This report provides hydrologic data related to water-level measurements in observation wells in western and south-central Kansas during January 1981. Annual water-level measurements are made by personnel from the Division of Water Resources, Kansas State Board of Agriculture, and from the U.S. Geological Survey . State-agency support for this cooperative program is provided by the Kansas Geological Survey.
Water-level measurements are made in mid-winter of each year, mostly in January, to minimize the effect of seasonal pumping. However, a few water-level measurements that are made in mid-winter of some years may reflect either the effects of recent pumping by the observation well or by nearby wells, or the effects of barometric-pressure changes. Thus, a significant change in water-levels for a particular well during a 1-year period may represent only a temporary condition, and any indication of a developing trend should be based on a comparison of changes that occur over a period of several years.
Hydrologic data in this report relate water-level changes from: (1) A "base-reference year" ( predevelopment year), (2) a year of abnormally high rainfall and minimum pumpage (1966 or 1974) , and (3) each of seven consecutive years of measurement (1975-81). The "base-reference year" is designated as 1940 for the southwestern area, 1944 for the south-central area, and 1950 for the northwestern and west-central areas (fig. 1). Water levels for the "base-reference year" are established by measurements made during that year and by interpretation of maps showing water-level altitudes. Depth to bedrock, used in computing saturated thickness of water-bearing deposits, are based on driller' s logs, reported depths of wells, and interpretation of maps showing the altitude of the bedrock surface.
