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CHICAGO — The Chicago River never has to fear getting pinched on St. Patrick's Day, as it is always bursting with the color green from an annual iconic holiday tradition.

Thousands of people lined the Riverwalk in Chicago on Saturday as the water was transformed into a river straight out of the Emerald City.

As of Monday afternoon, the water is still a shimmering green and can be viewed on a livestream as the color slowly fades. The river stayed green for several days in 2024.

Each year, the Chicago Journeymen Plumbers Local 130 union uses boats to go around the river, spraying a concoction of dye into the water. The recipe for the dye has never been released publicly, and while the color may look toxic, the union promises the dye is environmentally friendly, according to NBC Chicago.

The most surprising part? The plumbers' secret mixture is orange. But once the dye starts to set in, it transforms the water into a brilliant green.

The tradition of dyeing the river began in 1961. According to the story, a dye plumbers used to detect leaks in the sewer system along the Chicago River turned the water green. The business manager of Chicago Plumbers Local 130 then got an idea, called the mayor and said he wanted to dye the Chicago River green for St. Patrick's Day.

And every year since, the plumbers have dutifully boarded their boats, poured gallons of dye overboard, and transformed the murky river into a magnificent Irish green waterway.

Although the river gets dyed bright green every year, it feels especially fitting this year after the color green has been making headlines from the hit musical movie "Wicked." The film broke the record for highest-grossing movie adaptation of a Broadway musical and internationally made more than $734 million in its theatrical run.