Per- and Polyfluoroalkyl Substance Concentrations, Age Estimates, Redox Categories, and Related Data for Groundwater from the Great Miami Buried-Valley Aquifer, Southwestern Ohio, 2019–20

This data release presents results of chemical analyses of groundwater sampled during summer and autumn of 2019 and spring of 2020 from 23 wells in the Great Miami buried-valley aquifer (GM-BVA) of southwestern Ohio. Groundwater and quality-control samples were analyzed to determine concentrations of selected per- and polyfluoroalkyl substances (PFAS). Groundwater and related quality-control samples were collected from 22 of 23 wells and analyzed for 24 different PFAS by two different laboratories that used slightly different proprietary isotope-dilution based adaptations of U.S. Environmental Protection Agency (USEPA) method 537.1, referred to as method 1 and method 2. Results from PFAS analysis of groundwater samples and quality-control samples, including sequential replicate samples and field blanks are presented in this data release. Reporting and detection limits for analyses of individual PFAS and recovery data for isotopically labeled surrogate compounds added to each sample by the analyzing laboratory, are also included in the data release. The GM-BVA is a glacial outwash and alluvial fill aquifer that is the sole source of water supply for much of the region. The study was performed by the U.S. Geological Survey, in cooperation with the Miami Conservancy District, Dayton, Ohio. This data release includes details of the sampled wells, tritium-helium-3 and tritium-based estimates of groundwater age from prior (1999 and 2000) and current (2019-2020) groundwater samples, and redox (reduction/oxidation) classifications and related water-quality constituent concentrations from groundwater samples collected in 1999, 2000, 2019 and 2020 from the same wells sampled by this effort for PFAS. Field groundwater-quality parameters measured from the sampled wells in 1999–2000 and in 2019–2020 groundwater sample collection are also presented.