Each autumn, the Heritage Days fling open the doors to places usually off-limits in Île-de-France, from gilded salons to the treasures of the region’s civil engineering. On the weekend of September 19 and 20, 2026, the event invites curious children and adults alike to view river heritage with fresh eyes. It’s an opportunity to set foot on the quays of Chatou and discover how the Seine is tamed in daily life.
Nestled in the heart of the Island of the Impressionists, the commune of Chatou instantly evokes the the Maison Fournaise, where Renoir painted the canotiers at table. Yet, just a few metres from these bucolic banks, art yields to technical prowess. Built initially in 1933 with imposing lifting gates, the first dam already regulated the river's flow downstream of the capital.
Fully modernized by Voies navigables de France (VNF) between 2009 and 2013, the site today stands as France’s largest flapgate dam. Its main mission: keep a constant water level to ensure commercial and recreational river navigation, while helping to prevent floods. Set lower than its 1930s predecessor, the contemporary structure was designed to blend into this classified landscape, without breaking the horizon cherished by 19th‑century painters.
Crossing the service footbridge offers a direct glimpse of the river’s churn and the dance of its moving sluice gates. Local lore says that old lockkeepers sometimes helped stranded makeshift boats that had drifted away from nearby guinguettes, a folklore that only adds to the site’s charm. Beyond the hardware of the valves, the structure also houses a fish pass. This engineered passage lets migratory species, from eels to sea trout, move upstream without hindrance, preserving the ecological continuity of the Seine basin.
An on-site visit offers a window into the delicate balance between human activity, river logistics, and the preservation of biodiversity in Île-de-France. Read on to discover the full lineup of tours and activities planned for this exceptional weekend:
Visit to the Chatou Dam
On the occasion of European Heritage Days 2026, Voies navigables de France invites you to (re)discover the world of inland waterways.
Freight transport, leisure boating, biodiversity preservation, nautical recreation, agriculture, industry—the 6,700 km of rivers, streams and canals managed by VNF across France connect regions and activities, drawing on more than a thousand navigation structures rooted in national heritage and decisively geared toward the future.
In 1933, the first Chatou dam was built and put into service to regulate the river. Obsolete and difficult to manage, it was demolished 80 years later and replaced by a new automated model that delivers more effective regulation of the water body, especially during floods.
In its imposing scale and its landscape integration within a classified site (Île des Impressionnistes), thanks to architect Luc Weizmann and the technical finesse of the construction methods, the Chatou dam today stands as a benchmark in the field of public works and civil engineering.
It is the largest sluice dam in France—each gate weighing nearly 170 tonnes. It maintains the Seine’s level over 32 km up to the Suresnes barrage (92), and nearly 9 million tonnes of goods pass through its lock each year. The site comprises a dam topped with a pedestrian bridge, a fish passage, a lock and a control room. As part of the heritage, some equipment from the old dam remains on the left bank.
Participation requirements: Free - Free | Reservation required - https://reservation.seine-saintgermain.fr/ecluses-et-barrage-de-chatou.html, 01 30 09 39 89
Schedule: Saturday, September 19, 2026 — 10:00–11:00, 11:15–12:15, 14:00–15:00, 15:15–16:15, 16:30–17:30 | Sunday, September 20, 2026 — 10:00–11:00, 11:15–12:15, 14:00–15:00, 15:15–16:15, 16:30–17:30
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Dates and Opening Time
From September 19, 2026 to September 20, 2026
Location
Chatou Dam
1 Quai du Nymphee
78400 Chatou
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