green river
Credit: Scott Olson/ Getty Images

We all look forward to the uber Instagram-worthy pictures of the Chicago river turning green for St. Patrick’s Day. But have you ever wondered what they use to dye the Chicago river green? We figured it was just some genuine leprechaun magic and didn’t think much of it.

But now, we’re surprised to find out that the tradition didn’t start as a festive, holiday tradition — it started as a way to find illegal dumping in the river! A tweetstorm from Chicago’s March for Science account illuminated us to the real origin of the green river this morning — and it has nothing to do with St. Patrick’s Day.

And apparently, the endeavor we’ve all come to look forward to is still maintained by the local plumbers, which is pretty neat.

What you also might not know if you haven’t been to Chicago around St. Patrick’s Day is that the green in the river doesn’t last particularly long. But on the up side, it’s environmentally friendly!

But wait, there’s more — a video of the green dye being disseminated and it’s SO COOL.

And remember when we said the green river is the MOST picture perfect?

Yeah, we weren’t kidding, because a quick glance in the #chicagoriver hashtag shows us a ~whole new world~ that looks kinda like a Tim Burton film or something.

Whatever the origin of the green river tradition, we’re happy to learn that it’s eco-friendly. And we hope it continues for a long, long time…or at least long enough for us to make it to Chicago on St. Patrick’s Day so we can get a pic of our own.