RIO DE JANEIRO — Rio de Janeiro will not make good on its Olympic pledge of slashing the flow of raw sewage and garbage into the Guanabara Bay, where the 2016 games’ sailing and wind surfing competitions are to be held, the state’s top environmental official acknowledged Friday.

Brazilian official’s promise to cut the flow of pollutants into the bay by 80 percent was a key part of the city’s Olympic bid document and widely held up as among the most enduring legacies of the games.