Grande Dixence Dam

Grande Dixence Dam
Location of Grande Dixence Dam in Switzerland
Location	Hérémence, Switzerland
Coordinates	46°04′50″N 07°24′14″E / 46.08056°N 7.40389°E / 46.08056; 7.40389Coordinates: 46°04′50″N 07°24′14″E / 46.08056°N 7.40389°E / 46.08056; 7.40389
Status	In use
Construction began	1950
Opening date	1961
Operator(s)	Grande Dixence SA Energie Ouest Suisse
Dam and spillways
Type of dam	Gravity dam
Impounds	Dixence (river)
Height	285 m (935 ft)
Length	700 m (2,297 ft)
Width (base)	200 m (656 ft)
Dam volume	6,000,000 m3 (210,000,000 cu ft)
Reservoir
Creates	Lac des Dix
Total capacity	400,000,000 m3 (320,000 acre·ft)
Catchment area	46 km2 (18 sq mi)
Surface area	4 km2 (2 sq mi)
Maximum water depth	284 m (932 ft)
Power station
Commission date	1965, 1998
Installed capacity	2,069 MW
Annual generation	2,000 GWh

The Grande Dixence Dam is a concrete gravity dam on the Dixence at the head of the Val d'Hérémence in the canton of Valais in Switzerland. At 285 m (935 ft) high, it is the tallest gravity dam in the world and is part of the Cleuson-Dixence Complex. With the primary purpose of hydroelectric power generation, the dam fuels four power stations, totaling the installed capacity to 2,069 MW, generating approximately 2,000 GWh annually, enough to power 400,000 Swiss households.

The dam withholds Lac des Dix (Lake Dix), its reservoir. With a surface area of 4 km², it is the second largest lake in Valais and the largest lake above 2,000 m in the Alps. The reservoir receives its water from four different pumping stations; the Z’Mutt, Stafel, Ferpècle and Arolla. At peak capacity, it contains approximately 400,000,000 m³ (1.4×10¹⁰ cu ft) of water, with depths reaching up to 284 m (932 ft). Construction on the dam began in 1950 and was completed in 1961, before officially commissioning in 1965.

In 1922, Energie Ouest Suisse (EOS) became established with a few small power stations. To generate substantial amounts of electricity, EOS looked to the Valais canton which contains 56% of Switzerland's glaciers and stores the largest amount of water in Europe. In 1927, EOS acquired the license for the upper Dixence basin. In 1929, 1,200 workers constructed the first Dixence dam which would be complete in 1935. The first dam would supply water to the Chandoline Power Station which has a capacity of 120 MW.

After the Second World War, growing industries needed electricity and construction on the Cleuson Dam began in 1947 and was completed in 1951. The original Dixence dam was submerged by the filling of Lac des Dix beginning in 1957, it can still be seen when the reservoir level is low. Plans for the Super Dixence Dam were now being finalized by the recently founded company, Grande Dixence SA. Construction on the Super Dixence Dam soon began later in 1950. By 1961, 3,000 workers had finished pouring 6,000,000 m³ (210,000,000 cu ft) of concrete, completing the dam. At 285 m, it was the world's tallest dam at the time, but it was surpassed by the Nurek Dam of Tajikistan in 1972 (300 m). It remains the world's tallest gravity dam.