Tokyo 2020 Publishes Odaiba Water Survey Results

The Tokyo Organising Committee of the Olympic and Paralympic Games (Tokyo 2020) and the Tokyo Metropolitan Government (TMG) today announced the results of water quality and temperature surveys conducted at Odaiba Marine Park, the venue for the Tokyo 2020 Marathon Swimming and Triathlon events. The surveys were conducted on 21 days mirroring the scheduled dates of the Olympic Games Tokyo 2020 and on five days mirroring those of the Paralympic Games.

The results revealed that day-to-day water quality at Odaiba varies significantly depending on weather conditions, and in particular whether it has rained or not. In August 2017, there was rainfall in the Tokyo area on 21 consecutive days, the second highest number of consecutive days of rain recorded in August since 1977. The results further showed that the marathon swimming water quality standards specified by the International Swimming Federation (FINA) were attained on ten days, and the triathlon water quality standards specified by the International Triathlon Union (ITU) were attained on six days. Tokyo 2020 accordingly plans to implement water quality improvement measures in advance of the Tokyo 2020 Games.

One of the planned measures is the installation of underwater screens, which tests have shown to be particularly effective in improving water quality. During 2010–2012, the TMG conducted experiments at Odaiba Marine Park whereby single- and double-layer underwater screens were installed, and it was shown that the quantity of faecal coliforms flowing in from offshore was reduced by around 90 percent during periods of light rain. TMG and Tokyo 2020 will jointly test other measures—including the installation of triple-layer underwater screens—which are expected to help achieve the recommended water quality.

Based on the results of the water surveys and on the outcome of future water quality improvement measures, Tokyo 2020 will consider all necessary measures to ensure the smooth operation of events at Odaiba Marine Park, including amendments to event dates and/or times in response to weather conditions.

Odaiba Marine Park has been used as the venue for Japan's National Triathlon Championships for more than 20 years, and more than 2,000 athletes in total have participated in those championships. The Japan Swimming Federation held its Tokyo Marathon Swimming events there during 2009 - 2013, and the Japan Open Water Swimming Championships have also been held there since last year.

TMG and Tokyo 2020 will continue to make the best possible preparations to ensure that the venue satisfies all relevant International Federation standards, and that all athletes can perform at their best.

The results of water quality and temperature surveys

1. 2017 Survey Details

  • Survey period: (mirroring the planned dates of the relevant Olympic & Paralympic events in 2020):
    • 21 days including the period July 24 to August 9 (planned Olympic event dates)
    • 5 days during the period August 25 to September 6 (planned Paralympic event dates)
  • Survey location: Odaiba Marine Park
  • Survey conducted by: TMG (Bureau of Olympic and Paralympic Games Tokyo 2020 Preparation, Bureau of Ports and Harbors) and Tokyo 2020 jointly
  • Measurements:
    • For Marathon Swimming: the quantity of faecal coliforms; the presence of oil film; the level of COD (Chemical Oxygen Demand); water transparency; water temperature
    • For Triathlon: the quantity of escherichia coli and enterococci bacteria; pH levels; water temperature
  • Sampling locations:
    See diagram areas labelled 1,2,3: these were selected along the courses currently planned for the Marathon Swimming and Triathlon events
Sampling locations

2. Summary of Survey Results

  • Marathon Swimming: FINA water quality and temperature standards attained on 10 days
    Item Results Standards Agreed for Marathon Swimming
    Quantity of faecal coliforms 10~7,200 per 100ml 1,000 or less per 100ml
    Oil film Detected on August 5 and 6 Not present
    COD (Chemical Oxygen Demand) 1.3mg~10.0mg per litre 8mg or less per litre
    Water transparency 0.3~3.4m 0.5m or above
    Water temperature 24.6~31.5℃ 31℃ or less at a depth of 40cm

    FINA rules stipulate that the standards set by appropriate local hygiene organisations or safety agencies in each country are acceptable measures for the certification of water quality. Accordingly, Tokyo 2020 uses the water quality standards determined by Japan's Ministry of the Environment as indicators, and these were the standards used in these tests.

    Rules governing water quality for open water swimming are published by the International Swimming Federation (FINA) on their website at http://www.fina.org/content/open-water-swimming-rules(Open in a new window)

  • Triathlon: ITU water quality and temperature standards attained on 6 days
    Item Results Standards Agreed
    for Triathlon
    Quantity of escherichia coli 10~5,300 per 100ml 250 or less per 100ml
    Quantity of enterococci 0~720 per 100ml 100 or less per 100ml
    pH 7.3~9.5 6~9
    Water temperature 23.9~31.5℃ 32℃ or less at a depth of 60cm

    Rules governing water quality for Triathlon events are published by the International Triathlon Union on their website at http://www.triathlon.org/uploads/docs/itusport_competition-rules_2017.pdf(Open in a new window)

Prevailing Weather Conditions
In August 2017, there was rainfall in the Tokyo area on 21 consecutive days, the second highest number of consecutive days of rain recorded in August since 1977.

3. Future Measures

  • Water quality improvement measures in advance of the Tokyo 2020 Games:

    TMG and Tokyo 2020 will consider installing additional underwater screens (increasing from dual level screens to triple level); these have been shown to suppress the quantity of faecal coliforms flowing from offshore during periods of light rain. Tokyo 2020 and the TMG will consider various other measures to achieve the recommended water quality.

    Underwater screens
    Courtesy of TMG
    Conceptual image of underwater screens
    Courtesy of TMG
  • Management of operations during the Games

    Based on the results of the water quality surveys and the status of future water quality improvement plans, Tokyo 2020 will consider comprehensive measures including amendments to event dates and/or times in response to weather conditions.