“Delightful! Delicious! Delovely!,” Cole Porter and his friends reportedly gushed as they sailed past famed Sugarloaf Mountain and into Rio de Janeiro’s gorgeous Guanabara Bay, thus inspiring the 1936 Broadway classic. Given the bay’s beauty, prime location and ocean breezes, it’s not hard to understand why the striking water body was picked as the sailing venue for the Rio 2016 Summer Olympics Games.

The problem, however, is that the bay over the decades has become increasingly clogged by sewage, polluted runoff and floating debris from the 15 cities that border it. A 13-year, US$760 million cleanup effort initiated in 1994 proved unequal to the task of collecting and adequately treating the bulk of the sprawling, steadily growing region’s sewage. By 2006, in fact, only 13% of the bay region’s sewage received treatment. And a $550 million follow-on effort launched in 2012 is expected to fall well short of ensuring treatment of all sewage here, even though it likely will continue through and beyond the Summer Olympics.

The result is an increasingly conspicuous clash between the paradisiacal image that Rio de Janeiro likes to project to the world and the reality of Guanabara Bay water-quality threats ranging from fecal matter and oily street runoff to discarded objects such as tires, plastic bottles and even sofas. This tension has been become particularly apparent as Rio de Janeiro prepares to host the Summer Olympics. With the Games little more than 14 months away, many here are complaining that holding the sailing races in Guanabara Bay would not be safe.

Competitors are wary.

“Welcome to the dump that is Rio,” Germany’s sailing team announced in a 2014 statement after seeing debris floating in the portion of the bay where races will be held. For his part, Brazilian Olympic sailing champion Lars Grael has described the bay as “dark, brown, and stinking.”

Other environmental concerns have arisen about the Rio Games, to be sure. For instance, construction of the Olympic golf course on what had been protected municipal forestland has drawn heavy criticism from environmental advocates, as has the designation of a frequently sewage-tainted lagoon for rowing and canoeing competitions.

But by far the most closely watched environmental issue in the run-up to the Games has been pollution of the bay.

International Olympic Evaluation Committee (IOC) Chair Nawal El Moutawakel, visiting Rio in February to monitor preparations for the games, said at a news conference that the IOC is “holding Brazil to its commitment to treat 80% of the sewage going into the bay.” She appeared to be reacting to a statement by Rio de Janeiro state Governor Luiz Pezão, who had said days earlier that this pledge, made by the Brazilian Olympic Committee in 2007, would be “very difficult to meet.” Experts say that despite the doubts, it is highly unlikely at this stage that the International Olympic Committee (IOC) could force Brazil to meet the target.

Rio de Janeiro state officials first vowed to clean up Guanabara Bay after the U.N. Earth Summit in 1992 drew attention to the bay’s long-standing water-quality problems. So in 1994, the Inter-American Development Bank (IDB), the Japan Bank of International Cooperation (JBIC) and the Rio de Janeiro state government committed US$760 million for a 13-year program to do just that.

Environmentalists and former government officials say the program did little to clean up the bay because the funding, all of which has been spent, was insufficient and poorly allocated. Despite the construction of five large sewage plants and the installation of collection systems, much of the wastewater generated by the Guanabara Bay area’s population of 12 million people is still dumped untreated into rivers leading to the bay.

Carlos Minc, former head of the Rio de Janeiro State Environmental Secretariat (SEA), says the share of sewage that receives treatment in the cities ringing the bay has risen from 13% in 2006 to 40% in 2014. Gov. Pezão said at his news conference that currently 49% of the region’s sewage is being treated.

Adauri Souza, executive secretary of the Guanabara Bay Institute, an environmental nonprofit promoting cleanup of the bay, agrees with many advocates here that the city’s hopes for a successful Summer Olympics must be used as an incentive to make more progress. Says Souza: “After the Olympics is over, nothing will prod this city to cleaning up the bay.” Souza agrees with Axel Grael—brother of Lars Grael and a former state environmental official involved in drafting the original bay cleanup plan—on why the initial sewage-treatment initiative was ineffective.

“State authorities miscalculated how difficult it would be logistically to lay the sewer [lines] to homes, especially those in outlying shantytown neighborhoods,” Souza says. “And those systems [pipelines and mains] are needed for the big treatment plants to work at full capacity. So, idle-capacity plants are now treating less sewage and only doing primary sewage treatment [removing 40% of organic matter] and doing it less efficiently than if they were working at full capacity. Had the state built smaller plants doing both primary and secondary treatment [ridding sewage of 98% of its organic matter], connected to fewer homes, it would be much further along in its bay cleanup efforts.”

Perhaps the most egregious case of poor state government planning of the bay cleanup program was construction of a mammoth sewage treatment plant at São Gonçalo, a working class, shantytown-ringed city of over 1 million people. Completed in 2001, the R$200 million (US$65 million) plant only began doing primary sewage treatment in 2014 because sewage collection infrastructure was not completed until then. The plant, expected to provide secondary treatment before the end of the year, only handles sewage for a portion of the city and is slated to be supplemented by another new plant by 2018 as part of the cleanup program’s second phase.

In 2007, when the cleanup program had used the last of its original funds, both the Rio de Janeiro state government and its state water company (Cedae) were insolvent on account of having taken on a great deal of debt. So they didn’t ask the ICB or JBIC for more cleanup money. Even if they had, the federal government, the guarantor of any loans that they took out, likely would have refused to authorize them.

