A waterways survey team with the U.S. Army Corps of Engineers Pittsburgh District goes through a lock and dam on the Allegheny River to employ a multibeam sonar for a demonstration in Pittsburgh May 7, 2021. The sonar helps provide the district with digital imagery that can detect water depth, erosion or obstructions that may impact navigation on the Pittsburgh rivers. (U.S. Army Corps of Engineers Pittsburgh District photo by Michel Sauret)