Brett Kelly, a geographer and sonar survey team member with the U.S. Army Corps of Engineers Pittsburgh District, unwraps a multibeam sonar before a demonstration on the Allegheny River in Fox Chapel, Pennsylvania, 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)