News Release, Kansas Geological Survey, March 29, 2010
LAWRENCE--Groundwater levels rose in south-central Kansas for the third year in a row as declines continued in portions of western Kansas according to preliminary data compiled by the Kansas Geological Survey (KGS), based at the University of Kansas.
The Survey 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 in January as part of their annual assessment program.
In western Kansas, the average water level decreased most in the southwest, where it dropped nearly a foot and a half. West-central counties had a moderate decline while the northwest had a slight increase. Timing of precipitation led to those differences.
"The greatest influence on how much groundwater is pumped out of the aquifers for irrigation is rainfall, or lack of it, during the growing season," said Brownie Wilson, the Survey's water-data manager.
In southwest Kansas the average groundwater level fell 1.48 feet following a 2-foot drop measured in January 2009 and a 3-foot drop the year before.
"The drought in southwest Kansas was maybe not as bad as in the last few years, but the counties along the Kansas-Oklahoma border had several months spanning the growing season with below normal precipitation levels," Wilson said. "In May they only received 5 to 10 percent of their average rainfall amounts."
Northwest Kansas from Cheyenne County to Trego County, experiencing above-normal rainfall in the summer, averaged an increase of 0.18 feet. West Central Kansas--Wallace to Lane counties--had a decline of 0.42 feet. Both areas had slight declines the year before.
Approximately 80% of the 39,000 non-domestic water wells in Kansas are located in the region underlain by the High Plains aquifer, which includes the Ogallala Aquifer, the main source of water in western Kansas.
In south-central Kansas, April 2009 precipitation was above average. There wells are mainly drilled into the Great Bend Prairie aquifer--underlying Pratt and Stafford counties and parts of several surrounding counties--and the Equus Beds aquifer north and west of Wichita.
Water level measurements in January 2010 showed an average rise of 0.63 feet in the Great Bend Prairie aquifer and 0.003 feet in the Equus Beds. In January 2009 they were up 1.63 feet and 0.58 feet, respectively, after significant gains were recorded in January 2008.
Although regional trends were discernible, localized measurements varied. While most well measurements in Stevens, Grant, Finney and Gray counties declined at least 2 feet, a few wells in the region registered gains of 5 or more feet. Measurements from the Dakota aquifer, underlying the Ogallala aquifer, also increased 5 or more feet in a widespread area of Hodgeman County.
Results of the measurements are provisional and subject to revision based on additional analysis. The measurement data is available at http://www.kgs.ku.edu/Magellan/WaterLevels/index.html.