There are exactly 21 days to go until the Opening Ceremony and only 19 until the first events of Paris 2024 (8 men's football matches and 12 rugby sevens matches on Wednesday 24th, the official start of the Games with the football matches between Spain-Uzbekistan at the Parc des Princes and Argentina-Morocco at the Geoffroy Guichard stadium at 3 pm Central European Summer Time).

The Seine has improved in recent weeks after months of extremely high pollution levels (up to 13 times the maximum tolerable level for humans) and a last-minute problem with rising water levels following heavy rainfall in recent weeks.

In recent days, the river has shown suitable swimming indicators for several consecutive days, but the excessive flow will force organisers to make adjustments for the Opening Ceremony and the Triathlon and Open Water Swimming (10km) events.

The improvements are largely due to the sunny weather in the first days of the French summer, although the river flow is "four to six times" higher than the "typical summer flow", according to the Paris City Hall and Regional Prefecture's weekly bulletin.

Despite this, "the quality of the water in the Seine has improved" and "met the thresholds set by European directives for six days" at "almost all four sampling points", they reported with satisfaction.

Samples taken during the week of 24 June to 2 July showed that concentrations of the faecal bacteria Escherichia coli were below the legal limits at all four monitoring sites on 26, 28 and 29 June and 2 July.

On 27 June and 1 July, only one control point showed a concentration above the threshold of 1,000 colony forming units per 100 ml, the limit set by international sports federations for the approval of events.

The concentration of enterococci, the other faecal bacteria measured for the approval of sports events and swimming, was below the regulatory threshold on all six days.

The key date for the Olympic organisers is approaching: after the opening ceremony on the river on 26 July, the Seine will host the triathlon (30 and 31 July, 5 August), the open water swimming (8 and 9 August) and the paratriathlon (1 and 2 September), which will pose a major challenge.

In the event of heavy pre-competition rainfall, which could increase pollution levels, the organisers' 'Plan B' is to postpone the affected events by a few days, but not to change the venue, trusting that nature will play a temporary trick on them.

In recent weeks, concern has shifted to the high flow of the river, which a week ago was around 500 m³/s, almost five times higher than normal for this time of year. Potential flooding is currently ruled out as the river is 1.7 metres high, with flooding occurring from 3.5 metres.

Current water levels are not affecting navigation, but have already caused the postponement of the Opening Ceremony rehearsal on 24 June.

The higher the flow, the faster the boats move, so it is "not worth rehearsing a precisely timed show with 15 minutes less", according to the Paris Prefecture, which does not consider a flow of "between 300 and 500 m³/s" to be a major problem, although it will require adjustments such as removing taller boats from the parade.

The weather forecasts for the next few days are not overly optimistic, with a risk of storms - the main concern for the organisers at the moment (apart from safety, of course).

One potential ally could be found 200km east of the capital, where four artificial lakes help regulate the river's flow. However, these reservoirs were heavily filled during the winter in anticipation of a very dry summer, so the help may not be substantial.