7 Interesting Facts About the Semois

The Semois is a tributary of the Meuse. It springs from a plateau and winds its way through the valley. Deep meanders and hilltop villages characterize this picturesque landscape. The Semois originates in Arlon. Although the distance from its source to its mouth (in Monthermé, France) is only about 70 km as the crow flies, the river’s total length is nearly three times that — 195 km — due to its countless meanders!The Semois flows for about 20 kilometers through French territory, where its name is spelled Semoy. Since 2022, part of the valley has been protected as the Vallée de la Semois National Park.

This beautiful river plays an important role in the region — in the development of tourism, local recreation, spatial planning, biodiversity, heritage, and much more.

1. The Semois winds its way for 40 kilometers through the territory of Bouillon — a true water paradise!

No fewer than 40 kilometers of the Semois meander through the Bouillon area. For anglers, kayakers, hikers, mountain bikers, photographers, and nature lovers, it’s a true paradise!

There are wonderful kayak routes:

• Downstream from Bouillon: Bouillon–Poupehan/Frahan, with Semois Kayaks

• Upstream: Dohan/Sati–Bouillon, with Kayak Les Épinoches, ending in Bouillon.

The pedal boats in the city center are a favorite among families, and on sunny days, it’s a pleasure to swim in the river. You can find more information about permitted swimming areas here: www.restaurant-meandre.be/post/zwemmen-in-regio-bouillon.

2. The weir ensures enough water for recreation in summer and prevents flooding in winter

After several consecutive dry summers that left the water level extremely low, a needle weir was built in 1961 in the center of Bouillon. A needle weir consists of a series of vertical beams (“needles”) held upright by a removable frame. This mechanism keeps the water level high enough in the town’s central basin during dry months.

The weir, operated manually by the municipal services and fully opened in winter, has proven its effectiveness over the years — both in preventing floods and in maintaining sufficient water levels for leisure activities. Thanks to it, Bouillon can proudly call itself a river city — or perhaps even a riverside resort!

3. “Hunger stones”: messages from the past

In the Semois, you can find several stones engraved with messages about water levels. These are the so-called “hunger stones”, visible only during periods of prolonged drought.

Our ancestors carved such inscriptions into riverbed stones (like in the Elbe or the Rhine) during severe droughts, fearing famine as a result.On Bouillon territory, several stones dating from the 20th century can be seen during extreme low-water periods, notably near Lauwé (Germauchamps), Vannette (Les Hayons), and along the Sentier Ladmirant (near Camping Halliru).

4. The Semois once harbored freshwater pearl mussels — efforts are underway to bring them back!

According to the tale of Nignan, the last pearl fisherman, pearls could once be found in the Semois.

A few years before the war, Nignan could be seen every day leaning against the wall of the Pont de Liège. He didn’t work, was well-dressed, and everyone wondered how he made a living. One day, he confided to a friend:

As unbelievable as it may sound, the freshwater pearl mussel (Margaritifera margaritifera) once thrived in the Semois. Around 1950, several million mussels covered the riverbed, though only one in several thousand contained a pearl.

Overfishing wasn’t the only cause of their disappearance. Clean water and the presence of river trout — whose gills host the mussel larvae — are essential for their survival. Several conservation programs coordinated by DEMNA (Department for the Study of the Natural and Agricultural Environment) are working successfully to restore suitable habitats. In some streams in the province of Luxembourg, this species has already returned.

Another, also endangered species still found in the Semois is the Batavian river mussel, a freshwater mussel whose shells are easy to find — though sadly, they produce no pearls.

5. Declining fish populations and the effort to restock the river

In recent decades, fish stocks in the Semois have declined sharply for various reasons. The DNF (Department of Nature and Forests) works to maintain populations by restocking the river with trout bred in fish farms (piscicultures).

Every late April, La Maison du Pêcheur Bouillon, in cooperation with the DNF, organizes a fish restocking day — truly worth seeing!

6. The enchanting Ardennes mist — once key to the famous Semois tobacco

In the early morning, the meandering valleys of the Semois are often covered with a mysterious veil of mist: the famous Ardennes brume.

From the village of Rochehaut, this magical mist is often visible. The picturesque village of Frahan, situated on a peninsula called Les Crêtes and encircled by the Semois, is inseparably linked to Rochehaut, located over 100 meters higher. From this vantage point — classified as Patrimoine majeur de Wallonie — one enjoys a breathtaking panorama of the valley.

This brume once played an important role in the tobacco cultivation that was vital to the region. Between 1850 and 1930, Semois tobacco saw a remarkable boom: over 10 million plants were grown in the valley at its peak. Despite the unpredictable climate and challenging soil, the valley proved ideal, as the morning mist gave the tobacco its distinctive flavor.

After 1930, the cultivated area declined sharply. Today, the activity continues on a small but thriving scale. Antoine Poncelet, the last remaining tobacco grower, supplies three manufacturers — one of whom, Vincent Manil, preserves the heritage at the Musée du Tabac in Corbion. Also in Corbion, Jean-Paul Couvert, the last of a long line of tobacco producers, passionately keeps the tradition alive in his small workshop and nostalgic shop. The Semois tobacco, it seems, has not gone up in smoke!

7. The seductive Semois can also be destructive

As beautiful as it is, the Semois can also be devastating. Floods and, in harsh winters, drifting ice once caused serious damage.

In the past, during severe winters, the Semois would freeze completely. When the ice began to melt, large chunks broke loose and drifted downstream, sometimes destroying bridges, especially the wooden ones.

From that time comes the legend of “L’Homme de Chiny”: