Canal du Midi feeder channels: Montagne Noire water to Naurouze

Rigole de la Montagne, Saint-Ferréol, Rigole de la Plaine: follow the path of water Riquet designed, from the Montagne Noire to the Seuil de Naurouze, on foot or by bike.

A canal that crosses a watershed only lives if it can be fed at its highest point. That is the whole genius of Pierre-Paul Riquet: to fill the Canal du Midi at the Seuil de Naurouze, he went to fetch the water of the streams of the Montagne Noire, the "Black Mountain" north-east of Toulouse in south-west France, and carried it along two long channels called rigoles to the summit of the canal. The Rigole de la Montagne gathers the waters of the massif; the Saint-Ferréol reservoir stores them; the Rigole de la Plaine, some 38 kilometres long, carries them from Pont-Crouzet to Naurouze. This water supply system, still in use today, is part of the canal inscribed as a UNESCO World Heritage Site in 1996. It can now be explored on foot and by bike, just a short drive from the Château du Falga.

Why did the Canal du Midi need its feeder channels?

Linking the Atlantic to the Mediterranean was an old dream. The obstacle was not so much distance as water: between the Garonne and the Aude, the canal has to climb to the Seuil de Naurouze, the watershed between the two seas, then descend again. Every boat passing through a lock below takes some of the water of the upper reach with it. Without a constant supply at the highest point, the canal would simply drain away.

Riquet, born in Béziers in 1604 and a tax farmer in Languedoc, had spent years observing the Montagne Noire and its torrents. His idea, backed by Louis XIV in 1666, was to capture these waters on the southern slope of the massif and divert them towards Naurouze along a gentle, continuous gradient. The works employed up to 12,000 labourers; Riquet died in 1680, one year before the canal opened. According to the Occitanie regional tourist board, some 76 kilometres of feeder channels supply the canal, in addition to its reservoirs.

Keep the order of the route in mind; it will guide your visit:

the water intakes of the Montagne Noire, including Alzeau near Arfons, where the Rigole de la Montagne begins;
the Voûte de Vauban at Les Cammazes, which carries the water beneath a ridge;
the Bassin de Saint-Ferréol, a great reservoir on the Laudot stream;
Pont-Crouzet, near Sorèze, starting point of the Rigole de la Plaine;
Revel, the Moulin du Roi and the former Port-Louis;
Les Thoumazès, where the channel crosses the Laudot;
the Seuil de Naurouze, its octagonal basin and the obelisk raised in memory of Riquet.

The Rigole de la Montagne: where does the canal's water come from?

It all starts in the beech and fir forests of the Montagne Noire. The Alzeau water intake, in the commune of Arfons, lies at about 645 metres above sea level. From there, the Rigole de la Montagne follows the contour lines and collects the streams of the hillside along the way: the Alzeau, the Bernassonne, the Lampy, the Rieutort, the Galaube. In places its trench was lined with bricks to limit leakage.

In Riquet's original design, the channel emptied into the Sor river at a place called Le Conquet, nicknamed the "Saut du Sor". The river then ran down to the plain, where the water was picked up again. But experience showed that the Saint-Ferréol reservoir, fed by the Laudot alone, struggled to fill. From 1686, under the direction of Vauban, the channel was extended by a few kilometres to Les Cammazes, where a masonry tunnel of about 120 metres, the famous Voûte de Vauban, takes it under the ridge and pours it into the Laudot, upstream of the reservoir. Today you can follow the path beside the channel and walk through the tunnel, torch in hand; we devote a whole article to it: Les Cammazes and the Voûte de Vauban.

Later, other works completed the system: the Lampy Neuf dam, built in 1782, and, in the 20th century, the Cammazes dam on the Sor, built in the 1950s by the Institution des Eaux de la Montagne Noire.

Saint-Ferréol, the reservoir that changed the history of dams

Riquet's stroke of genius was to add to his channels a reserve able to see the canal through dry summers. Following a proposal by the Chevalier de Clerville, he had the Laudot valley dammed near Saint-Ferréol. The foundations were begun in April 1667. The embankment, some 780 metres long and around thirty metres high, was among the largest dams of its time; the fountain-maker Pierre Campmas and the engineer François Andréossy contributed a decisive share of their know-how. The reservoir, which holds several million cubic metres of water, was raised at the end of the 1680s, at the time of Vauban's works.

Today the Lac de Saint-Ferréol is a place for walks and swimming, but it remains a working reservoir: the water released from it rejoins the Laudot, then the Rigole de la Plaine. We tell its story in more detail in our article on the Lac de Saint-Ferréol.

The Rigole de la Plaine: from Pont-Crouzet to the Seuil de Naurouze

The Rigole de la Plaine begins at Pont-Crouzet, in the commune of Sorèze, where the Sor valley emerges from the Montagne Noire, at about 245 metres above sea level. An intake there diverts part of the Sor. Riquet cleverly reused an older medieval channel that already supplied the town of Revel from Pont-Crouzet. About two metres wide, the channel then descends over some 38 kilometres, on a gradient so slight that the water seems almost still, to the Seuil de Naurouze, at around 190 metres.

It runs along the old ramparts of Revel and reaches the Moulin du Roi, a flour mill that once belonged to the Riquet family. A little further on, the Port-Louis basin recalls a forgotten ambition: at the end of the 1660s Riquet widened the channel to make it navigable and carry stone for the works, and it was opened to boats between Revel and Naurouze around 1670. The little trading port never achieved the hoped-for success and was soon abandoned; its site is now home to the municipal swimming pool. To discover the bastide town itself, see our article on Revel and its market.

