Fonseranes locks can be easily reached thanks to a marked-out route as far as Orb aqueduct, and it is not-to-be-missed if you are looking to discover the engineering structures of the Canal du Midi.
Fonseranes locks is undoubtedly the most spectacular sight on the Canal du Midi! The eight successive locks (oval-shaped of course) and 9 lock gates allow boats to cross an impressive 21.50 metres in height difference!! This is one of Pierre-Paul Riquet's ingenious creations.
From Toulouse, the Canal du Midi arrives in Béziers with a 54-kilometre-long canal pound (section without locks). The canal remains at an altitude of 31.54 metres for this section. But at Fonseranes, the canal needs to suddenly lose 25 metres in altitude to reach the Orb river, which is a compulsory section for boats sailing to Adge.
For the canal to cross this huge height difference and reach the Orb, an extraordinary lock was built. Riquet had already found a successful solution to this in Castelnaudary, and so he knew that the secret was to build a lock with multiple lock chambers.
Bearing in mind the height difference between the canal and the river, Riquet and his team decided to build eight successive lock chambers, so double the amount at Saint-Roch lock in Castelnaudary! Construction work on Fonseranes locks began in 1667 and was completed in 1680.
It is an impressive engineering structure! It is 315 metres long and covers a total height difference of 21.18 m, making it the biggest staircase lock ever built in France.
Between 1854 and 1856, the construction of the Orb aqueduct meant that Fonseranes locks needed to be modified. This structure meant that the canal now passed 16 metres up over the river.
From then on, the lock reached the river at the 7th lock chamber. The normal level of Orb canal pound was fixed at an altitude of 17.94 metres, therefore taking the total difference in height down to 13.60 metres. Since 1856, boaters have only needed to pass through six of the Fonseranes lock chambers.
However, the 7th and 8th lock chambers could still be used whenever boats needed to reach the Notre-Dame canal pound.
We speak of nine locks in Béziers, but also of an eight-chamber lock… Originally, there were eight chambers and nine sets of lock gates to cross through. But in 1856, when the Orb canal aqueduct was opened, the connection to Fonseranes locks and the new route was created at the 7th lock chamber. So a boat sailing from Toulouse to Marseillan has to pass through 6 chambers. But there are still 8 altogether at Fonseranes.
Upstream from Fonseranes locks, there was a welcome service for the 'barque de poste' barge for travellers either arriving or departing from this location. At this mooring point, there was also an inn and stables.
These buildings now house the tourist office where you'll find all the information you'll need for exploring the area. You can also go to an interactive cinema showing here called 'Voyage dans le temps sur le Canal du Midi' (Travel back in time on the Canal du Midi). There's also a restaurant with a great view of Saint-Nazaire cathedral.
Did you know?
In Occitan dialect, font means a spring and seranne appears to mean a hill. So could it be a mountain spring that gave its name to this famous lock? The spelling has also changed a lot throughout the centuries: Fontcerane, Fontcerannes, Fonséranes, Fonsérane, Foncerannes, Fonceranes...
So many different spellings have been used, from the original plans to old postcards, and the detailed plans describing the Béziers lock. 'Fonserannes' was the chosen spelling in official Canal du Midi documents for a long time. This is also the spelling you will see on the plaque at the lock keeper's house. Over the past ten years or so, the version from the Petit Robert dictionnary has been adopted as the standard spelling: Fonseranes.
At the end of the 1970s, the French State initiated a modernisation programme for the Canal du Midi and its branches. On the Canal du Midi route, the locks were 30 metres long and 6 metres wide at the lock gates. The modernisation programme involved extending lock chambers to 40 metres in length, in accordance with the Freycinet gauge, to allow 38.50-metre-long barges to pass through.
This work began on the Canal de Garonne from 1970 to 1974, and then at either end of the Canal du Midi. But they encountered a problem in Béziers, because it wasn't possible to modernise the Fonseranes locks without changing the entire system!
The solution was to build a water slope, just like the one that had already been built at Montech (Tarn-et-Garonne) on the Canal de Garonne.
The idea was that a boat would enter a chamber filled with water and a tractor mounted on tyres would be used to pull the boat upstream or downstream by moving the volume of water using hydraulic cylinders.
The construction work began in 1979 but was suspended in 1984. The system worked but was not very reliable and so the slope ended up being abandoned.