Major element, trace metal, and B, Li, S, and Sr isotopic composition of coal combustion product porewater, pondwater, and groundwater associated with coal ash impoundments at various locations in the United States, 2009–23

Coal‑fired power plants generate large volumes of coal combustion products (CCPs) that can release trace elements to groundwater. Conventional geochemical indicators such as major ions and trace metals can signal CCP impacts but may be insufficient when background concentrations are naturally elevated or when multiple contaminant sources exist. Stable isotope ratios provide an additional tool for distinguishing CCP‑derived leachate from ambient groundwater. To expand on prior limited‑scope studies, the U.S. Geological Survey (USGS) compiled a dataset of boron (B), lithium (Li), sulfur (S), and strontium (Sr) isotopic compositions, together with major ion and trace element concentrations, for 80 samples of CCP porewater, pondwater, and surrounding groundwater collected during fall 2023 at 18 CCP management units at 15 coal-fired power plants across diverse physiographic and hydrogeologic settings in the United States. Additional data on B, Li, and Sr isotopic composition for samples collected during 2009–23 at 32 of the 80 locations were included in the compilation. The dataset may be used to support evaluation of isotopic distinctions between upgradient groundwater and CCP‑affected waters and assessment of how isotopic signatures vary with coal type, CCP material, and management practices. This research was funded by the Electric Power Research Institute (EPRI) through a Technical Assistance Agreement between EPRI and the USGS.