Organisers of the Rio 2016 Olympics admit they are "concerned" about water pollution in the sailing venue, but say the Games will be delivered "on time".
About 48% of sewage pumped into the Guanabara Bay is untreated, while illegal dumping is a big problem.
Last month government officials stated they would miss their target of an 80% reduction in water pollution by the start of the Olympics next August.
"There is a huge problem with garbage," Mario Andrada told BBC Sport.
The Rio 2016 director of communications continued: "It [the state of the sailing venue] is a concern because the water is not fully clean, but it will be safe for the Olympics."
Last year, International Olympic Committee (IOC) vice-president John Coates claimed Rio was the "worst" prepared host city he had ever seen.
Olympic sailors also complained about floating debris and even dead animals found in the water when they competed in the Rio test event last August, and drug-resistant "super-bacteria" were found in December.
However, Andrada insists the IOC is pleased by their progress and that significant improvements have and will continue to be made regarding the condition of the Rio waters.
"People ask 'why don't we moved the venue?'. If we don't clean the bay now then it never will be and this is a legacy commitment to Rio," he said.
|What impact can polluted water have on sailing?|
|"When you have plastics and debris floating in the water it can damage the boats and you could eventually have a race decided by garbage and that's the biggest issue for us," says five-time Olympic sailing medallist turned Brazilian head sailing coach Torben Grael|
Lobbyists claim reducing water pollution is one of many promises organisers have broken, and Giselle Tanaka from the People's World Cup and Olympics Committee believes people will take to the streets to protest as they did ahead of last year's football World Cup.
She told BBC Sport: "The general feeling is that the people of Rio will be worse off after the Games and I believe people will protest because they are unhappy.
"We are so close to the Olympics now that they have other priorities to get the sports venues ready - so we know none of the social or environmental legacy investments will be made."
The group and fellow lobbyists Golf for Who? took the development of the Olympic golf course to court in a bid to halt the work on a nature reserve.
However, Games organisers won the initial round and they foresee no further delays on the site where many of the holes are nearing completion.
"It is impossible with this kind of event and renovation to have 100% of people happy and enthusiastic," said Municipal Olympic Company president Joaquim Monteiro.
"People have the right to complain and argue but we are using the Games to transform Rio and after the Olympics the golf course will be open to the public and be wonderful facility for Rio."
The city will host 22 test events in 2015, with a further 20 in the months leading up to the Olympic Games opening ceremony on 5 August 2016.
"We are confident the Games will be delivered on time and on budget," said Monteiro.
The London Olympics and Paralympics cost about £9 billion, with estimates for the Rio Games suggesting a figure close to £12 billion.