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Groundwater sources face threats of pollution, droughts, and increasing demand

Tests conducted in water pools at Carlsbad Caverns National Park found pollution from above had worked its way underground. Among the chemicals detected: chromium, nitrates, caffeine, as well as hydrocarbons, which likely came from the parking lot on the surface.
About 25% of America's 332 million people get their drinking water from groundwater beneath the surface.
Caves and karst play an important role in the world's drinking water supply. About 20% of the world's supply can be found in them.
Every year, about half a million people visit Carlsbad Caverns, which boasts majestic, high-ceiling "rooms" underground.
Drought, coupled with increased demand from population growth, is impacting the water table far below the surface.
Posted at 6:55 AM, Aug 18, 2022
and last updated 2022-08-18 09:55:45-04

CARLSBAD, N.M. — Descending from the bright sunshine down into another world comes easily at Carlsbad Caverns.

"This is one of the greatest caves in the world,” said Rod Horrocks, chief of resources at Carlsbad Caverns National Park, an underground labyrinth of more than 100 caves beneath southern New Mexico. "In the early days, people had no idea about caves."

Caves and karst play an important role in the world's drinking water supply, holding about 20% of it.

"They're out of sight, out of mind,” Horrocks said. “A lot of people don't think about them and yet they're so integrated, connected to everything we do to our water system."

Every year, about half a million people visit Carlsbad Caverns.

"To aid visitor access to the cave, they built all of the infrastructure right on top of the cave,” Horrocks said, adding, “worst place they could have built it."

It turned out, though, to be the perfect place to run tests to see how the pollution created on the surface makes its way to the water that drips and collects down in the caves.

"From hydrocarbons coming off the parking lot and going into the cave to leaky sewer lines, just all kinds of things can cause problems to the cave," Horrocks said.

It’s a problem not just there, but potentially in other parts of the country, too.

About 25% of America's 332 million people get their drinking water from groundwater beneath the surface. A map from USGS shows the locations of the principal aquifers in the U.S., which are located in nearly every region of the country from Florida to Michigan to Arizona and beyond.

So, what did the tests find at Carlsbad Caverns?

"We found chromium in the water. We found nitrates in the water. Caffeine—it goes through us and it's very persistent and it's found pretty much in water everywhere," Horrocks said.

There is also another issue: drought, especially in the West.

"We go through droughts every 20 years or so, but nothing of this magnitude," said Tom Cech, former co-director of the One World One Water Center at the Metropolitan State University of Denver.

Drought, coupled with increased demand from population growth, is impacting the water table far below the surface. Carlsbad is not immune, either.

"This is ‘Longfellow's Bathtub.’ In 2015, when they designed these lights, it was pretty much full up to the shelf stone - spectacular. And then, we've had this really bad drought since then and it's dropped a couple of feet,” Horrocks said, adding that if drought conditions continue, in the coming years, "We could see the pools in Carlsbad dry up."

It is a threat no one wants to see at any other underground water source critical to life.

Starting in 2021 and continuing into 2022, the world is celebrating the International Year of Caves and Karst, to bring attention to these unique formations and the threats they face. You can also find information about it by clicking here.