Officials explain the cause of water turning black in Niagra Falls.
The mystery surrounding a foul-smelling black cloud that appeared in water at the base of the Niagara Falls on the US-Canadian border has been explained.
The experts explain that the discharge - which at one point was feared to be an oil leak - was caused by residue from black carbon filters used to clean the water.
Apologizing for the inconvenience the Niagara Falls Water Board (NFWB) has said in a statement that the "inky water" was the result of "routine, necessary and short term change in the waste water treatment process" at its plant near the city of Buffalo.
The leak happened during maintenance work on Saturday.
