The Gran Rû

A work of hydraulic engineering between history and community

Origins and purpose

The Gran Rû is the largest of Courmayeur’s 31 historic irrigation channels, likely built between the 13th and 16th centuries. It diverted water from the Dora di Ferret to irrigate the wide yet dry meadows located on the left side of the valley, stretching between La Saxe and Courmayeur, and beyond the town towards Verrand.

The route

The canal’s water intake was located just above the Entrèves bridge. From there, it followed the base of Mont de La Saxe, crossed a street in the village of La Saxe, passed over the Sapin stream, and continued towards the Villair road. Near Villa Raggio, it descended just behind the parish church, skirted the village, and then crossed the southern meadows as far as the Verrand stream, before continuing alongside the Pré-Saint-Didier–Courmayeur road to reach the meadows of Palleusieux.

The “Rû”, true works of hydraulic engineering, were widespread throughout the Aosta Valley. Historical sources already mention at least two Rû dating back to the end of the first millennium, while the 13th, 14th and 15th centuries saw their expansion across the region’s valleys and alpine pastures. These essential infrastructures deeply shaped the agricultural, environmental and economic landscape of the Aosta Valley.

Conflicts and transformations

During the 18th century, the Gran Rû became the subject of long disputes between Courmayeur and Pré-Saint-Didier over water sharing. The conflict was resolved only in 1790 through an official regulation. In the following centuries, the canal underwent several modifications and, during the 20th century, parts of it were replaced with iron and concrete pipes.

Decline

With the tourism boom of the 1960s and the gradual abandonment of agricultural meadows, the Gran Rû progressively lost its function. It was covered and largely erased from the landscape. Today, the irrigation canal is no longer active, but its historic route can still be traced.

Memory and preservation

The Gran Rû still lives on in local memory and place names, such as Via del Gran Rû. Since 2022, the municipality has restored the path running alongside the canal and, in 2025, rebuilt the wooden canal bridge over the Val Sapin stream, restoring dignity to a structure that tells centuries of history, ingenuity and community life in the Aosta Valley.