Watch again: Chicago River dyed green to celebrate St Patrick's Day

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Watch again as the Chicago River is dyed green to celebrate St Patrick’s Day on Saturday (16 March).

St. Patrick’s Day falls on Sunday this year, but the Windy City is starting its celebrations a day early.

The river dying begins west of Columbus Drive and east of Orleans Street and is followed by the downtown St. Patrick’s Day Parade.

The tradition dates back to 1962 when Richard J. Daley was the mayor of Chicago, but the idea stems back from the Plumbers Local Union.

The green dye was initially used to identify how sewage was getting into the water and showed where there were leaky pipes.

In festive spirit, the Plumbers Local Union decided to dump 100 pounds of dye in the river for St. Patrick’s Day, and it lasted a week.

Now, about 40 pounds of vegetable-based dye is used each year and the river stays green for just a few hours.

The dye is harmless to wildlife.

The process is carried out by two boats. One boat dumps the powder dye while the other stirs it around the water.