A front-page article in the Wednesday, June 17, 2015, Washington Post was titled "Earth's groundwater re- serves dwindling." Other news sources used even scarier headlines. So the question of the day is, are we running out of water?

Rest easy, everyone. No, we are not running out of water. The same amount of water still exists on earth as when dinosaurs roamed the earth. However, the article raises a serious concern that all over the planet, we are using groundwater at a faster rate than it can be replaced by natural recharge.

In other words, water is anoth- er natural resource that we are mining. The difference is that it is possi- ble that groundwater can be replaced rather quickly if conditions are right, while coal and oil, once mined, are irreplaceable in real time.

Recall that of all the water on earth, approximately 97 percent is salt water. Of the three percent fresh water, two percent is locked up in the Antarctic and Greenland glaciers. This leaves one percent fresh water either in streams, lakes, or as ground- water. Interestingly, about 99 percent of this one percent is groundwater. Groundwater supplies 35 percent of all the water used by humans world- wide, and agriculture accounts for more than half the groundwater use.

So where did the information about declining groundwater re- serves come from? It turns out that it comes from NOAA satellite data collected over the ten-year period ending in 2013. The NOAA data detected declines in water levels in many aquifers worldwide.

Jay Famiglietti of the Jet Pro- pulsion Laboratory in Pasadena, California, was quoted in the article, "The water table is dropping all over the world. There's not an infinite supply of water."

I've met Jay and he is a promi- nent and articulate scientist. I agree with him that there's not an infinite supply of water because, is there an infinite supply of anything? How- ever, I would argue that his state- ment doesn't go far enough. I would rather he had said, 'there's not an infinite supply of groundwater.' Bet- ter yet, I would have preferred he said, 'there's not an infinite supply of FRESH groundwater' or 'of PO- TABLE groundwater.'

I suppose it is possible, given the heavy reliance on groundwater that some aquifers could become dewatered. One consequence of drawing down the water table or de- watering an aquifer is that the sands, gravels or other materials comprising the aquifer could compress. In other words, the materials comprising the aquifer would become compacted.

If the aquifer material is com- pacted, what could this lead to? It could lead to land subsidence that could have serious economic conse- quences for those with possessions like homes on the land surface. In fact, subsidence due to mining of groundwater is a relatively common occurrence.

Right now, fresh water is cheap, too cheap.

However, if we do dewater certain aquifers, for example, Cali- fornia's Central Valley Aquifer, the cost of fresh water could change dramatically. For example, we know how to remove salt from ocean water. But this is very expensive, as is the salt removal process, the disposal of removed salt, and even more so, the transport of the desalinized water to the areas where it is needed.

So the upshot of dewatering aquifers in the long term will be a significant increase in the cost of fresh water, something that will dra- matically affect the world economy.