This is a detailed pedigree of the data sets, figures, tables, and R-code for the technical support document: Background Specific Conductivity and Associated 5% Extirpation Estimates in Arkansas. EPA/600/R-22/215. The data set includes curated data for specific conductivity, major ions, estimated background SC from observed and modeled data, and estimated 5% extirpation values. This dataset is associated with the following publication: Cormier, S., C. Wharton, and Y. Wang. Background Specific Conductivity and Associated 5% Extirpation Estimates in Arkansas. U.S. Environmental Protection Agency, Washington, DC, USA,