A test run meant to allow Olympic athletes to familiarize themselves with the marathon swimming course in the Seine River was canceled Tuesday over concerns about water quality in the Paris waterway.

Paris 2024 spokesperson Anne Descamps confirmed that World Aquatics made the decision to cancel the exercise.

The cancellation comes a day after the triathlon mixed relay event was held in the river that runs through the center of the French capital. The portion of the Seine in which the triathletes swam is much shorter than the course for the marathon swim, which has races scheduled for Thursday and Friday.

Representatives from World Triathlon and the International Olympic Committee along with Paris Games organizers and regional and weather authorities met Sunday night to review water tests. The results indicated the water quality at the triathlon site had improved over the preceding hours and would be within the limits mandated by World Triathlon by Monday morning, they said in a statement.

In a very close sprint finish, the team from Germany won the gold medal in the team relay Monday, with the United States taking silver and Britain clinching bronze.

The plan to hold the swimming portion of the triathlons and the marathon swimming events in the Seine was an ambitious one. Swimming in the river has, with some exceptions, been off-limits since 1923 because it has been too toxic.

World Triathlon released data Tuesday showing that when the triathletes swam Monday, the levels of fecal bacteria E. coli and enterococci were within acceptable levels.