Fotomontage Schrägseilbrücke über den Grimselsee

Enlarging Lake Grimsel

More water already flows into Lake Grimsel than it can hold - this being mainly in the summer months. By increasing the level of the existing dams by 23m more than 75% more water can be stored which allows the water to be better utilised throughout the year.

Most Important Building Stages:

  • Overhaul of Spittallamm Dam
  • Elevation of the Spittallamm and Seeuferegg dams by 23 m
  • Rerouting of the Grimsel pass road, construction of a cable-stayed bridge


  • More efficient use of the very large inflows, seasonal balancing
  • Energy reserves for longer periods of limited electricity supply
  • Contribution to flood control along the Aare
  • Long-term with accentuated climatic changes: back-up in long periods of dry weather

Facts & Figures:

  • Increasing the storage capacity from 95 to 170 million m3
  • Energy capacity of the extra storage volume: 240 GWh;
  • the larger lake: 510 GWh
  • Investitment: CHF 260 million CHF (Stand 2006, +/- 20 %)
  • (80 million CHF for the overhaul of the Spittallamm dam)
  • Construction duration: approx.  6 years