Point of transition

Point of transition

Fictional representation of the Coteau-du-Lac canal
© Rogers Communications Inc / Rex Wood / 1967

The "Coteau rapids" are located between Lake St. François and Lake St. Louis, and are the narrowest and most turbulent section of the entire St. Lawrence River. In the less than 13 km separating the Great Lakes from the St. Lawrence Valley proper, the River hurtles over three sills for a total drop of 25.6 m.

A bypass

The history of Coteau-du-Lac begins nearly 7 000 years ago. Bordering the St. Lawrence River, which forms the sole transportation corridor in the area, the point at Coteau-du-Lac offers a prime, natural stopping ground for travellers. Along this stretch of the St. Lawrence, a series of violent rapids effectively block access to boats and ships, and require travellers to portage. The point at Coteau-du-Lac represents a bypass that the Autochtones were the first to use.

Types of watercraft

Towing Canadian boats, late 18th century
© National Archives of Canada / C-19353, 1898

During the 17 ^th century, the French who had settled along the shores of the St. Lawrence adopted the canoe, a light type of watercraft which made for simple portaging when travelling upstream and easy running of rapids when travelling downstream. Around the turn of the 18th century, a new type of watercraft gained favour: the " batteau ", a flat-bottomed barge offering the size, shape and cargo capacity required for transporting greater volumes of goods in relative safety.

A new era: Channel-building

As it was quite difficult to portage " batteaux ", the French built a "rigolet" canal at the Coteau-du-Lac rapids toward the mid-18th century. This channel consisted of a rock embankment set out about three metres parallel to the shore, thus forming a shallow yet navigable corridor. Boats using the channel were protected from the violent, fast-running current of the nearby rapids.