Green River Chicago: Why is This a St Patrick’s Day Tradition?


The Chicago River is dyed green every year for St Patrick’s day. But why?

St. Patrick’s Day is celebrated worldwide, and many unique and unusual traditions are associated with the holiday. One of the strangest traditions is the practice of dyeing entire rivers or bodies of water green in honour of the day.

One of the most famous examples is the Chicago River, dyed green every year on St. Patrick’s Day. Strangely, the tradition started not as a St Patrick’s Day thing, but to work out where pollution originated.

Dying the Chicago River: Where it Began

The tradition began in 1962, when city officials used green dye to trace illegal sewage discharges into the river. The dye turned the water bright green, and the tradition was born.

The river was historically used as a dumping ground for waste from various sources, including industry, agriculture, and human sewage.

In the early 20th century, the river was so polluted that it earned a reputation as one of the most polluted waterways in the United States and became a public health hazard. To clean up the river, the city of Chicago diverted its flow away from the lake it drained into, Lake Michigan. Lake Michigan is the source of Chicago’s drinking water.

Engineers made the river run towards the Mississippi river instead, so pollutants could be carried away from the city.

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The idea of dyeing the river green was conceived to trace illegal sewage discharges that were still occurring. At the time, a group of plumbers’ union officials noticed that dye used to detect leaks in pipes turned the river green, and they suggested using the dye for St. Patrick’s Day.

The city of Chicago embraced the idea, and the practice of dyeing the river green on St. Patrick’s Day has become an annual tradition ever since. It’s important to note that the dye used today is a non-toxic vegetable-based dye that is not harmful to the environment or wildlife.

The River Today

The Chicago River is still regularly monitored for pollution and contamination, including when it is dyed green on St. Patrick’s Day. In fact, the river dyeing is now done in conjunction with the Chicago Department of Environment and other agencies responsible for monitoring the quality of the river water.

Before the dye is released into the river, tests are performed to ensure it is safe and non-toxic to humans and the environment. Additionally, the dye is carefully monitored to ensure that it dissipates quickly and does not harm aquatic life or the river’s ecosystem.

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Water samples are taken and tested during and after the dyeing process to ensure that the river remains safe and clean. If any contamination is detected, appropriate measures are taken to address the issue.

So while the tradition of dyeing the Chicago River green on St. Patrick’s Day may seem like a whimsical celebration, city officials still take very seriously, and all necessary precautions are taken to protect the health and safety of the public and the environment.

Today, the practice draws huge crowds of spectators who watch the river turn a vibrant shade of green. While it may seem strange to some, it has become an iconic symbol of St. Patrick’s Day and is widely recognised worldwide.

Don’t forget to celebrate St Patrick’s Day with this potato fondue.



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