In 1961, the city of Savannah, Ga. tried to dye the river behind its City Hall green, however, the best it could do was create colored streaks in the water. The following year, Mayor Richard J. Daley — a politician of Irish-American descent who was raised in a heavily Irish neighborhood in Chicago — had been hoping to turn Lake Michigan green for the holiday. Lake Michigan green was a bit too much to ask, a group of Chicago plumbers identified the right formula for turning a city river the perfect shamrock shade, and a new holiday tradition was born. And finding the perfect shade was truly a happy accident as the plumbers union's business manager noticed bright green stains on another worker's coveralls while on a different job, according to Ilinois's tourism site. That first year, the Chicago Journeyman Plumbers Union dumped 100 pounds of dye into the river, turning it green for a solid week. Nowadays, the union uses about 40 pounds of vegetable-based powder dyes that are more environmentally friendly and turn the river green for just a few days. The hue can last for days, depending on the weather. Every year, thousands of people brave the early morning cold to catch a glimpse of boats dropping dye into the river before the city's parade begins its march through downtown