Story highlights Officials start to clean up scores of dead fish from the Lagoon Rodrigo de Freitas

Pollution was a problem even before the preparations for the Olympic games began

Last week video showed a separate incident, where floating trash caused a sailing accident

(CNN) The bad news for Rio de Janeiro ahead of the 2016 Olympics keeps coming after scores of dead fish appeared in the Rodrigo de Freitas lagoon.

With just over a year to go before the city hosts the Games' rowing and canoe competitions, officials with the legislative assembly of Rio de Janeiro Monday launched an investigation into the causes of death both in the lagoon and in other lakes and bays in the state in which this phenomenon has occurred.

The group will work in partnership with the State Environmental Institute (INEA) and the Secretariat of State for the Environment.

Officials defended the belief that the latest rains caused a temperature change of the water and the excess of decaying organic matter, which would have led to a black of oxygen, killing the fish.

The note released by officials highlighted that the amount of dead fish has generated a bad smell and inconvenience to those who live near the lagoon and all the tourists who flock to the area.

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