Water-surface elevation measurements were performed for a range of flow events up to bankfull discharge within four reaches of the Big River, Missouri. The study reaches are Site W (STW), Rockford Beach (RFB), Phelps Bend (PHB), and Washington State Park (WSP). The water-surface elevation measurements were collected to provide hydraulic model calibration data in support of research assessing the hydraulic conditions of freshwater mussel habitat in the Big River. Data were collected either manually or by boat in the study reaches using a Global Navigation Satellite System (GNSS) receiver. Calibration data also included water-surface elevation data from bathymetry and terrestrial lidar surveys. Models were calibrated by adjusting the input parameters until the simulated water-surface elevations throughout the reach most closely matched the observed water-surface elevations, by minimizing root mean squared error (RMSE).