Spillway tunnels

Upstream as downstream from the village, the entrances and exits of the spillway tunnels are located at the river level, below the paths leaving the village.

Period XX

Accessibility No

Visitable No

The violent floods of Roya have created historical damage on the walls of the village, along the river. The need to contain the floods, for the safeguarding of the lake control valve that feeds the hydroelectric plant at Piène-Basse, has benefited the banks of the village and the neighborhood facing it.

If the Roya river level is higher than the side dam’s located upstream of the village, the flood is contained and part of the water is sent through the two tunnels downstream the village. It protects the village banks of the river as well as the EDF restraint.

The structure consists of a small lateral dam on the left bank, followed by two drains leading water into the two spillway tunnels passing under the rocky ridge of the village.

The lateral dam determines the level of water preserved in the river, and lets the high water flow.

The two tunnels were dug in the Cretaceous rock. Their facade, dam and drains, were equipped with masonry stone cladding. The dam and drains were concreted afterwards for better flood resistance.

Conditions of visit

Tunnel entrance: visible from the Upper Bridge, north of the village.
Tunnel exist: visible from RN 6204 road (dangerous roadside parking) and from Libre path, after the Genoa gate.
Visible at a distance only.
Access to tunnels formally prohibited due to unpublished releases of water in Roya, from EDF dams upstream. Danger of death. (EDF : French public hydro company – Electricité de France)


Additional information


  • Botton Charles, Histoire de Breil et des Breillois, Les Editions du Cabri, Breil-sur-Roya, 1996.

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