TRRP has hardcopy aerial photography collected by the U.S. Bureau of Reclamation during the 1974 high flow event, flown on January 17 (rising limb) and January 21 (falling limb). The Lewiston streamgage measured daily average flow of 9520 cfs and 12,980 cfs on these dates. The instantaneous peak of 14,400 was measured on January 18. Of the two available sets of imagery, the 21sthad slightly better image quality and better representation of the flood event. These photos were processed in AgiSoft Metashape using Structure-from-Motion methods to model a 3D point cloud and to georectify and drape the photos over the point cloud, resulting in an orthophoto mosaic dataset. This mosaic provides the best available view of this major post-dam flow event.

See TRRP_MetadataSupplement.pdf for processing details.