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National Groundwater Awareness Week

March 11-17 is National Groundwater Awareness Week


   Major aquifers of the United States. Map by Jake Aydelott (2016).


Groundwater is a precious (and in some locations, finite) resource that accumulates in areas of water-bearing permeable rock known as aquifers.  If the rock above the aquifer is premeable to water movement, the aquifer is described an unconfined.  Unconfined aquifers are readily recharged by the downward percolation of surface water.  Confined aquifers are overlain by impermeable rock that prevents downward water movement from land directly above the aquifer.  These aquifers are recharged by lateral water seepage through areas of permeable rock that may be a considerable distance from the confined aquifer.  Confined aquifers are typically much deeper than unconfined aquifers, and the water in a confined aquifer may be thousands of years old.  Agriculture thoughout much of North America relies on withdrawl of groundwater to irrigate crops.  Some of the country's largest, and most agriculturally important, aquifers are confined aquifers.  When water is withdrawn at a faster rate than the aquifer can recharge, the aquifer becomes depleted.  The Ogallala aquifer is one such agriculturally important and over-used aquifer.  Excessive withdrawl of water from aquifers can lead to various issues such as soil salination, land subsidence, and saltwater intrusion in coastal areas.

Center pivot irrigation, Big Horn County, Wyoming. Photographs by VR Schmalhofer.


Groundwater supplies a sizable fraction of the drinking water used in the United States (~37%), and contamination of groundwater is a serious issue in many areas.  Testing of well water on a regular basis is important to assess the safety of drinking water supplies.  More information about well water testing is provided by AIG. 




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