Editing Ogallala Aquifer (section)

===Change in groundwater storage===
Ground water levels decline when the rate of extraction by irrigation exceeds the rate of recharge. At places, the water table was measured to drop more than 5&nbsp;ft (1.5&nbsp;m) per year at the time of maximum extraction. In extreme cases, the deepening of [[water well|wells]] was required to reach the steadily falling water table. In the 21st century, recognition of the significance of the aquifer has led to increased coverage from regional and international journalists.<ref>[http://www.nwanews.com/adg/Business/167660/ "Shrinking aquifer looms as big problem for farms"] {{webarchive|url=https://web.archive.org/web/20090204014036/http://www.nwanews.com/adg/Business/167660/ |date=2009-02-04 }}. Nancy Cole, ''Arkansas Democrat-Gazette''. September 24, 2006. Last accessed October 24, 2006.</ref><ref>[http://www.amarillo.com/stories/100406/opi_5471882.shtml Column - Mansel Phillips: "Too many thirsty industries, not nearly enough water"] {{Webarchive|url=https://web.archive.org/web/20130615174945/http://amarillo.com/stories/100406/opi_5471882.shtml |date=June 15, 2013 }}. Mansel Phillips, ''Amarillo Globe News''. October 4, 2006. Last accessed October 24, 2006.</ref><ref>[http://journalstar.com/news/opinion/another-sign-of-long-term-water-worries/article_56f379fb-2e2c-56e2-ad47-79b026e877ac.html "Another sign of long-term water worries"], ''Lincoln Star Journal'', October 8, 2006. Last accessed November 20, 2012</ref><ref>[[Daily Telegraph|Daily Telegraph (UK)]] Saturday Magazine Issue no 48,446 (dated 5 March 2011) pp 26-32 "High and Dry" Report by ''Charles Lawrence''</ref>

[[Water conservation]] practices ([[terrace (agriculture)|terracing]] and [[crop rotation]]), more efficient irrigation methods (center pivot and [[drip irrigation|drip]]), and reduced area under irrigation have helped to slow depletion of the aquifer, but levels are generally still dropping in areas including southwestern Kansas and the [[Texas Panhandle]]. In other areas, such as parts of eastern and central Nebraska and of the region south of [[Lubbock, Texas]], water levels have risen since 1980.

The [[center-pivot irrigator]] was described as the "villain"<ref name=NYT20May2013>{{cite news|newspaper=New York Times|title=Wells Dry, Fertile Plains Turn to Dust|date=19 May 2013|first=Michael|last=Wines|url=https://www.nytimes.com/2013/05/20/us/high-plains-aquifer-dwindles-hurting-farmers.html?smid=pl-share}}</ref> in a 2013 ''[[New York Times]]'' article, "Wells Dry, Fertile Plains Turn to Dust" recounting the relentless decline of parts of the Ogallala Aquifer. Sixty years of [[intensive farming]] using huge center-pivot irrigators has emptied parts of the High Plains Aquifer.<ref name=NYT20May2013 /> Hundreds to thousands of years of rainfall would be needed to replace the groundwater in the depleted aquifer. In Kansas in 1950, irrigated cropland covered {{cvt|250,000|acre|ha}}; with the use of center-pivot irrigation, nearly three million acres of land were irrigated.<ref name=NYT20May2013 /> In some places in the Texas Panhandle, the water table has been drained (dewatered). "Vast stretches of Texas farmland lying over the aquifer no longer support irrigation. In west-central Kansas, up to a fifth of the irrigated farmland along a {{convert|100|mi |km|adj=mid | swath}} of the aquifer has already gone dry."<ref name=NYT20May2013 />

The center-pivot irrigation system is considered to be a highly efficient system which helps conserve water. However, by 2013, as the [[water consumption]] efficiency of the center-pivot irrigator improved over the years, farmers chose to plant more intensively, irrigate more land, and grow thirstier crops rather than reduce water consumption--an example of the [[Jevons Paradox]] in practice.<ref name=NYT20May2013 /> One approach to reducing the amount of groundwater used is to employ treated recycled water for irrigation; another approach is to change to crops that require less water, such as [[sunflower]]s.<ref>[http://www.denverpost.com/news/ci_4433612 Jeremy P. Meyer, "Farmers' tower of power"], ''Denver Post'', 2 October 2006. Last accessed October 24, 2006</ref>

Several rivers, such as the [[Platte River|Platte]], run below the water level of the aquifer. Because of this, the rivers receive groundwater flow (baseflow), carrying it out of the region rather than recharging the aquifer.

The $46.1-million [[Optima Lake]] dam in western [[Oklahoma]] was rendered useless when the dropping level of the aquifer drastically reduced flow of the [[Beaver River (Oklahoma)|Beaver River]], the lake's intended source of water.<ref>Logan Layden, "If you Want to Build a New Lake in Oklahoma, Forget History",  March 28, 2013, StateImpact Oklahoma{{cite web |url= https://stateimpact.npr.org/oklahoma/2013/03/28/the-lessons-of-history-no-longer-apply-when-it-comes-to-building-lakes/  |title= The Lessons of History No Longer Apply when it comes to Building Lakes |work= StateImpact Oklahoma website |access-date= 2015-06-01}}</ref>