Lake Michigan

What's That Green Stuff Leaking Into Lake Michigan?

No, St. Patrick's Day didn't come early this year.

NBCUniversal, Inc.

Did you see a green substance leaking into Lake Michigan on Chicago's North Side Thursday? No, St. Patrick's Day didn't come early this year - and it's not anything to worry about either.

The bright green hue could be seen spreading into the water at around 11 a.m. near Olive Park off Navy Pier in the city's Streeterville neighborhood.

The substance is actually part of an environmentally-friendly dye that was put into the water as part of routine maintenance at the water treatment facility, according to Megan Vidis, a spokeswoman for the city's Department of Water Management.

The dye was not threatening in any way, Vidis said, presenting no danger to people or animals. She added that it would eventually dissipate, but it was unclear how long that might take.

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