The U.S. Geological Survey has released a new report detailing changes of groundwater levels in the Ogallala Aquifer, and the news isn’t good.
The report presents water-level change data in the aquifer for two separate periods: from 1950 — the time prior to significant groundwater irrigation development — to 2013, and 2011 to 2013.
A crucial source of irrigation water, the aquifer underlies about 112 million acres (175,000 square miles) in parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas and Wyoming.
In 2011, the total water stored in the aquifer was about 2.92 billion acre-feet, an overall decline of about 267 million acre-feet, 8%, since pre-development.
Change in water stored from 2011-13 was an overall decline of 36 million acre-feet. The overall average water-level decline in the aquifer was 15.4 feet from pre-development to 2013, and 2.1 feet from 2011-13.
From 1950-2013, Texas and Kansas were by far the worst offenders, with decreases in water storage of 158 feet and 67 feet, respectively. Conditions appeared to be better further north in Nebraska, Wyoming and Colorado.
“The measurements made from 2011 to 2013 represent a large decline,” says Virginia McGuire, USGS scientist and lead author of the study. “This amount of aquifer depletion over a 2-year period is substantial and likely related to increased groundwater pumping.”
Similar to water storage, the drop in water levels was also worse in the southern Plains than in Nebraska, South Dakota and Wyoming, where conditions appear to be stable. From 2011-13, Texas led the way with an average water-level drop of 3.5 feet, followed by Kansas (3 feet), Colorado (2.2 feet), Oklahoma (2 feet) and Nebraska (1.5 feet).
It shouldn’t be overlooked that western Kansas and Oklahoma, and northwestern Texas, have been mired in a prolonged drought, which means the aquifer isn&rsquo't being recharged relative to water use, and more water is needed to irrigate crops.
The USGS study used water-level measurements from 3,349 wells for pre-development to 2013, and 7,460 wells for the 2011 to 2013 study period.
The problems some of these states are facing with their agricultural water supply for farming have been well documented. But I think this just reinforces the need for growers and ag stakeholders to start embracing modern, efficient irrigation methods on a more widespread basis.
They must also give serious consideration to implementing no-till practices that will build soil structure and allow fields to absorb and retain more precipitation. Hopefully, that will help make water use more efficient and preserve a crucial economic and natural resource.
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