Revision 2.0 by Sydney Foks on December 22, 2022 and revision 3.0 by Leah Staub on March 30 2023. To review the changes that were made, see “version_history_nwm.txt” in the attached files section. Source data include daily mean streamflow observations from the National Water Information System (NWIS) database and runoff predictions from the National Water Model version 2.1 retrospective simulation (https://registry.opendata.aws/nwm-archive/) that were aggregated from an hourly timestep into daily mean values. Daily streamflow errors were calculated by comparing predicted and observed mean daily flow.