A timelapse video has been released showing Chicago River being turned green in time for St Patrick’s Day.
The system of rivers and canals running through the US city is dyed green annually and usually lasts around five hours once it has been turned fully green.
The tradition actually arose by accident when plumbers used fluorescein dye to trace sources of illegal pollution discharges. The dyeing of the river is still sponsored by the local plumbers union.
Fluorescein dye was banned by the United States Environmental Protection Agency (EPA) after it was found to be harmful to the river, and the parade committee has since switched to a mix involving forty pounds of powdered vegetable dye.
In 2009 First Lady Michelle Obama, a Chicago native, requested that the White House fountains be dyed green to celebrate St. Patrick’s Day.
