Data for water wells and ground water in Harris and Galveston Counties were collected during 1984-89 by the U.S. Geological Survey. This report presents a compilation of records for 243 wells in Harris and Galveston Counties and drillers' logs for 174 of these wells. Water-level data and chemical-quality data of water for new and previously inventoried wells were also collected. Water levels in 521 wells and chemical analyses of water from 249 wells are presented in this report.