L'Assomption River

L'Assomption River Rivière L'Assomption
File:Rivière l'Assomption (Saint-Jean-de-Matha) 2005-08-22.jpg Assomption River at Chutes Monte-à-Peine Park in Matawinie Regional County Municipality
File:L'AssomptionRiverMap.png
Location
Country	Canada
Province	Quebec
Region	Lanaudière
Physical characteristics
Source	L'Assomption Lake
• location	Saint-Guillaume-Nord
• coordinates
Mouth	Rivière des Prairies
• location	Repentigny
• coordinates
Length	200 km (120 mi)
Discharge
• location	Rivière des Prairies

The Assomption River (in French Rivière l'Assomption [ʁivjɛʁ lasɔ̃psjɔ̃], named after the Assumption of Mary) is the most important waterway in the Lanaudière region of Quebec, Canada. It is over 200 kilometres (120 mi) long, and has a drainage basin (watershed) of 4,220 square kilometres (1,630 mi²). Its source is the Mont Tremblant massif. Seven significant rivers flow into the Assomption (de la Boule, Versailles, Noire, la Chaloupe, Ouareau, Saint-Esprit, and Achigan) before it flows into the Rivière des Prairies at Repentigny, Quebec.

About 150,000 people live in the drainage area of this river.

Geography

The L'Assomption River watershed overlaps two natural environments, the Laurentian Mountains and the St-Lawrence lowlands, which cover about a third of the watershed area. Its relief is a uniform plain with some hills—from 0 to 100 metres (0 to 328 ft)—dominated by agricultural lands. The texture of the soil is rather fine and rests on an impermeable argillaceous (clay) base.

The Laurentian Mountains form part of the Canadian Shield. They are separated from the lowlands by a well-defined escarpment that rises about 150 metres (490 ft). This escarpment has many waterfalls. The Laurentians Mountains have an average height of 230 metres (750 ft) in the south and 460 metres (1,510 ft) in the north. And there are even mountains of over 600 metres (2,000 ft) in the Mont Tremblant massif where the L'Assomption River forms.

Hydrography

From north to south the average slope of the river decreases. The steeper slopes of the highlands create a fast current whereas the lowland flats produces a slower flow. Moreover, the river meanders a lot which is especially evident at the town of L'Assomption, almost completely surrounded by a large loop of the river.

The L'Assomption River watershed has 490 lakes of which 24 have a surface area larger than 1 square kilometre (250 acres). Most of the lakes are in the Laurentian highlands.

Water quality

Urban and industrial pollution

The water quality of the L'Assomption River is seriously affected by the area's social-economic conditions. Since 1950, the situation has been complicated by the urbanization of the river banks, by diversified agriculture, and by industrialisation along the southern portion of the river. Although the source of pollution has changed since 1950, because of strict environmental laws and the use of water purification equipment, water pollution is still not fully curbed.

Over 150,000 people live in the river's watershed in 43 municipalities, of which the most important are Repentigny, Joliette, Le Gardeur, and L'Assomption. In addition, the northern portion of the river's watershed is a popular vacation area, swelling the population by about 45,000 people during the vacation season.

The majority of the municipalities take their drinking water from the river and provide it to more than 100,000 people. The drinking water supply to other residences and country cottages, distributed over approximately 90 percent of the watershed area, comes from water wells.

Agricultural pollution

Besides the urban and industrial pollution, agricultural pollution also contributes greatly to the environment's contamination.

Agriculture has a dominant position along the river: in 1995 there were 1,305 producers with 60,221 hectares (148,810 acres) under cultivation and possessing 73,563 animals.

Agricultural pollution takes several forms: direct pollution (discharge of manure directly in the rivers) and diffused pollution (infiltration of fertilizer products in the groundwater). Diffused pollution is difficult to control because it has a multitude of sources throughout the whole region. Yet without a solution to this problem the water quality of the river will never have the desired quality.

Drainage basin watercourses

Order	Label	Mouth	Coordinates	Length (km)	Source	Coordinates	Region
1	L'Assomption River	Rivière des Prairies		200	L'Assomption Lake		Lanaudière
2	L'Achigan River	L'Assomption River		83.8	L'Achigan Lake		Lanaudière
3	Jourdain River	L'Achigan River		19.4	Duquette Lake		Laurentides
4	Abercromby River	L'Achigan River		10.8	Connely Lake		Laurentides
5	Beauport River	L'Achigan River		20	Lac de la Crosse		Laurentides
6	La Petite Rivière	L'Achigan River		13	Saint-Calixte		Laurentides
7	Saint-Esprit River	L'Assomption River		90.4	Huard Lake		Lanaudière
8	Saint-George Creek	L'Assomption River		19.2	Saint-Alexis		Lanaudière
9	Ouareau River	L'Assomption River		80	Ouareau Lake		Lanaudière
10	Burton River	Ouareau River		16.9	Racette Lake		Lanaudière Laurentides
11	Jean-Venne River	Ouareau River		20.9	Lac des Îles		Lanaudière
12	Kenny River	Jean-Venne River		10.4	Heroux Lake		Lanaudière
13	Beaulne River	Ouareau River		9.2	Beaulne Lake		Lanaudière
14	Dufresne River	Ouareau River		29.6	Dufresne Lake		Lanaudière Laurentides
15	Rouge River	Ouareau River		56.5	Couture Lake		Lanaudière
16	Blanche River	Rouge River		17.8	Lac des Français		Lanaudière
17	Le Grand Ruisseau	Rouge River		15.1	Sainte-Mélanie		Lanaudière
18	Trudel River	Ouareau River		7.6	Chertsey Lake		Lanaudière
19	Nord River	Ouareau River		6.5	Lac du Pin Rouge		Lanaudière
20	Versailles River	L'Assomption River		12.5	spring		Lanaudière
21	Grande rivière Swaggin	L'Assomption River		8.7	Lac des Cèdres		Lanaudière
22	Petite rivière Swaggin	Grande rivière Swaggin		12.6	Vauvert Lake		Lanaudière
23	McGee River	L'Assomption River		14.4	Marguerite Lake		Lanaudière
24	Lavigne River	L'Assomption River		16.9	St-Amour Lake		Lanaudière
25	Rivière de la Boule	L'Assomption River		14.7	Laré Lake		Lanaudière
26	Noire River, Matawinie	L'Assomption River		52.6	Lemieux Lake		Lanaudière
27	Blanche River	Noire River, Matawinie		10.8	Lac à Canards		Lanaudière
28	Leprohon River	Noire River, Matawinie		16	small lake		Lanaudière
29	Crique à David	Noire River, Matawinie		17	Lac à la Pluie		Lanaudière
30	Ruisseau du Point du Jour	L'Assomption River		20.6	Lanoraie		Lanaudière

List of towns crossed

File:Lassomption-vue air.jpg

The large meander of the L'Assomption River at the Town of L'Assomption

• Saint-Côme
• Saint-Alphonse-Rodriguez
• Sainte-Béatrix
• Saint-Jean-de-Matha
• Saint-Félix-de-Valois
• Sainte-Mélanie
• Saint-Ambroise-de-Kildare
• Notre-Dame-de-Lourdes
• Notre-Dame-des-Prairies
• Saint-Charles-Borromée
• Joliette
• Saint-Thomas
• Saint-Paul
• L'Épiphanie
• L'Assomption
• Repentigny
• Charlemagne

External links

• Corporation de l'Aménagement de la Rivière l'Assomption
• De l'Outaragasipi à la Rivière l'Assomption