Interactive Map of wells and related data of Illinois.The ISGS is an official repository for records of wells drilled in the state of Illinois in our Geoscience Information Stewardship Section. Paper records are archived for over 700,000 wells. Some of these records go back as far as the late 1800s. Water and related well data can be accessed for private water wells, engineering borings, and stratigraphic borings. Many of the paper records have been converted to digital and are searchable within the ILWATER Interactive Map.