A century ago, Paris buried the Bièvre because it had become a health hazard. It is now being uncovered again for much the same reason — public health, only with the threats reversed. Where the city once feared disease from a fouled waterway, it now faces heatwaves, flash floods and shrinking habitat, and an open river helps with all three.
Nearly four kilometres of the Bièvre have been restored or reopened so far, enough for it to regain its formal status as a watercourse. In the suburb of Haÿ-les-Roses, pipework has been removed, the bed excavated and the banks landscaped and planted. In Arcueil and Gentilly, the work included a flood retention area where water quality is monitored regularly. Inside Paris itself, hundreds of metres are due to surface in Parc Kellermann on the south-eastern edge of the city by 2028.
The river runs 36 kilometres from its source at Guyancourt, southwest of the capital, to its confluence with the Seine — the only tributary that flows through Paris. Its disappearance was industrial. Tanneries, dyers and laundries settled along its banks because the water was free of limestone, and their waste turned it into an open sewer. By 1912 the authorities had sealed the Parisian stretches in concrete and folded the river into the sewer system; the remainder outside the centre was closed off by 1935, and suburbs such as Gentilly covered their sections in the 1950s. "We made it disappear, like it was the river's fault," says Raphaël Morera, co-director of France's National Centre for Historical Research.
Money, sewage and the limits of digging
Campaign groups began pressing for its release in the 1980s. A 2006 French law made river restoration a national priority, building on the EU Water Framework Directive of 2000. The funding has since become substantial: in December 2025 the Seine-Normandie water agency allocated a further €68.6 million for work between 2026 and 2030, on top of €76 million disbursed from 2020 to 2024.
Much of the effort is unglamorous plumbing. Marie Bontemps, a project manager at the public body that manages the Bièvre watershed, works with residents and businesses that still discharge wastewater into the river, often without knowing it. "They think it's going into water treatment facilities, but it flows into the Bièvre," she says. Between 2020 and 2024 the wastewater load fell by the equivalent of roughly 2,400 people a day.
The river will never fully return. In parts of Paris it lies ten to 15 metres underground, beneath houses and metro tracks, and uncovering a stretch means heavy excavation and sometimes felling trees. What is achievable is patchwork — cooler corridors, retention capacity, green space.
Paris is not alone in the attempt. Seoul and Madrid have run comparable projects, and the Seine has seen biodiversity rebound after a long-term management programme. Globally, the World Wildlife Fund's Freshwater Challenge, launched in 2023, aims to restore 300,000 kilometres of rivers and 350 million hectares of wetlands by 2030.