The Mississippi embayment of southeastern Missouri is a 4 ,000-square-mile agricultural area that is presently (1979) undergoing rapid development for irrigation. In July 1974, a project was initiated to evaluate the water resources of the area, determine the extent of irrigation, and to assess the future potential for irrigation supplies. This report provides well drillers, well owners, water users, and potential irrigators with the basic hydrologic data collected during the project. The 10 tables and eight figures show the location of irrigation wells, water-level networks to monitor ground-water and surface-water conditions, a pumpage network to estimate amounts of water used for irrigation, geologic data, municipal-well data, and water-quality data for selected wells. (USGS)