These data were compiled to model the effects of flow regime and bed grain size distributions on rates of gross primary production (GPP) in the Colorado River below Glen Canyon Dam, AZ, USA. The objectives of our study were to quantify daily and weekly scale effects of an experimental flow regime on GPP in the Colorado River. The experimental flow was conducted at Glen Canyon Dam from May-August in 2018, 2019, and 2020 and contrasted steady-low flows on weekend days with business-as-usual hydropeaking flows during weekdays. This data release only contains data through 2019. These data represent daily-scale estimates of GPP, discharge, turbidity, water depth, and canyon shading for eleven reaches on the Colorado River below Glen Canyon Dam in AZ, USA during May and June of 2018 and 2019. These data also contain ~8 years of weekly-scale estimates of GPP at three long term gaged sites in the same system together with weekly mean discharge and gamma, a proxy of the bed grain size distribution. Finally, these data contain paired measurements of turbidity and light attenuation from the Colorado River during 2018-2020. These data were collected by the U.S. Geological Survey - Southwest Biological Science Center, Grand Canyon Monitoring and Research Center. These data can be used to look at spatial and temporal (daily, seasonal, and year-to-year) patterns in riverine GPP and associated predictor variables. These data can also be used in studies examining the relationship between turbidity and light attenuation.