Dyeing To Know: The Environmental Impact of Chicago's Green River

Every St. Patrick's Day, Chicago transforms its river into a vibrant emerald spectacle, captivating locals and tourists alike. This unique tradition is now a hallmark of how the city celebrates its Irish heritage. However, the emerald river is raising questions about the tradition's environmental impact.

The practice of dyeing the Chicago River green began in 1962, but its roots lie in a less festive endeavor. In the 1960s, city workers used green dye to trace illegal sewage discharges into the river. This practical application caught the eye of Stephen Bailey, then business manager of the Chicago Plumbers Union. Bailey suggested using the dye to color the entire river for St. Patrick's Day, creating a new tradition.

Initially, the city used an oil-based dye, which has since been replaced with a more environmentally friendly powder. When mixed with water, this orange powder turns a brilliant green. The exact formula remains a closely guarded secret, adding an air of mystery to the annual event.

The river transformation occurs on the Saturday before St. Patrick's Day. Members of the Chicago Journeymen Plumbers Union Local 130 release the dye from boats, continuing the tradition started by their predecessors. The process has been refined over the years, with two motorboats now working in tandem – one to disperse the powder and another to mix it evenly.

Thousands of spectators gather along the riverbanks and bridges to witness this spectacle, which kicks off the city's St. Patrick's Day festivities. The vibrant green hue typically lasts for several hours, though traces may remain visible for days.

As environmental awareness has grown, so have questions about the impact of dyeing the river. However, recent studies suggest that the environmental effects may be minimal.

Austin Happel, a researcher at the Shedd Aquarium, conducted a study tracking fish behavior during the dyeing process. His findings indicate that fish in the river showed no significant changes in behavior during or after the event.

“We didn’t see changes in what they were doing that day, or even the next couple of days afterward, so it doesn’t seem to be causing them to be agitated.”

This contrasts sharply with their reactions to other environmental stressors, such as sewage overflows, which cause fish to flee affected areas.

The city maintains that the dye used is environmentally safe. However, some environmental groups argue that the practice sends the wrong message about river stewardship, especially given the significant improvements in the Chicago River's health over recent decades. As you know, we don't want people emptying their garbage into the river — acting like they're on tour with the Dave Mathews Band.

While the tradition of dyeing the Chicago River green remains popular, it's important to consider both its cultural significance and environmental implications.

As the city continues this beloved custom, ongoing research, and environmental monitoring will be crucial in ensuring that this emerald spectacle remains a source of joy without compromising the river's ecosystem.