Sourcing water within the Eastern Townships, it ends its journey in Lake Saint-Pierre where it is a tributary to the Saint Lawrence River; altogether it is 177 km (110 mi) long.

[1] Although the number of species of living organisms has greatly decreased, a tenacious ecosystem still thrives along many parts of the Yamaska, some efforts are made by the citizens of various municipalities to alter human impact on the environments that connect to the stream.

This Amerindian name references baie de Lavalilière (Lavallière Bay), at the river's mouth where vegetation grows abundantly in a marsh.

A varied fauna and flora exists along the Yamaska, reflecting the various regions it traverses; species of birds, fish, amphibians, reptiles, mammals, crustaceans, insect, fungi, lichen, algae and many more populate its waters, banks, and surrounding marshes.

The main fish cruising its waters are white sucker (Castostomus commersonii) and Cyprinidae; more polluted areas are occupied by brown bullhead (Ameiurus nebulosus).

[7] Inventories carried at Mont Yamaska allowed to observe over fifteen species of amphibians and even reptiles (such as the painted turtle (Chrysemys picta) and Common Garter Snake (Thamnophis sirtalis)).

Since their installment, the collective murals have gained much renown and visibility due to their location just off a popular cycling network (a large portion of it within meters of the river).