By Jennifer Young

March means the coming of spring to some, but to most Chicagoans, it’s the time of year when city officials transform the murky waters of the Chicago River into an enchanting emerald green display, attracting over 400,000 spectators. Dyeing the river green dates to 1962 as a way to celebrate St. Patrick’s Day and the city’s Irish heritage. The tradition got its start under Mayor Richard J. Daley’s administration (1955-1976), but it continues today as a time-honored Chicago event.

The Pantagraph. 3/18/62

Each year on the morning of the city’s famed St. Patrick’s Day Parade, members of the Chicago Plumbers Union begin the 45 minute process of dyeing the river. They putter out into the river and use ordinary flour sifters to sprinkle 40 pounds of a secret orange powder into the river.

The powder, nicknamed “Leprechaun Dust,” turns green upon making contact with the water. While the precise formula isn’t publicized, environmentalists have been able to confirm that it is a vegetable-based dye that’s used each year. The dye is regarded as completely harmless, and the river typically retains its brilliant green for 24-48 hours.

Although Irish himself, Mayor Daley didn’t arrive at the idea of dyeing the river by chance. During his tenure, he was committed to transforming the riverfront to encourage real estate development.

Unfortunately, the river was prime dumping ground for sewage and other pollutants. To clean up the Chicago River, Daley authorized city officials to dump a specially-formulated green dye into the waterway that would allow them to pinpoint the primary dump spots.

The tradition of dyeing the river actually stems from the desire to clean it up, allowing it to become the scenic attraction it is today. The best place to watch the dying process is on the east side of Michigan Avenue.

Some prefer the west side of the Columbus River Bridge for witnessing the event. Even if the weather is rainy or snowy, the team of river dyers will be out ensuring the Chicago River takes on its majestic green hue.