The Colorado River serves over 40 million people in the southwestern US. Second to the quantity of water in the river is the quality of that water, given that the major uses are agriculture and municipal. Since 2018, our lab group has conducted annual boat-based Lagrangian water quality surveys of the upper Colorado, ranging from Pumphouse (below Kremmling and Gore Canyon) down to Lake Powell (over 300 miles). We collect high frequency (every 10 seconds) water quality data from sensors (temperature, specific conductivity, dissolved oxygen, turbidity, dissolved nitrate, pH) and samples for stable isotope analyses every ~3 miles. We are seeking to determine the fine spatial scale water quality changes between tributaries in order to determine what controls these changes (land use, non-point source discharges, etc.). In this talk we will review these results in light of data collected at USGS stream gages and annual flow dynamics.