Pumpkin Spring – The Grand Canyon’s Arsenic Pool

2 April 2012

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Below the rim of the Grand Canyon runs the beautiful Colorado River.  Many take trips down its length but among the majestic scenery is something which they do not quite expect – a huge, enormous gourd-like squash. Jutting out from the canyon wall and perched above the river, this highly unusual formation is known as Pumpkin Spring.

If you raft the river, this hot spring is at mile 212.9 to be exact.  Over the millennia the Pumpkin like spring has grown to the extent that is could be said to resemble something from a Roald Dahl novel. Dahl would probably have approved – although the spring might look enticing it isn’t quite as friendly as it appears.

Pumpkin Spring is a travertine, which is a form of limestone especially deposited by hot springs. It builds up and forms weird shapes, as you can see here and often has a fibrous appearance as if it is made of vegetable matter. This natural bowl spills bitter water into the river but beware of what has been deposited within.

Photograph by kind permission of Flickr User Ben Kimball

The waters inside the pumpkin certainly look deliciously warm, it has to be said.  However, they are not considered safe as they contain high levels of arsenic, not to mention concentrations of copper, zinc and lead.  Although some cannot resist its charms and jump right in, a good shower is recommended afterwards. As for drinking the water, forget it!

It is probably the only truly dangerous water in the Grand Canyon.  Put it this way, the state health standard for safe water is 50 milligrams of arsenic per liter.  The levels at Pumpkin Spring were recently measured and revealed a shocking 1100 milligrams of arsenic per liter.

Arsenic poisoning is not pleasant. It begins with headaches, bewilderment, relentless diarrhea, and lethargy.  If untreated it can lead to vomiting, blood in the urine, cramping muscles, hair loss, stomach pain, coma and death. Of course, a quick dip in Pumpkin Spring would not precipitate any mortal danger but better safe than sorry – look, but don’t dip!

First picture - Flickr User Al_hikesAZ


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