Mar 18
Every year on St. Patrick’s Day, the river is dyed green.
Bill King, the administrator of Chicago’s St. Patrick’s Day committee, stated that “the idea of dyeing the Chicago River green originally came about by accident when a group of plumbers were using fluorescein dye to trace illegal substances that were polluting the river”.
The United States Environmental Protection Agency (EPA) outlawed the use of fluorescein for this purpose, since it was proven to be harmful to the river. The secret ingredients used to dye the river green today are claimed to be safe and not harmful to the thousands of living organisms that find a habitat in the Chicago river.
from wikipedia
