The countdown to the thirty-third modern Olympic Games is becoming increasingly stressful for French organisers and politicians. Billions of euros have been spent on cleaning up a river that is now unfit for swimming or Olympic competitions. 

Despite politicians' optimistic claims that everything will be perfect for the opening ceremony on 26 July, the emblem of Paris 2024 remains unprepared. Excessive water flow and high levels of bacteria have caused alarm in the French capital. 

What was supposed to be a great achievement (the cleaning of the river) and its legacy is now in danger of becoming the biggest failure of the Games. Organisers are at the mercy of nature and, despite current denials, heavy rainfall in the coming weeks could wreck all plans.

The iconic river, which stretches 777km across France and flows into the English Channel, is due to host the opening ceremony on 26 July, as well as the triathlon and open water swimming events. 

Although the rainy and grey spring has given way to a dry and sunny summer, the recent rainfall has had a significant hydrological impact. The results of the river's water quality analysis, published this Friday by the Paris City Council and the Regional Prefecture with data from 17-23 June, show a significant increase in the concentration of faecal bacteria compared to the previous two weeks. 

The concentration of 'Escherichia coli' and enterococci must not exceed 1,000 and 400 units per ml of water respectively for swimming to be authorised. However, at the beginning of the week analysed, the 'Escherichia coli' concentration peaked at 13,000 and then fell to between 2,000 and 6,000 by the weekend. 

Although it sounds like a horror story, this is the harsh reality in France. At times, the water was up to 13 times the permitted limit for swimming, which was a major blow to hopes. The other bacteria, with levels that should be between 100 and 500 CFU/100 ml, were well over 1,000 and even 2,000 at times. 

"The water quality remains poor due to unfavourable hydrological conditions: rain, high water flow, low sunlight, temperatures lower than usual for this time of year and pollution from upstream," the city council and prefecture said. "We hope that the situation will improve this week, given the weather forecasts," the regional prefecture added. Prefect Marc Guillaume had already warned on Wednesday that swimming would not be allowed at the beginning of July.

Time is running out and there is no solution in sight.The usual bacteriological problem is now being compounded by the water flow, which could complicate the opening ceremony parade.

During the week under review, the flow of the river reached six times the normal level, peaking at 666 cubic metres per second on Sunday 23 June, when the normal range for this period is between 100 and 150 cubic metres. This led to the postponement of the inauguration rehearsal. Although the flow then dropped slightly, it has remained stable since Thursday at around 430 m³/s, three times the desired level.

Too much water is not only dangerous for the swimmers, but also poses problems for the planned nautical parade during the opening ceremony, as it increases the speed of the boats carrying the delegations, disrupting the precise timing of the event.

The triathlon water events are scheduled for 30 and 31 July and 5 August, with the open water swimming events on 8 and 9 August. The paratriathlon is scheduled for 1 and 2 September. Whether these events will take place as planned is uncertain and will be decided on the road.

In the event of heavy rainfall, untreated water (a mixture of rainwater and sewage) could end up in the river, a situation that the newly inaugurated retention facilities are designed to prevent. 

The city council and the prefecture noted that the rains of 17 and 18 June activated for the first time the Austerlitz dam, inaugurated at the beginning of May. 

If this infrastructure proves inadequate in the event of heavy rainfall, the organisers' plan B is to postpone the planned events by a few days. 

Only time will tell how the Seine dilemma will be resolved for Paris 2024.