Cassandre Beaugrand from France won the women's triathlon on Wednesday morning to give the host country its sixth gold medal.
The 27-year-old completed the course of a 1500m swim, a 40km cycle and a 10km run in one hour, 54 minutes and 55 seconds.
Julie Derron from Switzerland won the silver medal and Beth Potter from Britain took the bronze.
Organisers had to cancel training this week in the river and postponed the men's race on Tuesday after the Seine was found to be too dirty for athletes following heavy rainstorms last week.
World Triathlon and the Paris organisers announced at 4am local time on Wednesday that the women's race would go ahead, followed by the rescheduled men's event.
Surge
Beaugrand, who trains in Britain, finished the 1500m swim in 22 minutes and 32 seconds – the sixth fastest. Her bike ride left her in eighth.
But she seared through the field in the 10km run to collect France's first individual gold in the event which became an Olympic discipline in 2000 in Sydney.
The men's race was due to start at around 11am in Paris.
French president Emmanuel Macron said before the Games that he hoped the country's athletes would finish within the top five in the medals table.
Early on the fifth day of competition, the French delegation lay in second position with six golds among its haul of 19 medals.
On Wednesday night, Léon Marchand, winner of the 400m individual medley on Sunday, will attempt to add golds in the 200m butterfly and the 200m breaststroke to his collection.
The 22-year-old swam four times across the heats and semi-finals on Tuesday in his quest for glory.
"It's a lot for my system," he said after his heats on Tuesday. "I'm going to have to sleep well, eat a lot and I'll be ready."
