WITH a year to go to the Olympics, Paris is in the final phase of a historic clean-up which will soon see swimmers and divers back in the River Seine.
Banned for a century because of the filthy water, city swimming is set to be one of the major legacies of the Games thanks to a €1.4bn (£1.2bn; $1.6bn) regeneration project universally hailed as a success.
Not only are three Olympic events – triathlon, marathon swimming and paratriathlon – scheduled to take place in the Seine in central Paris, but by 2025 three open-air swimming areas will be accessible from the quayside.
“When people see athletes swimming in the Seine with no health problems, they’ll be confident themselves to start going back in the Seine,” predicts Pierre Rabadan, deputy Paris mayor in charge of the Olympics. “It’s our contribution for the future.”
Like many Western cities, Paris saw its river quality decline drastically thanks to upstream industrial sewage and the sanitation demands of a burgeoning population.
Aquatic life suffered to the point where in the 1960s only three species of fish were recorded in the city. In 1923 the authorities banned swimming, though an annual Christmas cross-river competition survived until World War Two.
One of the main problems has been the 19th Century “single-system” drainage infrastructure, which unites used water from kitchens and bathrooms with sewage from toilets.
In normal times this flows through a complex of under-street tunnels to treatment centres in the outskirts. However when there is heavy rain, the system is saturated and the excess has to be drained into the Seine.
Improvements over the last 20 years have already led to a sharp reduction in faecal bacteria entering the river.
“But the difficulty has been in eradicating those last few percentage points to ensure it can be officially classified as clean,” says Samuel Colin-Canivez, chief engineer for sanitation at Paris city hall.