Even though several stormwater reservoirs, such as the Bassin d’Austerlitz, have been built to capture rainwater and slowly release it after bad weather has passed, they cannot capture all the rain that falls from the sky if a sufficient amount of rain is concentrated in a short period of time. In such situations, the runoff must be released into rivers, causing bacteria levels to rise.
“Variations due to climate change are a big problem, and this only makes it harder,” Dan Angelescu, CEO of water-quality monitoring startup Fluidion, said at a July 31 press conference at his company’s offices in the Paris suburb of Alfortville. The company, which makes devices that collect water samples from remote locations and transmit the measurements to a central station, has been working with Paris authorities since 2016 to analyze water quality at another swimming facility north of Paris, Reservoir La Villette, which is already open to the public.
“Unless new projects to collect waterway runoff are implemented in the coming years, swimming access in the Seine and the opening of recreation and sports areas will likely become weather dependent, with swimming very likely to be closed on rainy days,” says Lois Moogin, a Postdoctoral Research Fellow in Exercise and Environmental Physiology in Loughborough University’s School of Sport, Exercise and Health Sciences.
Even without an increase in extreme weather, keeping the Seine clean enough to swim in the face of normal weather events, such as normal summer rains, is a big challenge, says Jean-Marie Mouchel, a hydrology professor at Sorbonne University. “There are many non-exceptional weather events that affect water quality. We need to make our systems more efficient to improve water quality in the face of these events.” Water quality data from last summer bears this out: While the Seine was unswimmable roughly 30 percent of the time, Paris wasn’t enduring an unusual rainfall event a third of the time.
Experts also say there needs to be improvements in how water quality is monitored, and what information is shared with the public and when. “It’s important that bacteriological data is published daily, along with information on the associated risks,” says Mugin, which could include gastrointestinal disorders and possible eye and skin infections.
“Monitoring is going to be important,” Angelescu says. “Having technology that can monitor the right risks, measure the actual risk from all bacteria, and provide results quickly is going to be crucial.” Traditional monitoring methods used to determine the triathlon (which did not use fluidons) require samples to be taken from the river and sent to a laboratory, which takes much longer than real-time monitoring.
That’s why Fleurydon has been trialling its technology at the triathlon venue near the Pont Alexandre III during the Olympics, focusing on the following levels: E. coli The team ran experiments with bacteria to show how a faster system with on-site treatment could work in a river. Their results are published in near real time on an open data site, and the company says its technology provides a more accurate and up-to-date picture of water quality.
