Rigole de la montagne

The rigole de la montagne (English: trickle of the mountain) was an important facet of the Canal du Midi, engineered by Pierre-Paul Riquet in southern France.

Each boat traversing its length would require a large quantity of water in the locks in order to climb or descend.

To placate mill owners fearful that they would lose too much water from the Sor, the rigole de la montagne would supplement the Sor upstream from the rigole de la plaine at Conquet.

He also had the idea of digging a tunnel through the Cammazes ridge to connect the rigole de la montagne to the reservoir in the valley without utilizing the Sor river at all.

The path included a 121-metre (132 yd) long, 2.7-metre (9 ft) diameter tunnel at the village of Les Cammazes.