RIO DE JANEIRO >> Brazil will not make good on its commitment to clean up Rio de Janeiro’s sewage-filled Guanabara Bay by the 2016 Olympic Games, state environmental officials acknowledged in a letter obtained Saturday by The Associated Press.

In the May 7 letter addressed to Sports Minister Aldo Rebelo, Rio’s state environment secretary, Carlos Francisco Portinho, asks for more funding for depollution efforts but acknowledges that at current investment rates, it will take more than a decade to significantly reduce the levels of pollution in the bay, where the Olympic sailing events are to be held.

In Brazil’s 2009 Olympic bid, officials promised that the city’s waterways would be cleaned up, “setting a new standard of water quality preservation for the next generations.”

But an AP analysis last year of a decade’s worth of government data on Guanabara and other waterways showed that sewage pollution indicators consistently spiked far above acceptable limits, even under Brazilian laws that are far more lenient on pollution than the United States or Europe.

Authorities pledged to cut by 80 percent the flow of pollution into Guanabara Bay by the 2016 Games through the expansion of the sewage network and the construction of River Treatment Units, or RTUs, built at the mouths of rivers flowing into the bay. The facilities would filter out much of the sewage and trash.

But little progress has been made on either front, and with just over two years to go until the Olympics, nearly 70 percent of the sewage in the metropolitan area of 12 million inhabitants continues to flow untreated, along with thousands of tons of garbage daily, into area rivers, the bay and even Rio’s famed beaches like Copacabana and Ipanema.

With Rio in the international spotlight ahead of next month’s World Cup to be held in 12 Brazilian cities, the stench of raw sewage that greets those arriving at the international airport, and the stream of images of the garbage-strewn waters of the once-pristine bay, have become a major embarrassment for authorities. Associations representing Olympic athletes have also begun to sound the alarm bells, raising questions about possible health hazards for athletes.

In the letter, Portinho requested the Sports Ministry give Rio state $70 million to help build two new RTUs. He acknowledged that even if the funds were released and the treatment units built, they, along with two other existing units, “would represent a reduction of over 50 percent of the pollution flowing into Guanabara Bay” — well below the promised reduction.

Portinho added that given the “urgency of the matter and its fundamental role in the event, it is of great importance that the funds be released in order to allow construction (on the two RTUs) to begin in the second half of 2014.”

Reached by telephone, Marisa Bastos, a spokeswoman for Rio’s environment agency, confirmed the authenticity of the letter. She said it was a copy of an earlier letter sent to the Ministry of Cities.

In the letter, Portinho wrote that even if authorities were to tackle the bigger problem of a lack of basic sanitation by expanding the sewage network, it would prove are too little, too late for the Olympics.

“Even if the necessary resources to implement sanitation systems in the waterways mentioned were released . it would not be possible to plan and implement all the projects within a timeframe that would make a significant difference in the water quality in Guanabara Bay by the 2016 Olympics,” the letter stated.

It added that several state agencies “have been studying the issue and concluded that the beneficial effects on the waters of Guanabara Bay will only occur in at least a decade, if the current levels of spending on sewage collection and treatment are maintained.”

Authorities here have consistently maintained that Rio was on track to meeting its Olympic commitments.

Several Olympic sports federations raised fears that Rio’s polluted waters could prove harmful to athletes’ health. Exposure to fecal matter can cause Hepatitis A, dysentery, cholera other diseases.