New dam saved Mont-Saint-Michel's island status, Macron says

French President visited the Unesco world heritage site on its 1,000th anniversary

France's Mont-Saint-Michel during President Emmanuel Macron's two-day visit to Normandy. Reuters

A new dam and infrastructure works have saved the famous Mont-Saint-Michel abbey's status as an island by reversing the silting of its bay, French President Emmanuel Macron said on Monday.

An old dam across the Couesnon River in front of the mount protected agriculture and the nearby town of Pontorson from floods.

But it also stopped the river's vigorous outflow during low tide, which had flushed sediment out into the bay and for centuries helped Mont-Saint-Michel to remain an island during high tide.

Gradually, the island was turning into a rocky hill in the sand, surrounded by water only during spring tides a few times a year and connected to the mainland with a causeway that further slowed the water's flow and became an unsightly parking lot.

"In order to transmit, one must preserve," Mr Macron said during a visit to celebrate the monument's 1,000th anniversary.

"But for decades, Mont-Saint-Michel threatened to silt up completely, which would have realised the old dream of English generals to take the mount as if it was a hilltop amid fields."

He said a new hydraulic dam project started in 1995 and completed in 2015 was now proving it is able to gradually flush sand out of the bay.

"In just a few years, the silting up of the bay has been stopped and we have restored the possibility of an island," Mr Macron said.

In recent years, the parking lot has been moved inland, and visitors can now access the site with only shuttle buses, on foot or by bicycle over a new bridge on stilts that lets the water pass under it.

A Unesco world heritage site since 1979, the Mont-Saint-Michel is one of France's top tourist attractions, with nearly 2.8 million visitors in 2022.