The U.S. Geological Survey (USGS) developed a systematic, quantitative approach to prioritize candidate basins that can support the assessment and forecasting objectives of the major USGS water science programs. Candidate basins were the level-4 hydrologic units (HUC4) with some of the smaller HUC4s being combined (hereafter referred to as modified HUC4 basins). Candidate basins for the contiguous United States (CONUS) were grouped into 18 hydrologic regions. Thirty-three geospatial variables representing land use, climate change, water use, water-balance components, streamflow alteration, fire risk, and ecosystem sensitivity were initially considered to assist in ranking candidate basins for study. The two highest ranking candidate basins in each of the 18 regions were identified as semi-finalists for selection as “Integrated Water Science Basins.” The initial 33 geospatial variables are included within this data release. Also included in this data release are the polygon layers of the modified HUC4 basins and the hydrologic regions used for the analyses and a separate data dictionary to define the variables.