Is the Chicago River Dye Eco-Friendly? Behind the St. Paddy’s Day Tradition

What is the Chicago River dyed with? Though the St. Patrick's Day tradition looks like an ecological disaster, it isn't actually bad for the environment.

Lizzy Rosenberg - Author

Mar. 15 2022, Published 3:22 p.m. ET

Chicago River
Source: Getty Images

Cities nationwide are currently gearing up for their annual St. Patrick's Day celebrations — including Chicago, which just dyed its river green. In addition to hosting parties citywide, the Windy City's "green river" is a festive phenomenon which attracts thousands of visitors every year. But because rivers in the U.S. are notorious for ecological destruction, we can't help but wonder what the Chicago River is dyed with. Is it safe?

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"The dye used is a food grade dye also used in medicine, as the colorant for antifreeze and as a tracer dye. The Illinois EPA found that at the concentration used in the Chicago River, it is completely non-toxic," reads a statement from the EPA, as per NiCHE Canada.

"We didn’t do a lab test on a sample of the dye [intended for the Chicago River]. EPA contacted the Plumbers Unions on what was in the dye. Then, EPA’s toxicologist reviewed the dye’s ingredient and deemed it safe.”

Others feel differently, though. NiCHE Canada's Isaac Green says it has a negative undertone.

"Dyeing the river continues and perpetuates the notion that we can modify rivers to suit our tastes with no regard to the consequences. Thus, even if the dye itself isn’t ecologically harmful, the process of dying the river can sustain harmful ecological ideas," Green writes. "... the dye allows people to believe the river isn’t 'natural,' therefore justifying its treatment as a sewer."

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Chicago St. Patrick's Day
Source: Getty Images

Is the green dye used in the Chicago River environmentally-friendly?

Even though the green Chicago River looks undeniably toxic, to say the least, it doesn't seem as though the dye is actually doing anything to harm the environment. According to The Independent, it's been dyed for several years by the Chicago Plumbers Union Local 130. Former Chicago Mayor Richard Daley initially came up with the idea, but for Lake Michigan. But he soon realized the lake was too big to dye on a large scale, so they opted to dye the river, instead.

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Initially the dye, which used to be made of fluorescein, was used to test leaky pipes, and it would last for a week. But environmentalists have since identified environmental issues behind using oil-based fluorescein in a natural body of water, so in 1966, the plumbers union transitioned to using what's used currently: a low-impact orange powder that's made from vegetables. The mixture, which they call "Leprechaun Dust," turns green as soon as it hits the water, and lasts for 48 hours.

And while those behind the tradition pertain the tradition is environmentally harmless, many wonder if it's sending people the wrong message. Does it give off an err of carelessness?

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Chicago River Dyeing Environmental Impact
Source: Getty Images

Is the annual tradition an environmental hazard?

Environmentalists worry that even though dyeing the river green is low-impact, it could influence people to dump whatever they want into the river, essentially using it as a "trash can." We are trying our best to save the rivers as a nation, as many rivers across the country have been ravaged by pollution. So, this could exude a negative message.

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Additionally, sometimes rogue Chicagoans participate in illegal dyeing — when the tradition was called off due to COVID in 2020, according to Euro News, many got in trouble for dumping their own green dye into the river. Likewise, this sometimes happens in other parts of the river, because only the stretch downtown is allowed to be dyed. And since the vegetable mixture used to dye the river is a secret recipe, the illegally-dumped dye may not be as eco-friendly.

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