Intro:

Dead fish continue to wash up on on the banks of the Rodrigo de Freitas lagoon in Rio de Janeiro.

Script:

Dead fish continue to wash up on on the banks of the Rodrigo de Freitas lagoon in Rio de Janeiro.

It's scheduled to hold Olympic rowing and canoeing competitions during the 2016 games.

Fish die-offs are a frequent occurrence in Rio's waterways, which are choked with raw sewage and garbage.

The latest incident, affecting thousands of small silvery fish called twaite shad, began several days ago.

Neighbours are complaining about the stench, caused by the rotting fish bobbing in the shallows.

"It is one more Brazilian shame," said photographer Alex Moutinho, who has lived near the lake for over three decades.

In a statement, the city's environmental secretariat said the latest incident was the result of recent rains and high sea levels, which caused the lake's water temperature to plummet.

Rio's water quality has become a contentious topic ahead of the 2016 Olympics.

Authorities had pledged to clean up some of the waterways including the Guanabara Bay ahead of the games but now admit those promises won't be met, sparking sailors to voice worries about possible health and safety threats posed by competing in the sewage- and garbage-filled waters.

A cleanup of the bay was touted as one of the enduring legacies of the 2016 games, but little progress has been made in reversing decades of environmental degradation in the once-pristine waters.

With the games just a year-and-a-half away, few observers have hope of improvement.

Hundreds of millions of dollars have been spent on successive cleanup projects stretching back decades, with repeated dismal results.