A huge clean-up has been launched in the Rodrigo de Freitas Lagoon after 65 tonnes of dead fish filled the waters which are set to play host to the 2016 Olympic rowing events.

The lagoon, authorities say, became deoxygenated after heavy storms, which washed ‘a large amount of organic matter’ into the lake.

The clean-up is still underway, and is not the first time that the lagoon has suffered such misfortune. In 2009 an estimated 100 tonnes of dead fish, predominantly shad, had to be removed from the waters after a similar incident.

As you can see from the picture above, taken during the Pan-Am Games in 2007, the lagoon hosted rowing successfully.

But you can see the horrific pictures of the Lake as it is this week below: