 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.It was to collect water from the Alzau stream, as well as others, and divert them to the River Sor at Conquet.In 1664, Louis Nicolas de Clerville had the idea for a single large dam of the Laudot valley near Saint Ferreol, which became the Bassin de Saint-Ferréol.