Well and chemical groundwater data contained in three tables were collected during a 4-year study started in 1972 to determine the geology and water resources of Hand and Hyde Counties, South Dakota. Physical, hydrologic, and geologic data for 2,729 wells and test holes have been entered into computer storage in the Groundwater Site Inventory File of the U.S. Geological Survey 's National Water Data Storage and Retrieval System WATSTORE. Water quality data from 300 chemical analyses has been stored in the Water Quality File of WATSTORE and is computer printed int he chemical analyses table by aquifer. (USGS)