MOVING MOUNTAINS FOR WATER

According to to a recent report, withdrawal of large volumes of groundwater in California's Central Valley is causing nearby mountain ranges to rise and may also be triggering small earthquakes.*

Over the past 150 years, the aquifer in this area has been depleted by about 160 cubic kilometers of groundwater. A concern beyond the loss of such water is that the resulting mountain movement could stress the San Andreas Fault.

The United States Geological Survey (USGS) reports that from 1900 to 2008, U.S. aquifers were depleted by more than twice the volume of water contained in Lake Erie and explains more than 2% of the observed global sea level increase during that period. In the period 2000-2008, the depletion rate averaged 25 cubic kilometers per year. Municipalities in the Gulf Coastal Plain, High Plains, Pacific Northwest and Desert Southwest have experienced declines of groundwater levels up to hundreds of feet. As an example, pumping from the large and important Ogallala aquifer since the 1940s has resulted in a lowering of the water table of up to 160 feet.

According to USGS, use of groundwater in the highly populated Milwaukee-Chicago corridor has reduced groundwater levels by as much as 900 feet. In the last half of the 20th century, Chicago suburbs experienced accelerated growth, with their water systems almost exclusively relying on groundwater. As pumping increased, wells were drilled deeper , not only to get more water but water of higher quality. As growth continued, however, wells became less reliable-- particularly deep wells such at the 1500 foot level or more, which began to mine salt water. Fortunately, for most of these communities eventually Lake Michigan water became available, enabling wells to be retired. Of course, cities away from Lake Michigan do not have Lake water as an option.

Draining of fresh water aquifers is not limited to the United States. It is a global issue. So, what is the point? It should be obvious. If this trend continues unabated by common sense conservation and development of alternative sources of supply, withdrawal of groundwater may not just move mountains--but people everywhere may have to move mountains to find water.
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*Science News, June 14, 2014, p.9