Fosse Dionne: where does your water really come from?

Fosse Dionne is a karst spring (a karst is an irregular region of limestone with sinkholes, underground streams and caverns) that spews an average of 311 liters of water per second, which is an unusually high discharge, although the speed with that sprouts from the ground varies from season to season.

The Celts consider this spring sacred and the French used it as a public swimming pool for a time. And no one has managed to find out where exactly the water comes from, that is, the origin of the spring, because those who wanted it, discovered in the attempt.

Fosse Dionne, which translates to “divine well”, is a circular stone pool built in the 18th century. In the Middle Ages, it was thought that there was a snake that navigated deep within the heart of the Fosse Dionne, and some even thought that it was the portal to another world. The spring features prominently in accounts of miracles performed by the 7th-century monk Saint John of Rome, who arrived in the area in 645 AD. to clean the spring, which at the time was an unusable swamp.

The great mystery of the Fosse Dionne spring is where the water actually comes from. Certainly, a lot of water comes out and, like other karst springs, the water emerges from a network of underground limestone caves. However, no diver has been able to find its origin, and many who have tried have not come back alive.

In fact, no one even attempted to plumb the depths of Fosse Dionne until 1974, when two divers set out to navigate the spring’s labyrinth of chambers and narrow tunnels. None of those divers came back to tell what they had seen. In 1996, another diver tried it.

For many years afterward, divers had been banned from diving in this pool, until the spring of 2019, when diver Pierre-Éric Deseigne undertook to explore 370 meters of tunnels. Fortunately, he returned alive, but without finding the source of the spring. Nor did he find another dimension or a monstrous snake.

Furthermore, the properties of karst springs make them unsuitable for the supply of drinking water. Its uneven flow does not allow constant consumption, especially in summer, when there is less flow but greater demand. Furthermore, poor filtering and high hardness lead to poor water quality.

Perhaps one day it will be possible to find its precise origin, which for the moment remains a mystery. Although rather a prosaic mystery.

Leave a Reply

Your email address will not be published. Required fields are marked *