This data release contains two sets of estimated values at selected sites within the Colorado River Basin: 1) daily specific conductance at 143 sites in the Upper Basin and 3 sites in the Lower Basin (WY 1980-2022); and 2) daily baseflow discharge at 100 sites in the Upper Basin and 3 sites in the Lower Basin (WY 1980-2022). The estimates of daily baseflow discharge will be used as input to an application of the USGS GSFLOW model, which is a coupled groundwater and surface-water flow model based on the integration of the USGS Precipitation-Runoff Modeling System (PRMS-V) and the USGS Modular Groundwater Flow Model (MODFLOW).