Val d'Arguenon

The Arguenon River in Jugon-les-Lacs, winds its way through Jugon history.

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The Arguenon (Breton: Argenon) is a 53.4 km coastal river in the Côtes-d'Armor department of Brittany, France. It rises near Le Gouray in the Mené region and flows northward into the English Channel (Bay of Arguenon) near Saint-Jacut-de-la-Mer and Créhen. Its course is closely tied to Jugon-les-Lacs, a Petite Cité de Caractère whose development and identity have been shaped by water for over a millennium.

 

Medieval Foundations (11th–13th Centuries)

In the 11th century, the powerful Counts of Penthièvre (notably Eudon) chose a strategic rocky spur at Jugon, naturally defended by the Arguenon and the Rosette rivers, to build a castle. This site became a key stronghold in the Penthièvre region. The town grew around it, with the river and associated wetlands providing natural defenses, fish resources, and power for mills.

 

Monks from the Abbey of Marmoutier (Tours) played a major role in the 13th century by draining marshy areas and creating the Grand Étang de Jugon (about 60 hectares), initially for fish reserves and milling. Numerous mills along the Arguenon and its tributaries (e.g., Rosette, Rosaie, Rieule) ground grain, fulled wool, and processed oak bark for tanning, generating seigneurial income and supporting local crafts. The river system turned Jugon into an important economic and defensive center during the Wars of Breton Succession.

 

Early Modern to 19th Century

The medieval castle was largely destroyed under Cardinal Richelieu in the 17th century. The Arguenon remained vital for local agriculture, transport (navigable in sections downstream toward Plancoët), and small industry. 19th-century canalization and infrastructure improvements (bridges, quays) supported modest commerce, though upstream sections stayed rural and sinuous.

 

20th–21st Century Transformations

The river's modern landscape was profoundly altered in 1972 with the construction of the Ville-Hatte dam (near Pléven). This created the large Lac de l'Arguenon (reservoir of ~200 hectares, over 10–17 km long), primarily to supply drinking water to the department via a treatment plant. The lake submerged parts of the valley, forming a scenic but regulated body of water spanning multiple communes (Jugon-les-Lacs, Plédéliac, Plorec-sur-Arguenon, Pléven).

 

Today, Jugon-les-Lacs is defined by its dual lake system: the historic Étang de Jugon and the newer Lac de l'Arguenon. The river supports biodiversity (trout upstream, pike/perch/sandre in lakes), fishing, hiking (e.g., around the lakes), and tourism. It has faced challenges including floods (notably 1974 and 2010), sedimentation, and eutrophication in the reservoir.

 

The Arguenon embodies Brittany’s intimate relationship between human settlement, water management, and nature — from medieval fortifications and monastic engineering to modern water security and leisure. Its history at Jugon-les-Lacs illustrates how a modest coastal river has sustained, defended, and defined a community for nearly a thousand years.