Paris 2024 Olympic Games | Because of the rains, the Seine too polluted a month and a half before the events

Dark clouds over the Games? A month and a half before the events of the Paris 2024 Olympic Games which are to be held in the Seine, it displayed pollution levels well above regulatory standards. The fault is gloomy weather which is not over, according to the forecasts.

The rains and storms of recent days in Ile-de-France left little room for suspense. The river water quality bulletin published Friday by local authorities confirmed it: a few days before the start of summer, the Seine remained unfit for swimming.

According to the graphs posted online, the level of concentration of fecal E.Coli bacteria was greater than 1,000 colony forming units (CFU)/100 ml, the threshold used by the international triathlon and open water swimming federations to authorize the holding tests, almost every day from June 10 to 16.

In question: a “very rainy weather“catching”the high flow of the river, which does not promote good water quality“, explain the Paris town hall and the regional prefecture. “Rain, high flow, little sunshine, temperatures below seasonal norms“form one”unfavorable hydrological and meteorological context“, which explains that “water quality remains degraded“, they still remind us.

These two institutions are at the head of the Bathing Plan, in which the State and communities have invested 1.4 billion euros to make the Seine and its main tributary, the Marne, suitable for swimming. But if this plan “arrives safely“, “there is no doubt that the quality of the water today is not up to par“, recognized the regional prefect Marc Guillaume during a press briefing on the Olympics, which start on July 26.

The samples published Friday “do not correspond to the standards that we will have this summer“, he then said. “As soon as the conditions are met, the plan will be able to produce all its effects“, assured the senior official, “confident that the tests will be held at the end of July and beginning of August in the Seine“. Time is running out for the organizers, and the weather for the next two weeks does not give cause for optimism, with generally rainy weather until July 5, according to Météo France.

Suddenly rising on Friday, to more than 500 m3/second, compared to around 300 the previous week, the flow of the river poses not only a problem for the quality of the water, but also for the safety of the events. Even for the opening ceremony on July 26, an unprecedented nautical parade on the Seine, a general rehearsal of which is to be held on Monday.

The last partial rehearsal, finally organized on Monday, had been postponed for several months. “If we have too strong a flow, it poses a serious problem for the opening ceremony“, estimated hydrologist Jean-Marie Mouchel in a reaction to AFP. Contacted by AFP, the Organizing Committee (Cojo) said it had not “no particular concerns“.

Star of these Olympics, the Seine will host the opening ceremony as well as the triathlon events (July 30 and 31, August 5), swimming-marathon (August 8 and 9) and paratriathlon (September 1 and 2). But suspense remains over the holding of the Olympic events since the “test events” of August 2023 which had to be largely canceled due to insufficient water quality.

Plan B consists of postponing the tests for a few days, but not changing location. Before that, the mayor of Paris Anne Hidalgo announced on Wednesday that she would swim to set an example “after July 14, i.e. the 15th, 16th or 17th“. The original date, June 23, was abandoned due to bad weather and early elections.

In the event of intense precipitation, untreated water – a mixture of rain and wastewater – can be released into the river, a phenomenon that retention works inaugurated just before the Games are intended to prevent. The Austerlitz retention basin also operated for the first time on Tuesday during a big storm, receiving 40,000 m3 of water out of a capacity of 50,000, the town hall indicated on Wednesday.