Rowan, a 75-year-old retired police officer, is the man behind the famous ritual of a windy city. The Parade of St. Patrick's Day is world famous, primarily because of its unique tradition of staining the Green River.
"The original Mayor Daley in the 1950s wanted to do something special, he wanted to paint the whole green lake in Michigan, but it was too big to do. The next best thing was the Chicago River," Rowan told CNN.
A friend of the mayor Richard J. Delhi came to him with an intriguing idea in 1961. He noticed the overalls of a plumber painted with a striking shade of green. Substance is a color used to test for leaks in pipes. This was the moment of lighting where a great custom of Chi-Town was conceived. The Chicago River was first green in 1962, to the satisfaction of many Irish Chicago people.
Rowan's father, Tom Sr., Worked in the police naval unit in charge of the patrol boats of the department. Daily gave it to Tom Sr. And to his colleague Michael Butler the responsibility for dropping the color into the river from their boats. They brought their teenage sons to help them, who did the family work of Rowans and Butlers.
Since 1962, the crew for color is "exclusively for both families".
Half a century later, Tom Jr. will lead a crew of six through two ships, with the crew of the sons and grandchildren of Tom Sr. And Michael Butler.
"Rowans and Butlers are the focus of Chicago's family, they have carried this tradition through their generations," Chicago Levy president of Chicago Chicago Chamber of Commerce told CNN.
"The color of the Green River is a great Chicago tradition, and we have Tom Rowan and Mike Butler to thank for that," said Chicago Mayor Rahm Emanuel.
The recipe for color is a tightly guarded secret
The color itself is an orange powder, obtained from environmentally friendly vegetables.
But what exactly is the color made of?
"It's like the Coca-Cola recipe – we do not tell anyone," said Rowan.
Many other cities have tried and failed to repeat the coloring process. A city official recently tried to understand the secret recipe, but Rowan said he was holding tight and did not reveal anything. "I was not born last night."
Orange dust only turns the shampoo green after hitting the water. The magical transformation led to it being called "Leprashan Dust". More than 40 kilograms of the secret formula have fallen into the river. It is dispersed using a common kitchen accessory: "The blade is a tested and tested method," said Rowland.
Two ships are needed for staining.
"A boat will make coloring, and the other boat will make the mixing. You need to dismantle the water."
The second ship is called "Mixmaster".
"We give the river a great dose, and then we go and see if we have missed some places," he said.
The methods have changed over the years.
"One of the ways my father tried was with fire-proof fire extinguishers. The orange color went through local buildings and people, but we did not receive any complaints," Rowan tells.
The color of the crew is at the beginning of the day of St. Paddy
On the morning of the parade, the crew will be out of the water, starting at 9 am (10 am ET). It takes about two hours to get the perfect shade of green. Big crowds squeeze along the shores to follow the miraculous greening of the Chicago River.
"There are people who are trying to see us from 7 am. About 30,000 see when we finish."
St. Patrick's Day starts at noon. Rowans and Butlers will be rewarded with Irish coffees after a cold morning, covered from head to toe in orange color. The color leaves the nail a few weeks, says Rowan, making people think they are heavy smokers.
The river remains green for only a few hours.
The river was once colored in blue
Tom Rowan once got off the tradition once and dyed the river another color. To celebrate the infants who won the World Series in November 2016, he helped turn the brilliant blue river into their honor.
Asked about the future, Rowan said that even after 54 years, he does not intend to retire from duty to color. But, he noted, he is "one of the nine children Rowan, so there will always be someone who will fill that ship".
"It's a family business, it's a tradition."