10 Tons of Dead Fish Found in Brazil Lake near Olympic Park

Environmental officials are investigating the cause of an enormous fish kill in Rio de Janeiro.

About 10 tons of dead fish were found late last week in a lake that sits near the city's future Olympic park.

Initial suspicions from biologists suggest raw sewage being dumped or otherwise allowed to enter the lake as the likely cause of the fish kill, according to a report by The Associated Press.

The Cedae sewage company in Rio contends that all of its treatment plants are operating normally but that it would send teams out to investigate whether any pipes were leaking, the AP reported.

Denildo Barcalo, a fisherman and biologist's assistant said he suspects the sewage company to be at fault.

"In reality, they say that it's rain water, but the truth is only sewage dumped in here, not counting sewage from other areas that ends up here without treatment. They said they would have sewage treatment, but up until today they haven't done anything," Barcalo said, according to Euronews.

In March of this year the site where rowers are meant to compete in the 2016 Olympic Games was found overwhelmed with about 65 tons of dead fish. The massive fish kill in Rodrigo de Freitas Lagoon was attributed the the water deoxygenating after a "large amount of organic matter" made its way into the lake after a storm, the Herald Sun reported.

A similar incident in 2009 resulted in the removal of 100 metric tons of dead fish, according to The Guardian.

Photos taken by The Associated Press of last week's fish kill can be found here.