JO Paris 2024. The Seine finally clean ? The river was suitable for swimming for several days at the end of June

La Seine a été propre à la baignade plusieurs jours de suite fin juin. imageBROKER.com – imageBROKER/Jearu

La Seine a été propre à la baignade plusieurs jours de suite à la fin du mois de juin, ont annoncé la mairie de Paris et la préfecture de la région, ce jeudi 4 juillet.

The Seine was clean for swimming for several days in a row at the end of June, for the first time since the weekly publication of results during the month, according to the results of bacteriological analyses published on Thursday, four weeks before the Olympic events planned in the river.

Results linked to good weather

These first good results, linked in particular to sunny weather in the first days of summer, were obtained despite a flow of the river "four to six times" higher "than the usual summer flow", underline the town hall and the regional prefecture in their weekly bulletin.

Despite this, “the quality of the water in the Seine has improved” to become "complies with the thresholds defined by the European directive over six days" for "almost all four points" collection, they congratulate themselves. For both authorities, this improvement "is the consequence of the return of the sun and heat", but also "of the work carried out as part of the Plan to improve the water quality of the Seine" that they have been co-piloting since 2016.

The readings for the week of June 24 to July 2 show concentrations of fecal bacteria Escherichia coli below regulatory thresholds on June 26, 28, 29 and July 2 on the four sites of levy. On June 27 and July 1, only one site displayed a concentration above the threshold of 1,000 colony-forming units (CFU)/100 ml, the limit set by international sports federations for give the green light to the tests.

Plan B consists of postponing the tests for a few days

The high concentration at the Pont Marie on June 27 "could be due to occasional local pollution which did not have any effect. rsquo;impact on the downstream", estimate the local authorities. The concentration of enterococci, the other fecal bacteria measured to authorize or not sports events and swimming, was below the regulatory thresholds these same six days. The moment of truth is approaching for the organizers of the Games: after the opening ceremony, the Seine must host the triathlon events (July 30 and 31, August 5), swimming-marathon (August 8 and 9) and paratriathlon (September 1 and 2).

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 before the Games are intended to prevent. If these structures prove insufficient in the event of heavy rain, plan B consists of postponing the tests for a few days, but not changing location.