The Yamaska River is a river in southern Quebec

Quebec

Quebec or is a province in east-central Canada. It is the only Canadian province with a predominantly French-speaking population and the only one whose sole official language is French at the provincial level....

, Canada.

Its source is the Sutton Mountains region of the Eastern Townships

Eastern Townships

The Eastern Townships is a tourist region and a former administrative region in south-eastern Quebec, lying between the former seigneuries south of the Saint Lawrence River and the United States border. Its northern boundary roughly followed Logan's Line, the geologic boundary between the flat,...

 of Quebec. It flows north-west to Farnham

Farnham, Quebec

Farnham is a town located in the province of Quebec, Canada. It is part of the Brome-Missisquoi regional county municipality, in the administrative region of Montérégie. The population as of the Canada 2006 Census was 7,809, making it the second most populated community in the RCM.- History :The...

 and from there north to the Saint Lawrence River

Saint Lawrence River

The Saint Lawrence is a large river flowing approximately from southwest to northeast in the middle latitudes of North America, connecting the Great Lakes with the Atlantic Ocean. It is the primary drainage conveyor of the Great Lakes Basin...

 at Sorel-Tracy

Sorel-Tracy, Quebec

Sorel-Tracy is a city in southwestern Quebec, Canada and the geographical end point of the Lake Champlain Valley at the confluence of the Richelieu River and the St. Lawrence River, on the western edge of Lac Saint-Pierre downstream and east of nearby Montreal. The population as of the Canada 2006...

. Altogether it is 177 km (110 mi) long with a drainage basin

Drainage basin

A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

 of 4784 square kilometres.

Its basin is characterized by urban, industrial, and intensive agricultural use. Consequently the river is seriously polluted, especially from agricultural waste and pesticides. Nevertheless, many municipalities use the river as their source for drinking water.

Its name comes from an Amerindian name meaning "where rushes

Juncus

Juncus is a genus in the plant family Juncaceae. It consists of some 200 to 300 or more species of grassy plants commonly called rushes...

 grow", referring to the abundant rushes in the marsh at river's mouth (Lavallière Bay). The name underwent many mutations: Maska, Ouamaska, Hiamaska, and Hyamaska. In the Abenaki language

Abenaki language

The Abenaki language is a dialect continuum within the Eastern Algonquian languages, originally spoken in what is now Vermont, New Hampshire, northern Massachusetts and Maine...

, the site was designated Mamaska, meaning "toad".

Tributaries

Among its main tributaries are the Noire, South-East Yamaska, and North Yamaska Rivers.

River sub-basin	Left or right tributary (in downstream order)	Sub-basin surface area (km²)	Sub-basin under cultivation (percentage %)
Yamaska	n/a	1759	57.7
Yamaska Nord	right	303	28.2
Yamaska Sud-Est	left	411	22.5
Noire	right	1571	42.7
Salvail	left	206	53.7
David	right	326	59.8
Pot au Beurre	left	208	45.8