Tourists Have Been Admiring the Vibrant Colors of Yellowstone’s Natural Pool for Many Years. In Reality, They’re Looking at Trash

Every now and then, there’s a news story about Yellowstone and the large number of tourists it attracts. Most of these stories aren’t positive. In July, for example, a report about a significant explosion at the site reminded us that four million people visit it each year.

Among the various attractions in the park, none are quite as impressive as the Morning Glory geothermal pool, where tourists marvel at the stunning array of colors. What many of them don’t realize is that there isn’t much to celebrate about it.

What happened? Historically, Morning Glory blew away park visitors with its crystal-clear blue waters. Local residents remember it as the main attraction in the early days of Yellowstone, described by many as inexhaustible and breathtakingly beautiful.

However, its mesmerizing appearance also began to attract different kinds of people. In fact, the large influx of tourists has brought about a diverse group, including those who end up throwing various objects into the pool. The result is a strange situation: Tourists stare in awe at Morning Glory’s “natural” colors, but what they see isn’t natural. It’s a result of human interference.

Some context. Morning Glory is a serene hot spring located in Yellowstone National Park. The pool is renowned for its vibrant display of colors. It starts with shades of blue and green in the center and transitions to reddish yellows and oranges at the edges. It was named in the 1880s after the namesake violet-blue flower due to its sapphire coloration.

Historical accounts and early photographs from the 19th century show that the geothermal pool was once almost completely blue and relatively transparent. However, something extraordinary began to happen in the second half of the 20th century and became more pronounced over the years: The hot spring acquired several new colors, including oranges, yellows, and greens. What kind of wonder had caused this change in hues?

Unfortunately, nothing good.

Human trash. According to the Geological Survey, the hot spring’s color change is due to visitors throwing various items, such as garbage, coins, and rocks, into it. The debris created a blockage at the vent’s base, causing a drop in pool temperatures due to restricted hot water flow.

As a result, the lower temperatures changed the delicate balance of the pool’s ecosystem, which allowed specific microbes to thrive and create mats with various colors and textures. Interestingly, a 2015 study explored the link between the colors of Yellowstone’s thermal pools and their microscopic inhabitants. It explained how diverse microbial mats reflect light in unique ways, resulting in different colors on the surface.

More garbage at Morning Glory than anywhere else. Many of Yellowstone’s hot springs have a multi-colored appearance. This is mainly due to cooler edges, which allow more microbial growth compared to their high-temperature centers.

Morning Glory is unique because it has undergone a radical hue change over decades. In 1970, rangers realized the extent of the problem and decided to clean it up. They partially drained the hot spring and dredged up as much trash as possible. The shocking discovery was that they found hundreds of coins, presumably thrown in for “good luck.”

Nothing to be done. The critical situation led the park's caretakers to develop a routine cleaning action plan that lasted until the early 1990s when it became clear that the original blue color wasn’t going to return. During those years, rangers found tons of coins. Additionally, the park’s main road used to run right through Morning Glory, which would explain some of the metal pieces that looked like car parts dumped at the bottom of the pool.

Jeff Henry, a former Yellowstone ranger who participated in the 1991 cleanup, recounted, “There were a lot of rocks that didn’t belong there, and I think we found some hats that probably had blown off people’s heads and fallen in the pool. And they, wisely, didn’t try to retrieve them.”

The blue color we’ll never see again. As such, what the hundreds of tourists see every day when they stop by the pool isn’t a masterpiece of nature. It’s the result of the garbage they’ve thrown over the decades. Humans are one of the greatest dangers on the planet. We saw this recently with the catastrophic aftermath a single bag of Cheetos could have had in the Carlsbad Caverns in New Mexico. Unfortunately, something tells me that more and more situations like this will occur in the future.

Image | Matthew Paulson

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