RIO DE JANEIRO – It’s stinking clear almost from the moment a visitor leaves the airport here. Whether it’s the trash floating in the canals or the junk lolling on the waves of the bay, the filth is easy to see.

The water here has become one of the main stories of the Olympics, from the smell to the detritus to the toxicity to the failed promise to clean it up. Rio’s waters have been found to contain viruses up to 1.7 million times more hazardous than an American beach. Rowers and sailors will take extraordinary precautions to avoid getting sick, including bleaching paddles and trying to somehow keep their mouths shut.

There are those, however, who will have to deal with the water longer than a few races: fishermen.

There are fewer than 20,000 left of them, by one estimate, made fewer by the oil refinery in the area. Some have stayed because they want to, some because they have to.

Earlier this summer, sitting along the edge of the Guanabara Bay, a man lined up rows of halibut he caught that day. He gave his name as Vargas, age 65, and he said he had been fishing there for 42 years.

“It’s OK,” he said through a translator. “The lake is not polluted. It’s algae.”

It certainly is polluted, as one longtime Rio biologist called it a “toilet.” That’s literal, as raw sewage has been flowing directly into the bay here. That hasn’t stopped Vargas from coming here most weekdays.

“It’s the same fishing,” he shrugged. “I’m never sick.”

There’s a bit of disagreement among experts as to where people like Vargas rate on the reasonable-to-reckless scale.

“I would suspect that fishermen who claim no harm from eating fish drawn from polluted waters are also drivers who don’t wear seatbelts so as not to be trapped in a crashed car,” said Marc Leavey, a primary care specialist at Mercy Medical Center in Baltimore. “There are a whole series of diseases that can be contracted by eating fish from polluted waters, from chemical toxicity to bacterial diseases.”

Still, other experts see how a fisherman like Vargas could remain symptom-free.

“If they’re doing this, and in this setting, they’ve probably built up immunity,” says Brooke Mayer, an associate professor of environmental engineering at Marquette. “If we went to a developing country, our risk is very high. But they might not get infected.”

The other factor at play here might be location. Vargas says he fishes in the middle of the bay, away from where the garbage and fecal matter has gathered. Another fisherman, 37-year-old Jose Carlos Daniel, hangs out further up the shore.

“I’m more concerned about street violence,” he said evenly. “Robberies, fights.”

Daniel also said he’s been coming here for years and doesn’t plan to stop. Only 13 percent of the bay is usable for fishermen, but when that’s your living, that’s better than nothing.

“Just because there is fecal pollution doesn’t mean it’s 100 percent disease-causing,” said Metin Duran, a professor of environmental engineering at Villanova. “I wouldn’t say this is reassuring; there is definitely risk. It’s just not sure that everyone is going to get sick.”

Every expert states the obvious: Fishing in Rio is a risk. And at least one of the locals has called it quits. Luis Roberto Soares, 48, said he fished here for five years and then stopped. There was too much junk and too little fish. He looked out at the water, which was nearly black.

“The smell, the color,” he said. “It should be cleaned.”

Despite the promises of the government, it may never be cleaned. So the few who are bold enough, or desperate enough, will keep taking their chances long after the Olympics are over.

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