While most of the world worries about how to stop sea levels from rising, engineers in a corner of Normandy are working on a €220 million project to do just the opposite: raise tides back up.

Mont Saint-Michel, with its Gothic abbey perched on a granite islet off the Normandy coast, is both a feat of human will and a marvel of rugged natural beauty. At low tide, it is encircled by dangerous quicksand. At high tide, the sea surges in as fast as a trotting horse, filling the bay with surf.

Over time, the islet has lost some of its grandeur. In fact, it is no longer much of an island: the coast is creeping in. Human development is mostly to blame. A 19th century causeway leading to the Mont stopped currents from flowing freely and flushing silt far out to sea. With tons of extra sediment dumped into the bay, 25 hectares of salt marsh are gaining on the Mont annually.

If we do nothing, Mont Saint-Michel will be surrounded by grass in 2042,” said Francois-Xavier de Beaulaincourt, the engineer overseeing the state-financed project to undo the damage. After an expected green light from the Government, major work is to start in early 2006.

The project aims to be gentle with the bay’s unique ecosystem. A new reservoir will be built on a local river to boost its power to flush out sediment, without disrupting the seals, amphibians and shellfish who live here. A new dam with eight sluicegates will also help guide sediment downstream. The Mont will stay open to tourists during work, scheduled to end in 2009.
The causeway and its ugly parking lot will be ripped up. Visitors will park cars inland, taking a shuttle or walking across a delicate new bridge that will let water pass underneath. By 2042, scientists say, the seabed’s level should drop by 70cm, with tides swirling freely again.

For centuries, the faithful trekked to the Mont from across Europe, risking their lives along the final stretches of quicksand. The first small shrine was built on the rock about 1300 years ago, by a bishop who said he was following orders from the Archangel Michael, who visited him in a dream.

The abbey has outlasted fires, tidal waves and attempted invasions. During the French Revolution, it was converted into a prison and its Benedictine monks banished – prompting a campaign to save the Mont. Victor Hugo compared it to the wonders of Ancient Egypt, writing that “Mont Saint-Michel appears like something sublime, a marvellous pyramid”.
Today, the Mont draws three million visitors a year, making it France’s third largest tourist destination after the Eiffel Tower and the Palace of Versailles. Naturally, plans to touch the beloved landmark have stirred passions.

Bay tour guides, trained to navigate surf and quicksand, fret about unforeseen consequences of tampering with the tides. They worry the project may leave the bay filled with pockets of water, making it impossible to hike through.
“They want to sacrifice the bay for the sake of Mont Saint-Michel,” says guide Stephane Gueno, who fell in love with the region’s nature as a child. “They’re thinking mainly of mass tourism.”

The project’s backers say fears of pooling water are unjustified. To ensure the plan would work, scientists built a 900m2 scale model in a hangar. Using data from 1975, they simulated 22 years of tide movements until the model matched up with the bay as it was in 1997. Then, sure the model was accurate, they tested ways to reroute the water.
The project’s manager acknowledges that tampering with the bay will bring unknowns in the distant future.
“We have a very precise idea of what will happen 50 years after construction, and a good idea of what will happen this century,” says de Beaulaincourt. “But after that, there are parameters we can’t master. Could there be a global warming that would raise the level of the sea, for example?”

Managers have also fielded questions about the project’s ballooning price tag, which has delayed the cash-strapped Government’s final approval. The price has tripled from the estimate a decade ago of €74 million.
By comparison, Italy’s plan to protect Venice – called the Moses project for the biblical figure who parted the Red Sea – will cost €3.33 billion. Due for completion by 2010-11, it envisions hinged barriers built on the Adriatic seabed that would rise when high tides threaten the city.

Mont Saint-Michel Mayor Patrick Gaulois, whose office overlooks the bay and grassy marshes where sheep graze, says he often thinks about the irony of the projects on opposite sides of Europe: one to save a city from water, and one to save the water from the land. He cannot imagine the Mont surrounded by grass.

“There’s a kind of magic in this place, to see the abbey in the middle of the sea,” Gaulois says. “It has outlasted 1000 years of storms, and I tell myself, it’s indestructible, nothing can happen to it.”