The source of the Saine, a karst spring

The Saine, or formerly the “Sène” springs from an intimate location at the foot of a rocky amphitheatre under the eastern slope of the Croz Mont mountain forest. Its waters have travelled a long way underground through galleries that have been carved over time into the limestone. Its flow rate varies, not according to the rainfall on that day or the previous day, but according to the rainfall having occurred several days before over the massif. The source once sprung from much higher up in the rocky fault. Today, it only uses these old exits during times of high flow rates. Above Foncine-le-Bas, the flood and temporary waters of the Creux des Joyaux are said to occur due to excess waters in the Saine’s underground reserves.