This data release (version 5.0, February 2022) consists of a Microsoft® Access database and Microsoft® Excel workbook that contain water-level data and other hydrologic information for wells on and near the Nevada Test Site (currently the Nevada National Security Site). The three worksheets in the Microsoft® Excel workbook also are provided as individual comma-separated values (CSV) files. The data release supports U.S. Geological Survey Data Series 533 (https://pubs.usgs.gov/ds/533/). The Microsoft® Access database contains water levels measured from 930 wells in and near areas of underground nuclear testing at the Nevada Test Site. The water-level measurements were collected from 1941 to 2021. All water levels in the Microsoft® Access database are stored in the USGS National Water Information System (NWIS) database available at https://waterdata.usgs.gov/nv/nwis. The Microsoft® Access database also provides information for each well (well construction, borehole lithology, units contributing water to the well, and general site remarks) and water-level measurement (measurement source, status, method, accuracy, and specific water-level remarks). Additionally, the database provides hydrograph descriptions (hereinafter hydrograph narratives) that document the water-level history and describe and interpret the water-level hydrograph for each well. Multiple condition flags were assigned to each water‑level measurement to describe the hydrologic conditions at the time of measurement. The condition flags describe the general quality (accuracy), temporal variability, regional significance, and hydrologic conditions of the measurements. The Microsoft® Excel workbook contains hydrographs and locations for the 930 wells, which are interactively presented in the workbook as an interface to the Microsoft® Access database. This workbook is designed to be an easy-to-use tool to obtain the water-level history for any well in the study area. Water-level data can be restricted to certain wells, dates, or hydrologic conditions by using the Microsoft® Excel built-in AutoFilter. Additional information provided in the workbook includes selected well-site information, water-level information, contributing units, the hydrograph narratives, and hyperlinks to the NWISWeb (http://waterdata.usgs.gov/nv/nwis/) site home page for each well. Information presented in the workbook for all water levels in the database also includes measurement source, status, method, accuracy, remarks, and hydrologic condition flags. Interpretations for individual water-level measurements and for the period of record for the wells have been incorporated into the water-level remarks, flags, or hydrograph narratives.