Tourists’ Trash Caused the Oddly-Colored Geysers at Yellowstone, Study Finds

For anyone who’s visited visited Yellowstone, our nation’s first national park, and marveled at the the vibrant hues of its hot springs—indigos, vermillions, and chartreuses—there’s evidence to suggest that the park’s technicolor spectacle is actually the result of tourist trash—tossed pennies, trash, and random objects.

A recent study conducted by the University in Montana and Germany’s Brandenburg University of Applied Sciences has determined that the thermal springs used to be a deep blue, but vandalism, especially to the Morning Glory Pool, has resulted in a rainbow of colors. And there’s no telling yet the true toll this abuse.

Tourist damage is not new: After WWII in 1947, a park geologist removed 55 wheelbarrows of debris from Yellowstone’s geysers and springs.

With the study’s findings as hard evidence, the national park system can begin an education campaign for visitors to help preserve some of our most precious—and fragile—national treasures. So next time you’re at Yellowstone (or any other park) and want to make a wish by tossing a coin into its gorgeous geysers, save it and donate to the U.S. National Parks Service instead.

This article originally appeared on Travel + Leisure.

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