OKLAHOMA CITY (AP) - Groundwater levels are declining in an aquifer that serves parts of Oklahoma and seven other states, according to a new report by the U.S. Geological Survey.
The report documents changes in groundwater levels in the High Plains Aquifer, also known as the Ogallala Aquifer, from 1950 - before significant groundwater irrigation was developed in the area - to 2013, and from 2011 to 2013.
Measurements between 2011 and 2013 represent a large decline in groundwater levels, said USGS scientist Virginia McGuire, lead author of the study.
"This amount of aquifer depletion over a two-year period is substantial and likely related to increased groundwater pumping," McGuire said. The USGS study used water-level measurements from 3,349 wells from 1950 to 2013 and 7,460 wells for the 2011 to 2013 period.
In 2011, water stored in the aquifer totaled about 2.92 billion acre-feet, an overall decline of about 267 million acre-feet, or 8 percent, since pre-development of groundwater irrigation. Change in water levels between 2011 and 2013 was a decline of 36 million acre-feet.
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The overall average water-level decline in the aquifer was 15.4 feet from 1950 to 2013, and 2.1 feet from 2011 to 2013.
The High Plains Aquifer underlies about 175,000 square miles in Oklahoma and Colorado, Kansas, Nebraska, New Mexico, South Dakota, Texas and Wyoming. The USGS has published reports on water-level changes in the High Plains Aquifer since 1988. Congress requested the reports in response to substantial water-level declines in large areas of the aquifer.
"This multi-state, groundwater-level monitoring activity tracks water-level changes in all eight states through time and has provided data critical to evaluating different options for groundwater management," McGuire said.
