The U.S. Geological Survey (USGS) collected hydroacoustic data of the St. Croix River adjacent to the Osceola (WI) boat ramp for hydrographic and benthic mapping prior to the reconstruction project implemented by the National Park Service (NPS). The dataset is a collection of still-shot images to be used as ground-truth data for geologic substrate. The still-images (jpeg format) were captured from underwater video using an Aqua-Vu system. For statistical analysis, the videos were sampled at random point locations. A short video captured the surficial geologic sediment type at each location. This collection of images directly corresponds with the geospatial shapefile containing sample location coordinates, a general description of interpreted sediment type, and an indication of mussel presence/absence in the attribute table.