Lac de Saint-Ferréol: the Canal du Midi's reservoir, a family day out

Riquet's dam, a soaring water jet, the Voûte des Robinets, pine-shaded beaches and a lakeside walk: our guide to the Lac de Saint-Ferréol, beneath the Montagne Noire.

The Lac de Saint-Ferréol is the great reservoir that has fed the Canal du Midi since the seventeenth century. Held back by a dam conceived by Pierre-Paul Riquet, it covers some sixty hectares at the foot of the first wooded slopes of the Montagne Noire, where the Haute-Garonne, Tarn and Aude departments meet, south-east of Toulouse in south-west France. People come today to swim, to walk around the lake, to sail, or to understand, by stepping inside the dam, how water from the mountains found its way to the Mediterranean. From the Château du Falga it is one of our favourite outings: some twenty minutes by car, via Revel, for a whole day of history and fresh air.

Why did Riquet build a lake in the Montagne Noire?

A canal that crosses a watershed must be supplied with water at its highest point. For the Canal du Midi, that point is the Seuil de Naurouze, at about 190 metres above sea level, between the Atlantic and Mediterranean basins. Pierre-Paul Riquet's genius was to realise that the water needed would come neither from the Garonne nor from the Aude, but from the streams of the Montagne Noire, captured and channelled to the watershed by feeder channels known as rigoles.

That water still had to be stored for the summer, when the streams run dry. Hence the idea of a vast reservoir in the Laudot valley, at roughly 350 metres. First sketched by the Chevalier de Clerville, commissioner-general of fortifications, the project was taken up and carried through by Riquet. The first stone of the dam was laid in April 1667, and the first filling trials took place in 1673. Riquet died in 1680, a few months before his work was complete: the canal was filled on 2 May 1681, while the reservoir was still only partly full.

Attentive readers of our Journal will notice the date: it was also in 1681 that Philippe Caffarel received the seigneury of Le Falga, a few leagues away. The Lauragais was changing, and the plain beneath our windows would soon send its wheat down to the Mediterranean by water. For the rest of the house's story, see the history of the château.

How has the Saint-Ferréol dam lasted three centuries?

The Saint-Ferréol dam is regarded as the first dam designed specifically to supply a navigation canal, and as the oldest large French dam still in service. Its dimensions convey the ambition behind it: an embankment some 780 metres long and around thirty metres high, more than 140 metres thick at its base. In its day it was the largest structure of its kind in France.

The story does not end with Riquet. A few years after the canal opened, Vauban, inspecting it, judged the water supply insufficient. From 1686–1687 the main wall was raised and the downstream embankment strengthened to increase the reservoir's capacity. In the same campaign Vauban had the Voûte des Cammazes bored, a tunnel that lets the Rigole de la Montagne pass through a ridge to reach the lake. We devote an article to it: Vauban's tunnel at Les Cammazes.

The system still works on the same principle. The Laudot and the Rigole de la Montagne, which gathers the waters of several Montagne Noire streams (the Alzau, the Vernassonne and the Lampy among them), fill the lake. On the way out, the water joins the Rigole de la Plaine, which runs down across the Lauragais to the Seuil de Naurouze. The whole journey is told in our article on the rigole and the waters of the Montagne Noire. The dam now belongs to Voies navigables de France, which manages the canal.

Is the Lac de Saint-Ferréol a World Heritage Site?

Yes, together with the canal. When the Canal du Midi was inscribed on UNESCO's World Heritage List in 1996, it was not only the ribbon of water between Toulouse and the Étang de Thau that was recognised, but an entire hydraulic system, of which the Bassin de Saint-Ferréol is the centrepiece. The lake had already been listed as a protected site in 1944, and the dam was added to the supplementary inventory of historic monuments in 1997. The official listing can be found on the UNESCO World Heritage website.

What to see below the dam: the water jet, the Voûte des Robinets and the park

The most surprising part of the visit lies downstream of the embankment. In the nineteenth century a romantic English-style park was laid out beneath the dam, planted with exotic trees, crossed by shaded paths and enlivened by cascades. Its most famous curiosity is the gerbe: a jet of water, driven by the pressure of the lake alone, that rises more than twenty metres. Children look for it the moment they enter the park; adults marvel that a fountain can work without a single pump.

Inside the structure itself, the Voûte des Robinets is the other highlight. This vaulted gallery, about 70 metres long, runs beneath the embankment to three nineteenth-century valves once used to regulate the flow of water leaving the lake. You can hear the mass of water rumbling overhead. The gallery is visited on a guided tour with light and sound effects; bookings are made online, and we advise checking available slots before you set off.

