THE RIVER — The annual dyeing of the Chicago River a bright emerald green kicks off at 10 a.m. Saturday as the local plumbers union continues the 63-year-old St. Patrick’s Day tradition.

Thousands of people are expected Downtown Saturday morning to check out the process.

Friday’s night expected storms are projected to end well before the dyeing begins. Saturday is expected to be mostly sunny, with a high near 65 degrees and strong winds blowing up to 35 mph in the morning, with the potential for 55 mph gusts.

The river dyeing kicks off 10 a.m. Saturday, with Journeymen Plumbers Local Union 130 members dumping their proprietary blend of dyes into the river between Columbus Drive and Orleans Street. Crowds typically swell along the river to take it all in — as well as lots of photos and videos.

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The plumbers local has been behind the tradition since 1962. The effect typically lasts for several days and has become a symbol of the city that’s been well documented in tv shows, movies and your social media feeds for the next few days.

The idea was spawned by Stephen Bailey, who was the union’s business manager in the early ’60s and thought the dye — used to trace leaks in buildings — would be a nice way to celebrate St. Patrick’s Day.

Although the exact concoction remains a closely guarded secret, it is vegetable-based. Dyeing the river only requires about 40 pounds of powdered dye, which is spread by people in two to three motorboats — one with the dye and the others to stir it up with their wake.

Chicago River dyed in honor of St. Patrick’s Day on March 12, 2022.

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