Fonserannes Locks are staircase locks on the Canal du Midi near Béziers.
It consists of eight ovoid lock chambers (characteristic of the Canal du Midi) and nine gates, which allow boats to be raised a height of 21.5 m, in a distance of 300 m. Whilst the flight was built as an 8-rise, to allow boats to cross the River Orb on a level, rejoining the canal a little further downstream, the crossing of the Orb was long ago replaced by an aqueduct.
Boats now enter and exit the lower end of the flight through the side of chamber seven, which is maintained at its upper level, and it is operated as a 6-rise.
The eighth chambers, which lock down into the Orb, is now disused.
The side exit from chamber seven causes some confusion in describing the chain of locks. While most sources now ignore the disused eighth chamber in describing the flight, many sources still describe it as a 7-rise, despite the fact that chamber seven is operated at a fixed level.
Traditional buildings such as the stables and the lock keeper's house still remain. These and the locks have made the Fonserannes Lock the third most popular tourist destination in Languedoc-Roussillon, after the Pont du Gard and the town of Carcassonne. In 1983 an inclined plane was built for boats too large for these locks to bypass them, but the project encountered severe technical problems and was abandoned in 2001 (see Fonserannes water slope).
Though Pierre-Paul Riquet rightly receives so much credit and acknowledgement for the creation of the Canal du Midi, we may forget that many individual parts of the canal were built by subcontractors other than Riquet. The subcontractors for these locks were two illiterate brothers, Michel and Pierre Medailhes. Many of the workers were women.