The swimming segment of a practice run for the Olympic triathlon in Paris was canceled due to poor water quality in the Seine River, raising concerns ahead of the men's and women's events scheduled for next week. Heavy rains during the Olympics opening ceremony led to increased pollution levels, specifically E. coli, which were above the safe limit. Despite these issues, Paris officials remain optimistic that the water quality will improve, citing past trends of recovery within 24 to 48 hours following rainfall. Significant investments, totaling 1.4 billion euros, have been made to clean the river, including infrastructure to manage excess rainwater. Organizers have a contingency plan to postpone the events or eliminate the swimming leg if conditions do not improve by race day. Triathletes are taking precautions, with some increasing their probiotic intake to bolster immunity against potential waterborne illnesses.