The dataset folder entitled “MissR” holds data structures consisting of statistical predictions of daily salinity time series for the Mississippi River (MissR) group, generated from the makESTUSAL software repository described by Asquith and others (2023b). The statistical methods included multiple methods of machine learning, which produced the daily salinity prediction and attendant credible uncertainties included in the data release. The geographic scope of the MissR group includes the predictions for thirteen locations defined using agency code and salinity site abbreviations.