PARIS – The dawn rain slowed to a drizzle just before 8 a.m. Wednesday in Paris, just as 46 of the fittest women in the world trotted onto the Pont Alexandre III, descended a flight of stairs onto a floating dock and dove into the Seine, bacteria be damned.

After years of planning, construction of a $1.5 billion sewage retention tank system, months of jitters, and a final 24-hour delay as mother nature cleaned up the latest sewage overflow as best it could, this elite collection of Olympic distance triathletes did the thing that has grossed out pretty much everyone for 100 years.

Was the river clean? Let’s say clean enough, and leave it at that.

At 3:30 a.m. on Wednesday, Olympic organizers and representatives of a regional environmental agency, the City of Paris and the prefecture of the Ile-de-France region performed the test that the Seine has been failing since the weekend downpour that soaked the opening ceremony and sent untold gallons of fresh sewage into the urban waterway.

Unlike the previous three days, when organizers canceled two training swims and postponed the men’s race for 27 hours, this time the river passed the test. But, officials determined, with levels of E.Coli and enterococci under the threshold risk for bacteria, viruses and other diseases that health experts and the world governing bodies for triathlon and swimming have set for open-water competition.

And so, with the sound of a high-pitched bleep, they set off, thrashing through the murky gray-brown waters on a day when the more immediate hazards turned out to be the slick pavement that caused a series of spills as cyclists tried to avoid one another and navigate the tight turns of perhaps the most picturesque of urban courses.

The Eiffel Tower and the Grand Palais loomed above the 1,500-meter swim. The triathletes cycled past the Musee D’Orsay and the Assemblee National. The Arc de Triomphe flashed within sight as they zipped onto the Champs-Elysées during the seven loops that comprised the 25-mile ride. And they hit many of the hot spots once more during the 6.2 mile run.

This was one of those moments organizers had dreamed of when they first designed the plan for these Games a decade ago – competition through the heart of Paris, a video postcard from one of the world’s most breathtaking cities.

And hopefully no one gets sickened from ingesting or dousing in that river water.

Taylor Knibb of the United States said she crashed in training over the weekend and had the cuts and scabs all over lower left leg to show for it. She debated for days whether to take antibiotics before going into the water. She opted not to.

She said she simply decided to not think about the pollution and just focus on the race. Struggling to swim upstream, she thought: “I just want to be done with this.”

Her teammate, Taylor Spivey said a real issue Tuesday was the current and swimming back upstream in the second part of the first leg. It was as strong a current as she has ever competed in, she said, since triathlons generally don’t take place in rivers.

“I felt like I was on a treadmill,” she said.

None of this came as a surprise to anyone who had anything to do with locating the race in the Seine. Olympic organizers, Paris officials, the leaders of World Triathlon, all of them wanted their competition at the center of the city and the Games themselves. The alternative likely would have been a lake far outside of town. No one fancied that.

Also, the Olympics often serve as a way to unleash spending on dream projects that might never get done ordinarily. Officials have been talking about making the Seine swimmable for more than 30 years. The sewage retention project became one of the legacies of the Games, something organizers could point to when asked whether going through all this trouble to host was worthwhile.

Next summer, three swimming areas in the Seine will open to the public. That is the plan anyway, along with three more races in the river before these Games finish.

To the racing: Flora Duffy of Bermuda, the defending Olympic champion, led a tight lead pack by a hair after the swim, the segment that is more about survival and trying to put some hurt on competitors than establishing a lead. The cycling leg brought some thinning, with Duffy sharing the work at the front with Maya Kingma of the Netherlands, Georgia Taylor-Brown of Britain and the hometown favorite, Cassandre Beaugrand of France.

Still the way triathlon has evolved, with more and more standout runners migrating to the sport and learning to swim and cycle adequately enough to get to the final leg, this race was always going to come down to the run. After 82 minutes, Julie Derron of Switzerland slipped on her running shoes and led the race into its final segment.

Beaugrand runs to victory at Pont Alexandre III. (Ezra Shaw/Getty Images)

Spivey, of the United States, was the first of the contenders to slip off the back of the pack. Duffy, who needed to push the pack harder on the bike but wasn’t able to, and Taylor-Brown fell off by the end of the first loop, as a lead group of four separated from everyone else.

As it so often does, that made for some cruel Olympic math. Four contenders, three medals, with two Frenchwomen, Beaugrand and Emma Lombardi, hanging with Derron and Beth Potter of Britain, as legs all over the course began to turn to goo.

Derron ran without fear, sticking to the front on a still, thick morning with no headwind to worry about, her stride smooth, her shoulders steady. Beaugrand edged onto her shoulder with two miles left, with Potter and Lombardi trailing stubbornly behind as the bell sounded, signifying the final loop.

Then Beaugrand made her move. Coming in, one of the big questions other than the health of the river was whether the racing in front her home fans would inspire Beaugrand or whether the pressure would prove too heavy a burden.

In the final mile, with thousands of flags waving and the noise building in the heart of the city, Beaugrand left no doubt, surging, three then seven then 10 and 20 meters ahead and grabbing the tape at the finish and pulling it to her face before collapsing onto the carpet. Derron took the silver. Potter nabbed the bronze.

Alex Yee, right, runs out of the Seine toward the next leg of the race during his gold medal run. (Marijan Murat/picture alliance via Getty Images)

In the men’s race, Alex Yee of Britain won a brilliant and dramatic gold medal. The 26-year-old upgraded the silver he won in Tokyo three years ago to gold after surging clear of New Zealand’s Hayden Wilde, coming back during the run (of course).

He becomes only the second British man to bring home individual triathlon gold after Alistair Brownlee did so in back-to-back Games in London and Rio de Janeiro. France’s Leo Bergere made it a multi-event medal double for the hosts.

Italy’s Alessio Crociani was first out after navigating the energy-sapping 1.5km section the best of the field before embarking on the six-lap, 40km bike, which was tight throughout. Wilde surged on the second lap of the 10km run, putting him in strong position for gold.

But in one of the most dramatic finishes of these Games so far, Yee roared back, passing Wilde on the entry to the Pont Alexandre III with only meters remaining before slowing to an almost walk to take the tape and Olympic glory.

“I have so much respect for Hayden and how much he made me dig there,” Yee said. “He was an amazing athlete and for me, almost two laps in I thought that silver was on the cards but I owed it to myself to give myself one last chance.”

While Tuesday was a triumph for organizers, the Seine has a long way to go.

Three more Olympic races are supposed to take place in the river – the mixed triathlon relay, and two long distance swimming races.

That is the stated program, at least. Another downpour could turn the triathlon into a duathlon and send the swim races out to the flat water canoe venue east of the city.

Less glamorous, perhaps. But less contaminated, too.

Ben Burrows contributed reporting.

(Top photo: Michael Steele/Getty Images)