What to do in summer > Sports and leisure > Natural world > Irrigation channels (bisses) > Grand Bisse de St-Jean

Grand Bisse de St-Jean

After restoration works lasting two years, water can now once again flow down the length of the Grand Bisse de St-Jean. An easy walk between Grimentz and Mayoux follows the route of these irrigation channels typical of Valais.

The Grand Bisse de St-Jean has a dual function:

  • Tourism : the Grand Bisse provides a pleasant family walk, graded “easy”, with the various restoration works on the Bisse having opened up sights of additional interest along the way
  • Agricultural : along a small section of its course, the bisse has had its original function restored, and some farmland across from Mayoux is again irrigated by its waters

Abandoned since the late 1950s, the Grand Bisse de St-Jean has recently been restored to allow water to flow once again. Two years of targeted work were needed to achieve this:

  • The clearing of the bisse
  • The dredging of the bed
  • The construction of small sluices
  • The installation of conduits for some sections
  • The consolidation and repair of the banks in accordance with clearly-specified standards

The Grand Bisse starts from the Torrent des Marais (Grimentz), crosses St-Jean d’en Haut and finishes at Mayoux. All along its course it collects water from a number of small mountain streams. The upper part of the bisse runs through concrete conduits, whose open sections allow the water to flow beneath the open skies. After St-Jean, the bisse falls by 40 m and runs into a stone bed.

Practical information

Grading : T1
Length : 3.9 km
Access : From Grimentz (post office), follow the signposts to St-Jean and descend towards La Gougra
Altitude of starting point : 1430 m
Altitude of finishing point : 1260 m