Paris 2024: Seine Marathon Swim Test Canceled Over Water Quality

Paris: A scheduled test for Olympic athletes to familiarize themselves with the marathon swimming course in the Seine River was canceled on Tuesday because of water quality concerns.

World Aquatics made the decision early Tuesday morning, citing fluctuating bacteria levels in the long-polluted river. The Seine is set to host the swimming portion of the triathlon and the marathon swimming events at the Paris Olympics.

Another marathon swimming test is scheduled for Wednesday, with a decision to proceed to be made early that morning. The women’s marathon swim competition is set for Thursday, and the men’s event is scheduled for Friday.

The cancellation follows the triathlon mixed relay event held on Monday, where water quality was within acceptable levels for E. coli and enterococci. The triathlon and marathon swimming events start and finish at the Pont Alexandre III, with the marathon course extending further down the river.

Water Quality Challenges

Water samples from early Monday showed E. coli levels ranging from “good” to “very good” at four collection points in the Seine. However, enterococci samples taken Sunday led to the cancellation, as Monday’s improved levels still fell short of World Aquatics standards at one test site.

According to World Aquatics and World Triathlon guidelines, “good” water quality can include up to 1,000 colony-forming units of E. coli per 100 milliliters and up to 400 units of enterococci. A sample from Port du Gros Caillou showed 436 units of enterococci, slightly above the acceptable range.

Organizers remain optimistic about holding the marathon swimming events as planned, citing favorable weather forecasts and a positive outlook. Paris Mayor Anne Hidalgo expressed confidence in the river’s improved condition, having swum in the Seine herself last month to demonstrate its safety.

Efforts to Improve Seine Water Quality

Swimming in the Seine has been largely banned since 1923 due to toxic water conditions. Paris has invested 1.4 billion euros ($1.5 billion) in infrastructure improvements to make Olympic swimming events possible. This includes a large basin to capture excess rainwater, sewer renovations, and upgraded wastewater treatment plants.

The Seine’s water quality is heavily influenced by weather conditions. Heavy rains can cause wastewater overflow into the river, increasing bacteria levels, while warm, sunny weather helps reduce germs.

Despite mostly hot and sunny weather during the Games, several instances of heavy rain have raised concerns. Water quality issues led to the cancellation of previous test swims and the postponement of the men’s individual triathlon.

Of the more than 100 athletes in the recent triathlon events, four fell ill afterward, though it’s unclear if the Seine’s water was the cause.