These data are high-resolution bathymetry (riverbed elevation) in ASCII format, generated from hydrographic surveys near six highway bridge structures over the Gasconade River in central Missouri. These sites were surveyed in June 2017 to help identify possible effects from extreme flooding on May 1-2, 2017. At the five downstream sites, hydrographic data were collected using a high-resolution multibeam echosounder mapping system (MBMS), which consists of a multibeam echosounder (MBES) and an inertial navigation system (INS) mounted on a marine survey vessel. Data were collected as the vessel traversed the river along planned survey lines distributed throughout the reach. Data collection software integrated and stored the depth data from the MBES and the horizontal and vertical position and attitude data of the vessel from the INS in real time. At the upstream-most site, hydrographic data were collected using a high-resolution multibeam scanning echosounder system (MSES), which consists of a multibeam profile echosounder and high-precision pan-tilt base unit mounted on a tripod. Data were collected as the MSES unit rotated about various tripod setups distributed throughout the reach. Data collection software integrated and stored the range and angular measurements from the MSES. For all the sites, data processing required computer software to extract bathymetry data from the raw data files, to edit and align the data, and to summarize and map the information. First posted October 3, 2017 Revised May 15, 2019, ver. 2.0