In recent decades, improvements in monitoring technologies and analytical methods, combined with health research, have increased national attention to the presence of emerging contaminants in surface water. Detections of one particular group of contaminants, per- and polyfluoroalkyl substances (PFAS), have heightened public and congressional interest in the U.S. Environmental Protection Agency’s (EPA’s) authorities under the Clean Water Act (CWA) to address PFAS in surface water.