Yellowstone’s thermal springs attract millions of visitors every year. The simmering ponds with their vivid colors have thrilled visitors for decades. But scientists have found that, many years ago, these thermal springs were not the color they are today. Now they often take green, blue, yellow and red colors depending on when you are observing them. Researchers have found that it was a pond of deep blue color long before Yellowstone was made a national park in 1872..

Pollution Gave Yellowstone's Thermal Springs Unique Color

Scientific evidence

In a study led by Paul W. Nugent of Montana State University, researchers provided scientific evidence to back up their claims that pollution is responsible for the fluorescent colors of Yellowstone’s thermal springs. Findings of the study were published in the journal Applied Optics. Nugent and his colleagues used computer modeling to examine what the magma-heated pools looked like in the past.

Scientists said that the colors we see today is a direct consequence of pollution. Tourists throw trash, coins, rock and other rubbish into the pool. Over time, the vents that tap into the Earth’s superheated mantle became partially choked. The blockages reduced the temperature in the pools and altered what type of bacteria could live in the water, resulting into changed color patterns.

Bacteria give Yellowstone pools their color pattern

Water in the geothermal pools of Yellowstone ranges between 140 and 194 degrees Fahrenheit. That’s a perfect environment for thermophile bacteria. Researchers said that the fluorescent color patterns that we see today are caused by vast communities of microbes, primarily thermophilic cyanobacteria. Different microbes prefer to live in different temperature zones. Their arrangement leads to concentric patterns of greens, browns, yellows, blues and oranges.

The blue color is the result of light scattering in the water, suggesting how deep pools like Morning Glory are at the center. These Yellowstone pools were far too hotter in the past, so not many microbes could inhabit them.