Tours start from Le Réservoir, espace découverte du canal du Midi, housed in the former engineer's house at the foot of the dam. It first opened in 2008 as the Musée et jardins du canal du Midi; under its new name it now presents the history of the canal, the figure of Riquet and the men who built it, its engineering works and its water-supply system. Temporary exhibitions complete the visit; one recently marked the first filling of 1673. Opening hours and visiting conditions change with the seasons, so check with the Aux sources du canal du Midi tourist office in Revel.

Where can you swim at the Lac de Saint-Ferréol?

The lake is lined with pine-shaded beaches where families from Toulouse have long come to keep cool. Swimming is supervised in summer, in July and August; outside supervised hours and periods, you swim at your own risk. Diving from the dam is forbidden, and you quickly see why when you take in the height of the structure.

A few tips, drawn from our own days by the water:

• Arrive early at summer weekends: the lake is very popular and the shores fill up quickly by late morning.
• Plan for shade and a picnic: the pines offer pleasant shelter from the sun, and several restaurants line the lake for those who prefer to lunch at a table.
• Bring water shoes for younger children, depending on which shore you choose.
• Save the water jet for late afternoon: after the beach, a shaded stroll through the park is the perfect transition before heading home.

Walking around the lake: how long does it take?

The lakeside walk is an easy loop of about 4.5 to 5 kilometres, almost flat. Allow an hour to an hour and a half at a gentle pace, more if you stop often. Part of the route is shaded by pines, and the regional tourist board describes it as accessible to pushchairs and wheelchairs along most of its length.

Along the way you cross a footbridge near the village of Saint-Ferréol, step across the Laudot on stepping stones, and see the lake from ever-changing angles: the long straight line of the dam on one side, the wooded hills of the Montagne Noire on the other. The keenest can extend the walk by going down to the water jet, or continue by bike along the Rigole de la Plaine greenway, which reaches the Canal du Midi in about fifteen kilometres.

Which water sports can you enjoy on the lake?

The lake is also a leisure lake. The Espace sport et nature La Calypso offers, depending on the season, canoeing, sailing and pedal boats, as well as mountain biking and a treetop adventure course for a change of pace. Teenagers often find their happiness there while younger children stay on the beach. As always, activities and opening days vary, so it is best to check before you come, especially outside July and August.

How to plan a family day out from Le Falga

The lake is about twenty minutes from the château by car, via Revel. Here is the day we often suggest to our guests:

• In the morning, the Revel market if you are there on a Saturday, under the great fourteenth-century covered hall. It is all described in our article on Revel, the bastide and its market.
• Late morning, a visit to Le Réservoir and, if you have booked, the Voûte des Robinets: an hour of discovery that gives meaning to the rest of the day.
• Lunch, a picnic under the pines or at one of the lakeside restaurants.
• In the afternoon, a swim or the walk around the lake, then a stroll through the park to the water jet.
• In the evening, return via Sorèze, a few minutes away, to see the abbey school where the Caffarelli brothers studied: Sorèze and its abbey school.

Out of season, the lake changes character. The beaches empty, the pines smell of resin, and early-morning mist clings to the ridges of the Montagne Noire. It is the ideal time to walk around the lake with binoculars round your neck and to visit the site in peace. For more ideas nearby, see our guide Lauragais: what to see and do.

Frequently asked questions

Can you swim in the Lac de Saint-Ferréol?
Yes. Swimming is supervised in July and August on the beaches along the lake. Diving from the dam embankment is forbidden.

How long does it take to walk around the lake?
The loop is about 4.5 to 5 kilometres and takes an hour to an hour and a half, on an easy and largely shaded path.

Is the Lac de Saint-Ferréol part of a UNESCO World Heritage Site?
Yes, as part of the Canal du Midi, inscribed in 1996 together with its water-supply system, of which the Bassin de Saint-Ferréol is the main element.

What is the Saint-Ferréol water jet?
It is a fountain in the park below the dam, powered solely by the pressure of the lake, which rises more than twenty metres high.

Staying at the Château du Falga, close to the lake

We love seeing our guests come back from Saint-Ferréol with their hair still wet, full of stories about the water jet and the underground gallery. The château welcomes up to 21 guests in summer, with its pool and park, for large family gatherings; the Petite Maison, a cottage for four, is let all year round and is perfect for autumn walks around the lake. To plan your stay, write to us.

To find out more, the regional tourist board offers a fine presentation of the site: From Saint-Ferréol to the Canal du Midi.

Sources: Tourisme Occitanie (Lac de Saint-Ferréol; De Saint-Ferréol au canal du Midi), UNESCO – Canal du Midi, Mérimée database via Monumentum (Saint-Ferréol dam, historic monument listing 1997), French Committee on Dams and Reservoirs (Saint-Ferréol dam monograph), Wikipedia (Bassin de Saint-Ferréol), France Vélo Tourisme and Vinci Autoroutes (Le Réservoir, espace découverte du canal du Midi), Banque des Territoires (opening of the Musée et jardins du canal du Midi, 2008), Visorando (lake loop).