Halfway between the lake and the center of Crans-Montana, a new footbridge inaugurated in spring 2020 offers an aerial perspective. It allows walkers to safely discover this legendary hike.
Please note: until 1st November, buses to Lake Tseuzier only run on Wednesdays, Saturdays and Sundays.
In the Middle Ages, this canal built on a rock face brought water to the crops. The route, now perfectly safe, was carved into the rock during the first half of the 15th century. A real source of life, it was carefully maintained by villagers until 1946, when a water supply tunnel was inaugurated. To preserve this route for tourists, the Montana development company decided to take charge of its maintenance.
The Bisse du Ro is a construction about 5.5 km long illustrating truly the difficulties encountered by the inhabitants of our regions at the end of the Middle Ages and the ingenuity they had to demonstrate in the struggle for the water supply necessary for their survival.
Indeed, the bisse crosses several times rocky diagonals, corridors with a smooth tendency, forest on scree, or zones of significant avalanche passages.
When you follow its trail you will discover all this. The bisse is now replaced by a gallery dug to overcome the well-known difficulty of maintaining its flow. Indeed, between leaks and annual damage, it was no longer possible to ensure acceptable safety of use. You therefore take it at the bottom of the dam of Lac de Plans-Mayens and engage on its course in the Riѐre valley. On its first 3 kilometers, even if sometimes impressive, there are no really dangerous spots. Then from point 1598, it is highly recommended to be cautious. You go another 500 meters and leave the Riѐre valley to enter the wild valley of Ertentse.
It is then in this wild, raw and intact mountain that we are able to grasp how much our predecessors fought their whole lives to get water for their houses, their crops as well as to pasture their animals during the hot summer seasons while in the villages the fodder was harvested that would allow passing the winter.
This Ertentse valley is a place which still, even if it is more accessible via Ayent and Tseuzier, awakens in the hearts of the local people strong feelings linked to the work of the ancestors.
Author’s recommendation
This particular bisse can be discovered both going and returning. You can therefore follow it partly and then retrace your steps. On the way back, you will discover things you probably did not see on the way there. If you do it in its entirety, from its source, several routes present themselves; you must then prepare your hike beforehand considering the weather, distances, and elevation changes by following the official tracks according to the information provided on the walking map.
We advise against using a dorsal baby carrier as you frequently need to bend down to avoid rock walls along the bisse.
We also ask you to keep your dogs on a leash.
Derived from the technical difficulty and the stamina requirements.
Track types
Safety information
Certain passages are not recommended for people prone to vertigo.
Follow the marked trails. Please respect the fauna, flora: nature.
Check the weather conditions before your departure.
Crans-Montana Tourism & Congress declines all responsibility in case of accident.
Tips and suggestions
For any other information: www.crans-montana.ch/rando
Roadbook
Departure from Lac de Tseuzier - Er de Chermignon Pra du Taillour - Former Bisse du Ro - Plans-Mayens - Arrival at Lac Grenon, Route du Rawyl
Lac de Tseuzier
Mondralèche
Cascade - Ancien Bisse du Ro
Hanging bridge of the "Bisse du Ro"
Prise d'eau du Bisse du Ro
Lettre géante "R"
Lac de Chermignon
Place de jeux - Lac Grenon
Etang Grenon
Public transport
Public-transport-friendly
The Tseuzier Dam is accessible in summer/autumn from Sion station by postal bus 351 towards Anzère until the stop « St Romain (Ayent), Centre ». Then change and take postal bus 352 towards « Anzère, Barrage de Tseuzier » to the last stop. This bus runs from June 20.From Crans-Montana, it is also possible to reach the Tseuzier Dam. First, take postal bus 353 towards Sion from the stop « Crans, Poste ». Then get off at the stop « Botyre (Ayent), centre ». Finally, take the postal bus on the other side of the road to « Anzère, Barrage de Tseuzier ». Timetable link: https://www.crans-montana.ch/horaires_bus_cm_tseuzier.
Cross the dam. The trail starts on the other side of the lake.
Get Timetable to destination
Directions
Take the Sion East highway exit and follow the direction to Ayent then when you arrive at Botyre take the direction to Tseuzier/Rawyl Dam. The journey takes about 40 minutes from the highway exit to your final destination.
Parking
It is possible to park near the Tseuzier/Rawyl Dam next to the start of the hike.
Coordinates
Author’s map recommendations
Summer hiking map, available at the tourist office.
Crans-Montana-Sierre walking map, mpa edition by orell füssli, 1:25,000 scale, 2019 edition
Book recommendations for this region:
Equipment
Good walking shoes.
The weather changes rapidly at altitude, plan to have suitable clothing.
Localization
Derived from the technical difficulty and the stamina requirements.

User Questions