Concerns about water quality in the Seine River led Paris Olympics organizers to postpone the men’s triathlon Tuesday, with officials hoping the swimming portion of the race will be able to go forward in the long-polluted waterway in the coming days following an expensive cleanup effort.

Organizers said they will try to hold the men’s triathlon Wednesday instead. The women’s competition also is scheduled that day, but both will only go forward if water tests show acceptable levels of E. coli and other bacteria in the river. Friday is also planned as a backup date.