 Prior to the opening of the aqueduct in 1858, the Canal du Midi traversed a short section of the Orb itself.The opening of the aqueduct allowed boats to avoid the sometimes dangerous and unpredictable river which often caused extended delays - in 1779 exceptional floods caused the river section to be impassable for seventeen days.Various schemes were proposed to bypass the Orb; an aqueduct of over 1 km in length was proposed in 1739 and in 1756 a plan to carry the canal in a tunnel "under" the Orb was put forward.