It starts at the outlet of Lake Ashuapmushuan, and flows first in a north-easterly direction for about 30 kilometres (19 mi) whereafter it continues south-east to Saint-Félicien.

As a wild undeveloped river, and accessible from Quebec Route 167 close to Lake Ashuapmushuan, it is a popular destination for canoe camping.

The reserve prohibits logging, mining, and hydro-electric development, while protecting critical landlocked salmon habitats, biodiversity, and sites of archaeological interest.

The river is enclosed in narrow valleys for a large part of its course, with powerful rapids and a dozen waterfalls, of which the most impressive are the Chaudière Falls.

The Ashuapmushuan River Basin is home to several archaeological sites that show that indigenous people occupied the area for thousands of years.

[1][4] In 1685, French fur traders set up a trading post on the eastern shore of Lake Ashuapmushuan that remained almost continuously in operation until the middle of the 19th century.

[1] The Ashuapmushuan River and its tributaries provide spawning grounds and habitats for landlocked salmon (Salmo salar ouananiche).