This report presents hydrologic data used in the Southern Sand Hills hydrogeology study, which encompasses an area of approximately 4,330 square miles in west-central Nebraska. These data include summary logs of 64 test holes drilled in or adjacent to the study area. Water level data for 240 wells are included. These wells were measured in spring and fall of 1982 and spring of 1983. Water quality samples were collected from 62 irrigation wells. Water quality data include analyses for 18 routine constituents on samples from all wells and analyses for 8 trace constituents on samples from 25 wells. Rainfall data were collected at 30 sites by local observers from April 1982 to October 1983. Surface water data for 103 stream sites in the study area are included. Water discharge was measured at these sites as part of seepage surveys conducted from 1978 to 1982 to determine where and how much streams were gaining or losing water. (USGS)