Last year, Chicago still dyed the river green -- but the city did it as a surprise so as not to draw large crowds in the midst of the pandemic.
WATCH: Chicago pulls off surprise, dyes river green for St. Patrick's Day 2021
Here's everything you need to know about this unique St. Patrick's Day tradition for 2022:
When time do they dye the Chicago River green?
The Chicago River dyeing happened Saturday morning, taking place just west of the Columbus bridge to the east of Orleans before Wolf Point. Watch a time-lapse video in the media player above.
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How does Chicago dye the river green for St. Patrick's Day?
The dyeing of the Chicago River is the work of Chicago Plumbers Union Local 130. They use a proprietary dye to turn the Chicago River green in three boats, two with the secret sauce and a chaser vessel to mix it up. The dye is essentially food coloring concocted by the plumbers years ago to help trace leaks in buildings.
How long does the Chicago River stay green?
The dye will stay in the river for 24 to 48 hours.
What is the Chicago weather forecast like for Saturday morning?
Saturday will be sunny but very cold and breezy, with wind chills only in the single digits. The temperature is expected to hit 20 by the time the river dyeing starts at 10 a.m., but it will only feel like 5 degrees.