Data release includes the U.S. Geological Survey (USGS) estimate of spring nitrogen fluxes from nine tributaries to the Chesapeake Bay from 1985 to 2020. Data are presented from tributaries within the USGS River Input Monitoring (RIM) network identified by site numbers: 01491000, 01578310, 01594440, 01646580, 01668000, 01673000, 01674500, 02035000, 02041650. Periods of estimation include January through May and November through May. The estimates are made using up-to-date streamflow and all total nitrogen analyses available as of June 1 of the reporting year.