Génissiat dam

Génissiat dam
Génissiat dam
Location of Génissiat dam in France
Official name	Barrage de Génissiat
Country	France
Coordinates	46°03′10″N 5°48′44″E / 46.052811°N 5.81225°E / 46.052811; 5.81225Coordinates: 46°03′10″N 5°48′44″E / 46.052811°N 5.81225°E / 46.052811; 5.81225
Dam and spillways
Height	104.00 m
Length	165.00 m
Width (crest)	9.00 m
Width (base)	57.00 m
Dam volume	440,000 m3
Reservoir
Total capacity	56.00 hm3
Power station
Installed capacity	420 MW
Annual generation	1,700,000,000 kWh

The Génissiat dam is a hydroelectric dam on the Rhône in France near the village of Injoux-Génissiat. Construction began in 1937, but was delayed by World War II, and the dam did not start generating power until 1948. By 1949 it had the greatest capacity of any dam in Europe.

The concept of damming the Rhone had been discussed since the 19th century. In 1906 the Harlé-Blondel-Mähl group published a proposal for a great dam at Génissiat. They were supported by the Groupe Giros-Loucheur and by Schneider. They had to compete with a rival proposal by a Franco-Swiss group, and both groups appealed to geologists to support their claims. The French speleologist and expert on limestones Édouard-Alfred Martel declared that the Génissiat scheme was pure folly: It would be impossible to anchor the dam in the limestone, which was anyway porous and would not retain the water. The Swiss Maurice Lugeon, a specialist in large dams, refuted his arguments, declaring that the limestone would hold and calling Martel an amateur experimental geologist. There was no immediate outcome to this debate, but later Lugeon's views were confirmed by tests by the Compagnie Nationale du Rhône.

The Compagnie Nationale du Rhône (CNR) was founded in 1933 to undertake construction and operation of the dam. In 1934 the state granted the concession to harness the river. The architects were Léon Bazin, Pierre Bourdeix and Albert Laprade. Pierre Danel was the engineer of the spillways and Paul Galabru was the overseeing engineer.

Preliminary work began in February 1937, and official authorization to undertake the project was granted on 21 June 1938. The Léon Chagnaud et fils company was given the contract to divert the Rhone from the site. They built a temporary dam from steel rods and rock to divert the water into two underground channels, both 12 metres (39 ft) wide, 8 metres (26 ft) high and 500 metres (1,600 ft) long. The diversion was opened successfully in April 1939, handling 500 cubic metres (18,000 cu ft) per second of water.

World War II (1939-1940) caused delays. On 21 March 1940 the Entreprise de Construction du Barrage de Génissiat (ECBG) was created, a consortium of public works companies. In June 1940 the site was flooded. After the armistice between France and Germany of 22 June 1940, work resumed slowly. Many of the workers joined the underground resistance, and there were several incidents, including a deadly one on 12 February 1944.