Grande Dixence hydroelectric power plants, Hydroelectric complex in Valais, Switzerland.

Grande Dixence is a hydroelectric complex on the left bank of the Rhône in Valais, built around the Grande-Dixence gravity dam: 285 m high, 700 m long along the crest, 200 m thick at the base and 15 m at the top, holding 6 million m³ of concrete. Its reservoir, Lac des Dix, reaches 2,364 m and feeds four power plants via some 100 km of tunnels and four pumping stations.

EOS obtained the concession for the upper Dixence basin in 1927, and 1,200 workers built the first Dixence dam between 1929 and 1935, feeding the Chandoline plant (120 MW). After the war, Cleuson dam followed in 1947–1951, then Grande Dixence S.A. began the present dam in 1950; 3,000 workers finished pouring 6 million m³ of concrete in 1964, submerging the old dam. The Cleuson-Dixence scheme added the Bieudron plant in 1993–1998.

The complex takes its name from the Dixence river and the Cleuson dam, and the company Grande Dixence S.A. was founded in 1951. The first Dixence dam, built from 1929 to 1935 by 1,200 workers, was submerged in 1957 by the reservoir of the new dam but reappears when the lake level is low. The former Chandoline plant, out of service since July 2013, has been converted into an events centre.

The dam crest sits at 2,365 m and is reached by cable car from the valley; the reservoir peaks in September and is lowest in April, when the submerged first Dixence dam emerges from the water. The crest is 700 m long and 15 m wide, wide enough to walk across.

The Bieudron plant holds three world records: a gross head of 1,883 m, Pelton turbines of 423 MW each, and alternator poles of 35.7 MVA. Its three turbines total 1,269 MW, making it Switzerland's most powerful plant.