Researchers at the U.S. Army Engineer Research and Development Center use colored dye to observe hydraulic processes of the filling and emptying chamber on a 1:25 scale model of Emsworth Lock located on the Ohio River. The team is assisting the U.S. Army Corps of Engineers Pittsburgh District’s Upper Ohio Navigation Project by using models to test the new lock and dam systems along the upper Ohio River. (U.S. Army Corps of Engineers photo by Jared Eastman)