Observed and projected global changes in the magnitude and frequency of river flows have potential to alter sediment dynamics in rivers, but the direction of these changes is uncertain. Linking changes in bank erosion and floodplain deposition to hydrology is necessary to understand how rivers will adjust to changes in hydrologic flow regime induced by increasing societal pressures and increased variability of climatic conditions. We present analysis based on aerial imagery, an aerial lidar dataset, intensive field surveys, and spatial analysis to quantify bank erosion, lateral accretion, floodplain overbank deposition, and a floodplain sediment budget in an 11-km long study segment of the meandering East River, Colorado, USA, over 60 years. Assuming steady state conditions over the study period, our measurements of erosion and lateral accretion close the sediment budget for a smaller 2-km long intensive study reach. We analyzed channel morphometry and snowmelt-dominated annual hydrologic indices in this mountainous system to identify factors influencing erosion and deposition in nine study sub-reaches. Results indicate channel sinuosity is an important predictor for both lateral erosion and accretion. Examination of only hydrologic indices across the study segment regardless of sub-reach morphology, indicate that the duration of flow exceeding baseflow and the slope of the annual recession limb explain 59% and 91% of the variability in lateral accretion and erosion, respectively. This work provides insight into hydrologic indices likely to influence erosion and sedimentation of rivers and reservoirs under a shifting climate and hydrologic flow regimes in snowmelt-dominated systems.