The critical feature of the Canal du Midi was to provide sufficient water to ensure that the lock system continued to function, even through the summer months.
[1] In 1668 Riquet built a loading basin, near Revel, on the rigole de la plaine between Pont Crouzet, on the river Sor, and Naurouze, called Port Louis.
The feeder between this point and Naurouze was expanded in order for boats to ferry stones.
[1] In 1669 Riquet widened the rigole de la plaine enough to support navigation.
Pierre Borel had the original idea for this feature.