.
• Needs

Dams

Main floods (1971 to 1996)

Environment

Fauna

Flora

Pollution