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.

The swimming portion of a practice run for the Olympic triathlon was cancelled Sunday because of concerns about water quality in the Seine River, but Paris officials said they’re confident that triathletes will be able to swim during the actual events this coming week.