The city maintained its annual St. Paddy’s tradition.

Today is St. Patrick’s Day, and as it does every year, the city of Chicago, Illinois is going whole-hog on it. The whole city is decked out in Irish green imagery and the citizenry are ready to party, but more interesting than that is the return of an annual tradition that was temporarily paused during the highs of the COVID-19 pandemic. To celebrate St. Patrick’s Day, the Chicago River has been dyed a bright shamrock green.

This tradition has been in place since the 1950s, when Mayor Richard J Daley had a chemical cocktail poured into the water to determine the source of an ongoing pollution problem. As a side effect, these chemicals turned the waters bright green, which the populace enjoyed. The chemicals were swapped out for a more benign vegetable-based dye in the 60s, and became an annual tradition ever since.

🇮🇪 It’s St Patrick’s Day on Thursday and that means one thing…

Turning a load of random landmarks around the world green.

Including the Chicago river.

But just because you can does it mean you should? 🤔

— Euronews Green (@euronewsgreen) March 16, 2022

While the green river is fun and festive, local environmentalists have been calling for an end to the practice for years. “Dyeing the river perpetuates the notion that it can be treated any way anyone wants, rather than protected as a valuable natural resource,” Margaret Frisbie, executive director of Friends of the Chicago River, told Euronews.

“Now more than ever our land and waterways need protection and our traditions need to evolve to reflect that.”