News Release, Kansas Geological Survey, Oct. 1, 1996
The report, by Survey water specialists John Woods and Jeff Schloss, is based on the measurement of 1,500 wells across the state in January, 1996, by the Kansas Geological Survey, the U.S. Geological Survey, and the Division of Water Resources of the State Department of Agriculture.
In the wells that were measured, water levels dropped an average of about six inches from January 1995 to January 1996. The wells dropped about 20 inches during the previous measurement period of January 1994 to January 1995. The slowing rate of decline in the past year was probably due to above-average precipitation in some parts of the state in 1995, which lessened the need for irrigation.
"Water levels rose in parts of south-central Kansas, where the water table is shallow and pumping for irrigation is less," said Schloss. "Levels continued to decline in western Kansas where the water table is deep and irrigation pumping is significant."
Many of the wells measured in western Kansas pump water from the Ogallala Formation. In southwestern Kansas, these wells showed an average decline of about 19 inches. Wells showing the largest declines, as much as 10 feet or more, were in Stanton, Stevens, and central Haskell counties. In the time since irrigation began in southwestern Kansas, water levels declined as much as 150 feet in western Grant County, representing about a 50 percent drop in the amount of the Ogallala Formation that is saturated with groundwater.
In west-central Kansas, the average well declined a little less than one foot in 1995-96, compared to slightly more than a foot during the previous measurement period. Decreases of one to 10 feet were found in Greeley, Wallace, Wichita, Scott, and Lane counties.
In northwestern Kansas, water levels dropped an average of about five inches. Areas of greatest decline, from five to 10 feet, occurred in Rawlins and Thomas counties. In the time since irrigation began in northwestern Kansas, the greatest declines show up in Sherman, Sheridan, and Thomas counties, where irrigation is heaviest.
Water for irrigation in south-central Kansas is most commonly taken from geologic deposits, such as sand and gravel, that are shallower and younger than the Ogallala Formation. Because these formations are closer to the surface, they are more easily replenished in times of high precipitation. Wells in south-central Kansas averaged an increase of about eight inches in 1995-96, primarily because of higher precipitation that lessened the need for irrigation. Sharp declines, as much as four to 10 feet, were measured in southwestern Pratt County.
The report, January 1996 Kansas Water Levels and Data Related to Water-level Changes, shows depth to water for each well measured on a yearly basis during the 1990s. Copies are available from the Kansas Geological Survey, 1930 Constant Ave., Lawrence, KS 66047. The cost is $10.00, plus $3.00 for handling and postage. Kansas residents should add 6.9% sales tax to the entire amount of the order.