How is the Chicago River dyed green for St Patrick's Day?

As it's St Patrick's Day on March 17, the city of Chicago is already getting into the spirit of the holiday with its annual tradition of dying the city's river green.

It all began back in 1961, when chairman of the Chicago Journeymen Plumbers Local Union, Stephen Bailey spotted a worker wearing green-stained coveralls who had been using green dye to trace a leaky pipe from a building into the river.

When Baily asked what the river looks liked mixed with the dye, he was told "a beautiful green," as per Chicago Tribune who warned the story "may contain more than its share of blarney."

This sparked the idea to use the dye to turn the river green, and so in 1962 the Chicago Journeymen Plumbers Local Union decided to approve of Bailey's wish and tipped one hundred pounds of fluorescein into the Chicago River which left the river emerald green for an entire week.

Mayor Daley tasked Tom Rowan Sr. who worked on the police marine unit in charge of the department’s patrol boats and his colleague Michael Butler to drop the dye in the river and both brought their sons for the occasion.

Before this, former Chicago Mayor Richard Daley originally proposed turning Lake Michigan green but the plan, for a 22,400 square mile body of water, was deemed too difficult, as per The Independent.

So what's the transformation process like?

Ever since, the river is transformed each year - though rather than a week, it's green for just 48 hours thanks to the current 40-pound secret orange formula which is said to be eco-friendly and made from vegetables.

To turn the river green, the dyeing starts the morning of the parade which always takes place on a Saturday (March 11 for this year).

That's when six members of the local Plumbers Union aboard two boats, where one drops the powder into the river and the other stirs the water to create the green hue.

The crew that does this job consists of family members from the original union members that dyed the river - the Butlers and the Rowans.

In 1843, Chicago held it's first St Patrick's Day parade and is now one of the biggest in the US.

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