Lying in the depths of the Mattertal valley, Z’Mutt is the most powerful pumping station in the Grande Dixence complex. It is fed by water from the Bis and Schali glaciers which overlook the Vispa river, and also by the streams flowing from the Gorner glacier.

Z’Mutt uses four pumps with a total power of 88 MW to pump around 140 million cubic metres of water per season. This water is pumped out into a penstock which conveys it to the Trift tunnel (altitude 2400 m), at the level of the main collection conduit.

The area of the landscape covered by concrete has been restricted. The only large element which is visible is the arch dam blocking the gorge. Apart from the service building, all the other installations (gravel traps, sand traps and pumping station) are underground.

Balancing reservoir Construction 1962 Commissioned 1964 Height 74 m Crest 144 m Capacity 840'000 m3 Area 4 hectares Type arch dam

Pumping station Power 88 MW Flow rate 17,4 m3/s Lift heights 470 m and 365 m