Superb site, at the downstream outlet of the Jonction canal on the Aude river. This canal, put into operation in 1787, allows to make the connection between the Canal du Midi and the Canal de la Robine de Narbonne. The Gailhousty site consists of a lock, a spillway, a bridge and a dry dock. Upstream of the lock, the canal is protected from the floods of the Aude thanks to a system of dikes which surround it up to Sallèles-d'Aude.
Downstream of the lock is a space designed to be able to be submerged during heavy floods: the spillway.
The bridge is designed to allow rapid access to all points of the site, is of a neat architecture, with a low arched vault and four quarter-circle staircases placed at each corner. In times of flood, it is necessary to be able to react quickly and maneuver the defense systems in time. Placed on the downstream head of the lock, it participates in the system of containing the strongest floods.
The monumental spillway, 30 meters long, is located on the left bank of the canal between the Gailhousty lock and the Aude. Its front facade on the canal side is pierced with vertical crenellations that plunge into the water.
At the back, it has 5 arched openings at the foot of which launches an 8km long landing channel called "La saignée" directed towards the Capestang pond.
This building houses no less than 15 oversized valves. It is not intended to evacuate excess water from the Jonction canal but must allow the passage of flood water from the Aude river. Originally, it was planned that this water loaded with fertile silt would be directed into the Capestang pond to fill it and promote crops there.