US Groundwater Supply Is Less
than Thought
by Nancy Hearn

The US groundwater supply is smaller than originally thought.  And this is significant since many rural areas of the U.S. rely primarily on groundwater for both domestic and agricultural use.

A new research study published in November 2018, conducted by scientists from the University of Arizona, the University of California, Santa Barbara, and the University of Saskatchewan, provides new insights into the depths of fresh water availability in the most prominent basins in the United States.

Importance of US Groundwater Supply

Groundwater is the main source of water for domestic use for at least half the people living in the U.S. 

In addition, at least 40 percent of all water used for agricultural irrigation comes from groundwater.

However, where I live in Arizona, as well as many rural areas around the country, we rely solely on groundwater for both domestic and agricultural use.

According to the researchers, they estimated that more than  5 billion people around the world live in areas of water scarcity, most of which rely on groundwater. 

And in many cases worldwide, significantly more water has been taken out of their groundwater basins than is coming in.

Groundwater Supply in U.S. and the World

The bottom line to the study is that the researchers found that the average depth of groundwater in the U.S. overall is about 1,800 feet.

This is the point at which the water transitions from fresh water to brackish groundwater.

Previous studies suggested that fresh groundwater is available down to depths of 6,500 feet.  That is a huge difference, almost 5,000 feet.

In addition, in parts of the eastern U.S., the researchers found brackish groundwater at less than 1,000 feet. 

Thus, in these areas, drilling deeper wells is not a long-term solution for supplying the need for fresh water, wrote the researchers.

Since the groundwater estimates for the U.S. were so much lower than previously thought, the researchers suggest that the global amount of available fresh groundwater is most likely much less than previously determined.

Fracking Also Affects Potable Water Supply

In addition to the basic problem of the potable supply of water being less than previously thought, hydraulic fracturing (or fracking) is also affecting potable water, according to the same researchers.

The injection of water, chemicals or sand that occurs with fracking drives water containing hydrocarbons into surrounding areas that contain potable water.

Unfortunately, it may take many years and many dollars to determine how much separation is needed to protect groundwater from oil and gas activities.

Reference

UANews.Arizona.edu; Groundwater in peril: Potable supply less than thought; 2018.

Further reading

Water Contaminants from Fracking

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