Pollution Concerns Arise Around Tokyo Site for Triathlon & Open Water Swimming

With the Tokyo Olympics now 9 days (yes, just 9 days) away, we’re getting down to the wire with preparations, which this year, also have to include COVID-19 precautions. This morning, SwimSwam Editor-in-Chief Braden Keith wrote an update on the weather forecast for the Games, which had become a source for concern in recent days. The long-range forecast had been for a heat wave, with temperatures exceeding 100 degrees Fahrenheit. The current forecast is now calling for a few scattered thunderstorms on opening weekend, followed by bouts of rain. The good news in all of this is that the rain should work to keep the temperature cooler than previously expected, as now the temperatures for the outdoor sites are expected to be roughly average for this time of year.

While the worst of the heat fears seem to be waning for open water swimmers, triathletes, and other athletes based in outdoor venues, the issue of water quality persists. Just earlier today, Bloomberg reported on the status of Tokyo Bay, the open water swimming venue for triathletes and open water swimmers. Bloomberg’s report actually sums itself up quite nicely in just two words: “It stinks.”

The issue here isn’t simply that the water is smelling bad in the bay, open bodies of water can give off unpleasant smells at times for any number of reasons. Where the problems lie in this specific case is that there have been concerns over the pollution in Tokyo Bay for a very long time. This is due to the Tokyo metropolis having a mixed sewage system. In a mixed sewage system, drainage for rainwater and sewage are combined, not separate.

Tokyo’s mixed sewage system works so that waste water and runoff drain into seven rivers, as well as numerous streams and canals, all of which has to be treated before it feeds out into Tokyo Bay. The system works exactly as it’s supposed to most of the time. However, Tokyo lies in an area which is subjective to typhoons and flooding, which will quickly overload and backup drainage systems.

According to Bloomberg’s report, during times of flooding, “untreated sewerage gets flushed directly into the bay,” in an effort to avoid flood damage. So, what happens to the untreated waste water that gets pumped directly into the bay? For the most part, it simply stays in the bay. According to research by Koibuchi, due to the size and depth of the bay, approximately 60% of the water in the bay is from the rivers and Tokyo’s drainpipes.

We know that this dumping of untreated water into the bay has caused issues in the past. In fact, as Bloomberg points out in their report, during a 2019 water test prior to a paratriathlon race, E. coli was detected in more than double the amount allowed for competition by the International Triathlon Union. A local newspaper quoted one athlete as saying the bay “smelled like a toilet.”

In response to that water test, Tokyo put forward new efforts to clean up the pollution in the bay. These steps included dumping massive amounts of sand into the bay, putting in polyester screens to protect against E. coli, and installing new storage tanks to hold flood runoff, so it can be treated before being released into the bay.

Despite these measures, the bay has been emitting an unpleasant smell for a few weeks, according to Bloomberg’s report. Water tests will be conducted as the Games approach, but there is very little time left to clean up the water if it doesn’t meet the safety criteria. The triathlon is set to take place beginning on July 26th, which is just 12 days away. Open water swimming competition is set to begin on August 4th.

The full report from Bloomberg Business can be found here.

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3 months ago

Wow, this is disgusting! Our US Olympian Haley Anderson has been talking about this for over a year!


3 months ago

Welcome to most of the waterways in the populated world. The western Gulf of Mexico was on fire a few days ago and now the eastern Gulf is inundated with dead fish.

3 months ago

It’s unacceptable that a hosting country/city force athlete to swim under such conditions. I recall that concerns were shared at Rio 2016 also.

Takahiro's excuse
3 months ago

Suck it up. Swimming in sewer water that is 87 degrees with air temps of 90 and unreal humidity is because we endured a big earthquake 10 years ago, getting the sympathy vote. Everyone should suffer now too. Social harmony via collective suffering is the Japanese way we are now sharing with the world. This is what NBC just paid me to write for not holding the games in a humane October timeframe

3 months ago

Couldn’t be timed any better. Great stuff! Open water always gets so much respect and attention. I believe that this happened in 2016 as well, but it’s okay. Trial and error with career-long efforts on the line is no biggie! Can’t wait to see how 2024 goes for this side of the sport! 🙂 🙂 🙂 🙂 🙂