SAVANNAH, Ga. - Inside a colorful, decorated classroom at Marshpoint Elementary School, Brian Moore, a regulatory specialist with the U.S. Army Corps of Engineers Savannah District, poured a gallon of water over a row of sponges. "We use sponges to represent wetlands because they absorb and filter water," Moore explained to a group of third-graders. "Wetlands filter water so that it's clean for us to drink."