Many users left comments criticising the workers' for chaining and apparently killing the snake instead of leaving it in its natural habitat.
However, it remains unclear whether they killed the snake or not.
One user wrote: "I'm not sure this is real, but if it is, shame on these people for killing it! A snake that big has probably been alive for a very long time now, just to be killed for a few pictures?? What a waste..."
The Guinness World Record for the longest snake in captivity is currently held by Medusa, a snake in Kansas City, US, which measures 7.67m long.
The Belo Monte Dam is a controversial hydroelectric dam complex under construction on the Xingu River.
It is set to be the fourth-largest dam installation in the world behind the Three Gorges Dam in China.