In seeking to host the Summer Olympics, Brazil promised “green games for a blue planet.” It pledged to clean up waterways around future Olympic sites, including a lagoon in front of the planned Olympic Park, and to remove 80 percent of the sewage flowing into the bay where most sailing races would be held.

It appears none of these goals will be reached when the Olympics open Aug. 5. Instead of the Green Games, these may be the Filth Olympics.

“When we talk about environmental legacy, we are talking about public health,” said David Zee, an oceanographer who has studied Rio’s waters for decades. “In this aspect, Rio is a failure.”

Nobody understands this more than the fishermen who live near the main Olympic Park and athletes village, situated on the picturesque Jacarepagua Lagoon.

It will be impossible to clean these waters in time for the opening ceremony on Aug. 5. Photos by Lianne Milton for The Washington Post. (Dom Phillips,Jason Aldag/The Washington Post)

On a recent evening, fisherman José Ferreira skimmed his narrow wooden boat across the still, dark waters of the lagoon as a pink, tropical sunset framed the Olympic Park on his right.

But a rotten smell ruined this bucolic scene. Ferreira, 67, had just paddled out of a black tributary that bubbled with gasses such as sulfur and methane and was covered with swaths of gigoga, an Amazon plant that thrives in polluted water.

Jacarepagua Lagoon is one of four lakes in an interlinked system connected to the sea. The lagoons and many of the rivers feeding into them are heavily polluted. A day earlier, gray scum swirled on the Pavuninha River, which skirts one side of the Olympic Park.

Ferreira and the few dozen fishermen living in the area say they can no longer scrape a living from these waters, which are so polluted that dead fish sometimes float on the surface.

“This lagoon is dead. There is nothing left,” said Francisco Costa, 57, president of their association.

The West Rio suburbs, the site of the Olympic Park and Olympic Village, grew up rapidly in recent decades, and the sanitation infrastructure failed to keep pace, Zee said. Instead, communities just dumped sewage into rivers and lagoons.

Complicating the response to the problem, different government entities manage the bodies of water across the city.

Rio state is responsible for most of the city’s sewage and the lagoons. The state-controlled sewage company, CEDAE, said in an email that the situation has improved dramatically from 2007, when it treated none of the sewage in the neighborhoods around these lagoons. Today it handles 90 percent of sewage in the Barra da Tijuca neighborhood and 60 percent of the sewage in Jacarepagua.

But the company’s performance is open to question. In April, police took samples from sewage stations and said they were investigating whether the company dumped raw or barely treated sewage into the lagoons and into Guanabara Bay, where sailing races are to be held. CEDAE said it is cooperating with the investigation.

An impoverished community along the shores of Camorim Lagoon, one of several fetid and sewage-infested lagoons in the Barra da Tijuca area. Pollution and raw sewage are in the lagoons that surround the Olympic Park and Olympic Village. (Lianne M. Milton/For The Washington Post)

A fisherman awaits a game of cards in his community fishing village in the Jacarepagua lowlands. Keeping people in low-income areas from dumping raw sewage into the water “involves a change of culture,” said Rio Environment Secretary Carlos Muniz. (Lianne M. Milton/For The Washington Post)

The Rio city government is responsible for many of the local rivers. Carlos Muniz, the environment secretary, said it could not stop people in low-income settlements — known as favelas — from dumping raw sewage into the water.

“It is a long-term problem that involves a change of culture,” Muniz said in an interview. He said the city has ended this problem on Jacarepagua Lagoon’s south side, which is dominated by upmarket condominiums, but had been unable to do so in other areas.

As part of Rio’s Olympic commitments, the city agreed to build five river-treatment units to clean water flowing into this lake system, but only one was completed. A spokeswoman for the city, who spoke on the condition of anonymity because of internal regulations, said it made sense to build the river-treatment units only once the state had cleaned up the lagoons.

The state government drew up a $194 million plan to dredge the heavily silted lagoons, which might enable more seawater to get in and flush out waste. But the project was held up by requirements for extra environmental studies. Now the studies are finished, but the state government recently declared a “state of calamity” in its finances.

While the state is responsible for most lagoons, the city government looks after the Rodrigo de Freitas Lagoon, a postcard-perfect location near Ipanema Beach where rowing and canoeing events will be held. There are no gas bubbles here. But last year, the Associated Press published independent studies showing high levels of viruses and, in some cases, bacteria from human sewage in this lagoon as well as in Guanabara Bay and the waters off Copacabana Beach, where triathlon and marathon swimming events will be held.

The connected Carioca Stadiums and Velodrome, at right, at Olympic Park. (Lianne M. Milton/For The Washington Post)

A sewage-filled canal at Rio’s Olympic Park. (Lianne M. Milton/For The Washington Post)

The city provides daily bulletins on its water quality. Generally, these report that the water is safe — but not always. On June 16, about two-thirds of the lagoon was found “improper” for activities such as boating.

Four sailing-race lanes are inside the mouth of the 147-square-mile Guanabara Bay. While the state government originally promised to clean 80 percent of the raw sewage flowing into it by 2016, it gave up on that target. Now, about half the sewage flowing into it is treated, CEDAE said — thanks to new infrastructure that also means raw sewage no longer flows into the bay from an outlet at the Gloria Marina, where sailing races are based.

A fleet of 12 special boats is plucking 40 tons of floating garbage a month out of the bay. But many of the cities on the shoreline still pump raw sewage into it.

A spokeswoman for the state government's environment secretariat, who also spoke on the condition of anonymity because of internal regulations, said in an email that the cleanup efforts in the bay had suffered from a lack of cohesion among the government bodies responsible for it. The secretariat is developing a new model for managing the bay. “This way, we will avoid the mistakes of the past,” she said.

Biodiversity in the Jacarepagua Lagoon area is disappearing, said biologist Marcello Mello. The few fish in the water are mostly tilapia, taking the place of sea bass and shrimp. (Lianne M. Milton/For The Washington Post)

Biologist Marcello Mello holds up a gigoga plant, which acts as a natural filtration system for domestic wastewater contaminants. But the plant also harbors mosquitoes. (Lianne M. Milton/For The Washington Post)

No new model is planned for the Jacarepagua Lagoon system. On a recent boat trip, local biologist Marcello Mello pointed out wildlife in the area — long-beaked birds such as the maguari stork and white crane. “You see a lot of biodiversity — which is disappearing,” he said. Sea bass and shrimp once thrived in these waters. Now the few fish left are mostly tilapia, a hardy African river breed introduced in the 1960s to help feed the local population.

A process called eutrophication — in which plants and algae proliferate in waters oversupplied with nutrients, such as those with a lot of raw sewage — sucks oxygen out of the water, causing fish to suffocate, Mello said.

The boat sailed up a stream off the Tijuca Lagoon. Caimans lazed in milky, whitish-green water that reeked of raw sewage. Clumps of brown, organic matter floated past.

“This is the environmental legacy of the Olympics,” Mello said.

Laiston Luiz fishes in Jacarepagua Lagoon, in the shadows of new high-end condos. (Lianne M. Milton/For The Washington Post)