Famous Morning Glory Pool has turned green because of coins and trash thrown in it, but we've found a good substitute if dazzling blue is your favorite color.

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YELLOWSTONE NATIONAL PARK – If Morning Glory Pool just isn’t blue enough for you anymore, I found a good stand-in. True blue. Bluer than a blueberry.

The thing about the famous Morning Glory Pool, named by early park explorers for its remarkable color match for the heavenly-blue flower, is that, uh, it’s not blue anymore. It’s more green. And orange around the edges.

Don’t get me wrong. It’s still stunning. It’s just not blue.

The tale you’ll hear from park rangers is that over the decades, so many coins, so many candy wrappers, other litter and just plain trash, got thrown into the pool (by humans who don’t always do the name proud, if I may add an editorial comment) that it got plugged up, reducing the flow of superheated water from the bowels of the earth. Result? The pool got cool. Well, cooler.

It didn’t help that in the park’s early years, the main road went right along the edge of Morning Glory Pool, allowing motorists to litter into it with greater ease.

Morning Glory is still plenty hot. You wouldn’t want to go for a swim. Or dive in to rescue your dog, as an unfortunate visitor once did in another of the park’s hot pools (see the famous book, “Death in Yellowstone,” which gave me nightmares a few nights ago).

But it turns out that the temperature of these thermal pools has a lot to do with the thermophiles – a word they bandy around rather casually in this park – that live in it. Thermophiles are basically bacteria and other tiny creatures that can live in water that’s hot but not boiling. As Morning Glory cooled, orange and yellow bacteria thrived. And we know that blue – the pool’s original color — and yellow make green, right? So Morning Glory Pool should perhaps be renamed. Kiwi Fruit Pool, anyone?

Anyway – if your need for a dazzling blue pool is left wanting after you visit the Upper Geyser Basin, just head down the road a few miles to the Fountain Paint Pot area. There, along the half-mile nature trail, you’ll come across Silex Spring. And boy, is it blue. Gorgeously blue. I hope I’m not fracturing the science, but my understanding is that at 167 to 199 degrees (about the boiling point at this altitude of nearly 8,000 feet), the spring is too hot for most thermophiles. So what makes it blue, stays blue.

And Yellowstone visitors get another nice return on the $30 they spent at the entry gate.