These data are high-resolution bathymetry (riverbed elevation) in ASCII format, generated from hydrographic and velocimetric surveys of the Missouri River near structure 59-3-16.38(013) on U.S. Highway 59 at Atchison, Kansas, in 2009, 2010, 2011, and 2013, before, during, and after construction of of a replacement bridge. 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. Data processing required computer software to extract bathymetry data from the raw data files and to summarize and map the information.