Chicago dyes its river bright green as it opens St. Patrick’s Day celebrations

The Chicago River is once again glowing kelly green as the city opens its annual St. Patrick’s Day celebrations.

Thousands lined the river and packed bridges Saturday and erupted in cheers as members of the Chicago Journeymen Plumbers Union Local 130 sprayed dye into the water from boats, carrying on a tradition they began some 63 years ago.

The dyeing immediately precedes the annual downtown St. Patrick’s Day parade.

The day — which falls on Monday this year — celebrates Irish culture.

St. Patrick is the patron saint of Ireland and is credited with having brought Christianity there in the fifth century.

(The Chicago River is dyed green as part of annual St. Patrick's Day festivities Saturday, March 15, 2025, in Chicago. (AP Photo/Erin Hooley)

 (The Chicago River is dyed green as part of annual St. Patrick's Day festivities Saturday, March 15, 2025, in Chicago. (AP Photo/Erin Hooley)

The dye is nontoxic. While the river stays bright for several hours, some trace of color can remain for days.

The tradition was started by plumbers In the 1960s, Chicago city workers used a bright green dye to identify leaks in pipes, which would often stain their white coveralls, CNN reported in 2019.

In 1962, members of the Chicago Journeymen Plumbers Local Union who were feeling festive dumped 100 pounds of that dye into the Chicago River, which turned it green for an entire week, per the Illinois Office of Tourism.

The union has since perfected its viridescent formula, and these days.

Ref: Chicago dyes its river bright green as it opens St. Patrick’s Day celebrations

Photo Credit- AP Photo/ Erin Hooley