Despite the creation of many rainwater reservoirs, such as the Bassin d’Austerlitz, which collect rainwater and release it slowly after bad weather, if enough rain is concentrated in a low enough time, not all that falls from the sky can be captured. In this case, the runoff water has to be released into the river, which increases bacteria levels.
“[Weather] variability due to climate change is a serious problem that will only make things more difficult,” Dan Angelescu, CEO of water monitoring start-up Fluidion, said at a July 31 news conference at the company’s office in Alfortville, just outside Paris. The company makes remote water sampling devices that send readings to a central database, and since 2016 has worked with the Paris authorities to provide water analysis at the Bassin de la Villette, a separate swimming area north of Paris that is already open to public swimming.
“If new drainage projects are not implemented in the coming years, it is very likely that swimming in the Seine and the opening of recreational and sports areas will be dependent on weather conditions, with bathing bans in place after rainy days,” says Loïs Mougin, a PhD candidate in exercise and environmental physiology at the School of Sport, Exercise, and Health Science at Loughborough University.
Even without an increase in extreme weather, keeping the Seine clean enough to swim in the face of normal weather events — such as regular summer rains — is a major challenge, says Jean-Marie Mouchel, a professor of hydrology at the Sorbonne. “There are also many non-exceptional weather events that affect water quality. We need to make the system more efficient at improving water quality in the face of these events.” Water quality data from last summer backs up that point. The Seine was unswimmable about 30 percent of the time — but Paris didn’t face extreme rainfall a third of the time.
Experts say the way water is monitored, and what information is made available to the public and when, also needs to improve. “It’s crucial that bacteriological data is released daily, along with information on associated risks,” Mougin says. These include potential gastrointestinal problems, eye and skin infections.
“Monitoring is going to be critical,” Angelescu says. “Having technology that can monitor the right risks, measure the real risk from all the bacteria, and provide results quickly is going to be incredibly important.” Conventional monitoring methods, which were used to make decisions in the triathlon (and did not involve Fluidon), involve taking samples from a river and sending them to a lab—a process that is much slower than real-time monitoring.
Therefore, Fluidon tested its technology separately at the triathlon site near the Alexander III Bridge throughout the Games, focusing on levels E-coli bacteria to show how a faster system that includes on-site processing could work in the river. It publishes its results in near real time on open data siteand says its technology provides a more true and timely picture of water conditions.