This child item describes R code used to determine water source fractions (groundwater (GW), surface water (SW), or spring (SP)) for public-supply water service areas, counties, and 12-digit hydrologic unit codes (HUC12) using information from a proprietary dataset from the U.S. Environmental Protection Agency. Water-use volumes per source were not available from public-supply systems so water source fractions were calculated by the number of withdrawal source types (GW/SW). For example, for a public supply system with three SW intakes and one GW well, the fractions would be 0.75 SW and 0.25 GW. This dataset is part of a larger data release using machine learning to predict public supply water use for 12-digit hydrologic units from 2000-2020. Output from this code was used to calculate groundwater and surface water volumes by HUC12 for public supply. This page includes the following files: FCL_Data_Water_Sources_Flagged_wHUC_DR.R - an R script used to determine water source fractions by public-supply water service areas, counties, and HUC12s WaterSource_readme.txt - a README text file describing the script County_SourceFrac.csv - a csv file with estimated water source fractions by county HUC12_SourceFrac.csv - a csv file with estimated water source fractions by HUC12 WSA_AGIDF_SourceFrac.csv - a csv file with estimated water source fractions by public-supply water service area