The Bisses of Valais

Valais is the driest part of Switzerland, and for centuries its farmers moved meltwater from the glaciers to their fields through open channels built along the mountainsides. They are called bisses in French and Suonen in German, and many are medieval in origin. Some run in wooden troughs pinned to vertical rock, others are simple ditches through larch forest. Because water flows at a steady gentle gradient, the maintenance paths beside them are almost level, which makes them the easiest long walks in a canton where everything else goes uphill. Dozens have been restored and are walkable, from vineyard routes on the slopes above Sion to high channels running out under the glaciers.

What you actually see

• The channels themselves - open water running level along a hillside for kilometres.
• The rock sections - troughs and walkways pinned to cliffs high above the valley floor.
• The Rhone valley below - terraced vineyards, orchards and the river a long way down.
• The information boards - how the water was measured, timed and shared between farms.

When to go

Water usually runs from spring into autumn, and the paths are clear from April at low altitude and from June higher up. The vineyard bisses above Sion work well in early spring and again at the grape harvest. Midsummer afternoons on south facing slopes are hot with almost no shade, so start early and carry water.

Honest expectations

Level does not mean easy. Several routes run along exposed ledges with a chain to hold and a long drop below, and they are no place for anyone uneasy with heights or for small children. Some channels are dry outside the irrigation season, which removes the point of the walk. Signage varies between communes and restored sections close after rockfall.

Nearby

Sion with its two hilltop castles, and the vineyard terraces along the Rhone valley.