At Les Thoumazès, in the commune of Saint-Félix-Lauragais, the channel meets the Laudot coming down from Saint-Ferréol. A spillway regulates the flow here: it sends surplus water into the lower Laudot or closes the channel when levels are too high. The neighbouring keeper's house, dated 1761, shows the care lavished on the canal's buildings. The channel then passes below Saint-Félix-Lauragais and near the Lac de Lenclas, crosses the watershed near Graissens, spans the Castelnaudary–Revel railway on the Besombes aqueduct, then follows the hills of the Lauragais to Naurouze. All along the way, 59 stone bridges, wash houses and troughs tell of the life that grew up around this precious water.

On its own, this ribbon of water is the only source supplying the canal between Carcassonne and Toulouse, a stretch of more than a hundred kilometres. The channel was also listed as a protected natural site in 2001.

What is there to see at the Seuil de Naurouze?

The Seuil de Naurouze, in the commune of Montferrand in the Aude department, is the highest point of the canal. This is where the water of the Montagne Noire divides: one part flows towards Toulouse and the Atlantic, the other towards the Mediterranean. Riquet first had a great octagonal basin dug here, about 400 metres by 300, at the heart of a new town that was never built; the basin silted up quickly and was abandoned, and only a peripheral channel still traces its shape. The Écluse de l'Océan lies a few dozen metres away, the Écluse de la Méditerranée a little over five kilometres further on.

On a nearby knoll, among large boulders, stands the Riquet obelisk, raised by his descendants in the 1820s to honour the memory of the canal's builder. The avenues of plane trees, the shade and the silence make Naurouze a much-loved picnic spot, and the best place to grasp, at a glance, the ingenuity of the whole system.

Can you follow the Rigole de la Plaine on foot or by bike?

Yes, and it is one of the loveliest ways to discover the Lauragais. The service path along the channel, shaded by tall trees, is open to walkers along its entire length, and it carries the GR 653, the Arles route of the Way of St James to Santiago de Compostela. It is also part of La Véloccitanie (V84), the cycle route linking the Canal du Midi to the Mediterranean.

According to the French greenways association AF3V, the section developed as a greenway by the Haute-Garonne department runs from Revel, at the Moulin du Roi, to the Lac de Lenclas at the foot of Saint-Félix-Lauragais: just over 14 kilometres on a compacted surface suitable for all bikes. Beyond that, as far as Naurouze, the track remains an earth path for some twenty kilometres, with ruts and roots: pleasant by mountain bike in dry weather, trickier with a loaded bike and muddy after rain. A few road crossings call for caution, notably at Les Thoumazès. The climb up to Saint-Ferréol is very steep and best left to well-trained legs.

Our tips for making the most of it:

set off from Revel in the morning and ride out and back to the Lac de Lenclas, ideal with children;
to reach Naurouze, choose a mountain bike or walk, or cover part of the way on quiet country roads;
take water and a picnic: there are few places to stop for supplies along the path;
do not draw water from the channel: it is reserved for the canal.

Why are the feeder channels a World Heritage Site?

The Canal du Midi was inscribed on UNESCO's World Heritage List in 1996. The property, a 360-kilometre network of navigable waterways punctuated by 328 structures, is hailed as one of the most remarkable feats of civil engineering of modern times and as the first major canal with a summit level. UNESCO stresses that its original water supply system has remained intact: the channels and reservoirs of the Montagne Noire are therefore fully part of what makes the canal unique. To go further, the Canal du Midi page on the UNESCO website and the page on the water supply system on the official canal website are good starting points.

We love this little-known part of Riquet's work because it can be read in the landscape. No big boats here, just a slender thread of water, stone bridges, plane trees, and the certainty that without it the whole canal would run dry.

Frequently asked questions

How long is the Rigole de la Plaine?
About 38 kilometres, from the Pont-Crouzet intake near Sorèze to the Seuil de Naurouze, in the commune of Montferrand.

What is the difference between the Rigole de la Montagne and the Rigole de la Plaine?
The Rigole de la Montagne gathers the streams of the Montagne Noire, starting at the Alzeau intake, and leads them towards the Sor and the Saint-Ferréol reservoir. The Rigole de la Plaine picks these waters up at Pont-Crouzet and carries them across the Lauragais to the highest point of the canal.

Can you cycle the Rigole de la Plaine with children?
Yes, on the greenway between Revel and the Lac de Lenclas, which is flat and has a compacted surface. Beyond it, towards Naurouze, the earth track is better suited to mountain bikes and walkers.

Are the feeder channels part of the World Heritage Site?
The Canal du Midi has been a UNESCO World Heritage Site since 1996, and UNESCO highlights the integrity of its original water supply system, of which the channels and reservoirs are the heart.

Staying near the feeder channels at the Château du Falga

Revel, Saint-Ferréol, Sorèze and the Seuil de Naurouze are all easy to reach by car from Le Falga, in the Lauragais about an hour from Toulouse: enough for several days spent following the water, before returning in the evening to the shade of the park. For a large group, the château welcomes up to 21 guests; for two to four people, the Petite Maison is available all year round. Discover more of our outing ideas in the Lauragais, or write to us to plan your stay.

Sources: canal-du-midi.com (official canal website, water supply system and Rigole de la Plaine), UNESCO World Heritage Centre (Canal du Midi), Wikipedia (Rigole de la Plaine, Rigole de la Montagne, Seuil de Naurouze, Bassin de Saint-Ferréol), Occitanie regional tourist board, Tarn Tourisme (Voûte Vauban), AF3V (Rigole de la Plaine greenway).