With thousands of liters of raw human sewage pouring into the ocean every second from Rio de Janeiro, August’s Olympic Games have thrust into the global spotlight the city’s spectacular failure to clean up its waterways and world famous beaches. But just across the Guanabara Bay from Rio, the sister city of Niteroi is showing that a real cleanup is possible.

In Niteroi, 95 percent of sewage is treated and authorities say they are on track for 100 percent within a year, even though Rio’s failure to do its part means that sludge still flows in from across the bay. Rio has not only broken promises made to fix its sewage problem in time for the upcoming Summer Games, but the state has been downplaying expectations, even suggesting it might be 2035 before a full cleanup happens.

Niteroi’s success underscores key factors that stand in stark contrast to Rio: privatization of sewage management, major investment in infrastructure and a high level of accountability and collaboration between the city government and the utility to define targets and meet them.

In Rio’s Olympic bid document seven years ago, authorities pledged that an extensive cleanup — which included collecting and treating 80 percent of the city’s sewage — would be one of the games’ enduring legacies, but it simply never happened: An ongoing study commissioned by The Associated Press has shown that rowers, sailors and marathon swimmers will be exposed to waters so filthy they’re roughly equivalent to raw sewage.