Rio de Janeiro Olympic organizers said Tuesday they have “no plan B” for the 2016 games’ sailing competitions, despite a recent admission by the state’s top environment official that it will be impossible to meet pledges to clean up the raw sewage- and trash-filled waters where the events are to be staged.

Mario Andrade, spokesman of the Rio 2016 organizing committee insisted the sailing competitions “will be held in the Guanabara Bay, under the best possible Olympic conditions.”

Guanabara Bay has become a hot-button issue ahead of the 2016 games. It stinks of raw sewage and is dotted with abandoned couches, refrigerators and animal carcasses as well as, at low tide, with islands of human waste. Athletes have described the bay as an “open sewer” and raised concerns about hepatitis and other illnesses, as well as the possibility of potentially catastrophic high-speed collisions with floating detritus.

Brazil’s most respected health research institute said late last year it had found a drug-resistant super-bacteria on a beach near where the sailing competitions will get underway.

While Rio officials have maintained that cleanup efforts were on track, Rio’s new environment secretary, Andre Correa, acknowledged Friday there was no way to meet promises to slash by 80 percent the amount of sewage and trash that flow into the bay daily by the time the games are held.

“Removing 80 percent of the pollutants? It’s not going to happen. It’s not going to happen,” Correa told reporters at a news conference on Friday. He said that a nearly $4 billion investment would be needed to ensure full basic sanitation in all the communities that surround the bay, adding that there was no timetable for such a project.

Andrade, on the other hand, insisted authorities are on target and suggested the apparently contradictory positions might be the result of semantics. Andrade said the initial promise was to boost sewage treatment in the cities that surround the bay to 80 percent — not to reduce by 80 percent the amount of pollution entering the waters.

“They are technical differences that in some case can appear big but are in fact subtle,” he said, adding that when the Olympic bid was formulated in 2007, just 11 percent of total sewage produced in the cities that hug the bay was treated. Now it stands at around 50 percent, he said.

The official Olympic sustainability management plan calls for the construction of eight so-called river treatment units which would filter out “between 80 and 85 percent of the pollution that reaches the bay.” With only 18 months before the Olympics start, only two such units have been built.

“As far as the Guanabara Bay is concerned, what I wanted to say here today is that everything’s on track, everything’s is progressing,” Andrade said. “There is no plan B… There will not be any televisions floating in the sailing events.”

Biologist Mario Moscatelli, who has been campaigning for a clean-up of the bay and other Rio waterways for decades, said he’s seen “zero progress” on the ground.

“What was unthinkable is happening,” said Moscatelli, who oversees projects to bring back mangrove forests along the bay and who flies over bay on a monthly basis. “Once we got the Olympics, I thought the authorities here would be shamed into action.

“I dreamed of seeing the bay, if not clean, then on the way to being cleaned up,” he said. “I’m now seeing that dream transformed into my worst nightmare.”