LAWRENCE — Groundwater levels during 2018, on average, rose slightly or remained about even throughout most of western and central Kansas, according to preliminary data compiled by the Kansas Geological Survey.
“By and large, 2018 was a good year for groundwater levels,” said Brownie Wilson, KGS water-data manager. “Virtually all levels in south-central Kansas wells were up along with a good portion of those in northwest Kansas, and although southwest Kansas saw a few decline areas in the usual spots, they were not as great as in years past.”
The KGS, based at the University of Kansas, and the Kansas Department of Agriculture’s Division of Water Resources (DWR) measure more than 1,400 water wells in Kansas annually. Most of the wells are drilled into the High Plains aquifer, a network of water-bearing rocks underlying parts of eight states and the state’s most valuable groundwater resource.
Ninety percent of the collected data comes from wells tapping the aquifer. The other wells are drilled into other aquifers underlying the High Plains aquifer and shallow aquifers adjacent to surface-water sources, such as the Arkansas River. Most of the 1,400 wells have been measured for decades.
In Kansas, the High Plains aquifer comprises three individual aquifers—the widespread Ogallala aquifer that underlies most of the western third of Kansas, the Equus Beds around Wichita and Hutchinson, and the Great Bend Prairie aquifer around Pratt and Great Bend.
Water levels in the Ogallala aquifer are influenced mainly by the amount of water withdrawn each year, which in turn is affected by the rate and timing of precipitation. Recharge, or water seeping down from the surface, adds little groundwater to the Ogallala. In central Kansas, however, recharge has more of an impact because the Equus Beds and Great Bend Prairie aquifer are shallower and average precipitation in that part of the state is higher.
Most of the wells in the network monitored by the 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 .39 feet. Although down, the change was less than in 17 of the last 20 years when levels fell between .5 and 3.5 feet annually. A rise of .05 feet in 2017 was the only positive movement during that time.
For the second summer in a row, water flowed for a time from the Colorado state line to Garden City. The river, which interacts with its adjacent shallow alluvial aquifer, has been mainly dry in western Kansas for decades.
Wells monitored in GMD 3 are drilled into the Ogallala aquifer except in a few areas where they draw from the deeper 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 experienced a slight drop of .18 feet following a slight gain of .07 feet in 2017. The GMD includes portions of Wallace, Greeley, Wichita, Scott, and Lane counties, where the majority of wells are drilled into the Ogallala aquifer.
“West central was basically unchanged as a whole but the average is bookended by declines in Wallace County and rises in Scott County,” Wilson said.
Northwest Kansas GMD 4 had an average increase in water levels of .26 feet following a rise of .38 feet in 2017. 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 shallow alluvial sources associated with streams. Besides being influenced by precipitation, water-level results in part of GMD 4 were tied to crop loss.
“Some producers south of the Goodland to Colby area got hailed out early in the 2018 growing season,” Wilson said. “With hail damaged crops and higher precipitation rates in the eastern portion of GMD 4, wells there had less declines or even slight recoveries.”
Big Bend GMD 5 had an average increase of 1.21 feet following an increase of .30 feet in 2017. The GMD is centered on the Great Bend Prairie aquifer underlying Stafford and Pratt counties and parts of Barton, Pawnee, Edwards, Kiowa, Reno and Rice counties.
Equus Beds GMD 2, a major source of water for Wichita, Hutchinson and surrounding towns, experienced a gain of 1.35 following a 1.93-foot decline in 2017. The GMD covers portions of Reno, Sedgwick, Harvey and McPherson counties.
The KGS measured 581 wells in western Kansas and DWR staff from field offices in Stockton, Garden City and Stafford measured 223, 260 and 357 wells in western and central Kansas, respectively. Measurements are taken annually, primarily in January when water levels are least likely to fluctuate due to irrigation.
The results are provisional and subject to revision based on additional analysis. Data by well is available at http://www.kgs.ku.edu/Magellan/WaterLevels/index.html.