Olympic triathletes swam the Seine in bacteria levels more than 5 times higher than Ottawa River

When Olympic swimmers hit the Seine River in Paris for the triathlon competition Wednesday morning, they were swimming in water with a bacteria count that would be considered unacceptable in Ottawa.

After widespread speculation over whether the river would be clean enough for the athletes, the World Triathlon governing body and the Paris 2024 Summer Olympic Games found the water quality met the standard to allow the competitions to go ahead Wednesday morning.

"The results of the latest water analyses, received at 3:20 a.m., have been assessed as compliant by World Triathlon, allowing for the triathlon competitions to take place," says a statement issued by both organizations.

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The green light came just a day after the men's triathlon was postponed because the level of bacteria present in the river exceeded water quality standards.

Stephen Brown, an associate professor at Queen's University's School of Environmental Studies and department of chemistry, said the same thing wouldn't have happened in Ottawa — where the acceptable bacterial level for swimming and recreation is just a fraction of what's considered safe throughout Europe.

"Here in Ontario, we would close a beach if [bacteria was at] the same level as [it] was in the Seine this morning when they jumped into the water," he said.

Many people might be surprised to learn that the Ottawa River is far cleaner than a body of water deemed safe enough for Olympic athletes.

"A lot of people think because we have such a big population and we're right on the river, that the [Ottawa River] can be polluted," said Elizabeth Grater, science programs co-ordinator at Ottawa Riverkeeper.

"The fact that we can go confidently swim in the Ottawa River is just something to really, really emphasize.- Elizabeth Grater, science programs coordinator at Ottawa Riverkeeper

She said the waterway's condition used to be poor — especially in the 1900s, when industrial waste and raw sewage were entering the river on a regular basis. The city has come a long way since then by improving sewage management and reducing the amount of foreign material that makes its way into the river.

But few people in the Ottawa area seem to know how clean the river is. In 2020, Ottawa Riverkeeper and Abacus Data surveyed 800 Ontario and Quebec residents who lived within 30 kilometres of the Ottawa River. They found that 59 per cent of participants viewed the water in the river as dirty or very dirty. Only 28 per cent considered the water safe for swimming.

Grater said she takes a dip in the river outside the NCC River House every week.

"I think it's just such a nice thing to be able to have [the river] outside of a big city," Grater said. 

"The fact that we can go confidently swim in the Ottawa River is just something to really, really emphasize. And in this conversation we're having about the Seine and about water quality. I think it's a beautiful moment to try to highlight the Ottawa River."

Testing for E. coli in Ottawa

Throughout the summer, Ottawa Public Health (OPH) collects water samples daily from City of Ottawa supervised beaches to test for the presence of E. coli bacteria.

The city follows standards set by the Ontario Ministry of Health. Provincial guidelines suggest the average presence of E. coli should be less than 200 colony-forming units per 100 ml of water.

"When elevated levels of E. coli are detected in the water, it is used as an indication that it may be more likely that other disease-causing organisms are also present," said Blayr Kelly, environmental health program manager at OPH.

She said those bacteria can trigger skin, ear, throat or gastrointestinal illnesses.

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Grater said Ottawa Riverkeeper focuses on testing water quality at sites along the Ottawa River that don't fall under OPH's purview, like Remic Rapids Park and Lac Beauchamp. Often, Ottawa River E. coli counts fall well below Ontario's threshold at 20 to 50 colony-forming units.

The standards are far less stringent in Paris. Under the European Environment Agency's Bathing Water Directive — used by World Triathlon to determine if water quality is fit for competition — anything below 1,000 E. coli colony-forming units per 100 ml of water is considered safe for swimming.

Brown said that while levels of bacteria that high can cause illness, most Olympic triathletes are willing to take the risk.

He also said it's hard to gauge that risk from day to day because standard, culture-based tests like the ones Paris and Ottawa use take 24 hours to deliver results.

"You're always getting results from a sample that was collected a day before and hoping you understand the trends well enough to know what your levels are going to be on the day when you're actually swimming," he said.

Brown was part of a research team at Queen's that helped to develop IDEXX Tecta, an automated water test that can produce results in 12 hours.

It runs samples in an instrument designed to measure bacteria levels, eliminating the extra time it takes for lab technicians to count E. coli in microplates.

The test was selected as the water testing provider for the Tokyo 2021 Olympic Games and has been used at numerous World Triathlon events since 2018. 

Improving the state of the Seine

While the water quality standard in Paris doesn't measure up to Ottawa's benchmark, Brown said it should be noted that the city is working hard to make the Seine cleaner.

It's been illegal to swim in the Seine for more than a century because of the pollution. Paris has invested 1.4 billion euros in infrastructure to catch more stormwater runoff, preventing sewage and other waste from contaminating the river.

"If you want to improve the quality of water at a beach, the main thing is to identify the sources of E. coli and try to cut them off," Brown said.

Kelly said many factors can affect water quality at Ottawa's beaches, including rainfall, upstream pollution, water temperature, flow and elevation, winds and waves, and nearby wildlife and bird activity.

Regardless of E. coli levels, she said, beachgoers should practice safe swimming habits. OPH recommends:

• Swimming in supervised areas, where lifeguards are on duty from noon to 7 p.m. every day during the swimming season.
• Avoiding entering the water with an open wound.
• Keeping your head out of the water and the water out of your mouth.
• Showering as soon as possible after swimming and drying ears thoroughly with a towel.
• Washing or sanitizing hands after playing in the sand.
• Taking children to the toilet before entering the water.

E. coli counts and swimming guidelines for City of Ottawa supervised beaches are available on OPH's website.