News Release, Kansas Geological Survey, April 14, 2011
LAWRENCE--Groundwater levels dropped, on average, throughout western and central Kansas last year with the greatest decline in the southwest, according to preliminary data compiled by the Kansas Geological Survey (KGS), based at the University of Kansas.
In January 2011, KGS and the Kansas Department of Agriculture's Division of Water Resources (DWR) measured levels in approximately 1,400 water wells in 47 western and central Kansas counties as part of their annual assessment program.
Groundwater levels declined an average of nearly 3 feet in southwestern Kansas, compared to average declines of less than a foot in west-central, northwestern, and central Kansas.
Most of the measured wells are within the boundaries of the state's five Groundwater Management Districts (GMDs), organized by area landowners and large-scale water users and governed by local boards to help define and address water-resource issues.
"Declines were again highest in Southwest Kansas GMD 3 where January 2010 to January 2011 marked the third highest overall average decline since 1996," said Brownie Wilson, KGS water-data manager. "Much of this can be attributed to below normal precipitation patterns during most of the 2010 growing season."
Ninety percent of the nearly 1,400 measured wells draw water from the High Plains aquifer, which includes the extensive Ogallala aquifer, the Great Bend Prairie aquifer in west-central Kansas, and the Equus Beds aquifer north and west of Wichita. The rest are drilled into the deeper aquifer systems, such as the Dakota, or shallower aquifers along creeks and rivers.
In the Ogallala portion of the High Plains aquifer, precipitation influences the need to pump, which in turn, affects ground-water levels, Wilson said.
In GMD 3 in southwestern Kansas, where wells are screened mainly in the Ogallala aquifer and--in selected areas--the Dakota aquifer, water levels were down 2.97 feet as a whole from the previous year. Most of these declines occurred from the Arkansas River south into Grant, Haskell, and Gray counties.
GMD 3 also includes all or part of Finney, Stanton, Ford, Morton, Stevens, Seward, Hamilton, Kearny, and Meade counties. Water levels in GMD 3 dropped as a whole 3.03 feet and 1.48 feet, respectively, in the two prior years and have risen only once--0.04 feet in 1997--since 1996.
Average declines in each of the other four GMDs were less than a foot.
Western Kansas GMD 1, which includes portions of Wallace, Greeley, Wichita, Scott and Lane counties, had an average decline of 0.71 feet. That decline was slightly greater than drops the previous two years, which were 0.29 and 0.42 feet, respectively. Most of the area's wells, whose levels have dropped 12 of the last 15 years, are drilled into the Ogallala aquifer.
Measurements in Northwest Kansas GMD 4, covering Sherman, Thomas, Sheridan and parts of Cheyenne, Rawlins, Decatur, Graham, Wallace, Logan and Gove counties, showed an overall decline of 0.50 feet. The year before the average level was up 0.15 feet, the only rise in the region since 1996.
Areas north of GMD 4, mainly in Rawlins, Decatur, Norton and Phillips counties, had overall increases, with 2.5 feet and greater rises in localized parts of Norton and Phillips counties. In this area of the state, the Ogallala aquifer is generally less productive so most of the higher capacity wells are in alluvial river valleys.
Big Bend GMD 5, centered on the Great Bend Prairie aquifer underlying Stafford and Pratt counties and parts of Barton, Pawnee, Edwards, Kiowa, Reno and Rice counties, had the smallest average decline at 0.43. In the prior two years levels had risen about one-half foot per year following a 3.34 feet bump in 2007 due to far above average precipitation and flooding. Increases have been recorded in the area 7 of the last 15 years.
Water levels in the Equus Bed GMD 2 fell 0.68 following three years of increases. Levels rose 2.12 feet throughout 2007, 1.63 feet in 2008 and 0.3 feet in 2009. Rising water levels have also been recorded in the Equus Bed aquifer 7 of the last 15 years.
Much of the water supply for Wichita, Hutchinson and the surrounding area comes from the Equus Bed aquifer.
The High Plains aquifer is the primary source of municipal, industrial, and irrigation water for much of western and central Kansas. Approximately 80% of the 33,000 non-domestic water wells in Kansas are in the High Plains aquifer region of the state.
The same wells are measured each year to get an understanding of how the aquifer is behaving over the long term and how water levels are affected by climatic conditions and pumping. Measurements are taken primarily in January because water levels are least likely to fluctuate when irrigation wells aren't in use.
Results of the measurements are provisional and subject to revision based on additional analysis. The data are available at http://www.kgs.ku.edu/Magellan/WaterLevels/index.html.
Other information about the state's ground water is available from the KGS website, including a site dedicated to water rights information, http://hercules.kgs.ku.edu/geohydro/wimas/index.cfm.