St. Patrick's Day is a fun "holiday." Of all the non-federal ones, St. Patrick's Day is the holiday with what I'd say are the LEAST amount of responsibilities.

For Valentine's Day, you gotta go out shopping for gifts and candy and cards and the like. For Halloween, you gotta go out shopping for candy and costumes. And, of course, there are the parties. But for St. Patrick's Day? Wear something green and, if you're so inclined, have a green beer and some corned beef and cabbage.

Low-impact.

So, if you happen to be at Mammoth Cave National Park today and you notice the streams are green, you might have a little smile form on your face because you're thinking that they died them green, like the Chicago River in the Windy City.

Awww...but you'd be WRONG.

For starters, that dye is organic, so it isn't damaging the water. No, the dye is being used to trace the water's path. As we know, it always finds its own path AND level.

And if you'll scroll down through the comments, you'll see that this isn't the first time Mammoth Cave has used green dye to locate where and how the water flows.

I gotta tell ya, I was never a good science student, but this really fascinates me. Of course, there are all kinds of learning experiences available at Mammoth Cave, so I'm not surprised.

One more thing, the park didn't do this because it's St. Patrick Day. But it IS St. Patrick's Day, and they ARE doing it today.

Just an observation.

LOOK: Stunning vintage photos capture the beauty of America's national parks

Today these parks are located throughout the country in 25 states and the U.S. Virgin Islands. The land encompassing them was either purchased or donated, though much of it had been inhabited by native people for thousands of years before the founding of the United States. These areas are protected and revered as educational resources about the natural world, and as spaces for exploration.

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[SOURCE: WLKY-Louisville]