How Do They Dye the Chicago River Green

The Chicago River has been dyed green on the Saturday before St. Patrick’s Day, March 17 every year since 1962.  It coincides with Chicago’s St. Patrick’s Day Parade. Dyeing the River is a great tribute but after 57 years is it still considered safe with no environmental impact? How do they dye the Chicago River green?

Organizers of The St. Patricks Day Parade & River Dyeing say that since 1996 Fluorescein dye, a questionable oil-based product was switched to a more Eco-Friendly vegetable-based Dye that has no evidence of being hazardous, and for $1,000, no more than 45 min. work keeps the river green for up to 5 hours. 

Just as the Green Beers are hoisted to the sounds of Irish melodies across the cities and towns that celebrate this wonderful occasion, one city, Chicago stands out as the “wearin of the green” takes on a special meaning of, what it is to be very Irish on St. Paddy’s Day.


What is in the Green Dye Chicago Uses on St. Patrick’s Day.


The beautiful sparkling emerald green color that is released in the Chicago River every year on St Paddy’s Day is called Leprechaun Dust. The ingredient of the Dust is a secret. The orange dust turns green as soon as it hits the water in the river. For more than 58 years the country has turned its attention to what has become a tradition in America, the Turning of the Chicago River Green on St. Patrick’s Day.

Watch the Chicago River turn green for St. Patrick’s Day!



It began in Stephen Bailey’s office which was the Business Manager for The Chicago Plumber’s Union when he saw a plumber whose white coveralls were stained green. He had been part of a crew pouring green dye into the city’s waste systems to trace the flow of waste discharges that were dumped into the Chicago River.

The City was undertaking a Pollution Control plan enforcing illegal dumping into the river. The plumber explained, “We check at the river’s edge to see where the water is turning green.”  In 1962 the quest was for Major Richard Daley and his Administration to build a River Front area for the city. The main problem was that the river that ran through the city was being polluted by businesses dumping sewage into the river.

At that time, the plumbers used Disodium salt called fluorescein (a widely used chemical compound found in personal care, skin care, processed foods, cosmetic preparations, and cleaning products.), and was the Dye used to trace the sewer lines. It enables employees to visually see who was dumping into the polluted Chicago River.  It worked a little too well, turning the water in the river through the city green for a week.

When Bailey saw the green water in the river, this idea was born that Chicago could turn their river emerald green on St. Patrick’s Day with this harmless dye that the plumbers were using to stop the polluters, and that in turn would help with the building of the River Front Project. It was a great idea for the big Irishman. He tried a great idea that year on St Paddy’s Day 1962.


How Does Chicago Dye The River Green


That year, one hundred pounds of dye was poured into the river and the river was green for a week. In the following years, they experimented with the amount and type of dye used; finally, perfecting the process.

Today the river is dyed with 40 pounds of environmentally friendly dye, which keeps the river green for four to five hours. The Chicago River is dyed green the Saturday before each St. Patrick’s Day unless the holiday falls on a Saturday, which it did last year.

The Parade and Dyeing of the River will be the day before St. Paddy’s Day this year March,16th 2019. The dyeing process takes place between Wabash Avenue and Columbus Drive. Spectators can watch the boats from both sides of the river between these bridges.

In 1996, environmentalists discovered that the tracing dye to help spot polluters dumping into the river was actually a pollutant itself. An oil-based Chemical called fluorescein was used as the dye. It was declared a contaminant itself. Environmentalists, back then concerned about the welfare of the river’s goldfish complained to the Irish guys who spread the Leprechaun Dust every year in the river.

In 1996 the city came up with a vegetable-based dye that was an orange powder until it was mixed with water then it turned Green. It was completely Eco-Friendly.

While the exact ingrediants of this dye is unknown, over the years, the subject does keep coming up around this time of the year, whether it is toxic or not. According to City Officials and the Spokesman for the St. Patty’s Parade that also run the River Coloring, said that the formula is a secret and giving up the secret would be like “telling where the leprechaun hides its gold” there are plenty of details that the committee lets even non-leprechauns in on. But not this one.

