Dead fish have been washing onto the banks of Rio de Janeiro's Rodrigo de Freitas, a lake which will be used for rowing competitions in the 2016 Summer Olympic games.

It is not an uncommon occurrence in Rio, where waterways are extremely polluted with raw sewage and refuse, for fish to die en masse and wash up along the banks.

Days ago thousands of small silvery fish called twaite shad began washing up along the future Olympic site, causing locals to complain about the stench.

Workers of the city's waste management company labored on Monday to clear away the dead fish.

As reported by The Associated Press, Alex Moutinho, a photographer who has lived near the lake for more than three decades, described the frequent occurrence of dead fish.

"Every year there are these die-offs, sometimes bigger, sometimes smaller," Moutinho said. "It's one more Brazilian shame."

Rio’s environmental secretary said in a released statement that the latest incident was due to recent rains and high sea levels which caused the lake's water temperature to drop.

The statement made the point of saying that oxygen levels in the lake were normal and that the twaite shad are sensitive to variations in temperature.

Fish die-offs that have previously occurred in the lake have been blamed on pollution-related drops in oxygen levels.

The water quality in Rio has become a much debated topic as the 2016 Olympics approaches.

Authorities, who had promised to make an effort to clean up some of the waterways, now say that those promises will not be be met in time for the events.

On Sunday, residents concerned about the water quality of a canal in the Rio neighborhood of Recreio staged a protest in which hundreds of demonstrators linked arms along the Canal das Taxas.

Aside from these water concerns, Brazil has been facing major drought problems.

As reported in the Guardian, local artists have taken to painting protest murals addressing the issue.

Caio Tendolini, an activist, stated, “Management is the main problem, not climate change. The government has been saying this shortage happened because of rain, but we need solutions on a structural level.”