The Endangered Waters Beneath Our Feet


Fish-shaped Long Island, New York, is underlain by aquifers that are its sole source of drinking water. Photo courtesy of NASA/Wikimedia Commons.


Last week, the conservation organization American Rivers released its annual list of the nation’s most-endangered rivers.

I got to thinking, what if we had a sister list of most-endangered aquifers?

After all, water from underground meets 20 percent of U.S. water demand for drinking, crop irrigation and everything else. It also provides the base flows that keep many rivers and streams from drying up during the summer months.

So groundwater is crucial to our economies and ecosystems, yet it’s out of sight – and usually out of mind, as well.

Which is why a most-endangered aquifers list might help.

On such a list I would name the Ogallala Aquifer beneath the Great Plains, which supplies 27 percent of the nation’s irrigated farmland and has undergone decades of depletion. I would include California’s Central Valley aquifers, which are greatly over-pumped to grow the nation’s fruits and vegetables.

I would add coastal aquifers in Florida and the Carolinas, which are threatened by the intrusion of seawater.  In some areas, heavy pumping from those aquifers has reversed the hydraulic gradient: instead of groundwater flowing out to sea, ocean water moves in, polluting fresh drinking water with salt.

And then there’s the groundwater I sipped for seventeen years while growing up on New York’s Long Island.  For most of that time, all I knew was that our household water came from the big water tower elevated high above our community.  I didn’t know that the source of water for our backyard wading pool, Saturday night baths and summer lemonade was beneath my feet.

But it was, and that made our water vulnerable to so many things we Long Islanders did on the land above it – from applying fertilizers to dumping waste products to paving over wetlands and woodlands.  All that and more could damage the quality of the water we bathed in and drank. And it did.

Today, 3 million people call Long Island home.  Some 80 percent of Nassau County, where I grew up, is developed.  Most of the wetlands and open space are gone.  But the sole source of drinking water remains the layered aquifers beneath the fish-shaped island.

In a wonderful new video, New York-based GRACE Communications Foundation lays out the unique challenges Long Islanders face in safeguarding their drinking water.

“As important as clean water is to economic health, it’s even more important to human health,” GRACE program director Kyle Rabin reminds us in the video.

Among the solutions put forth – curbing fertilizer and pesticide use, responsibly disposing of pharmaceuticals and hazardous waste rather than flushing them down the drain, maintaining septic systems to reduce nitrogen pollution, and protecting open space to promote rainwater infiltration and aquifer recharge.

“We have no Plan B once our drinking water is gone,” warns Robert K. Sweeney with the New York State Assembly, who also appears in the video.  “It’s up to us to make sure that this resource is available for the future.”

The video’s opening segment is a must-see: on-the-street Long Islanders answer where they think their drinking water comes from.

Have a look.  Have a laugh.  And learn about the precious waters beneath our feet, and what we can do together to protect them.

Sandra Postel is director of the Global Water Policy Project and lead water expert for National Geographic’s Freshwater Initiative.  She is the author of several acclaimed books, including the award-winning Last Oasis, a Pew Scholar in Conservation and the Environment, and one of the “Scientific American 50.”

Sandra Postel is director of the Global Water Policy Project and author of Replenish: The Virtuous Cycle of Water and Prosperity. From 2009-2015, she served as Freshwater Fellow of the National Geographic Society. Sandra is also co-creator of Change the Course, the national water stewardship initiative awarded the 2017 US Water Prize for restoring billions of gallons of water to depleted rivers and wetlands. The recipient of several honorary degrees, she works to bridge science, policy, and practice to promote innovative ways of securing water to meet both human and ecosystem needs.
  • Joe

    Sand quarries in our town have exposed 30 or so acres of groundwater, there are no wetlands around them to filter run off from the dirty parts of the quarries, AND I imagine there are no laws in place to protect these exposures. See the exposure on google maps type in zip code 11953 or middle island.

  • Christian

    Everyone should buy a Berkey Water system or
    Pro-Pure system. Its under $300 and will give you
    the safest and best drinking water that you will never
    Have to worry again.

  • John


    God forbid there is a chemical or oil spill. With the porous sandy soils on Long Island, any spill will migrate rather quickly. It could be tragic even from a homeowner’s underground oil tank and even worse from a leaking underground tank at a gas station.

    The leaking tank could be a mile or more away from the open pit. Once it hits groundwater, so long as the groundwater flow is in the direction of the pit, the benzene or MTBE or TBA or xylenes or even the free gasoline or oil product will ride the water table like a skater on a frozen lake.

    On the positive side, it might be easier to cleanup if the gradient of such a leak is toward the pit, because most of the product will migrate there. But the soils in between the leak and the pit will remain affected, especially in the area of the soil where the water table rises and falls.

    If you have a private potable well, make sure to get it tested every so often. If you are on a commercial or city water system, the company or the city test the water very frequently–the results of which are public.

  • Loretta

    Christian: Our drinking water is perfectly safe already. We don’t *need* to invest money in a filtration system unless we *want* to. It is not necessary to protect our health. Furthermore, many people are a tad lazy when it comes to replacing the filter in a timely fashion, thus any naturally occuring materials that are captured by the filter (such as iron, which is in itself harmless and actually beneficial for the body) will accumulate and create a breeding ground for bacteria, thereby creating a problem that did not exist previously. If people are concerned about their drinking water quality they should contact their local health department or public water supplier (if they are on public supply) to either run tests for them or recommend certified labs. People should NOT have filter companies test their water for them, for obvious reasons. My comments herein refer specifically to drinking water that is provided by a public water supplier. If someone gets their water from a private well on their property, then they *definitely* should consider testing their water frequently and, if the opportunity arises, they should connect to a public water supplier.

    Kyle: My primary issue with the video and with Sandra’s comments is that they have lumped all of Long Island’s aquifer systems together. There are very specific differences in terms of potential exposure to contaminants based on demographics, wastewater treatment and geology. For example, over 90% of Nassau County’s population is served by sanitary sewers, so references to pharmaceuticals and other wastewater-related products is largely irrelevant. Inasmuch as I agree that we *must* be diligent and protect our sole source aquifer system, as well as the associated surface water bodies, I want to make sure people make decisions based on their particular suite of circumstances. I don’t want them to panic and think they are drinking “polluted” water when they are on a public water supply, for example. We must continue to strive for groundwater protection policies (such as better septic/cesspool maintenance in areas that are served by tem, and more stringent pesticide/herbicide etc. use laws, for example), but our best “weapon” is education. *Factual* education. Thanks for listening.

  • Bccnp1

    These issues are pretty simple if we ask ourselves who do we trust with our water?

  • […] at National Geographic Newswatch, Sandra Postel laments the out-of-sight, out-of-mind nature of groundwater. She gives her most […]

  • trevor

    Should you not be looking at the mega quarry issue in dufferin county just north of Toronto Ontario


    you cant tell me that digging 200 feet blow the water table will not cause a problem

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