The U.S. Geological Survey (USGS) in cooperation with the Miami Conservancy District, Dayton, Ohio, investigated the concentrations of per- and polyfluoroalkyl substances (PFAS) and related water chemistry in groundwater from the Great Miami buried-valley aquifer (GM-BVA) of southwestern Ohio in 2019 and 2020. Data in this release include selected characteristics of wells that were used for sampling, as compiled from water-well log reports in a publicly available database from the Ohio Department of Natural Resources and well information stored in the U.S. Geological Survey's Groundwater Site Inventory database. The 23 wells used for sampling were identified and sampled previously by the USGS National Water-Quality Assessment Program to assess the occurrence of a variety of inorganic and organic contaminants in the GM-BVA. Sampled wells were from parts of the GM-BVA in Butler, Champaign, Clark, Greene, Hamilton, Miami, Montgomery, Shelby and Warren Counties within the Great Miami River, Little Miami River and Whitewater River Basins in Ohio.