CLEVELAND — The Seine has been a big topic of conversation recently at the 2024 Paris Olympics. The river was front and center for the opening ceremony, but now the debate over water quality is coming to the forefront as competitions are underway.
The plan for the triathlon is to feature the Seine for the swimming portion of the race. However, the men’s event was postponed on Tuesday because of water quality issues. Other training events were also canceled earlier this week. The men’s and women’s events are both scheduled for Wednesday, but that will depend on further water quality tests. Friday is an additional backup day.
Swimmers in the Seine is certainly a unique idea, but the water quality has always been the biggest potential issue. Organizers have poured $1.5 billion into improving the quality of the water in preparation for the Olympics. While they’ve made significant investments, they can’t control the entire river or the weather that can impact the water quality.
The entire Seine River is nearly 470 miles long, starting in Dijon and ending at the English Channel. Paris is over halfway down the river. The entire basin drainage area is over 29,000 square miles. It is impossible to control that much surface area, even just the half or so that is upriver from Paris. Around 62% of the drainage area is agriculture, which means high potential for runoff from fields to get into the water. There are also numerous drainage systems that lead to the Seine.
The rain that fell during the opening ceremony was the second heaviest daily rainfall measured since early April in Paris. Rain also fell for basically all of the drainage basin on Friday and Saturday. That rain makes its way through the system and into the river, picking up runoff along the way. The runoff from that rain can cause significant changes in the pollution in the river. All that to say, there’s been a lot going into the river over the last few days. And the organizers can’t really do anything about it. The boats and activity on the river for the opening ceremony could have also contributed to higher pollution because of changing currents and activity that stirred up the riverbed.
Water sampling and testing have been ongoing multiple times per day. The quality limit is 1000 E.coli/100mL. Readings were looking good up to and through the opening ceremony. Since then, the effects of the rain have increased levels above that threshold and that is why the events have been postponed this week.
Conditions have generally been drier since Saturday which has allowed a lot of the runoff to work through. Much of the rain that fell Tuesday night will enter the Seine downstream of Paris. Other than a few widely scattered rain chances, they are expecting a good amount of warmth and some sunshine this week in Paris. That should hopefully help improve the water quality as the week goes on. The drier conditions are or have been, the healthier the river is.
Further testing will determine if the levels meet the criteria for competition before Wednesday and/or Friday.
The Seine isn't the only body of water to have issues with drainage and runoff. In Northeast Ohio we deal with similar issues for Lake Erie all of the time, especially for areas like Edgewater Beach with its proximity to rivers emptying into the lake. E Coli levels are measured frequently through the summer and swim advisories are issued as needed.
Here's a few instances of issues we've experienced locally in the past. You can also find updates on local beach and water quality through the Northeast Ohio Regional Sewer District.