It was the first dam in France to utilize a curved arch design to resist water pressure.
The construction was commissioned to manage the frequent water shortages impacting Saint-Étienne's industrial sector.
The dam is situated within a deep, narrow ravine known locally as the 'Gorge of Hell'.
Its creation necessitated the displacement of local stone and the use of massive granite blocks.
The reservoir behind the dam has largely silted up over the last century, transforming the lake into a wetland habitat.
It is recognized as a pioneering achievement in hydraulic civil engineering history.
The Barrage du Gouffre d'Enfer is a historic masonry arch dam located in the Gorges de l'Ondaine near Saint-Étienne. Completed in 1866, it was the first dam of its type constructed in France to provide water for the growing industrial demands of the city. The structure stands 54 meters high and is integrated into the rugged terrain of the Massif Central. It is currently part of a protected natural area popular for hiking, climbing, and outdoor recreation. The dam is no longer used for public water supply, having been decommissioned for that purpose in the late 20th century. Visitors can access the top of the dam via forest trails from the Planfoy area. The site serves as a gateway to the broader natural trails of the Pilat Regional Natural Park. Information panels on-site detail the historical significance of the dam's engineering.
The viewpoint on the trail overlooking the dam wall from the south side.
Wear sturdy, broken-in hiking boots due to the uneven and rocky nature of the trails.
Check weather reports in advance as mountain trails can become slippery after rainfall.
Carry a physical map or GPS device, as mobile signal is inconsistent within the ravine.
Do not attempt to swim in the reservoir or the surrounding waters, as it is strictly prohibited and dangerous due to debris.
Stay on marked trails to protect the fragile ravine ecosystem and refrain from climbing on the dam walls.
