White Jankowski Lawyers

A national and local pattern of groundwater depletion

May 30, 2013

On May 20, the USGS released a report that detailed groundwater depletion in the United States from 1900−2008.  The USGS found that between 1900 and 2008, U.S. groundwater reserves have depleted by a volume of water sufficient to fill Lake Erie twice. 

The USGS studied 40 major aquifer systems including the High Plains (or Ogallala) Aquifer, Dakota Aquifer, western alluvial basins, and deep confined bedrock aquifers like the Black Mesa Aquifer.  Four groundwater systems in Colorado were studied: the High Plains, Dakota, Denver Basin, and San Luis Valley aquifers.  Of those, only the Denver Basin and San Luis Valley aquifers are located exclusively in Colorado.  The USGS found that the High Plains Aquifer experienced a rate of depletion between 2001 and 2008 equal to 32% of the cumulative depletion during the entire 20th century!  The greatest depletions occurred in Texas.  The total depletion of the Dakota Aquifer was determined to be 20.3 cubic kilometers (km3) between 1900 and 2008, or 16,457,478 acre-feet.  (This volume is equal to approximately 400,000 Olympic-size swimming pools.)  The Dakota Aquifer was analyzed separately from the Denver Basin since it extends across five states.  Depletions in the Denver Basin totaled approximately 1.30 km3 between 1900 and 2008 (equal to approximately 1,053,927 acre-feet).  The San Luis Valley experienced a net depletion of about 3.6 km3 between 1900 and 2008 (approximately 2,918,568 acre-feet).  In short, Colorado’s large aquifers that were studied by the USGS are all part of the national trend of substantial depletion.

The USGS concluded that national groundwater use is on an unsustainable course, with water removal outpacing water recharge.  During the 20th century the volume of groundwater depletion totaled approximately 800 km3 (approximately 648,570,555 acre-feet), which increased by an additional 25% between 2001 and 2008.  This recent spike in groundwater withdrawal may be due to changes in weather such as more severe droughts, which cause communities to use more groundwater.  The report stated that “[i]n addition to widely recognized adverse environmental effects of groundwater depletion, the depletion also impacts communities dependent on groundwater resources . . . . the observed rates of depletion must eventually decrease as economic and physical constraints lead to reduced levels of extraction.”  However, the USGS noted that the rate of depletion was “leveling-off” and “self-limiting” in a few areas, particularly smaller western alluvial basins.