Scientists have confirmed that the multi hued hot springs in the Yellowstone National Park were Blue once.

The change in color is associated with the trash and pollution done by the tourists. These ponds were of deep blue color back in 1872 when Yellowstone was made a National Park.

Scientists have found that the color of these springs were not as they were many years ago. Now we can see them in the combination of red, yellow, green and blue depending upon the time they are observed.

The researchers from Montana State University made a study to find the reason behind this diversity in color. The study lead by Paul W. Nugent of Montana State University has already been published in the journal Applied Optics, have reconstructed the spectral history of Yellowstone’s Morning Glory Pool, Grand Prismatic Spring and Sapphire Pool.

Researchers explained that the reason behind the orange, yellow, and bright green color in the Morning Glory Pool is actually the microbial mats or complex community of bacteria. But originally the color of the water was originally deep blue.

The change in colors are actually brought upon by human activities like throwing trash and coins into these geothermal ponds.