People still complained about the eco-friendly dye and if it was harmless, Parade Spokesman said that, “if you drank it-except for the pollution in the river water-it wouldn’t hurt you. It’s just food coloring.” said Mel Loftus, the Spokesman who is now a consultant with the Plumbing Council of Chicagoland, and has worked on the parade since 1958, and been its coordinator since 1987 and is this year’s Grand Marshall.


How Much Dye is Used In the Chicago River


The Vegetable Dye used since 1996 takes about 40 lbs. to accomplish the Dyeing of the River. That amount will transform the river into a beautiful Emerald Green.

In the very first year of river dyeing, the boat crew used the Fluorescein Dye that was switched. That dye kept the river green for nearly a month and caused an outcry from the city. The new vegetable base Dye that was substituted in 1996, needed to be adjusted again. It was adjusted down to about 40 pounds to get the job done and that is how much they use today.

The Vegetable Dye costs about $1000.00 for a 40-pound container and the cost is paid for by the St. Patrick’s Parade Committee.

At 9 am the Saturday morning before St. Patrick’s Day, the crew meets on the North Branch of the Chicago River where the boat slips are. The crews use paper Hazmat suits and  2 sets of gloves, rubber, and cotton to transfer the Dye into one of the boats.

A fourth man from the crew will motor a small board boat out with them. They will make their way out to the locks at the entrance of the river to Lake Michigan to gauge the current of the water. And, by 11 a.m. or so, they will begin to dye the Chicago River green and the festivities with the Parade will all start around the same time.

Hundreds of marchers with instruments in full costumes and on floats that are preparing to start the parade will gather on the route along Wacker Drive, 30 feet above the water’s edge where the crew’s boats are. The Leprechaun Dust is coffee-canned out by one of the crew and applied to the river by a flour sifter. As he does this a second crew member on the same boat uses a second sifter and starts to add his portion of the dye.

While this is going on the second boat that is following right behind, Zig-Zags trailing their boat and using the prop from his boat to mix up the Leprechaun’s Dust from orange to yellow to a bright lime green color that is the intended color.  Just like a big cake mixer.

Bailey who was a personal buddy of Mayor Richard Daly was an extravagant Irishman who had other ideas for his favorite holiday like Painting the Wrigley Building green for a day but the owners nixed the idea. He also said that the Chicago River was not his first idea for dying water green but Lake Michigan was his first choice. That idea wouldn’t fly either.

How Long Does the Chicago River Stay Green

The Chicago River is Green. After everything is done, the Plumber’s Local crew regroups, as they head back up the North Branch of the river, where they will be covered with a dusting of orange powder. Remember the powder is orange until it is mixed with water, then turns green. All this is for 45 minutes of work and 4 or 5 hours that the green dye last in the water.

Some sparkling Emerald Color green to go along with some green beer and another St. Paddy’s Day Parade with festivities that are worth every effort it takes according to the guys at The Plumbers Local, gets done. They are the honored men that are given this highly praised position which they hold on tight to every year.

Even on St. Paddy’s Day which comes in frigid cold temperatures where the river is frozen over and the cleanup is almost impossible, they are happy to do it.

There was one year when the boys got orange dust all over them from mixing the dye, and some Irish revelers thought they were making a political statement wearing the orange color of hated Northern Ireland. On St. Paddy’s Day, this could get you killed and it nearly did.

Wearing Orange means that you are Protestant Irish and for the Queen and Throne. Not a good message for any Green-wearing Irishman from anywhere in the World even Chicago. Back in the Day. But these are the fond memories that the Plumbers Union shares over a pint.

Other cities in the US have contemplated adding the same Echo-Friendly dye in their waterways through their cities. Most of their regulators have rejected the idea because of environmental concerns they have over the chemical used even though it’s safe. Places like Broward County in Florida in 2005.  Michigan’s Department Of Environmental Quality nixed a Dye job for St. Patrick’s Day on the Saginaw River. The impression is that it’s not safe.

The Illinois Department of Public Health advises against dining too frequently on certain fish caught in the Chicago River because of concerns about mercury and polychlorinated biphenyls, a type of industrial chemical that the EPA has labeled a probable human carcinogen.

People see that as another reason not to worry about green dye. There are too many other dangerous things in that river and the world that are invisible and need to be looked at. Green Food Coloring ( Leprechaun Dust) on St. Paddy’s Day, shouldn’t be one of them.



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