27 June 2014

Barrage de Cusset

The geography and history of Lyon are defined by two rivers. Hemmed in to the west by the rocky outcrop that is Fourvière hill, the city's growth over the centuries has depended on its inhabitants' ability to cross, bridge and eventually settle on the opposite, eastern banks of first the Saone and then, much later, the far larger Rhone. 

But whereas the course of the Saone was comparatively easy to control, the mighty Rhone was prone to flash flooding, and numerous attempts to rein it in were literally washed away. So it wasn't until the late 19th century that someone came up with a plan that worked. 

The outcome was nothing short of revolutionary - for both Lyon and France as a whole.

The Canal de Miribel had been dug between 1848 and 1857 to enable boats to travel down the Rhône to Lyon without having to negotiate the myriad ever-changing islets of the area known collectively as the Ile de Miribel. But that did nothing to protect eastward-expanding Lyon from the whims of the powerful main river running through its centre or to secure a steady supply of drinking water for its inhabitants, which had been a problem since the mid-1700s.

A man with a dream
In 1881, an engineer called Jean-François Raclet (also referred to as Joannis or Joannes) put the finishing touches to an audacious and some would say "crazy" idea that he had first had four decades earlier: to turn part of the Rhône into an anneau bleu (blue ring) by digging a second, parallel, 19 kilometre-long canal south of the Canal de Miribel complete with its own hydroelectric dam. 

Ignored by the municipal authorities, who had neither the money nor the inclination for such an apparently Sisyphean venture, especially after France's doomed attempt to construct the Panama Canal, Raclet started knocking on the doors of the city's businessmen instead. 

In an era when electricity was beginning to replace steam as the force driving the industrial revolution and cities were starting to replace their dangerous gas-based lighting with electric street lamps, Raclet's proposal for a hydroelectric dam and therefore a cheap alternative to gas (the supply and price of which was monopolised by the Compagnie du Gaz de Lyon) was music to the ears of Lyon's factory-owners. 

In 1889, Raclet and 36 industrialists and bankers set up the Syndicat Lyonnais des Forces Motrices du Rhône (SLFMR), headed by the silk merchant Joseph-Alphonse Henry (1834-1913).

Raclet's wealthy backers clearly succeeded in convincing the city elders where he had not, because on 9 July 1892 a law was passed granting SLFMR a 99-year permit - France's first ever public utility licence - to exploit the waters of the River Rhône to generate electricity. 

Nevertheless, the authorities also set their own conditions. Mindful of the disastrous failure of previous projects, they demanded the inclusion of a second, regulatory dam (the Barrage de Jonage), a reservoir to store drinking water and an overflow system (déversoir) that could empty water into the Ile de Miribel if the Barrage de Jonage collapsed or the hydroelectric dam failed.
SLFMR's plans were thus duly amended and project was put into the hands of the architect Abel Gotteland (1851-1925).
The Rhône's "anneau bleu"
Between 1893 and 1899, some 3000 labourers - 12 times as many as had worked on the construction of the Eiffel Tower - set about the mammoth task of digging the new Canal de Jonage, the Barrage de Jonage and the reservoir, which was given the imaginative name Le Grand Large.

Chef de projet Abel Gotteland
The overflow system or "spillway" was impressive enough. Situated on the north side of the river just above the mouth of the Grand Large, the Déversoir d'Herbens comprised five semicircular basins side by side, through which water could be emptied into the adjacent fields.

However the centrepiece of the project was undoubtedly the 166m long and 11m high triple-level hydroelectric dam dubbed the Barrage de Cusset, designed by Albert Tournaits. Its neoclassical eastern façade, comprising two side wings with regular spans and a central avant-corps with a terraced roof and corniced windows, was said by the architect to have been inspired by Empress Sissi's Schönbrunn Castle in Austria.

To add extra force and therefore produce more electricity, the water in the canal was made to drop by up to 12 metres as it passed through the dam. A double lock alongside the dam ensured that boats could still pass by.

The 16 turbines inside the Barrage de Cusset
The inside of the dam was equally impressive, housing 16 turbines that could each generate 3800-4800kW.

Completed in 1899, the project proved an instant and overwhelming success. Not only did it indeed tame the fickle Rhône, from the outset the dam generating fully four times as much electricity than all of France's 136 other hydroelectric dams combined. 

The hydroelectric dam was also an economic success. From a mere 73 electricity subscribers in 1897, it had a thousand in 1899 and four times that figure the following year. By 1910, SLFMR had 40,000 customers, including of course the textiles, chemicals and auto industry. Marius Berliet, for example, used SLFMR electricity to drive his massive factories in Monplaisir and elsewhere. 

Indeed in more ways than one, the arrival of the dam and thus plentiful electricity helped thrust  Lyon into the modern era, since SFLMR laid underground electricity lines throughout the city for use in street lamps, factories and homes from as early as 1897 - in other words, long before the canal project was completed.

Cusset dam seen from the downstream side. The double lock is to the left.
Not surprisingly, therefore, the undertaking was honoured at the 1900 world's fair in Paris. Jean Sarrazin even wrote a poem about the glory of the canal, entitled "Jonage, de ton sein va chasser les ténèbres" (Jonage, your breast will chase away the darkness).

But SFLMR didn't rest on its laurels. In 1905, it applied for permission to add a thermal power plant to its hydroelectric one. However, this meant more than tripling the maximum permissible water flow-rate through Cusset Dam and required the construction of yet another dam further upstream, the Barrage de Jons, at the very top of the Canal de Miribel. Approval for this was finally given in 1939, though the necessary upgrading of Cusset's turbines lasted until 1952.

The déversoir - just in case
The Barrage-Usine de Cusset has remained in operation to this day. Nationalised in 1946, it became part of the new Electricité de France (EDF), which as recently as January 2002 was granted a  40-year extension to its licence. 

The dam still produces enough electricity to supply the needs of about 100,000 consumers, or about the population of Villeurbanne, Lyon's "tenth arrondissement".

Locate Cusset dam on Google Maps

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