Yellowstone tourists blamed for ruining pristine color of park’s Morning Glory thermal pool: ‘Thousands of coins’

Tourists have ruined one of Yellowstone’s most gorgeous thermal pools — turning its once-pristine blue waters into a mishmash of colors because of years of accumulated coins and trash, officials said.

The Morning Glory Pool — perched near the famous Old Faithful geyser — was for years a must-see attraction in the Upper Geyser Basin in Yellowstone National Park, according to Cowboy State Daily.

“There are some lovely quotes about its beauty and stunning blue colors, and likening it to the morning glory flower,” Yellowstone National Park historian Alicia Murphy told the outlet.

But those early visitors from more than a century ago weren’t all that concerned about the environment — and did not practice the stringent “Leave no trace” policy that outdoor enthusiasts live by today, according to park officials.

The brilliant blue pool of scalding water was treated like a wishing well, as visitors chucked coins, handkerchiefs, trash and all sorts of other debris into its depths.

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Murphy said tourists often tossed things into whatever crevice or hole they could find in America’s first national park — established on March 1, 1872 — in the hope that it would make something interesting happen.

“People didn’t understand the plumbing and how geysers worked,” she said. “There were lots of ideas about, ‘If we throw something into this pool, we might be able to make it erupt.’”

The items corrupted the pool’s natural beauty, and its deep-blue water is now a mix of greens, yellows, blues and oranges.

“I think there was some trial and error and a misunderstanding of the damage they were doing,” she added.

Murphy also attributed this to humans’ compulsion to throw things into bodies of water.

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“Wishing wells are a time-honored tradition. Flip a coin into a wishing well and make a wish,” she continued. “There is something about a pool of water that gives humans a weird instinct to throw things into it.”

The thermal pool’s changing temperature is likely a big reason its colors morphed, according to Mike Poland, scientist-in-charge of the Yellowstone Volcano Observatory.

“Temperature is a huge factor,” he said. “Hotter pools tend to be a brilliant blue, and cooler pools can be more colorful since bacteria can grow there.

“At Morning Glory, the temperature cooled because people throwing objects in caused the conduit to become partially blocked, and the temperature went down, allowing different types of bacteria to grow.”

Former Yellowstone ranger Jeff Henry said that at one time, the National Park Service held regular cleanups that he equated to “harvesting a crop.”

At Morning Glory, this meant bringing in fire trucks, pumping water out and sending a worker in to do the dirty work.

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“A guy was hooked up to a climbing harness so that he wouldn’t fall into the pool, and he was out there with a long-handled net, fishing things out of the water far down into the crater of the pool.”

The team fished out hundreds of objects during the laborious work, Cowboy State Daily said, as it tried not to damage the delicate thermal pool.

“We found tons, probably thousands of coins,” Henry added. “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 landed in the pool. And they, wisely, didn’t try to retrieve them.”

He can’t imagine the Park Service doing something similar now, however, given the difficulty of the work.

“Cleaning pools was done on a regular basis,” he said. “But values change, and they don’t clean the pools anymore, at least with the frequency and at the scale that we did.”

But people are also more considerate of the park’s wondrous landscape, he added.

“I don’t see anywhere near as many coins in pools as I used to back in my early days in the park,” he said. “The bottoms of the more accessible springs used to be paved with coins, but now it’s pretty rare to see anything thrown into the pools.

“I think people are much more respectful than they were in my early days,” Henry said. “It’s one way that values and behavior have changed over the years.”

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