Still, some additional state funding was provided, allowing the upgrading of four of the five big new plants (all but São Gonçalo) from primary to secondary treatment, the construction of sewage-collection lines and the installation of mains to connect them to the treatment plants.

Then, in 2012, when the state and Cedae were in better financial shape, the state launched the second phase of the bay cleanup, a US$550 million effort jointly financed by a $450-million IDB loan and $100 million from the state government to help reach the target of treating 80% of bayside cities’ sewage by 2016. That money is being used to build a sixth large sewage treatment plant; extend the sewage-collection network and connect them to existing treatment plants; and upgrade the São Gonçalo plant to secondary treatment.

SEA declined to be interviewed by EcoAméricas, saying it is reevaluating the cleanup program’s second phase. The agency’s website, however, says monthly water-quality tests last year at five locations where Olympic sailing will occur showed that fecal bacteria levels were within acceptable limits for bathing.

Rodolfo Paranhos, a marine biology professor at the Federal University of Rio de Janeiro who has studied the bay for 20 years, is skeptical. “The monthly tests the state conducted in 2014 were too infrequent to tell if the bay water on the sailing course is safe for bathing,” he says. “And those tests needed to measure the water not just for fecal [bacteria] levels, but for other pathogens such as viruses that cause hepatitis and cholera, to more accurately gauge how safe the bay is for bathing.”

He adds: “Although most, but not all, of the legs of the race course are fairly close to the mouth of the bay, where pollution is lower because water circulation is better, it will be difficult for Olympic officials to organize races only when the tide is coming into the bay, thus diluting the pollution along the race course.”

Says Mario Moscatelli, a Rio de Janeiro biologist now creating an environmental nonprofit to advocate for recovering coastal ecosystems: “The sewage from the several dozen ‘dead’ rivers flowing into Guanabara bay has not only killed off all fish and crustacean species in them, but has also contaminated the bay with fecal coliform bacteria and pathogenic microorganisms that can cause various diseases, from skin rashes and conjunctivitis to gastroenteritis and hepatitis.”

Adds Moscatelli: “So those competing in the 2016 Olympic sailing events face health risks, especially if rains before the race increase sewage flow into the bay and if at the time of the race, the tide is low and little Atlantic Ocean water enters the bay to dilute sewage concentrations.”

David Zee, an oceanography professor at the State University of Rio de Janeiro, calls Guanabara Bay “a health risk for anyone who sails there, including in the 2016 Olympics.” Adds Zee: “Although the level of that risk is impossible to quantify, it will increase for sailors with, say, a cold or flu, which lowers their immunity to disease. The risk will also increase for those sailing during low tide, when bay pollution is more concentrated, and for those sailing after heavy rains have washed more sewage into the bay. If all of these conditions are present during the 2016 Olympics sailing events, the health risk from contaminated water increases considerably.”

Former state official Axel Grael, who is now deputy mayor of Niterói and who has sailed in the bay’s waters since the late 1970s, sees the problem differently. “I don’t think Olympic sailing athletes face a major health risk because most legs of the race course are close to the less-polluted mouth of bay,” says Grael, whose two brothers have won Olympic gold, silver and bronze medals in sailing events. “The big problem is the floating debris, like a piece of wood or plastic bottle that could get wedged into a rudder. You want to avoid a scenario where a piece of debris decides a race.”

In February, Breno Osthoff, a 20-year-old Brazilian hoping to qualify for the Brazilian Olympic sailing team said in a televised interview that his sailboat hit a heavy plastic fish crate, capsizing and sustaining US$1,700 in damage. “During the last two years, every time I’ve raced my sailboat in the bay, it has collided with some type of debris, from a plastic bag to big pieces of wood,” he said in the interview.

The state has undertaken efforts to clean the floating debris from the bay. In 2008, SEA provided 10 eco-barriers—buoyed and weighted plastic mesh nets strung across the point where 10 of the region’s 35 rivers feed into the bay. The barriers catch floating debris ranging from plastic bottles and aluminum beverage cans to discarded television sets. Currently seven eco-barriers are in place, with the other three being repaired. The state is considering whether to install eco-barriers at the mouths of ten other rivers that flow into the bay.

About 300 tons of debris is collected every month from the eco-barriers by recycling cooperatives, which are paid mainly by supermarket chains required by law to help collect the recyclable packaging of goods they sell, and by 75 trash scavengers linked to the recycling cooperatives. Only 10% of the debris is recyclable, with the rest going to landfills, according to Kleber Pereira, director of the Febracom, the federation to which the cooperatives belong.

The state since January 2014 has underwritten Ecoboat, another private endeavor. Ecoboat operates three, box-shaped vessels whose bows are equipped with mechanical scoops that remove floating debris from the water as they crisscross the bay. In March, the state stopped funding Ecoboat pending a review of the bay cleanup’s second phase.

But this month state funding for Ecoboat—R$51,000 (US$17,000) monthly—was restored, though not at a level some here would like. The company is slated to resume operations in June.

“Our contribution to ridding the bay of floating debris has been sizeable,” says Lourenço Ravazzano, the operations director of Ecoboat. “If the state [of Rio de Janeiro] does not resume and intensify Ecoboat’s operations, the bay will be full of floating debris long before the 2016 Summer Olympics.”