Lac de Mauvoisin

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Lac de Mauvoisin
View of the lake from the dam
View of the lake from the dam
Location: Canton of Valais , Switzerland
Tributaries: various mountain streams
Drain: Dranse de Bagnes
Lac de Mauvoisin (Canton of Valais)
Lac de Mauvoisin
Coordinates 593 089  /  94059 coordinates: 45 ° 59 '53 "  N , 7 ° 20' 58"  O ; CH1903:  593,089  /  94059
Data on the structure
Lock type: Arch dam
Construction time: 1951 to 1957
Height of the barrier structure : 250 m
Height above the river bed : 180 m
Building volume: 2,030,000 m³
Crown length: 520 m
Power plant output: 28 MW
Operator: Forces Motrices de Mauvoisin SA, Sion
Data on the reservoir
Altitude (at congestion destination ) 1961  m above sea level M.
Water surface 2.08 km²
Reservoir length 4.9 km
Storage space 180 000 000  m³
Total storage space : 181 500 000  m³
Catchment area 113.5 km²
Design flood : 107 m³ / s
Map Lac de Mauvoisin.png

The Lac de Mauvoisin is a reservoir located at the back of the Val de Bagnes , in the southwest of the Swiss canton of Valais . In addition to the use of energy, the reservoir protects the Val de Bagnes from tidal waves that can be caused by the eruption of the Giétrogletscher .


The reservoir with an area of ​​2.08 km² has a length of 4.9 km, an average width of 500 m and lies at 1975  m above sea level. M. in the catchment area of ​​the Dranse de Bagnes . It is located in a deep valley surrounded by the high, glaciated mountain peaks of the Valais Alps . To the west of the lake is the 4314  m high Grand Combin , in the east the Ruinette ( 3875  m ) rises . The catchment area of ​​Lac de Mauvoisin is 114 km². These include several glaciers, the Giétrogletscher, the Brenay Glacier , the Otemma Glacier and the Mont Durand Glacier . In the open end of the valley to the south which is SAC - lodge Chanrion Hut .

View of the dam


The proponent of the use of hydropower in the Val de Bagnes was the civil and electrical engineer Albert Maret , who came from the valley and worked for Brown, Boveri & Cie. (BBC) worked in Baden . Between 1945 and 1949 he succeeded in obtaining concessions from the various affected communities, in which case he was in tough competition with the project to expand Lac des Dix.

In September 1947 the Forces Motrices de Mauvoisin SA (abbreviated FMMSA, German: Kraftwerke Mauvoisin AG ) was founded for the use of the hydropower of the Dranse de Bagnes. In addition to Albert Maret himself, Credit Suisse , BBC and Elektrowatt were involved in the company.

The construction of the power plant began in 1949 with the development of Mauvoisin by means of a road from Fionnay. The dam was built from 1951 to 1957 according to plans by Alfred Stucky .

The dam wall originally had a height of 237 m, but was increased by 13.5 m to 250 m between 1989 and 1991.

With the retreat of the Corbassière glacier at the beginning of the 2010s, the possibility of closing the valley below the glacier with a relatively small dam, so that a Corbassier lake would arise, in which 50 million m³ could be stored. In addition to storing the summer runoff, this lake could also serve as the upper basin of a Mauvoisin-Corbassière pumped storage power station , which would take advantage of the height difference between the new lake and Lac de Mauvoisin and could have an output of 500 MW.


With a storage volume of 210 million m³, Lac de Mauvoisin is the second largest reservoir in Valais after Lac des Dix . The arch dam is the highest working arch dam in Europe, because the Enguri dam in Georgia (271.5 m) is just outside Europe and the Vajont dam in Italy (261.6 m) is unused. In Switzerland, the dam wall is the second highest after that of Lac de Dix.

In addition to the natural catchment area, other side streams of the Dranse are channeled into the lake through tunnels. The operating company is Forces Motrices de Mauvoisin SA .

Water from Lac de Mauvoisin is fed through a tunnel to the Fionnay cavern center (138  MW ), where it is turbined and then passed on to an equalization basin. A 15 km long tunnel leads from this basin into the Rhône Valley . This water is turbined at the Riddes headquarters (225 MW). The storage system also includes the Chanrion plant (28 MW) south of Lac de Mauvoisin and the Champsec auxiliary power plant (5 MW) further down the valley in the Val de Bagnes. The total generator output therefore amounts to 396 MW, the standard energy capacity is around 1000  GWh annually .

Headquarters turbine mean
gradient (m)
Energy in GWh
(per year)
Bottleneck capacity
Chanrion 1 × double pelton 347 1964 72 28
Fionnay 3 × Francis 378 1958 286 138
Riddes 5 × double pelton 950 1956 668 225
Champsec 3 × Francis 535 1930 11 5.5
Total 1037 397

See also


Web links

Commons : Lac de Mauvoisin  - Collection of images, videos and audio files

Individual evidence

  1. ^ Giétroz: History of a Catastrophe. Televerbier, accessed June 7, 2020 .
  2. ^ Maret Albert. Médiathèque Valais, accessed June 6, 2020 .
  3. Le Demi-siecle de Maurice Troillet . Editions Saint-Augustin, S. 267 ( [accessed on June 6, 2020]).
  4. ^ Forces Motrices de Mauvoisin SA. Commercial register of the canton of Valais, accessed on June 7, 2020 .
  5. ^ Hans Wyer: The use of hydropower in the Valais . 11.1.3. Mauvoisin: Grant of concession to Ing. Albert Maret; Transfer of the licenses to the FM du Val de Bagnes; Project planning by Elektrowatt AG, p. 104 ( [PDF]).
  6. Wilfried Haeberli: Glacier Shrinkage: Dangers and Potentials of New Lakes in the High Mountains - Swiss Energy Foundation. Swiss Energy Foundation, p. Vii , accessed on May 24, 2020 .
  7. a b Mauvoisin. Valais / Wallis Promotion, accessed June 6, 2020 .