News Release, Kansas Geological Survey, Feb. 10, 2017
LAWRENCE--Groundwater levels in 2016, on average, rose significantly around Wichita, rose slightly in the middle of the state, and declined in much of western Kansas according to preliminary data compiled by the Kansas Geological Survey.
The KGS, based at the University of Kansas, and the Division of Water Resources (DWR) of the Kansas Department of Agriculture annually measure water levels in about 1,400 water wells in western and central Kansas. The collected data are used to monitor the health of the High Plains aquifer, the state's most valuable groundwater resource, and other groundwater resources.
"Before we measured I thought the results might be a little better than we saw last year because Kansas was drought free last spring and summer," said Brownie Wilson, KGS water-data manager. "Overall the declines in western Kansas were around their historical average, but moving east we saw significant rises in the water table."
The High Plains aquifer is a network of water-bearing rocks that underlies parts of eight states and in Kansas comprises three smaller aquifers. The largest of those is the far-reaching Ogallala aquifer. The others are the Equus Beds around Wichita and Hutchinson and the Great Bend Prairie aquifer encompassing Great Bend, Kinsley, Greensburg, and Pratt.
About 90% of the wells measured by the KGS and DWR are drilled into the High Plains aquifer. The rest draw water from the Dakota aquifer and other deeper systems or shallow alluvial aquifers along creeks and rivers.
Almost all of the water used in western and much of central Kansas--by irrigators, industry, and municipalities--is drawn from the High Plains aquifer. In some parts of western Kansas the water is nearing depletion after decades of pumping.
Overall in the 1,400-well network, levels fell an average of 0.21 feet, the smallest decline since 2007. Increases in the eastern part of the network, especially in the Equus Beds, helped boost that number.
Most of the wells in the network monitored by KGS and DWR are within the boundaries of the state's five Groundwater Management Districts (GMDs), which are organized and governed by area landowners and local water users to address water-resource issues.
In Southwest Kansas GMD 3, average levels dropped 1.09 feet compared to 1.04 feet the year before. Average levels there over the last 10 years have declined 23 feet. Wells monitored in GMD 3 are drilled into the Ogallala aquifer except in a few areas where they draw from the Dakota aquifer. The district includes all or part of Grant, Haskell, Gray, Finney, Stanton, Ford, Morton, Stevens, Seward, Hamilton, Kearny, and Meade counties.
Western Kansas GMD 1 saw a drop of 0.68 feet after seeing virtually no decline the year before. The GMD includes portions of Wallace, Greeley, Wichita, Scott, and Lane counties, where the majority of wells are drilled into the Ogallala aquifer.
Northwest Kansas GMD 4 average water levels fell 0.58 feet, nearly equal to the average of all annual declines since 1996. GMD 4 covers Sherman, Thomas, Sheridan, and parts of Cheyenne, Rawlins, Decatur, Graham, Wallace, Logan, and Gove counties. Groundwater there is pumped almost exclusively from the Ogallala aquifer and alluvial sources.
Big Bend GMD 5 is centered on the Great Bend Prairie aquifer underlying Stafford and Pratt counties and parts of Barton, Pawnee, Edwards, Kiowa, Reno, and Rice counties. The average groundwater level there rose 0.58 feet after falling 0.25 feet in 2015. Since 1996, annual levels there have risen 8 times and fallen 13 times.
Equus Bed GMD 2 is a major source of water for Wichita, Hutchinson, and surrounding towns. The average water level there rose 2.10 feet in 2016 after rising 1.44 feet in 2015 and dropping 1.22 feet in 2014. Since 1996, annual levels there have risen in 10 times and dropped 11 times.
"GMDs 2 and 5 are both managed using a safe yield approach, where the goal is to balance water appropriations with recharge," Wilson said. "Both districts appear to be very close to achieving that although they both have local areas where declines are a concern."
Both districts also have geological and precipitation advantages compared to western Kansas. A shallower water table and sandy soils allow water to reach the aquifer more readily in the central part of the state. Water levels to the west are much more greatly influenced by the amount of pumping that takes place and typically have much lower recharge rates, which even during an extremely wet season are negligible.
Currently, most of western Kansas is listed in a moderate to severe drought.
"If drought conditions continue this year, especially during the growing season, pumping demands from the aquifer will increase and water level declines will occur or worsen," Wilson said. "Hopefully we will get timely and plentiful rains this season."
The KGS measures approximately 570 wells in western Kansas each January and DWR staff from field offices in Stockton, Garden City, and Stafford measure 220, 224, and about 360 wells in western and central Kansas, respectively. Most of the wells, spread over 48 counties, are used for irrigation and have been measured for decades.
Measurements are taken primarily in January because water levels are least likely to fluctuate when irrigation wells aren't in use. Infrequently, however, later-than-normal pumping due to dry conditions may unduly affect measurement results.
Measurement results are provisional and subject to revision based on additional analysis. The data is scheduled to be available in early March at http://www.kgs.ku.edu/Magellan/WaterLevels/index.html.