PARIS (AP) — Olympic triathletes plunged into the Seine River Monday morning as the mixed relay event got underway after organizers said the bacteria levels in the long-polluted Paris waterway were at acceptable levels. 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.

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, with the United States taking silver and Britain clinching bronze.

The decision to allow the event to go forward with swims in the Seine came after Belgium’s Olympic committee announced Sunday that it would withdraw its team from the mixed relay triathlon after one of its competitors who swam in the river last week fell ill. It was not clear whether her illness had anything to do with her swim in the Seine. Paris spent 1.

4 billion euros ($1.5 billion) on infrastructure improvements to clean up the river that flows through its center. That included the construction of a gian.